CN104817989B

CN104817989B - A kind of Underfill adhesive composition and preparation method thereof

Info

Publication number: CN104817989B
Application number: CN201510169008.5A
Authority: CN
Inventors: 艾瑞克·C·王; 陈凤; 邱承林
Original assignee: Shenzhen Guang Hengwei Science And Technology Ltd
Current assignee: Shenzhen Guang Hengwei Science And Technology Ltd
Priority date: 2015-04-10
Filing date: 2015-04-10
Publication date: 2017-11-10
Anticipated expiration: 2035-04-10
Also published as: CN104817989A

Abstract

The invention discloses a kind of Underfill adhesive composition and preparation method thereof, said composition by weight percentage, includes following component：Modified epoxy 5wt% ~ 15wt%, modified bismaleimide 5wt% ~ 15wt%, filler 50wt% ~ 70wt%, curing agent 5wt% ~ 15wt%, curing agent accelerator 0.2wt% ~ 1wt%, diluent 5wt% ~ 10wt%, dispersant 2wt% ~ 8wt%, coupling agent 0.5wt% ~ 2wt%, ion adsorbent 0.1wt% ~ 2wt%；Wherein modified epoxy is polyester modified epoxy resin and/or carbonate-modified epoxy resin, and modified bismaleimide is acrylate modified BMI and/or organic-silicon-modified BMI.The Underfill adhesive composition has the good needs reprocessed performance, high reliability and high glass transition temperature, can meet packaging technology new at present.

Description

Underfill composition and preparation method thereof

Technical Field

The invention relates to an underfill adhesive in the fields of electronics and microelectronics, in particular to a high-performance and quick-repairing underfill adhesive composition for a smart phone module and a preparation method thereof.

Background

In the chip packaging process, because the Coefficient of Thermal Expansion (CTE) of the chip and the substrate is different, the stress borne by the solder balls connecting the chip and the substrate is often uneven, and the periphery is larger than the middle, so that when the chip bears cold and hot shock, the solder balls at the periphery are easy to fall off, and the connection reliability is greatly reduced. In order to compensate for the defect, a reinforcing material is usually added between the chip and the substrate, and the reinforcing material disperses and absorbs the stress borne by the surface of the chip, thereby achieving the purpose of improving the reliability of the product. This reinforcing material is referred to as an "underfill". The underfill is mainly applied to the packaging in the fields of electronics and microelectronics.

Underfill is a chemical glue (the main component is epoxy) that cures by the application of heat. In chip packaging, the underfill is applied directly to the chip or substrate and then cured by heating. The coating mode mainly comprises three modes of capillary type bottom filling, welding-aid (non-flowing) type bottom filling and pre-coating. The most widely used today is the capillary underfill process, which is particularly suited for the packaging requirements of Flip Chip On Board (FCOB) and Flip Chip In Package (FCIP). The capillary underfill process can be described as: the underfill is firstly dispensed on the edge of the flip chip, the glue can rapidly flow through the bottom of the chip through capillary action to complete the underfill process, and finally the curing of the glue is completed under the condition of heating.

With the development of electronic products toward miniaturization and multi-functionalization, the packaging form of chips is gradually changing, and advanced packaging forms such as Ball Grid Array (BGA), Chip Scale Package (CSP), wafer scale chip package (WLCSP), Land Grid Array (LGA), 3D chip package (3DIC), Through Silicon Via (TSV) and the like have come into force. The new packaging form solves the packaging problem of multifunctional, high-integration, high-speed, low-power consumption and multi-lead integrated circuit chips, but also puts more stringent requirements on the underfill, and puts higher requirements on the performances of the underfill in the aspects of high fluidity, high reliability, high glass transition temperature (Tg), low Coefficient of Thermal Expansion (CTE) and the like in more advanced packaging forms. The adhesive layer of the existing underfill packaging component needs to be removed during repair, the adhesive layer of the underfill packaging component using the traditional epoxy resin as a matrix is easy to split into blocks when being treated and damaged, and the adhesive layer is large in residual adhesive amount, difficult to clean and difficult to repair. Under the influence of self-performance, the Tg and the reliability of the underfill taking the epoxy resin as a matrix are both low. Thus, existing underfill adhesives have not been able to meet the needs of new processes.

Disclosure of Invention

The invention provides an underfill composition with good reworking performance, high reliability and high glass transition temperature and a preparation method thereof.

According to a first aspect of the present invention, there is provided an underfill composition comprising, in weight percent: 5 to 15 weight percent of modified epoxy resin, 5 to 15 weight percent of modified bismaleimide, 50 to 70 weight percent of filler, 5 to 15 weight percent of curing agent, 0.2 to 1 weight percent of curing agent accelerator, 5 to 10 weight percent of diluent, 2 to 8 weight percent of dispersant, 0.5 to 2 weight percent of coupling agent and 0.1 to 2 weight percent of ion adsorbent; the modified epoxy resin is polyester modified epoxy resin and/or carbonate modified epoxy resin, and the modified bismaleimide is acrylate modified bismaleimide and/or organosilicon modified bismaleimide.

According to a second aspect of the present invention, there is provided a process for preparing a composition of the first aspect, the process comprising: adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to a ratio at 65-75 ℃ and stirring at the rotating speed of 700-1700 r/min for 90-120 min; then stirring at a low speed, wherein the rotating speed is 20-120 r/min, and the time is 20-30 min; standing for 18-30 h for curing; dispersing the cured glue for 20-30 min by using 20-40 KHz ultrasonic waves; and (4) filtering the dispersion liquid, and then transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the composition.

The underfill composition of the invention adopts the modified epoxy resin as the matrix, and endows the underfill with good reworking performance; meanwhile, the modified bismaleimide is adopted, so that the underfill has the performances of high reliability and high glass transition temperature.

In addition, the filler in the underfill composition provided by the invention does not settle for a long time, and the underfill composition has good storage stability and long service life; the underfill has the advantages of strong capability of automatically forming a fillet, good wetting capability on element substrates, good bonding strength, low internal stress and low ion content, thereby effectively making up the defects of the existing underfill.

Drawings

FIG. 1 is a schematic diagram of the change of the structure of the underfill during the rework of the underfill package according to the present invention;

FIG. 2 is a graph of the reliability and rework of a prior art underfill (left) and an underfill of the present invention (right);

FIG. 3 shows a modified epoxy resin used in one embodiment of the present invention¹³C NMR spectrum;

FIG. 4 shows a modified epoxy resin used in another embodiment of the present invention¹³C NMR spectrum;

FIG. 5 shows a modified bismaleimide useful in one embodiment of the present invention¹³C NMR spectrum;

FIG. 6 is a comparison of the filling effect of an unmodified filler example 9 (left panel) and a modified filler example 1 (right panel) of the present invention, showing that the former has voids and flow lines, while the latter does not;

FIG. 7 is a Scanning Electron Microscope (SEM) image of the underfill of example 1 of the present invention showing that the filler is uniformly dispersed;

FIG. 8 is a graph of the storage modulus decreasing with increasing temperature for underfill compositions in accordance with one embodiment of the present invention and conventional underfills under heated conditions.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings.

The invention mainly aims at the contradiction relationship between easy repair and high reliability of the existing underfill, improves the formula of the underfill, and emphasizes the improvement of the performance by modifying key components in the formula, such as epoxy resin and bismaleimide.

The underfill composition according to one embodiment of the present invention comprises the following components in percentage by weight: 5 to 15 weight percent of modified epoxy resin, 5 to 15 weight percent of modified bismaleimide, 50 to 70 weight percent of filler, 5 to 15 weight percent of curing agent, 0.2 to 1 weight percent of curing agent accelerator, 5 to 10 weight percent of diluent, 2 to 8 weight percent of dispersant, 0.5 to 2 weight percent of coupling agent and 0.1 to 2 weight percent of ion adsorbent; the modified epoxy resin is polyester modified epoxy resin and/or carbonate modified epoxy resin, and the modified bismaleimide is acrylate modified bismaleimide and/or organosilicon modified bismaleimide.

1. Modified epoxy resin

As shown in fig. 1, the adhesive layer of the conventional underfill package component needs to be removed during repair, the adhesive layer of the underfill package component using the conventional epoxy resin as the matrix is easily broken into pieces after being treated and damaged, and the underfill layer is large in residual adhesive amount, difficult to clean and difficult to repair. One embodiment of the present invention effectively solves the problem of difficult repair of the encapsulated part by modifying the epoxy resin (i.e., polyester-modified epoxy resin and/or carbonate-modified epoxy resin) by introducing ester and/or carbonate groups. When the packaging part is repaired, the underfill adhesive layer is damaged at high temperature, and ester and/or carbonic acid groups replace other functional chain segments in the molecular structure of the adhesive layer and are firstly decomposed. At the moment, although the bonding strength of the adhesive layer is rapidly reduced, the structure capable of determining the molecular form is not damaged, the adhesive layer still keeps a complete network structure, the macroscopic appearance is a whole, adhesive residue is not easy to occur during the adhesive layer removing process, the cleaning is easy, and the repair of the packaging component is more convenient. In addition, the epoxy resin has the defects of peeling resistance, cracking resistance, poor impact property, large high-temperature moisture absorption, poor flame retardance and the like, and the impact toughness and the high-temperature moisture absorption property of the modified epoxy resin can be effectively improved by introducing functional structures such as long-chain flexible groups, ether bonds, propoxy groups and the like; the flame retardant property can be improved by introducing phosphorus element.

FIG. 2 shows the relationship between the reliability and reworkability of the conventional underfill (left drawing) and the underfill of the present invention (right drawing), showing that the conventional underfill is easy to repair and the reliability can be selected from only two, the easy-to-repair usually has low reliability and the high-reliability usually cannot be repaired; the underfill disclosed by the invention has better reliability and reworkability.

The polyester-modified epoxy resin and the carbonate-modified epoxy resin are named after modified groups. The modified epoxy resin containing a group such as an aliphatic ester, an alicyclic ester, an aromatic ester, or a urethane may be referred to as a polyester-modified epoxy resin. The modified epoxy resin may contain one or two or more of the above groups, and examples thereof include an aliphatic ester and an aromatic ester, an aromatic ester and a urethane, and an aliphatic ester and a urethane. The modified epoxy resin containing a group such as carbonate is referred to as a carbonate-modified epoxy resin, and may be a polycarbonate-modified epoxy resin. The carbonate is a compound in which hydrogen atoms of two hydroxyl groups (-OH) in a carbonic acid molecule are partially OR completely substituted by an alkyl group (R, R '), and has a general formula of RO-CO-OH OR RO-CO-OR'. The modified epoxy resin of the present invention may contain at the same time one or more of an aliphatic ester, an alicyclic ester, an aromatic ester, and a urethane, and may contain a carbonate ester. The pure polyester-modified epoxy resin or carbonate-modified epoxy resin means a modified epoxy resin containing only esters or carbonates, respectively, and is a preferred modified epoxy resin in the present invention.

The aliphatic ester referred to in the present invention refers to an ester substance containing an aliphatic chain, wherein the length of the aliphatic chain is, for example, 2 to 20 carbon atoms, and the aliphatic chain may be in a straight chain or branched form, may be saturated or may contain an unsaturated bond such as a double bond, and may be unsubstituted or may contain a substituent. The aliphatic ester generally refers to an ester formed by esterification reaction of aliphatic acid and aliphatic alcohol, but does not exclude other atoms or groups, such as phosphoric acid group and the like, and the phosphoric acid group-containing aliphatic ester can play a significant role in flame retardance and is also critical to the performance of the invention. If the structure has a ring structure, it can be called alicyclic ester.

The aromatic ester referred to in the present invention is an ester containing an aromatic group such as a benzene ring, a naphthalene ring, etc., wherein the number of the aromatic group is, for example, 1 to 6, and the aromatic group may be substituted or unsubstituted. Other groups than aromatic groups are not excluded, such as alkyl, alkene, alkyne and other hydrocarbon groups, and may also contain phosphate groups and the like, and aromatic esters containing phosphate groups can play a significant flame retardant role and are also critical to the performance of the invention.

The carbamate refers to an ester substance containing a carbamate group, that is, an ester formed by carbamate and an alcohol, wherein the alcohol can be aliphatic alcohol or aromatic alcohol, and the length of the aliphatic alcohol chain is, for example, 2 to 20 carbon atoms, and the aliphatic chain can be in a straight chain or branched chain form, can be saturated or can contain an unsaturated bond such as a double bond, and can be unsubstituted or can contain a substituent; the aromatic alcohol may have 1 to 6 aromatic groups, and the aromatic groups may be substituted or unsubstituted, and do not exclude other groups than aromatic groups, such as alkyl groups, alkene groups, alkyne groups, and the like, and may further include phosphate groups, and the like, and the aromatic ester containing phosphate groups can play an obvious flame retardant role, and is also critical to the performance of the invention.

In a preferred embodiment of the present invention, the modified epoxy resin has a chemical formula shown in formula 1 or formula 2:

one synthetic route to structural formula 1 is as follows:

one synthetic route to structural formula 2 is as follows:

in the above structural formula and synthetic route, R₁、R₂、R₃And R₄Each independently selected from an aliphatic ester, an alicyclic ester, an aromatic ester, a carbamate, or a carbonate. Aliphatic esters, alicyclic esters, aromatic esters, carbamates and carbonates have the definitions as described above. "independently of each other" means R₁、R₂、R₃And R₄There is no restriction between the choice of substituents, therefore R₁、R₂、R₃And R₄May be different from each other and may be two, three or four identical. If R is₁、R₂、R₃And R₄All selected from aliphatic ester, alicyclic ester, aromatic ester, carbamate, then the compound represented by structural formula 1 or structural formula 2 is called polyester modified epoxy resin; if R is₁、R₂、R₃And R₄Are selected from carbonates, the compound represented by structural formula 1 or structural formula 2 is referred to as a carbonate-modified epoxy resin.

Most preferably, R is as defined above₁、R₂、R₃And R₄Each independently selected from any one of structural formulas 3 to 10:

the group represented by the above structural formula 3 is called as propyl carbamate, and has functions of increasing activity of the composition, reducing curing shrinkage, skin irritation and toxicity, and reducing moisture absorption performance.

The group shown in the structural formula 4 is named as cyclohexyl carbamate, and has the functions of reducing the viscosity of the composition and increasing the stability.

The group represented by the structural formula 5 is called methacrylic acid phosphate monoester (PM1), and can improve the adhesion to a base material (metal or plastic), improve the curing speed, improve the dispersion function and improve the flame retardant function.

The group shown in the structural formula 6 is named as methacrylic acid phosphoric acid diester (PM2), and can improve the adhesion to a base material (metal or plastic), improve the curing speed, increase the flexibility, improve the dispersion function and improve the flame retardant function.

In order to further improve the impact toughness, reliability, flame retardancy and other properties of the composition, R is a chemical structural formula shown in formula 1₁、R₂、R₃And R₄At least one (e.g., one, two, three, or four) of them is selected from the group represented by structural formula 5 or structural formula 6; for the chemical formula shown in formula 2, R₁And R₂At least one (e.g., one or two) of them is selected from the group represented by structural formula 5 or structural formula 6. The research of the invention finds that the modified epoxy resin containing the group shown in the structural formula 5 or the structural formula 6 can obtain the best performance in all aspects, such as excellent repair performance, impact toughness, reliability and flame retardance.

The group shown in the structural formula 7 is named as lauryl methacrylate, and the lauryl methacrylate has a long flexible chain and is effective in improving the impact toughness of the modified epoxy resin.

The group represented by the above structural formula 8 is referred to as bis (2-methylallyl) carbonate; the group represented by the above formula 9 is referred to as allyl diglycol dicarbonate; the group represented by the above structural formula 10 is called isopropyl carbonate.

The groups represented by the above formulae 3 to 10 all have the property that at high temperatures they will decompose first instead of other functional segments in the molecular structure of the glue layer. Therefore, although the bonding strength of the adhesive layer is rapidly reduced, the structure capable of determining the molecular form is not damaged, the adhesive layer still keeps a complete network structure, the macroscopic structure is represented as a whole, adhesive residue is not easy to occur when the adhesive layer is removed, the cleaning is easy, and the repair of the packaging component is more convenient.

The modified epoxy resin used in one embodiment of the present invention has the following structural formula:

the preparation of the compound of formula I is as follows:

10ml of tetrachloromethane was dissolved in 40ml of anhydrous ethanol containing sodium cyanide, and the mixture was added to a 250ml flask, and the flask was placed in a water bath, heated to 70 ℃ and reacted for 30 minutes. Adding CO₂Stirring the aqueous solution for 20min, adding sodium carbonate, and continuously stirring for 20min to obtain S0.

10ml of carbamate, 10ml of methacrylic acid monoester phosphate (PM1), 10ml of acetylene alcohol are taken and 15ml of anhydrous ZnCl is added₂Heated with concentrated HCl (called Lucas (Lucas) reagent), 10ml of tetrahydrofuran was added slowly, followed by S0 and stirred to give S1.

Mixing 10ml of epoxy resin matrix ERL-4269 (UCC in USA) and 25ml of CH₃Adding anhydrous ZnCl into Cl₂Heating concentrated HCl (Lucas reagent), adding S1, stirring, adding 15ml of NaOH solution in anhydrous ethanol, adding 5ml of sodium dodecyl mercaptide, reacting with 20ml of DMF (dimethylformamide) at 190 deg.C for two hours, adding CO into the obtained solution₂The aqueous solution was stirred for 20min, after which 8g of sodium carbonate was added and stirring was continued for 20min to give S2.

Taking 10ml of cyclohexyl carbamate and 10ml of lauryl methacrylate, and adding anhydrous 5ml of ZnCl₂Is heated to give S3, called Lucas reagent.

Mixing S2 and S3, stirring for 30min, slowly adding 8ml tetrahydrofuran, stirring for 30min, and adding 10ml 5% NaOH to obtainTo the final product. Analyze it¹³The C NMR spectrum is shown in FIG. 3.

The modified epoxy resin used in another embodiment of the present invention has a structural formula as shown below:

the compound of formula II is prepared as follows:

dissolving dicyclopentadiene in anhydrous ethanol solution of NaOH, heating to 70 deg.C, stirring for 60min, adding solid or liquid CO₂And reacting for 12-24 h under the condition of MP about 190dc to obtain S0.

Mixing 10ml of epoxy resin matrix ERL-4269 (UCC in USA) and 25ml of CH₃Adding anhydrous ZnCl into Cl₂Heating concentrated HCl (Lucas reagent), adding S0, stirring, adding 15ml of NaOH solution in anhydrous ethanol, adding 5ml of sodium dodecyl mercaptide, reacting with 20ml of DMF (dimethylformamide) at 190 deg.C for two hours, adding CO into the obtained solution₂The aqueous solution was stirred for 20min, after which 8g of sodium carbonate was added and stirring was continued for 20min to give S1.

Taking 10ml of cyclohexyl carbamate and 10ml of isopropyl carbonate, and adding anhydrous 5ml of ZnCl₂Heating to 70 deg.C with concentrated HCl (Lucas) and stirring for 30-60 min to obtain S2.

And mixing and stirring S1 and S2 for 30min, slowly adding 15ml of tetrahydrofuran, stirring for 30min, adding 10ml of 5% NaOH, and refluxing for 3-5 times to obtain a final product. Analysis of¹³The C NMR spectrum is shown in FIG. 4.

2. Modified bismaleimide

Under the influence of self-performance, the Tg and the reliability of the underfill taking the epoxy resin as a matrix are both low. According to the invention, the modified bismaleimide is added into the matrix resin, so that the Tg of the underfill and the reliability of the underfill in the using process are effectively improved. In order to solve the problem that bismaleimide resin generally exists in a solid state and has poor compatibility with epoxy resin, the invention introduces aliphatic or alicyclic groups into bismaleimide molecular chains to modify the bismaleimide molecular chains. The modified resin is in a low-viscosity liquid state and has good compatibility with epoxy resin, the interpenetration degree of the two resins in a cured product is greatly improved, and the Tg of the underfill and the reliability of the underfill in use are also greatly improved. In addition, the invention can also introduce phosphorus element into bismaleimide resin to improve the flame retardant property.

The modified bismaleimide used in the invention is acrylate modified bismaleimide and/or organosilicon modified bismaleimide.

The acrylate modified bismaleimide is an ester-based (acrylate-based) modified bismaleimide containing an acrylic group, wherein the ester-based containing the acrylic group is an ester formed by acrylic acid and alcohol, wherein the alcohol used for forming the ester can be aliphatic alcohol or aromatic alcohol, and the length of the chain of the aliphatic alcohol is 2-20 carbon atoms, and the aliphatic chain can be in a linear chain or branched chain form, can be saturated or contain an unsaturated bond such as a double bond, and can be unsubstituted or contain a substituent; the aromatic alcohol may have 1 to 6 aromatic groups, and the aromatic groups may be substituted or unsubstituted, and do not exclude other groups than aromatic groups, such as alkyl groups, alkene groups, alkyne groups, and the like, and may further include phosphate groups, and the like, and the aromatic ester containing phosphate groups can play an obvious flame retardant role, and is also critical to the performance of the invention.

In one embodiment of the present invention, the modified bismaleimide has the chemical formula shown in formula 11:

wherein,R₁、R₂、R₃and R₄Each independently selected from acrylate or silicone groups, R5 is selected from

Wherein the acrylate has the above-mentioned definition.

Most preferably, the acrylate-based group has a chemical formula represented by formula 12, formula 13, or formula 14:

the organosilicon-based radical has the chemical formula shown in formula 15:

wherein n is 0-3, such as 0, 1,2 or 3; m is 0 to 5, such as 0, 1,2, 3,4 or 5; p is 0 to 5, for example 0, 1,2, 3,4 or 5.

The group represented by the above structural formula 12 is referred to as lauryl methacrylate; the group represented by formula 13 above is referred to as diethyl ethyl methacrylate phosphonate (DEMEP); the group represented by formula 14 above is referred to as dimethyl ethyl phosphonate acrylate (DAP).

In order to further improve the flame retardancy of the composition, R in the modified bismaleimide represented by the structural formula 11₁、R₂、R₃And R₄At least one (e.g., one, two, three, or four) of these is selected from formula 13(DEMEP) or formula 14 (DAP). Due to the phosphoric acid groups contained in the structural formulas 13 and 14, the flame retardance of the composition is greatly improved.

R in modified bismaleimide₁、R₂、R₃And R₄The substituents may be different from each other, or one, two, three or four of the substituents may be the same.

The modified bismaleimide used in one embodiment of the present invention has the following structural formula:

the compound of formula III is prepared as follows:

adding anhydrous ethanol solution into 250ml glass bottle, preheating to 50 deg.C, adding 10ml R₅Stirring diamine (II), 10ml Maleic Anhydride (MA) and 2g nickel acetate for 30min, adding 5ml acetic anhydride and 20ml DMF (N, N' -dimethyl formamide) as solvent, and stirring for 30 min. Adding CO₂Stirring the aqueous solution for 20min, adding 5g of sodium carbonate, heating to 70 ℃, and reacting for 30min to obtain S0.

10ml of diethyl ethyl methacrylate phosphonate, 20ml of dimethyl ethyl acrylate phosphonate and 10ml of isopropyl carbonate are taken and added with anhydrous 15ml of ZnCl₂Heating to 70 deg.C with concentrated HCl (Lucas) for 30-60 min to obtain S1.

Mixing S0 and S1, stirring for 30min, slowly adding 20ml tetrahydrofuran, stirring for 30min, and adding 10ml 5% NaOH to obtain the final product. Analyze it¹³The C NMR spectrum is shown in FIG. 5.

3. Filler material

The filler in the present invention may be selected from at least one of aluminum chips, aluminum powder, aluminum borate whiskers, alumina, anthracite, sodium antimonate, antimony trioxide, apatite, soot, attapulgite, barium metaborate, barium sulfate, barium titanate, bentonite, bismuth oxide, boron oxide, calcium carbonate, calcium hydroxide, calcium sulfate, carbon black, ceramic microspheres, clay, diatomaceous earth, ferrite, feldspar, glass beads, gold, graphite, calcium silicate hydrate, kaolin, magnesium oxide, magnesium hydroxide, molybdenum disulfide, nickel, polymer fillers, pumice, cryolite, rubber particles, sepiolite, silica gel, silver powder, talc, titanium dioxide, zeolite, zinc borate, and zinc sulfide, and is preferably silica, titanium dioxide, or attapulgite.

The filler of the invention has the following functions: the thermal expansion coefficient of the cured resin is reduced, the water absorption of the cured resin is reduced, and the aging resistance and the chemical resistance of the cured resin are improved; the shrinkage of the cured resin is reduced; the arc resistance of the resin condensate is improved, and other electrical properties are improved; improving the abrasion resistance of the resin condensate; the compatibilization effect, the cost reduction and the product competitiveness in the market are improved.

In order to further improve the properties of the composition, in particular the dispersibility of the filler, the present invention provides a filler modified with a silane coupling agent, wherein a typical but non-limiting example of the silane coupling agent may be at least one of hexamethyldisilazane, hexamethylvinylsilazane and vinylethoxysilane. A typical but non-limiting method for modifying the filler according to the invention is: firstly, the filler is put in a drying oven (100-120 ℃) to be dried for one day, and then the filler is mixed with absolute ethyl alcohol and deionized water according to the proportion of 1: 1: 1 volume ratio, and dispersing for 2 hours by using 30KHz ultrasonic waves for later use; adding a coupling agent (such as hexamethyldisilazane, hexamethylvinyl silazane or vinyl ethoxysilane) into absolute ethyl alcohol (the mass ratio of the coupling agent is 5%), fully stirring, mixing with the ultrasonic dispersion liquid, fully stirring at 70 ℃ for 2-3 h at the rotation speed of 1200 +/-300 r/min, finally performing high-speed centrifugal separation, performing ultrasonic dispersion, and repeating for 4-5 times to obtain the modified filler. The particle size of the general modified filler is 7-40 nm, preferably 10-25 nm, the average particle size is 20nm, the average particle size accounts for more than 85%, and the specific surface area is 5-80 m²/g。

The filler of the invention generally has the characteristic of three-dimensional network structure, unsaturated bonds and hydroxyl groups in different bonding states exist on the surface, so that the filler has high activity, and dispersed nanoparticles obtained by modifying the surface of the filler by using a silane coupling agent can improve the compatibility with resin, improve the insulativity, reduce the hygroscopicity, have good surface sphericity and are smooth and compact. If the filler is not modified, the surface is loose and has a negative influence on the viscosity, for example, in the process of forming fused silica at high temperature, the silica is oxidized, and in the process of cooling, oxygen is encountered to form ultrafine particles on the surface, so that the surface smoothness is reduced, the dispersibility is reduced, and the flow is influenced.

4. Curing agent

The curing agent is preferably a liquid curing agent, and if a solid curing agent is adopted, the particle size is required to be 3-8 mu m, the average particle size is 5 mu m, and the maximum particle size is less than 10 mu m.

The curing agents which can be selected in the invention are: maleic Anhydride (MA), Phthalic Anhydride (PA) and its derivatives, trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, 3,4, 4-benzophenonetetracarboxylic dianhydride (BTDA), dodecenylsuccinic anhydride (DDSA), methylcyclohexenetetracarboxylic dianhydride (MCTC), methylhexahydrophthalic anhydride (MHHPA), methylnadic anhydride (MNA), at least one of benzoyl hydrazine, sebacic dihydrazide (SPH), 2-methylimidazole, 1-methylimidazole, 2-heptadecylimidazole, 2-undecylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, triethanolamine and 3, 4-dimethylphenyl-substituted dicyandiamide; commercial CAPCURE3-800, CAPCURE WR-6, EPOMATE QX-10, EPOMATE QX-11 or EPIKURE QX-40 may also be used.

5. Curing agent accelerator

The curing agent accelerator may be at least one selected from benzyltrimethylammonium chloride, triethanolamine borate, triethanolamine titanate, tin octylate, quaternary phosphonium salts, dicyandiamide, DBU carbonate, imidazole metal salts, diethylaminopropylamine, Benzyldimethylamine (BDMA), N-dimethylaniline, 2-ethyl-4-methylimidazole, tris- (2-ethylhexanoate) salt of 2,4, 6-tris (dimethylaminomethyl) phenol, trioleate salt of 2,4, 6-tris (dimethylaminomethyl) phenol, and 2-ethylhexanoate salt of tris (dimethylaminomethyl) phenol.

The curing agent accelerator has the effects that the curing agent accelerator can accelerate the curing of epoxy resin, reduce the curing temperature and shorten the curing time. Since the accelerating action is performed in a six-membered ring transition state in which the charge is deviated among the curing agent accelerator, the curing agent, and the epoxy group, the electrophilic accelerator is effective for the nucleophilic curing agent, and the nucleophilic accelerator is effective for the electrophilic curing agent.

6. Diluent

The diluent may be at least one selected from the group consisting of 1, 2-cyclohexanediol diglycidyl ether, 1, 4-butanediol diglycidyl ether, 1, 4-cyclohexanedimethanol glycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether (TMPEG).

7. Dispersing agent

The dispersant may be at least one selected from the group consisting of water glass, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, triethylhexylphosphoric acid, sodium lauryl sulfate, methylpentanol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyglycol ester.

The dispersant is adsorbed on the surface of the solid particle to form an adsorption layer on the surface, so that a bilayer structure is formed on the surface of the solid particle, and the polar end of the outer dispersant has strong affinity with water, so that the degree of wetting the solid particle by water is increased. The solid particles are far away due to electrostatic repulsion, the reaction force among the particles forming the three-dimensional obstruction is improved, the interfacial tension between liquid and liquid or between solid and liquid is reduced, the surfaces of the condensed solid particles are easy to wet, the system is uniform, the suspension performance is improved, and the characteristic of no precipitation for a long time is achieved.

8. Coupling agent

The function of the coupling agent is as follows: modifying the surface of the filling particles; the organic functional group is combined with the resin, and the adhesive force of the resin is improved through the reaction of the inorganic functional group and the material interface; and the electrical property and the mechanical property under the humid environment are improved.

The coupling agent may be selected from silane coupling agents and/or titanate coupling agents. Preferably, the silane coupling agent is selected from at least one of gamma-aminopropyltriethoxysilane, 3- (2, 3-glycidoxy) propyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, N-beta- (aminoethyl) -gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-piperazinylpropylmethyldimethoxysilane, vinyltris (2-methoxyethoxy) silane, gamma-methacryloxypropyltrimethoxysilane and beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; preferably, the titanate coupling agent is at least one selected from the group consisting of isopropyl triisostearate, isopropyltris (dioctylphosphato) titanate, bis (dioctyloxypyrophosphate) ethylene titanate, bis (octylphenol polyoxyethylene ether) phosphate, tetraisopropylbis (dioctylphosphato) titanate, monoalkoxy unsaturated fatty acid titanate and pyrophosphoric acid type monoalkoxy titanate.

9. Ion adsorbent

The ion adsorbent can absorb free acid radical ions, improve the heat resistance and the water resistance of the composition and prevent the product from yellowing. An optional ion adsorbent is, for example, DHT-4A (which is an acid acceptor or a heat stabilizer) available from Nippon Kagaku K.K., IXE500 (which is an inorganic anion exchanger) available from Toyo chemical Co. The particle size of the ion adsorbent is 1.0 to 5.0 μm, and the average particle size is 3 μm, preferably 85%.

10. Other Components

The underfill composition of the present invention mainly comprises the above components, and may further comprise other components such as a dye, an antioxidant, etc., as required.

11. Underfill composition

The underfill composition comprises the following components in percentage by weight: 5 to 15 weight percent of modified epoxy resin, 5 to 15 weight percent of modified bismaleimide, 50 to 70 weight percent of filler, 5 to 15 weight percent of curing agent, 0.2 to 1 weight percent of curing agent accelerator, 5 to 10 weight percent of diluent, 2 to 8 weight percent of dispersant, 0.5 to 2 weight percent of coupling agent and 0.1 to 2 weight percent of ion adsorbent.

Wherein, the weight percentage of the modified epoxy resin is preferably 6wt percent to 12wt percent, and more preferably 8wt percent to 10wt percent; the weight percentage of the modified bismaleimide is preferably 6 wt% -12 wt%, and more preferably 8 wt% -10 wt%; the weight percentage of filler is preferably from 50 wt% to 65 wt%, more preferably from 50 wt% to 62 wt%, most preferably from 50 wt% to 60 wt%; the weight percentage of the curing agent is preferably 6 to 12 wt%, more preferably 8 to 10 wt%; the weight percentage of the curing agent accelerator is preferably 0.3 wt% to 0.8 wt%, more preferably 0.4 wt% to 0.6 wt%; the weight percentage of the diluent is preferably 6 to 9 wt%, more preferably 7 to 8 wt%; the weight percentage of the dispersant is preferably 3 wt% to 7 wt%, more preferably 4 wt% to 6 wt%; the weight percentage of the coupling agent is preferably 0.6 wt% to 1.5 wt%, more preferably 0.8 wt% to 1.2 wt%; the weight percentage of the ionic adsorbent is preferably 0.2 wt% to 1.5 wt%, more preferably 0.5 wt% to 1.2 wt%.

The principles and features of this invention are further described in conjunction with the following embodiments, it is to be understood that the examples are intended to be illustrative only and are not intended to limit the scope of the invention, and that various changes and modifications may be suggested to one skilled in the art upon reading this disclosure and are to be included within the spirit and purview of this application and scope of the appended claims.

The instruments and sources used in the examples are as follows: the stirrer adopts a planetary stirrer customized by American ROSS; the three-roller grinder is a three-roller grinder customized by American ROSS; DSC adopts DSC214 of Germany Katsu scientific instruments commercial (Shanghai) GmbH; TGA is TGA209F3 from Germany Kangchi scientific instruments and trade (Shanghai); TMA used is Germany Kangchi scientific instruments and trade (Shanghai) company TMA402F 3; the DMA adopts German Kangchi scientific instruments and trade (Shanghai) company DMA 242E/1; the viscosity testing instrument adopts the CAP2000+ of Bohler fly; the rheometer employs a modular rheometer workstation HAAK MARS III; the push-pull force tester adopts German Nordson Dage 4000; the microscope adopts a Nikon metallographic microscope optiphot-200; the scanning electron microscope used Japanese Hitachi S-4800.

Example 1

The formulation of the underfill composition of this example is as follows:

10g of modified epoxy resin (structural formula II)

10g of modified bismaleimide (structural formula III)

Filling: silica (hexamethyldisilazane-modified) 60g

Curing agent: CAPCURE 3-8005 g, dodecenyl succinic anhydride (DDSA)5g

Curing agent accelerator: 1g of tris- (2-ethylhexanoic acid) salt of 2,4, 6-tris (dimethylaminomethyl) phenol

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: triethylhexylphosphoric acid 2g

Coupling agent gamma-methacryloxypropyltrimethoxysilane 1.5g

Ion adsorbent: DHT-4A 0.5 g.

Adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to the proportion at 70 ℃ and stirring for 90min at the rotating speed of 1200 r/min; then stirring at low speed for 20min, wherein the rotating speed is 70 r/min; standing for 24h for curing; dispersing the cured glue for 20min by using 30KHz ultrasonic waves; and (4) filtering the dispersion liquid, and transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the high-quality underfill adhesive. Curing conditions are as follows: 130 ℃, and the temperature is: 5min, 150 ℃: for 1 min.

Example 2

The formulation of the underfill composition of this example is as follows:

15g of modified epoxy resin (structural formula II)

5g of modified bismaleimide (structural formula III)

Filling: 60g of spherical silica (modified with hexamethyldisilazane)

Curing agent: CAPCURE 3-8005 g, dimethylcyclohexenetetracid di-5 g

Curing agent accelerator: 1.5g of tris- (2-ethylhexanoic acid) salt of 2,4, 6-tris (dimethylaminomethyl) phenol

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: sodium dodecyl sulfate 2g

Coupling agent gamma-methacryloxypropyltrimethoxysilane 1g

Ion adsorbent: IXE5000.5g

Adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to the proportion at 70 ℃ and stirring for 120min at the rotating speed of 1200 r/min; then stirring at low speed for 30min, wherein the rotating speed is 70 r/min; standing for 24h for curing; dispersing the cured glue for 30min by using 30KHz ultrasonic waves; and (4) filtering the dispersion liquid, and transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the high-quality underfill adhesive. Curing conditions are as follows: 130 ℃, and the temperature is: 5min, 150 ℃: for 1 min.

Example 3

The formulation of the underfill composition of this example is as follows:

15g of modified epoxy resin (structural formula I)

15g of modified bismaleimide (structural formula III)

Filling: spherical silica (hexamethyldisilazane-modified) 50g

Curing agent: methylhexahydrophthalic anhydride (MHHPA)5g

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: fatty acid polyglycol ester 5g

Coupling agent 2g of gamma-glycidoxypropylmethyldiethoxysilane

Ion adsorbent: IXE 5002 g

Adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to the proportion at 70 ℃ and stirring for 90min at the rotating speed of 1700 r/min; then stirring at low speed for 20min, wherein the rotating speed is 120 r/min; standing for 24h for curing; dispersing the cured glue for 30min by using 30KHz ultrasonic waves; and (4) filtering the dispersion liquid, and transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the high-quality underfill adhesive. Curing conditions are as follows: 130 ℃, and the temperature is: 5min, 150 ℃: for 1 min.

Example 4

The formulation of the underfill composition of this example is as follows:

15g of modified epoxy resin (structural formula I)

10g of modified bismaleimide (structural formula III)

Filling: spherical silica (hexamethylvinylsilazane-modified) 55g

Curing agent: medinedicarboxylic anhydride (MNA)5g

Diluent agent: diethylene glycol diglycidyl ether 5g

Dispersing agent: fatty acid polyglycol ester 5g

Coupling agent beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane 2g

Ion adsorbent: DHT-4A 2g

Adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to the proportion at 70 ℃ and stirring for 120min at the rotating speed of 1000 r/min; then stirring at low speed for 30min, wherein the rotating speed is 100 r/min; standing for 24h for curing; dispersing the cured glue for 30min by using 30KHz ultrasonic waves; and (4) filtering the dispersion liquid, and transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the high-quality underfill adhesive. Curing conditions are as follows: 130 ℃, and the temperature is: 5min, 150 ℃: for 1 min.

Example 5

The formulation of the underfill composition of this example is as follows:

10g of modified epoxy resin (structural formula II)

10g of modified bismaleimide (structural formula III)

Filling: 60g of spherical silica (modified with hexamethylvinylsilazane)

Curing agent: sebacic dihydrazide (SPH)5g

Diluent agent: diethylene glycol diglycidyl ether 5g

Dispersing agent: fatty acid polyglycol ester 5g

Coupling agent 2g of gamma-glycidoxypropylmethyldiethoxysilane

Ion adsorbent: DHT-4A 2g

Adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to the proportion at 70 ℃ and stirring for 120min at the rotating speed of 1200 r/min; then stirring at low speed for 30min, wherein the rotating speed is 50 r/min; standing for 24h for curing; dispersing the cured glue for 30min by using 30KHz ultrasonic waves; and (4) filtering the dispersion liquid, and transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the high-quality underfill adhesive. Curing conditions are as follows: 130 ℃, and the temperature is: 5min, 150 ℃: for 1 min.

Example 6

The formulation of the underfill composition of this example is as follows:

10g of modified epoxy resin (structural formula II)

10g of modified bismaleimide (structural formula III)

Filling: silica (hexamethyldisilazane-modified) 60g

Curing agent: CAPCURE 3-8005 g, dodecenyl succinic anhydride (DDSA)5g

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: triethylhexylphosphoric acid 2g

Coupling agent 0.5g of gamma-methacryloxypropyltrimethoxysilane

Ion adsorbent: DHT-4A 1.5 g.

Example 7

The formulation of the underfill composition of this example is as follows:

10g of modified epoxy resin (structural formula II)

10g of modified bismaleimide (structural formula III)

Filling: silica (hexamethyldisilazane-modified) 60g

Curing agent: CAPCURE 3-8005 g, dodecenyl succinic anhydride (DDSA)5g

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: triethylhexylphosphoric acid 3g

Coupling agent 0.5g of gamma-methacryloxypropyltrimethoxysilane

Ion adsorbent: DHT-4A 0.5 g.

Example 8

The formulation of the underfill composition of this example is as follows:

10g of modified epoxy resin (structural formula II)

5g of modified bismaleimide (structural formula III)

Filling: silica (hexamethyldisilazane-modified) 70g

Curing agent: CAPCURE 3-8005 g

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: triethylhexylphosphoric acid 2g

Coupling agent gamma-methacryloxypropyltrimethoxysilane 1g

Ion adsorbent: DHT-4A 1 g.

Example 9

The filler of this example was unmodified and the formulation of the underfill composition of this example was as follows:

10g of modified epoxy resin (structural formula I)

10g of modified bismaleimide (structural formula III)

Filling: silica 60g

Curing agent: CAPCURE 3-8005 g, dodecenyl succinic anhydride (DDSA)5g

Diluent agent: 1, 2-cyclohexanediol diglycidyl ether 5g

Dispersing agent: triethylhexylphosphoric acid 2g

Coupling agent 0.5g of gamma-methacryloxypropyltrimethoxysilane

Ion adsorbent: DHT-4A 0.5 g.

As can be seen from the comparison of examples 1-8 with example 9, the unmodified filler is added under the condition of keeping other components unchanged, the aggregation of the filler is easy to occur, the viscosity of the product is increased, the direct effect of the increase of the viscosity is the reduction of the filling effect, and the undesirable phenomena of cavities (Viod) and Flow lines (Flow Mark) are easy to occur in the filling process, as shown in FIG. 6, the filling effect of the unmodified filler example 9 (left figure) and the modified filler example 1 (right figure) is compared, wherein the unmodified filler example 9 has cavities and Flow lines (arrow in figure).

Fig. 7 shows a Scanning Electron Microscope (SEM) image of the underfill of example 1, showing that the filler is uniformly dispersed.

The results of the performance testing of the underfill compositions prepared in examples 1-9 above are shown in Table 1.

TABLE 1

The underfill compositions synthesized in the above examples 1 to 5 and 7 according to the present invention have low viscosity by adding the modified epoxy resin and the modified bismaleimide, which can improve fluidity, high Tg, which can improve reliability, low CTE, which can reduce the probability of failure of the substrate, the chip, and the solder due to CTE difference during the cooling and heating cycles, and low water absorption, which can improve reliability and facilitate repair of the underfill.

The underfill composition synthesized in example 6 has a somewhat higher viscosity due to the smaller particle size of the filler used (average particle size < 20nm), which tends to aggregate; the underfill composition synthesized in example 8 has a somewhat higher viscosity due to a higher specific gravity of the filler (filler content > 65%); the underfill composition synthesized in example 9 has a somewhat higher viscosity because the filler used is not modified and tends to aggregate. But the underfill compositions synthesized in examples 6, 8 and 9 all have characteristics of high Tg, low CTE and low water absorption, similar to examples 1-5, 7, and thus the underfill compositions synthesized in examples 6, 8 and 9 also have good rework properties.

The underfill prepared in example 1 was compared to the two best commercially available products, UF3800 and UF3810 (Hamadonity Corp.) for performance testing, the results of which are shown below:

table 2 shows the Tg as a function of temperature, the test conditions being carried out at a rate of 10 ℃/min from-75 ℃ to 220 ℃.

TABLE 2

Temperature cycling	UF3800	UF3810	Example 1
				Tg	69	113	128
1 time of	72	98	128
				2 times (one time)	76	103	70

The results in table 2 show: after 2 cycles, the Tg of example 1 is reduced from 128 ℃ to 70 ℃, compared with UF3800 and UF3810, the Tg of example 1 is obviously changed, and the larger the Tg reduction is, the better the flexibility is, and the better the repair effect is. The inventors also tested examples 2-9 for changes in Tg with temperature, and the results were essentially the same as example 1.

Table 3 shows the results of the temperature cycling tests, with 15 chips placed on each plate, under test conditions from-55 ℃ to 125 ℃ at a rate of 30min per cycle, the number of cycles representing the number of cycles, with the results in the table such as "0/15" representing 15 test chips that were temperature cycled, 0 failed tests, and so on.

TABLE 3

Test object

Test conditions

400 times (one time)

600 times (one time)

800 times

1200 times

1400 times

2000 times

UF3800

-55℃～125℃

0/15

1/15

5/15

9/15

15/15

——

UF3808

-55℃～125℃

0/15

1/15

3/15

4/15

12/15

14/15

Example 1

-55℃～125℃

0/15

2/15

5/15

The results in table 3 show that: example 1 was tested with all 1200 cycles and was clearly superior to UF3800 and UF 3808. The inventors also tested the temperature cycling tests of examples 2-9, with results substantially the same as example 1.

Table 4 shows the results of the drop test, weight: 2.9Kg, height: 1 m; the results in the table as "0/15" indicate that 15 test chips were drop tested, 0 failed, and so on.

TABLE 4

The results in table 4 show that: example 1 was significantly better than UF3800 and UF3808 all by 4000 drop experiments. The inventors also tested the drop tests of examples 2-9, the results of which were essentially the same as example 1.

Table 5 shows the results of adhesion testing, with SiN chips adhered at 3mm²On the BT resin substrate.

TABLE 5

FIG. 8 shows a plot of the storage modulus decreasing with increasing temperature for the underfill composition of example 2 versus a conventional underfill (UF3800) under heated conditions, analyzed using a Universal V4.5A TA Instruments.

The results show that: the storage modulus of the underfill of example 2 is not very different from ambient to 100 ℃; the storage modulus of the underfill of example 2 dropped more rapidly when heated to around 210 c (rework temperature) and was more conducive to rework. The inventors also tested the storage modulus of the underfill of examples 1, 3,4, 5, 7 as a function of temperature, which was substantially the same as that of example 2.

The inventors investigated the effect of curing conditions on the glass transition temperature (Tg) of the product and the results of the experiments conducted with the underfill of example 1 are shown in table 6.

TABLE 6

Curing conditions	Tg(DSC),℃	Tg(DMA),℃
			130℃：5min，150℃：1min	128	155
120℃：5min，150℃：1min	122	150
			110℃：5min，150℃：1min	115	138
100℃：5min，150℃：1min	110	130

The results show that: the higher the Tg, the better the reliability of the product, and as the curing temperature increases, the Tg of the cured product increases, which is advantageous for product reliability. However, if the curing temperature is too high, the electronic components are damaged, so the curing temperature should be in a proper range, the reliability of the product can be ensured, meanwhile, the electronic components cannot be damaged, and the curing temperature is preferably set below 150 ℃.

The inventor researches the influence of curing temperature on warpage of FC-CSP packaged chips, wherein the chip size is 6.5mm, the chip thickness is 100 mu m, and the substrate thickness is 2-layer 0.17mm substrate packaging. The results of the experiments conducted with the underfill of example 1 are shown in table 7, showing warpage at 25 ℃, 50 ℃, 125 ℃, 175 ℃ and 250 ℃.

TABLE 7

The results show that: the curing conditions have a great influence on the warpage of the product after filling, and the general rule is that the higher the curing temperature is, the larger the warpage is. Positive numbers indicate protrusions and negative numbers indicate depressions. Example 1 used a 130 ℃: 5min, 150 ℃: curing for 1min, wherein the warpage of the product after the product is applied to 6.5mm chip filling and curing is-88.65 μm at 250 ℃ and is smaller than the standard of-90 μm of the standard design.

Example 10

The difference between this embodiment and embodiment 1 is that: the modified epoxy resin in this example has a chemical formula shown in formula 1, wherein R₁、R₂、R₃And R₄Respectively of structural formula 3, structural formula 4, structural formula 5 and structural formula 6, synthesized by the synthetic route of the invention; the modified bismaleimide has a chemical structural formula shown in a structural formula 11, wherein R₅Is composed ofR₁、R₂、R₃And R₄Respectively shown as structural formula 12, structural formula 13 and structural formula 14, and synthesized by the synthetic route of the invention.

Example 11

The difference between this embodiment and embodiment 2 is that: the modified epoxy resin in this example has a chemical formula shown in formula 1, wherein R₁、R₂、R₃And R₄Respectively of structural formula 3, structural formula 5 and structural formula 5, synthesized by the synthetic route of the invention; the modified bismaleimide has a chemical structural formula shown in a structural formula 11, wherein R₅Is composed ofR₁、R₂、R₃And R₄Respectively of structural formula 12, structural formula 13 and structural formula 12, and is synthesized by the synthetic route of the invention.

Example 12

The difference between this embodiment and embodiment 3 is that: the modified epoxy resin in this example has a chemical formula shown in formula 2, wherein R₁And R₂Respectively shown as structural formula 6 and structural formula 8, synthesized by the synthetic route of the invention; the modified bismaleimide has a chemical structural formula shown in a structural formula 11, wherein R₅Is composed ofR₁、R₂、R₃And R₄Respectively shown as a structural formula 12, a structural formula 13, a structural formula 14 and a structural formula 14, and synthesized by the synthetic route.

Example 13

The difference between this embodiment and embodiment 4 is that: the modified epoxy resin in this example has a chemical formula shown in formula 2, wherein R₁And R₂Respectively shown as structural formula 7 and structural formula 9, synthesized by the synthetic route of the invention; the modified bismaleimide has a chemical structural formula shown in a structural formula 11, wherein R₅Is composed ofR₁、R₂、R₃And R₄The compound is a structural formula 15, wherein n is 1, m is 3, and p is 2 in the structural formula 15.

Example 14

The difference between this embodiment and embodiment 5 is that: the modified epoxy resin in this example has a chemical formula shown in formula 1, wherein R₁、R₂、R₃And R₄Respectively shown as structural formula 7, structural formula 6, structural formula 9 and structural formula 10, and synthesized by the synthetic route of the invention; the modified bismaleimide has a chemical structural formula shown in a structural formula 11, wherein R₅Is composed ofR₁、R₂、R₃And R₄Respectively of structural formula 15, structural formula 13, structural formula 14 and structural formula 12, synthesized by the synthetic route of the invention; and the filler in this example is an unmodified filler.

The foregoing is a more detailed description of the present invention that is presented in conjunction with specific embodiments, and the practice of the invention is not to be considered limited to those descriptions. It will be apparent to those skilled in the art that a number of simple derivations or substitutions can be made without departing from the inventive concept.

Claims

1. An underfill composition, comprising, in weight percent: 5 to 15 weight percent of modified epoxy resin, 5 to 15 weight percent of modified bismaleimide, 50 to 70 weight percent of filler, 5 to 15 weight percent of curing agent, 0.2 to 1 weight percent of curing agent accelerator, 5 to 10 weight percent of diluent, 2 to 8 weight percent of dispersant, 0.5 to 2 weight percent of coupling agent and 0.1 to 2 weight percent of ion adsorbent; the modified epoxy resin is polyester modified epoxy resin and/or carbonate modified epoxy resin, and the modified bismaleimide is acrylate modified bismaleimide and/or organic silicon modified bismaleimide;

the modified epoxy resin has a chemical structural formula shown in a structural formula 1 or a structural formula 2:

wherein R is₁、R₂、R₃And R₄Each independently selected from the group consisting of aliphatic esters, alicyclic esters, aromatic esters, carbamates and carbonates, with the proviso that R is₁、R₂、R₃And R₄Not carbamate at the same time.

2. The composition of claim 1, wherein the modified bismaleimide has the chemical formula shown in formula III:

3. composition according to claim 1 or 2, characterized in that the filler is a filler modified with a silane coupling agent.

4. The composition of claim 3, wherein the silane coupling agent is selected from at least one of hexamethyldisilazane, hexamethylvinyl silazane, and vinyl ethoxysilane.

5. The composition of claim 1 or 2, wherein the filler is selected from at least one of aluminum shavings, aluminum powder, aluminum borate whiskers, aluminum oxide, anthracite, sodium antimonate, antimony trioxide, apatite, soot, barium metaborate, barium sulfate, barium titanate, bismuth oxide, boron oxide, calcium carbonate, calcium hydroxide, calcium sulfate, carbon black, ceramic microspheres, clay, diatomaceous earth, ferrite, feldspar, glass beads, gold, graphite, calcium silicate hydrate, magnesium oxide, magnesium hydroxide, molybdenum disulfide, nickel, polymeric fillers, pumice, steatite, sepiolite, silica gel, silver powder, talc, titanium dioxide, zeolite, zinc borate, and zinc sulfide.

6. The composition of claim 1 or 2, wherein the filler is selected from at least one of attapulgite, bentonite, and kaolin.

7. Composition according to claim 1 or 2, characterized in that the filler is chosen from rubber particles.

8. Composition according to claim 5, characterized in that the filler is chosen from silica, titanium dioxide or attapulgite.

9. The composition according to claim 1 or 2, wherein the curing agent is at least one selected from the group consisting of maleic anhydride, phthalic anhydride and derivatives thereof, trimellitic anhydride, pyromellitic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, 3,4, 4-benzophenonetetracarboxylic dianhydride, dodecenylsuccinic anhydride, methylcyclohexanetetracarboxylic dianhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, benzoyl hydrazine, sebacic acid dihydrazide, methylimidazole, 2-heptadecylimidazole, 2-undecylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, triethyiamine, 3, 4-dimethylphenyl-substituted dicyandiamide.

10. The composition of claim 1 or 2, wherein the curing agent is at least one selected from the group consisting of 2-methylimidazole and 1-methylimidazole.

11. The composition of claim 1 or 2, wherein the curing agent accelerator is selected from at least one of benzyltrimethylammonium chloride, triethanolamine borate, triethanolamine titanate, tin octoate, quaternary phosphonium salts, dicyandiamide, DBU carbonate, imidazole metal salts, diethylaminopropylamine, Benzyldimethylamine (BDMA), N-dimethylaniline, 2-ethyl-4-methylimidazole, tris- (2-ethylhexanoate) salt of 2,4, 6-tris (dimethylaminomethyl) phenol, trioleate salt of 2,4, 6-tris (dimethylaminomethyl) phenol, 2-ethylhexanoate salt of tris (dimethylaminomethyl) phenol.

12. The composition of claim 1 or 2, wherein the diluent is at least one selected from the group consisting of 1, 2-cyclohexanediol diglycidyl ether, 1, 4-butanediol diglycidyl ether, 1, 4-cyclohexanedimethanol glycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.

13. The composition of claim 1 or 2, wherein the dispersant is selected from at least one of water glass, sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate, triethylhexylphosphoric acid, sodium dodecylsulfate, methylpentanol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyglycol esters.

14. The composition of claim 1 or 2, wherein the coupling agent is selected from at least one of a silane coupling agent and a titanate coupling agent.

15. The composition as claimed in claim 14, wherein the silane coupling agent is at least one selected from the group consisting of γ -aminopropyltriethoxysilane, 3- (2, 3-glycidoxy) propyltrimethoxysilane, γ -methacryloxypropyltrimethoxysilane, γ -glycidoxypropyltrimethoxysilane, γ -glycidoxypropylmethyldiethoxysilane, N- β - (aminoethyl) - γ -aminopropylmethyldimethoxysilane, γ -aminopropylmethyldiethoxysilane, γ -piperazinylpropylmethyldimethoxysilane, vinyltris (2-methoxyethoxy) silane and β - (3, 4-epoxycyclohexyl) ethyltrimethoxysilane.

16. The composition of claim 14, wherein the titanate coupling agent is selected from at least one of isopropyl triisostearate, isopropyltris (dioctylpyrophosphate) titanate, bis (dioctyloxypyrophosphate) ethylene titanate, tetraisopropylbis (dioctylphosphato) titanate, monoalkoxyunsaturated fatty acid titanate, and pyrophosphoric monoalkoxy titanate.

17. A method of preparing the composition of any one of claims 1-16, comprising: adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to a ratio at 65-75 ℃ and stirring at the rotating speed of 700-1700 r/min for 90-120 min; then stirring at a low speed, wherein the rotating speed is 20-120 r/min, and the time is 20-30 min; standing for 18-30 h for curing; dispersing the cured glue for 20-30 min by using 20-40 KHz ultrasonic waves; and (4) filtering the dispersion liquid, and then transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the composition.

18. The method of claim 17, wherein the method comprises: adding the modified epoxy resin, the modified bismaleimide, the filler, the curing agent accelerator, the diluent, the dispersant, the coupling agent and the ion adsorbent into a high-speed stirrer according to a ratio at 70 ℃ and stirring at the rotating speed of 700-1700 r/min for 90-120 min; then stirring at a low speed, wherein the rotating speed is 20-120 r/min, and the time is 20-30 min; standing for 24h for curing; dispersing the cured glue for 20-30 min by using 30KHz ultrasonic waves; and (4) filtering the dispersion liquid, and then transferring the dispersion liquid into a vacuum defoaming machine for defoaming to finally obtain the composition.