TWI504641B - White polyimide film - Google Patents

Description

White polyimide film

This invention relates to a polyimide film, and more particularly to a white polyimide film having a high glass transition temperature.

Polyimine (PI) films are characterized by light weight, good elasticity, excellent mechanical properties, and good resistance to heat and chemicals. Therefore, PI film systems are widely used in the electronics industry, for example, in the manufacture of light-emitting diode (LED) devices, liquid crystal displays, and the like. However, with the development of the electronics industry, there are more and more requirements for the quality and characteristics of PI films. In particular, in some design requirements, special film colors, such as opaque white, may be required, which is a far cry from the yellow to brown color exhibited by conventional PI films.

In order to form a white polyimine film, one of the known methods is to coat a conventional polyimide film with a white resin (for example, an epoxy resin, an acrylic resin, or a polydimethylsiloxane) to form a so-called A dual-layered polyimide film. Although this method allows the polyimide film to be in a desired white color, the additionally coated resin generally increases the manufacturing cost and adversely affects the film properties. In particular, generally, the resin coating is poor in heat resistance, and when the PI film is exposed to thermal stress, it tends to be deteriorated or yellowed.

Another known method is to mix a white filler in a process for forming the polyimide film, which is typically carried out "one-step" to form a white polyimide film, however, The white polyimide film formed by the step method has poor chemical resistance and cannot meet the design requirements of the LED process.

In addition, in response to environmental protection, it is a future trend to replace lead-free solder in the process to replace the traditional lead solder, but the use of lead-free solder will increase the reflow temperature by 20 to 30 ° C. In general, the polyimide is transferred due to glass transfer. The temperature is not high enough to be used in such a process. Therefore, there is still a need to develop a white polyimide film having a higher glass transition temperature and excellent solder resistance in order to meet the requirements for semiconductor packaging.

The present invention provides a white polyimine film, comprising: a polyimine polymer obtained by reacting substantially a molar amount of a diamine monomer with a dianhydride monomer, the diamine monomer being benzene Diamine (PDA) and 2,2'-bis(trifluoromethyl)benzidine (TFMB), and the dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) Wherein the phenylenediamine is from 3 to 15 mol%, and the 2,2'-bis(trifluoromethyl)benzidine is from 85 to 97 mol%, based on the total moles of the diamine monomer; A white filler is uniformly distributed in the polyimine polymer.

The white polyimine film of the present invention comprises a polyimine polymer and a white filler distributed in the polyimide polymer.

In an embodiment, the polyimine polymer is synthesized by condensation polymerization of a diamine and a dianhydride, the molar ratio of the dianhydride to the diamine being substantially about 1:1, for example, about 0.90: 1.10 Or about 0.98:1.02. The diamine is a combination of phenylenediamine (PDA) and 2,2'-bis(trifluoromethyl)benzidine (TFMB); and the dianhydride is 3,3',4,4'-biphenyltetracarboxylate Acid dianhydride (BPDA).

In one embodiment, the PDA is from 3 to 15 mol% based on the total moles of the diamine, and may be, for example, 3 mol%, 4 mol%, 7 mol%, 10 mol%, 12 mol%, 14 mol%, 15 mol% or The value between any two points mentioned above; and the TFMB is 85 to 97 mol%, for example, 85 mol%, 87 mol%, 90 mol%, 92 mol%, 95 mol%, 96 mol%, 97 mol% or a value between any two points mentioned above.

In the white polyimine film, the white filler is uniformly mixed with the polyamidimide-based polymer. The white filler may be selected from one or more of the following groups: titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), calcium oxide (CaO), zinc oxide (ZnO 2 ), aluminum oxide (Al ₂ O ₃ ), Zinc sulfide (ZnS2), calcium carbonate (CaCO ₃ ), lead carbonate (PbCO3), lead hydroxide (Pb(OH)2), calcium sulfate (CaSO ₄ ), barium sulfate (BaSO4), cerium oxide (SiO ₂ ) Boron nitride (BN), aluminum nitride (AlN), basic zinc molybdate, basic calcium zinc molybdate, lead white, molybdenum White), lithopone (mixture of barium sulfate and zinc sulfide), and clay.

In some embodiments, the white filler is selected from one or more of the group consisting of TiO ₂ , Al ₂ O ₃ , CaCO ₃ , CaSO ₄ , SiO ₂ , BN, AlN, and clay. In one embodiment, the white filler is TiO ₂ , such as rutile TiO ₂ , anatase TiO ₂ , or brookite TiO ₂ . The weight percentage of the filler may range from about 15% to about 40% based on the total weight of the polyimide material, for example, but not limited to, 15%, 20%, 25%, 30%, 35. %, 37%, 40%, or a value between any two of the foregoing.

In the examples, the preparation method of the white polyimine film of the present invention is not particularly limited and can be produced by a method known in the art.

The preparation methods described below are illustrative and are not intended to limit the invention.

The solvent used to prepare the polyimine membrane of the present invention may be an aprotic polar solvent, preferably having a relatively low boiling point (e.g., less than about 225 ° C), such as dimethylacetamide (DMAC), Ethylacetamide, N,N'-dimethylformamide (DMF), N,N'-diethylformamide, N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO) ), tetramethylguanidine, N,N'-dimethyl-N,N'-propenylurea (DMPU), tetramethylurea (TMU), and the like. The diamine and the dianhydride are separately added to the solvent, and the mixture is uniformly mixed and reacted to obtain a polyamidonic acid solution.

Next, a dehydrating agent and a catalyst are added to the polyamic acid solution, and after stirring, a uniform precursor solution can be obtained. The dehydrating agent may include, for example, an aliphatic acid anhydride such as acetic anhydride and propionic anhydride, an aromatic acid anhydride such as phthalic anhydride and phthalic anhydride, and the like. The catalyst may include, for example, a heterocyclic tertiary amine (e.g., picoline, pyridine, lutidine, etc.), an aliphatic tertiary amine (e.g., triethylamine (TEA), etc.), an aromatic tertiary An amine such as xylylene or the like. In an embodiment, the polyamine: dehydrating agent: catalyst may have a molar ratio of about 1:2:1.

The white filler may be added to the polyamic acid solution at this stage, or may be added to the solvent together with the diamine or dianhydride in the previous step.

At this stage, other additives such as processing aids, antioxidants, light stabilizers, extinction coefficient modifiers, flame retardants, antistatic agents, thermal stabilizers, and ultraviolet absorbers may also be added to the polyaminic acid solution. , a reinforcing agent, etc., to impart the desired properties to the polyimide film.

Next, the precursor solution is applied as a layer and baked to form a film at a temperature of from about 90 ° C to about 350 ° C.

The white polyimide film formed may have a thickness of from about 5 micrometers (μm) to about 150 μm, such as between about 5 μm and about 75 μm, such as between about 10 μm and about 50 μm.

The white polyimine film of the present invention has the advantage of having both excellent mechanical properties and thermal properties. Specifically, the white polyimide film has a glass transition temperature (Tg) of 290 ° C or more, for example, 290, 291, 293, 295, 300, 320, 330, 350 ° C or higher. It can be observed that the Tg value of the white polyimide film is related to the film solder resistance. Further, the white polyimide film has an elongation of 40% or more, for example, 43, 45, 49, 50, 55% or more.

In addition to the above properties, the white polyimide film also exhibits a desired color having an L* value (L*-value) higher than about 90, and the L* value is a conventional "Lab color space". The color brightness in the indicator. In some embodiments, the white polyimide film can have an L* value of, for example, 91, 92, 93, 95, 97, 98 or more.

In some embodiments, the white polyimide film is also suitable for use in a reflective device, and may have a reflectance of 88% or more, such as 89, 90, 93, in addition to the above-mentioned characteristics of glass transition temperature, elongation, color, and the like. , 95, 97, 98% or more.

The invention is described in detail below by way of examples.

Example

<Example 1>

Preparation of white slurry

The TiO ₂ weight ratio of 1:1 was mixed with DMAC and ground for use.

Preparation of white polyimine film

63.85g (0.2mole) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and p-phenylenediamine (PDA) 0.67g (0.006mole) were added to 375g (g) of DMAc and stirred. After completely dissolving, 96.4 g of the above white slurry was added, and 60.48 g (0.206 mole) of 3,3',4,4'-biphenyl dianhydride (BPDA) was added and stirred at room temperature for 72 hours. A white polyamic acid slurry was obtained.

To the obtained white PAA slurry, acetic anhydride and methylpyridine (the molar ratio of the two were 1:7) were added, and after stirring for 3 minutes, the solution was applied on a glass plate and placed in an oven and baked at 80 ° C. Bake for about 30 minutes to remove most of the solvent. Then, it is baked at 170 ° C - 300 ° C for about 4 hours to form a film by baking, and then the film is peeled off from the glass plate to obtain a white polyimide film. The white polyimine film obtained above had a thickness of 25 μm and a TiO ₂ content of 30% by weight.

<Example 2>

The procedure of Example 1 was repeated except that the diamine component was changed to 62.98 g (0.198 mole) of TFMB and 1.12 g (0.01 mole) of PDA.

<Example 3>

The procedure of Example 1 was repeated except that the diamine component was changed to 62.09 g (0.194 mole) of TFMB and 1.58 g (0.015 mole) of PDA.

<Example 4>

The procedure of Example 1 was repeated except that the diamine component was changed to 60.73 g (0.19 mole) of TFMB and 2.28 g (0.021 mole) of PDA.

<Example 5>

The procedure of Example 1 was repeated except that the diamine component was changed to 58.4 g (0.182 mole) of TFMB and 3.48 g (0.032 mole) of PDA.

<Example 6>

The procedure of Example 1 was repeated except that the white slurry was changed to 56.3 g.

<Example 7>

The procedure of Example 1 was repeated except that the white slurry was changed to 39.7 g.

<Example 8>

The procedure of Example 1 was repeated except that the white slurry was changed to 150 g.

<Example 9>

The procedure of Example 1 was repeated except that the diamine component was changed to 58.4 g (0.182 mole) of TFMB and 3.48 g (0.032 mole) of PDA, and the white slurry was changed to 56.3 g.

<Comparative Example 1>

The procedure of Example 1 was repeated except that the diamine component was changed to 65.15 g (0.204 mole) of TFMB and no PDA was added.

<Comparative Example 2>

The procedure of Example 1 was repeated except that the diamine component was changed to 64.29 g (0.201 mole) of TFMB and 0.44 g (0.004 mole) of PDA.

<Comparative Example 3>

The procedure of Example 1 was repeated except that the diamine component was changed to 64.72 g (0.202 mole) of TFMB and 0.22 g (0.002 mole) of PDA.

<Comparative Example 4>

The procedure of Example 1 was repeated except that the diamine component was changed to 55.98 g (0.175 mole) of TFMB and 4.72 g (0.044 mole) of PDA.

<Comparative Example 5>

The procedure of Example 1 was repeated except that the diamine component was changed to 50.87 g (0.159 mole) of TFMB and 7.36 g (0.068 mole) of PDA.

<Comparative Example 6>

The procedure of Example 1 was repeated except that the white slurry was changed to 25 g.

<Comparative Example 7>

The procedure of Example 1 was repeated except that the white slurry was changed to 184 g.

<Comparative Example 8>

The procedure of Example 9 was repeated except that the white slurry was changed to 184 g.

The films obtained in the foregoing Examples and Comparative Examples were subjected to the following properties:

First, the glass transfer temperature (Tg)

The TCA (Model TA Instruments Q400) was used to measure the thermal expansion coefficient (CTE) of the sample as the temperature rises at a heating rate of 10 ° C/min. When the coefficient of thermal expansion rises rapidly, the corresponding temperature point can be determined as the sample. Glass transfer temperature.

Second, the reflectivity

The measurement was carried out using an integrating sphere spectrometer (X-RITE SP60), and the reflectance of the sample was measured at a wavelength of 550 nm.

Third, the elongation rate

The measurement was carried out using a universal material testing machine (Tinius Olsen H10KS), and the sample length (L ₀ ) and the tensile breaking length (L) before stretching were measured by a sample tensile test, and the elongation was calculated by the following formula: [(LL ₀ ) / L ₀ ] × 100%.

Fourth, L* value

It was measured using an integrating sphere spectrometer (X-RITE SP60).

5. Drifting tin test: The sample (3 cm × 3 cm) was placed in a tin furnace set to a temperature of about 288 ° C, taken out in 10 seconds for 1 minute, and then placed in a tin furnace three times. When the appearance of the sample is observed, if warpage, deformation, etc. are generated, it is judged as "no pass", and if there is no change, it is judged as "pass".

The test results are shown in Table 1.

As shown in Table 1, the polyimide film of Examples 1-9 had a high glass transition temperature (Tg can be higher than 290 ° C), high reflectance and white chromaticity values, excellent solder resistance, and maintained at the same time. The mechanical properties (ie, elongation), in addition to providing excellent reflectivity and white chromaticity values required as reflective materials, have better solder resistance and avoid warping or peeling in subsequent processes. .

Compared with the previous examples, Comparative Example 1 shows that if the diamine monomer does not contain PDA, the glass transition temperature of the obtained polyimide film is only about 265 ° C, which is significantly lower than the foregoing examples, and is tested in the soldering tin. There will be warpage in the middle. Comparative Examples 2 and 3 show that if the diamine monomer contains both TFMB and PDA, but the ratio of PDA is too low (less than 3 mol%), the glass transition temperature of the obtained polyimide film is still low, which is insufficient. Through the soldering test, the appearance still shows warpage.

In contrast, Comparative Examples 4 and 5 confirmed that if the ratio of TFMB in the diamine monomer is too low and the ratio of PDA is too high, the obtained polyimide film has a high glass transition temperature, but the film elongation is too high. Low (less than 35%) is not conducive to subsequent applications.

Compared with Examples 7 and 8, Comparative Examples 6 and 7 respectively show that when the amount of white filler (TiO ₂ ) added is too small and too much, the obtained polyimide film has a high glass transition temperature, but will reflect The rate and elongation have adverse effects and are not conducive to subsequent applications.

Compared with Example 9, Comparative Example 8 shows that when too much white filler (TiO ₂ ) is added, although the components and ratios of the diamine and the dianhydride are the same as in Example 9, the elongation of the obtained polyimide film is excessive. Low, not conducive to subsequent applications.

In summary, the white polyimine film of the present invention has a specific ratio of a combination of diamine monomers (ie, only PDA and TFMB), a specific dianhydride monomer (ie, only BPDA), and a specific ratio of white filler. The advantage of this formula is that it can reach a high glass turn at the same time. Temperature shift, excellent thermal properties (ie, solder resistance), good mechanical properties (such as elongation), high reflectivity, and high whiteness. Therefore, the white polyimide film of the present invention is suitably applied to a reflective layer of a semiconductor package, an LED or a display device.

The above description of the specific embodiments is intended to be illustrative of the invention, and is not intended to limit the invention. It will be understood by those skilled in the art that various changes or modifications may be made to the present invention without departing from the scope of the appended claims.

Claims (9)

A white polyimine film comprising: a polyimine polymer obtained by reacting a diamine monomer with a dianhydride monomer, the diamine monomer being phenylenediamine (PDA) and 2, 2' - bis(trifluoromethyl)benzidine (TFMB), and the dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA); wherein the diamine monomer Based on the total molar number, the phenylenediamine is 3 to 15 mol%, and the 2,2'-bis(trifluoromethyl)benzidine is 85 to 97 mol%; and a white filler is distributed in the polyazide. In the amine polymer. A white polyimine film as claimed in claim 1 which has a glass transition temperature of 290 ° C or higher. A white polyimine film as claimed in claim 1 which has an elongation of 40% or more. A white polyimine film as claimed in claim 1 which has an L* value above 90. A white polyimine film as claimed in claim 1 which has a reflectance of 88% or more. The white polyimine film according to claim 1, wherein the white filler is selected from the group consisting of titanium dioxide (TiO ₂ ), zirconium dioxide (ZrO ₂ ), calcium oxide (CaO), and zinc dioxide (ZnO ₂ ). , aluminum oxide (Al ₂ O ₃ ), zinc disulfide (ZnS ₂ ), calcium carbonate (CaCO ₃ ), lead carbonate (PbCO ₃ ), lead hydroxide (Pb(OH) ₂ ), calcium sulfate (CaSO _{4 )} ), barium sulfate (BaSO ₄ ), cerium oxide (SiO ₂ ), boron nitride (BN), aluminum nitride (AlN), basic zinc molybdate, basic zinc calcium molybdate, lead white, molybdenum white, One or more of the groups of zinc lanthanum and clay. The white polyimine film according to claim 1, wherein the white filler has a weight ratio of 15% to 40% based on the total weight of the polyimine. A white polyimine film comprising: a polyimine polymer obtained by reacting a diamine monomer with a dianhydride monomer, the diamine monomer being phenylenediamine (PDA) and 2, 2' - bis(trifluoromethyl)benzidine (TFMB), and the dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), wherein the diamine monomer Based on the total molar number, the phenylenediamine is 3 to 15 mol%, and the 2,2'-bis(trifluoromethyl)benzidine is 85 to 97 mol%; and a white filler is distributed in the polyazide. In the amine polymer, the white polyimide film has a glass transition temperature of 290 ° C or higher, an elongation of 40% or more, and a reflectance of 88% or more. The white polyimine film according to claim 8 , wherein the white filler is selected from the group consisting of titanium dioxide (TiO ₂ ), zirconium dioxide (ZrO ₂ ), calcium oxide (CaO), and zinc dioxide (ZnO ₂ ). , aluminum oxide (Al ₂ O ₃ ), zinc disulfide (ZnS ₂ ), calcium carbonate (CaCO ₃ ), lead carbonate (PbCO ₃ ), lead hydroxide (Pb(OH) ₂ ), calcium sulfate (CaSO _{4 )} ), barium sulfate (BaSO ₄ ), cerium oxide (SiO ₂ ), boron nitride (BN), aluminum nitride (AlN), basic zinc molybdate, basic zinc calcium molybdate, lead white, molybdenum white, One or more of the groups of zinc lanthanum and clay.