TWI788542B - Lead frame material, manufacturing method thereof, and semiconductor package using the lead frame material - Google Patents

Abstract

The lead frame material of the present invention has a conductive substrate and a roughened layer formed on at least one surface of the conductive substrate. When viewed in the cross-section of the aforementioned lead frame material, it is parallel to the surface of the aforementioned conductive substrate at a predetermined The number of grain boundaries existing in the surface of the aforementioned roughened layer measured within the length is 20 grain boundaries/micrometer or less. The lead frame material of the present invention is excellent in resin adhesion even after being used for a long period of time in a high-temperature, high-humidity environment.

Description

Lead frame material, manufacturing method thereof, and semiconductor package using the lead frame material

The invention relates to a lead frame material, a manufacturing method thereof, and a semiconductor package using the lead frame material.

In electronic equipment and electric equipment, a large number of resin-sealed semiconductor devices are assembled. Resin-encapsulated semiconductor devices are formed by sealing semiconductor elements and lead frame materials that are electrically connected to each other by wires and the like with molding resin. In such resin-sealed semiconductor devices, exterior plating such as gold (Au), silver (Ag), and tin (Sn) is often applied to the lead frame material in order to impart functions such as bondability, heat resistance, and sealing.

In recent years, in order to simplify assembly steps and reduce costs, a lead frame material (pre-plated frame (Pre-Plated Frame), hereinafter abbreviated as PPF) has been used, which is aimed at mounting semiconductor devices on printed substrates with solder or the like. , the surface of the lead frame material is preliminarily plated to improve wettability with solder (for example, Ni/Pd/Au plating) (for example, refer to Patent Document 1).

In addition, in order to improve the adhesion between the lead frame material and the molding resin in the resin-sealed semiconductor device, a technique of roughening the plated surface of the lead frame material has been proposed (for example, refer to Patent Document 2, Patent Document 3).

These techniques for roughening the plated surface are expected to (1) increase the bonding area between the lead frame material and the molding resin by roughening the plated surface of the lead frame material, (2) Molding resin becomes easy to catch to the unevenness effect (that is, the anchor effect (anchor effect)) of the plated film surface after roughening, etc.

Thereby, the adhesiveness of the molding resin to the lead frame material can be improved, peeling between the lead frame material and the molding resin can be prevented, and the reliability of the resin-sealed semiconductor device can be improved. [Prior Art Literature] (patent literature)

Patent Document 1: Japanese Patent No. 2543619 Patent Document 2: Japanese Patent No. 3228789 Patent Document 3: Japanese Patent Application Laid-Open No. 10-27873

[Problem to be solved by the invention] Due to the roughening of the plating surface as described above, the resin adhesiveness of the lead frame material has definitely been improved compared to conventional ones. However, it is known that the high level of reliability required in recent years, for example, after a 168-hour exposure test in a high-temperature and high-humidity environment at a temperature of 85°C and a humidity of 85%, gaps may appear between the lead frame material and the resin. case. This is considered to be due to a large number of packages such as Quad Flat Non-Leaded Package (QFN) and Small Outline Package (SOP) that have not been used in the past have been widely used. The level of requirements has become higher. From this, it can be seen that there is room for improvement in the resin adhesion of the lead frame material.

An object of the present invention is to provide a lead frame material, a method of manufacturing the same, and a semiconductor package using the lead frame material, which are excellent in resin adhesion even after long-term use in a high-temperature and high-humidity environment.

[Technical means to solve the problem] The main constitution of the present invention is as follows. [1] A lead frame material having a conductive substrate and a roughened layer formed on at least one surface of the conductive substrate, the lead frame material is characterized in that, when viewed in a section of the aforementioned lead frame material, parallel to The number of grain boundaries present on the surface of the roughened layer measured over a predetermined length of the surface of the conductive substrate is 20 grain boundaries/micrometer (pieces/µm) or less. [2] The lead frame material according to the above [1], wherein the height of the roughened layer is in the range of 0.1 micrometer (µm) to 5.0 µm when viewed in a cross section of the lead frame material. [3] The lead frame material according to the above [1] or [2], wherein the specific surface area of the outermost surface of the lead frame material is 120% or more. [4] The lead frame material according to any one of the above [1] to [3], wherein when observed in a cross section of the lead frame material, colocated grain boundaries below Σ5 are present in the roughened layer. The ratio of all grain boundaries in the roughened layer is 90.0% or more. [5] The lead frame material according to any one of [1] to [4] above, wherein the conductive substrate is selected from the group consisting of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy. composed of metals or alloys. [6] The lead frame material according to any one of [1] to [5] above, wherein the roughened layer contains at least one element selected from copper and nickel. [7] The lead frame material according to any one of [1] to [6] above, further comprising one or more layers formed on the roughened layer and having a layer different from that of the roughened layer. Composition, and contains at least one element selected from the group of nickel, palladium, rhodium, ruthenium, platinum, iridium, gold, silver and tin. [8] A method for producing a lead frame material, which is the method for producing a lead frame material according to any one of [1] to [7] above, wherein the production method is characterized in that the roughened layer is formed by electroplating. . [9] A semiconductor package made of the lead frame material described in any one of [1] to [7] above.

[Efficacy of the invention] According to the present invention, it is possible to provide a lead frame material, a method of manufacturing the same, and a semiconductor package using the lead frame material, which have excellent resin adhesion even after being used for a long time in a high-temperature and high-humidity environment. excellent.

Hereinafter, the present invention will be described in detail based on embodiments.

As a result of intensive research and development by the present inventors on the above-mentioned problems, it has been noticed that the more grain boundaries of the roughened layer exist on the surface of the roughened layer (hereinafter also referred to as the roughened layer), Resin peeling is more likely to occur after the high temperature and high humidity test. Also, it was found that by controlling the number of grain boundaries present in the surface of the roughened layer in the cross section of the lead frame material to be below a predetermined number, high shear strength of the resin can be maintained even after a high-temperature and high-humidity test ( shear strength), and as a result, we succeeded in obtaining a lead frame material with higher resin adhesion than before. This invention was completed based on this knowledge.

According to the lead frame material of the present invention, it has a conductive substrate and a roughened layer formed on at least one side of the conductive substrate. In addition, the number of grain boundaries existing in the surface of the roughened layer measured within a predetermined length parallel to the surface of the conductive substrate by observing the cross section of the lead frame material is 20 grain boundaries/µm or less.

The conductive matrix contains copper (Cu), iron (Fe) or aluminum (Al). As the conductive substrate, it is preferably composed of a metal or alloy selected from the group of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy because of its excellent conductivity and heat dissipation.

For example, examples of copper alloys include alloys disclosed by the Copper Development Association (CDA), that is, C18045 (Cu-0.3Cr-0.25Sn-0.5Zn), C19400 (Cu-2.3Fe-0.03P -0.15Zn). Moreover, 42 alloy (Fe-42Ni) can be mentioned as an example of an iron alloy. In addition, the numbers before each element represent the mass percentage in the alloy. These alloys and metals have different properties such as electrical conductivity, so they are appropriately selected according to the properties required for the lead frame material.

The thickness of the conductive substrate is not particularly limited, but is, for example, within a range of 0.03 millimeters (mm) to 1.00 mm, preferably 0.03 mm to 0.30 mm.

A roughened layer is formed on at least one surface of the conductive substrate. One side of the conductive substrate means the top or bottom surface of the conductive substrate. For example, the roughening layer may be formed only on the top surface of the conductive substrate or only on the bottom surface of the conductive substrate, or may be formed on both the top surface and the bottom surface.

Fig. 1 is a diagram schematically showing a lead frame material according to the present invention and for explaining how to count grain boundaries existing in the surface of a roughened layer. In addition, although FIG. 1 is a cross-sectional view of a lead frame material, in order to illustrate grain boundaries, oblique lines (hatching) are not added for simplicity.

As shown in FIG. 1, the number of grain boundaries existing in the surface of the roughened layer 30 obtained by measuring the cross section of the lead frame material 10 parallel to the surface of the conductive substrate 20 within a predetermined length L is 20 pieces/µm or less.

Specifically, the number of grain boundaries 32 present in the surface of the roughened layer 30 is counted as follows. Grain boundaries 32 of the roughened layer 30 are indicated by solid lines within the roughened layer 30 . The grain boundaries existing on the surface of the roughened layer 30 are shown as: grain boundaries 32 existing inside the roughened layer 30 when viewed in the cross section of the lead frame material 10 as shown in FIG. 1 The solid line extends to the surface (contour line) of the roughened layer 30 and intersects (intersection point); and, the grain boundary 32 existing in the roughened layer 30 and the surface (contour line) of the roughened layer The position of the intersection point is indicated by a hollow circle as a marker. Then, within the range of the predetermined length L parallel to the direction of the surface of the conductive substrate 20, the number of hollow circles, that is, the solid line representing the grain boundaries 32 existing inside the roughening layer 30 and the number of the roughening layer 30 The number of intersection points of the surfaces is the number of grain boundaries 32 of the roughened layer 30 existing in the surface of the roughened layer 30 as measured within the predetermined length L. In the lead frame material 10 shown in FIG. 1 , when the predetermined length L is 1 μm, the number of grain boundaries 32 present in the surface of the roughened layer 30 measured within the predetermined length L is 17/μm. .

When the molding resin is brought into close contact with the surface of the lead frame material 10, the grain boundary 32 present on the surface of the roughened layer 30 acts as a starting point, and cracks are generated in the molding resin or the molding resin is blown from A condition in which the lead frame material has delaminated. Therefore, the smaller the number of grain boundaries 32 present on the surface of the roughened layer 30 , the more the occurrence of such cracks and the reduction in resin adhesion can be suppressed. The number (number density) of grain boundaries 32 present on the surface of the roughened layer 30 is 20 grains/μm or less, preferably 18 grains/μm or less, more preferably 15 grains/μm or less. When the number of 32 is 20 pieces/μm or less, the occurrence of cracks and the decrease in resin adhesiveness can be sufficiently suppressed.

The grain boundaries 32 of the roughened layer 30 present on the surface of the roughened layer 30 can be measured by observing the cross section of the lead frame material 10 using a focused ion beam scanning ion microscope (FIB-SIM), for example.

The roughened layer 30 contains at least one element of copper and nickel (Ni). The roughened layer 30 is preferably composed of a metal or alloy selected from the group of copper, copper alloy, nickel, nickel alloy, and copper-nickel alloy in order to form a roughened shape with excellent resin adhesion.

FIG. 2 is a diagram schematically showing the lead frame material 10 according to the present invention and illustrating the height of the roughened layer 30 . Similar to FIG. 1 , although FIG. 2 is a sectional view of the lead frame material 10 , in order to illustrate the height of the roughened layer 30 , slanted lines, ie hatching, are not used for simplicity.

Observing the cross section of the lead frame material 10 , the height of the roughened layer 30 is preferably in the range of 0.1 μm to 5.0 μm, more preferably in the range of 0.1 μm to 3.0 μm. If the height of the roughened layer 30 is 0.1 μm or more, the anchoring effect on the resin will increase, and the specific surface area of the roughened layer 30 will increase, so the resin adhesion will increase. In addition, if the height of the roughened layer 30 is 5.0 μm or less, it is possible to suppress the part of the roughened layer from falling off, that is, the so-called powder fall, so the maintenance frequency of the roughened material used to remove the powder fall during manufacturing can be reduced, and the improvement can be achieved. productive. If the height of the roughened layer 30 is within the above-mentioned range, the above-mentioned effect will be fully enhanced.

Specifically, the height of the roughened layer 30 is as follows. As shown in FIG. 2 , first, a triangle is drawn by connecting the roots 41 a and 41 b on both sides of the convex portion 40 a of the roughened layer 30 and the apex 42 of the convex portion 40 a. Then, for this triangle, the height H of the triangle is measured with the connecting line of the root portions 41 a and 41 b as the base B and the apex portion 42 as the vertex. That is, a vertical line is drawn from the apex 42 to the base B, and the length of the vertical line (height H of the triangle) is measured. Then, the height H of the triangle is measured for a predetermined number of convex portions 40 a, and the average value of the measured values is defined as the height of the roughening layer 30 .

Here, the root portion 41a on one side of the convex portion 40a of the roughened layer 30 is located between the convex portion 40b adjacent to the convex portion 40a and the The lowest surface position (lowest point position) among the surface portions of the roughened layer 30 between the protrusions 40a. In addition, the root portion 41b on the other side of the convex portion 40a is the lowest portion of the surface of the roughened layer 30 between the convex portion 40c on the opposite side to the convex portion 40b and the convex portion 40a. The surface position (lowest point position) of . In addition, the apex 42 of the convex part 40a is the highest position in the convex part 40a.

Also about the measuring method of the height of the convex part 40b and the convex part 40c, it is the same as the method of the said convex part 40a.

The height of the roughened layer 30 can be measured by observing the cross section of the lead frame material 10 using a scanning electron microscope (SEM), for example.

In addition, the specific surface area of the outermost surface of the lead frame material 10 is preferably 120% or more, more preferably 140% or more. The specific surface area refers to the value of the percentage of the three-dimensional surface area to the two-dimensional surface area ((three-dimensional surface area/two-dimensional surface area)×100 (%)). The larger the specific surface area of the outermost surface (the outermost layer) of the lead frame material 10 , the more the contact area with the resin increases, so the resin adhesiveness is improved. When the specific surface area of the outermost surface of the lead frame material is 120% or more, the resin adhesiveness is sufficiently high.

The specific surface area of the outermost surface of the lead frame material 10 can be obtained, for example, by observing the surface using a three-dimensional white light interference microscope and calculating the percentage (%) of the three-dimensional surface area to the two-dimensional surface area.

In addition, when observed in the cross-section of the lead frame material 10, the ratio of colocated grain boundaries below Σ5 to all grain boundaries existing in the roughened layer 30 is preferably 90.0% or more, more preferably 92.0% or more. The higher the ratio of the above-mentioned cosite grain boundaries equal to or less than Σ5, the more the decrease in the resin adhesiveness of the lead frame after being left for a long time in a high-temperature and high-humidity environment is suppressed. If the ratio of the above-mentioned cosite grain boundaries equal to or less than Σ5 is 90.0% or more, the decrease in resin adhesiveness can be sufficiently suppressed.

The cosite grain boundary means a special grain boundary with high geometric coherency, and is defined as the smaller the Σ value of the reciprocal of the cosite lattice point density, the higher the coherency.

From the results of various experiments, the present inventors have found that when the ratio of colocated grain boundaries with a Σ value of 5 or less becomes 90.0% or more, the resin before and after the heat resistance test of the lead frame material, that is, in a high-temperature and high-humidity environment, before and after leaving Adhesion is well maintained. Here, it is estimated that the grain boundary with a large Σ value is a high-energy structure, so the grain boundary deterioration phenomenon is likely to occur, and peeling at the grain boundary is likely to occur due to heating, and it is considered that by forming a grain boundary with a small Σ value, the After that, the resin adhesion can be maintained well. Therefore, from the viewpoint of suppressing a decrease in resin adhesion after being left in a high-temperature, high-humidity environment, the lower the Σ value of the cosite grain boundary, the better. In addition, the higher the ratio of cosited grain boundaries equal to or less than Σ5, the higher the above-mentioned effect.

Electron Back Scatter Diffraction (EBSD) can be used to analyze the co-localized grain boundaries in the cross-section of the lead frame material, that is, the roughened layer. EBSD is a crystal orientation analysis technique that utilizes Kikuchi line diffraction (Kikuchi pattern) of reflected electrons that occurs when an electron beam is irradiated to a sample in a SEM.

In addition, the lead frame material 10 may further have one or more layers (not shown) formed on the roughened layer 30, having a composition different from that of the roughened layer 30, and containing nickel, palladium (Pd), rhodium One or more elements selected from the group of (Rh), ruthenium (Ru), platinum (Pt), iridium (Ir), gold (Au), silver (Ag) and tin (Sn).

When the layer formed on the roughening layer 30 is one layer, this layer, that is, the outermost layer of the lead frame is the surface layer. The substance constituting the surface layer is properly selected according to the required characteristics of the lead frame material. The surface layer is made of metal or alloy containing one or more elements selected from the group of gold, silver and tin. The surface layer is preferably composed of gold-cobalt alloy, gold, silver or tin because of excellent solder wettability.

The thickness of the surface layer is not particularly limited, but if the thickness is too large, the unevenness of the roughened layer 30 due to the height of the roughened layer 30 will be buried, so the effect of improving the resin adhesion may be reduced, so the surface layer The upper limit of the thickness is preferably 3.00 μm or less. Furthermore, when the material constituting the surface layer is mainly precious metals such as gold, the cost of the material will increase. Therefore, when noble metals are used, the upper limit of the thickness of the surface layer is preferably 1.00 μm or less.

When the layers formed on the roughened layer 30 are plural layers, the outermost layer is a surface layer, and the layer formed between the surface layer and the roughened layer 30 is an intermediate layer. The middle layer can be one layer or more than two layers. For example, when the middle layer is two layers, the layer on the roughening layer side is the middle lower layer, and the layer on the surface layer side is the middle upper layer. The intermediate layer improves the adhesion between the rough layer 30 and the surface layer, and suppresses diffusion and oxidation of the conductive base 10 and the rough layer 30 due to heat.

The intermediate layer is made of metal or alloy containing one or more elements selected from the group of nickel, palladium, rhodium, ruthenium, platinum and iridium.

The element and thickness of the intermediate layer can be selected according to the required characteristics. When the intermediate layer is one layer, if heat resistance is required, it is desirable that the thickness of nickel be formed within the range of 0.02 μm or more and 2.50 μm or less, more preferably 0.08 μm or more and 2.50 μm or less. In the range below 2.00μm. If adhesion to the surface layer or the roughened layer is required, it is desirable that the thickness of palladium, rhodium, ruthenium, platinum, and iridium be formed within the range of 0.014 μm or more and 0.100 μm or less. When the middle layer is two layers, the elements and thickness of the middle layer can be determined by the above combination. In addition, when the intermediate layer is composed of three or more layers, it is desirable to form it so that the total thickness does not exceed the range of 2.5 μm or less from the viewpoint of workability and roughened shape maintenance.

The thickness of the surface layer and the intermediate layer can be measured with a film thickness meter, such as a fluorescent X-ray film thickness meter.

Depending on the application of the lead frame material, the presence or absence of the surface layer and the intermediate layer, and the number of the intermediate layer are appropriately selected.

As the manufacturing method of the lead frame material, each layer can be formed by using a film-forming method such as plating (plating), cladding (clad), vapor deposition, and sputtering. From the viewpoint of quantity controllability, it is preferable to form each layer, especially the roughened layer, by electroplating. The composition of the plating solution and the plating conditions can be appropriately determined. In addition, in order to suppress the amount of raw materials used for the production of the lead frame material, single-side plating or differential-thickness plating (differential-thickness plating) is also an effective means.

As a method of controlling the number of grain boundaries (number density) existing in the surface of the roughened layer (plated layer) formed by the electroplating method, for example, when the roughened layer is formed by electroplating, controlling the electrodeposition ( electrodeposition) during crystal growth. In order to make the number of grain boundaries fall within the above-mentioned range, the voltage at the time of roughening formation (plating) can be adjusted suitably so that it may become 5V or more and 10V or less. In addition, in order to control crystal growth during electrodeposition, the flow rate of the plating solution around the conductive substrate becomes important. If the flow rate of the plating solution is high, a large number of small crystal grains will grow, so it can be adjusted appropriately. However, it is difficult to quantitatively measure the flow rate. When forming a roughened layer by electroplating while stirring the plating bath using a stirrer, the rotation speed of the stirrer can be appropriately adjusted. As a method of forming the roughened layer, it is particularly effective to appropriately change the current density, the concentration of the conductive salt in the plating solution, the bath temperature, and the like as other plating conditions.

Lead frame material, supports and fixes semiconductor components, as connection terminals for exchanging electricity and signals with the outside, such as for semiconductor packages. The lead frame material can be suitably used for transistors and capacitors, light emitting diodes (LEDs), and the like depending on semiconductor elements to be mounted.

According to the embodiment described above, the number of grain boundaries existing in the surface of the roughened layer of the lead frame material is controlled below a predetermined value, so that resin adhesion is improved even after a long period of use in a high-temperature and high-humidity environment. Also good.

The embodiments have been described above, but the present invention is not limited to the above-mentioned embodiments, but includes all the aspects included in the concept of the present invention and the claims, and various changes can be made within the scope of the present invention. [Example]

Next, Examples and Comparative Examples will be described, but the present invention is not limited to these Examples.

(Examples 1-19, Comparative Examples 1-5) For conductive substrates of the types shown in Table 1 and having a plate thickness, under the conditions shown below, as a pretreatment, after performing cathodic electrolytic degreasing and pickling, the electroplating method using the conditions shown in Table 1 and below, A roughened layer is formed on the conductive substrate. Next, when forming the intermediate layer (middle lower layer and intermediate upper layer) and the surface layer, the intermediate layer is formed on the roughened layer so as to have the thickness shown in Table 1 by the plating method under the conditions shown in Table 1 and below. , surface layer, etc. In this way, a lead frame material is obtained.

The pretreatment conditions are as follows.

[Chodic electrolytic degreasing] >Solution composition> Sodium hydroxide: 60g/L Liquid temperature: 60°C Current density: 2.5A/dm ² Processing time: 60 seconds

[pickling] >Solution Composition> 10% sulfuric acid Liquid temperature: room temperature Processing time: 30 seconds

Regarding the formation of the roughened layer, in a cylindrical electroplating tank with an inner diameter of 80mm, put a stirrer with a diameter of 5mm and a length of 30mm, and put 1L of plating solution, using a magnetic stirrer, at a speed of 0~ Change within 800r.p.m. to adjust the stirring state. The conditions for forming the roughened layer are as follows, and Table 1 shows the voltage (unit: V) and the rotation speed (unit: r.p.m.) of the stirrer during the roughening plating.

[Coarse Cu plating] >Solution composition> Copper sulfate: 5-10g/L as copper concentration Sulfuric acid: 30-120g/L Ammonium molybdate: 0.1-5.0g/L as molybdenum (Mo) metal Liquid temperature : 20～60°C Current density: 10～60A/dm ²

[Coarsening Ni plating] >Solution composition> Nickel sulfate: 10~50g/L Boric acid: 10~30g/L Sodium chloride: 30~g/L 25% ammonia water: 10~30mL/L Bath temperature: 50° C current density: 4～10A/ ^dm2

The formation conditions of the intermediate layer are as follows.

[Ni plating] >Solution composition> Nickel sulfamate: 300~500g/L Nickel chloride: 20~40g/L Boric acid: 20~40g/L Liquid temperature: 50°C Current density: 6~10A/dm ²

[Pd Plating] >Solution Composition> Tetraammine palladium(Ⅱ)chloride: 1-50g/L Ammonium sulfamate: 0.1-300g/L Glycolic acid: 0.001-100g /L ammonium phosphate: 0.1～50g/L ammonium chloride: 0.1～300g/L liquid temperature: 30～70°C current density: 0.2～50A/dm ²

[Rh plating] >Solution composition> Rhodium sulfate: 2~10g/L Sulfuric acid: 50~90g/L Liquid temperature: 50°C Current density: 0.1~5A/dm ²

[Plating of Ru] >Solution composition> Nitroso ruthenium chloride: 2～20g/L Ammonium sulfonic acid: 10～30g/L Liquid temperature: 60°C Current density: 0.1～50A/dm ²

The conditions for forming the surface layer are as follows.

[Strike plating of Au] >Solution composition> Potassium gold cyanide: 1～5g/L Citric acid: 10～60g/L Potassium citrate: 50～100g/L Liquid temperature: 40°C Current density: 0.1～1A/ ^dm2

[AuCo plating] >Solution composition> Potassium gold cyanide: 6~20g/L Citric acid: 60~120g/L Dipotassium hydrogen phosphate: 10~30g/L Cobalt carbonate: 0.1~2g/L Liquid temperature: 40 °C Current density: 0.1～5A/dm ²

[Au plating] >Solution composition> Potassium gold cyanide: 8~20g/L Citric acid: 10~100g/L Dipotassium hydrogen phosphate: 10~150g/L Liquid temperature: 60°C Current density: 0.1~10A /dm ²

[Ag impact plating] >Solution composition> Potassium silver cyanide: 1～5g/L Potassium cyanide: 50～150g/L Liquid temperature: 30°C Current density: 1～5A/dm ²

[Ag plating] >Solution composition> Silver cyanide: 10～100g/L Potassium cyanide: 20～150g/L Liquid temperature: 30°C Current density: 0.1～5A/dm ²

[Sn plating] >Solution composition> Tin sulfate: 20～120g/L Sulfuric acid: 30～150g/L Cresolsulfonic acid: 10～100g/L Liquid temperature: 20°C Current density: 0.1～6A/dm ²

[Cu plating] >Solution composition> Copper sulfate: 200g/L Sulfuric acid: 50g/L Liquid temperature: 40°C Current density: 5A/dm ²

The strike plating of Au was performed in Examples 3-15 and Comparative Examples 3-4, and Au plating was performed in Example 15 and Comparative Example 5. In addition, Ag strike plating and Ag plating were performed in Examples 16-17. Furthermore, Sn plating was performed in Examples 18-19. In Example 1, a roughened layer of Cu plating was formed, and in Example 2, a roughened layer of Ni plating was formed, and no intermediate layer and surface layer were formed. In Comparative Example 1, only the Cu-plated surface layer was formed without forming a roughened layer and an intermediate layer. In Comparative Example 2, a roughened layer of Cu plating was formed without forming an intermediate layer and a surface layer. In Comparative Example 5, plating of the intermediate layer and the surface layer was performed without forming a roughened layer.

>Assessment method> Then, the characteristics and evaluation of each layer and lead frame material were performed as follows. The results are shown in Table 1 and Table 2. In addition, the characteristics of each layer are measured at any time during the production of the lead frame material.

(number of grain boundaries) The roughened layer of the produced lead frame material was observed in section by focused ion beam scanning ion microscope (FIB-SIM). In the cross-sectional observation, when measuring parallel to the surface of the conductive substrate and setting the predetermined length L to 4 μm, the number of grain boundaries of the roughened layer existing on the surface of the roughened layer is measured, and the above-mentioned number per 1 μm of length is calculated. The number of grain boundaries (unit: piece/μm).

(Thickness of Intermediate Layer and Surface Layer) The thickness of the intermediate layer and the surface layer is measured by a fluorescent X-ray test method based on JIS H8501:1999. Specifically, using a fluorescent X-ray film thickness meter (SFT 9400, manufactured by SII NanoTechnology Inc.), with a collimator (collimator) diameter of 0.5 mm, arbitrary 10 points of each layer were measured, and the average of these measured values was calculated. value, thereby obtaining the thickness of the middle layer and the surface layer. In addition, when the surface layer is copper, the thickness is measured by the electrolytic test method based on JIS H8501:1999. Specifically, using an electrolytic film thickness meter (CT-4, manufactured by Densoku Instruments Co., Ltd.), each measurement was performed on a 1 cm ² area (arbitrary five locations), and the average value (n=5) was calculated to obtain The thickness of the surface layer. In addition, the electrolytic solution used in the electrolytic test method was K52 manufactured by Densoku Instruments Co., Ltd.

(coarsening layer height) The section of the produced lead frame material was sliced and observed at 20,000 magnifications using an SEM. The height of 10 convex parts randomly selected from the observation image of a roughened layer was measured, and the average value of these measured values was made into the height of a roughened layer. When 10 protrusions cannot be observed from the cross-sectional SEM image, the protrusions are observed using two to three cross-sectional SEM images having different imaging positions.

(specific surface area of the outermost surface of the lead frame material) The specific surface area of the outermost surface of the lead frame material, which was measured using a three-dimensional white light interference microscope (Contour GT-K, manufactured by BRUKER) as a percentage of the three-dimensional surface area to the two-dimensional surface area ((three-dimensional surface area/two-dimensional surface area) × 100 (%)) (the measurement conditions are 10 times the measurement magnification and use a high-resolution photosensitive coupling device (CCD) camera, and quantify without adding a special filter after the measurement), and the average value (n=5) as specific surface area (%).

(colocated grain boundary) In the analysis of the colocalized grain boundaries in the roughened layer profile, EBSD was used. In addition, in EBSD measurement, in order to obtain a clear Kikuchi line diffraction image, it is necessary to remove foreign matter attached to the measurement surface and to perform a mirror finish on the measurement surface. Therefore, after the resin is embedded in the measurement sample, cross-section polisher (CP) processing is performed, and polishing of the cross-section of the roughened layer is performed to obtain an observation surface.

For the EBSD measurement, a range of 6 μm×16 μm was scanned at a step size of 25 nm, and the height direction was clipped according to the thickness of the roughened layer so that only the roughened layer could be analyzed. The cross section of the roughened layer was analyzed using analysis software (Orientation Imaging Microscopy v5, manufactured by EDAX/TSL (currently AMETEK)). In order to exclude the influence of the resin within the observation range, the data of the grain size below 0.1 μm is removed, and only the data of the roughened layer is extracted, thereby calculating the Coincidence Site Lattice (CSL) from Σ1 to Σ49 . In addition, in the measurement object, when the orientation difference (deviation) of adjacent pixels (pixels) is 15° or more, it is determined to be a grain boundary. Table 1 shows the ratio of cosite grain boundaries below Σ5 to all grain boundaries in the roughened layer existing in the roughened layer as colocated grain boundaries.

(resin adhesion) Using a transfer die tester (Model FTS, manufactured by Kohtaki Corporation), a pudding-shaped test piece made of resin having a contact surface with a diameter of 2.6 mm was injection-molded on the surface of the produced lead frame material. A test for measuring shear force was performed on the test piece that was in close contact with the outermost surface of the lead frame material, and the resin adhesion between the lead frame material and the test piece was evaluated. The resins and devices used in the evaluation tests are shown below.

Resin: SUMIKON G630L (trade name), manufactured by Sumitomo Bakelite Co., Ltd. Device: 4000 Plus (trade name), manufactured by Nordson Advanced Technology

In addition, the measurement conditions of the evaluation test are as follows. Load cell: S50KG Measuring range: 50kg Test speed: 100μm/s Test height: 200μm Number of evaluation trials: 12

First, for the test piece that has been bonded to the lead frame material, the shear force was measured under the above measurement conditions, and the average value (n=12) was used as the resin bonding strength before the high-temperature and high-humidity test. Then, after putting the lead frame material that has been tightly bonded to the test piece into the high temperature and high humidity test (85°C, 85%RH, 168 hours), the shear force was measured by the above measurement conditions, and the average value (n=12 ) as the resin adhesion strength after the high temperature and high humidity test. Then, for the resin adhesion strength before and after the high-temperature and high-humidity test, rank 10kgf/mm2 or ^more as "A" (excellent), and rank 7kgf/mm2 or ^more and less than 10kgf/ ^mm2 as "B" (Good), 0kgf/mm ² or more and less than 7kgf/mm ² is ranked as "C" (impossible). A and B ranks are qualified. In addition, for the decrease ratio of the resin adhesion strength before and after the high-temperature and high-humidity test (suppression of the decrease in the resin adhesion strength), (resin adhesion strength after the high-temperature and high-humidity test/resin adhesion strength before the high-temperature and high-humidity test)× If the value of 100 (%) is more than 80%, it will be ranked as "A" (excellent), if it is more than 70% but less than 80%, it will be ranked as "B" (good), and if it is less than 70%, it will be ranked as "C" (impossible). A and B ranks are qualified.

Subsequently, the state of the peeled interface between the lead frame material and the test piece made of resin after the high-temperature, high-humidity test was visually observed. Then, the case where the resin remained on the lead frame material was made "◯", and the case where the resin was not left on the lead frame material was made "X".

In Examples 1 to 19, the state where the resin remained on the lead frame material was observed. This is presumed to be because, by forming the roughened layer in a state where the adhesiveness of the resin is suitable, the adhesion strength between the lead frame material and the resin increases, so that the interface between the lead frame material and the resin does not occur as in the past. Delamination of the resin due to peeling. As roughening plating conditions, under the optimal conditions of 5-10V and the stirring bar rotation speed set at 100-250r.p.m., crystal growth during electrodeposition can be controlled, thereby making it possible to manufacture a lead frame material whose resin is tightly bonded. Sex is more improved than before.

On the other hand, in the lead frame materials of Comparative Examples 1 to 5, the resin adhesiveness after the high-temperature and high-humidity test was unacceptable, and when shearing after the high-temperature and high-humidity test, the lead frame material and the resin ( The interface between the test pieces) was delaminated, and no resin was observed on the lead frame material.

[Table 1]

[Table 2]

10‧‧‧lead frame material 20‧‧‧Conductive substrate 30‧‧‧roughening layer 32‧‧‧grain boundary 40a, 40b, 40c‧‧‧Convex part 41a, 41b‧‧‧(convex part) root 42‧‧‧Apex B‧‧‧Base of triangle H‧‧‧The height of the triangle L‧‧‧predetermined length

Fig. 1 is a diagram schematically showing a lead frame material according to the present invention and for explaining how to count grain boundaries existing in the surface of a roughened layer. Fig. 2 is a diagram schematically showing a lead frame material according to the present invention and illustrating the height of a roughened layer.

Domestic deposit information (please note in order of depositor, date, and number) none

Overseas storage information (please note in order of storage country, organization, date, and number) none

10‧‧‧lead frame material

20‧‧‧Conductive substrate

30‧‧‧roughening layer

32‧‧‧grain boundary

L‧‧‧predetermined length

Claims (9)

A lead frame material, which has a conductive substrate and a roughened layer formed on at least one surface of the conductive substrate, the lead frame material is characterized in that: when viewed in the section of the aforementioned lead frame material, parallel to the aforementioned conductive The number of grain boundaries existing in the surface of the aforementioned roughened layer measured over a predetermined length of the surface of the substrate is 20 grain boundaries/µm or less. The lead frame material according to claim 1, wherein, viewed from a cross section of the lead frame material, the height of the roughened layer is in the range of not less than 0.1 micrometers and not more than 5.0 micrometers. The lead frame material according to claim 1 or 2, wherein the specific surface area of the outermost surface of the lead frame material is 120% or more. The lead frame material according to claim 1 or 2, wherein, viewed in the cross-section of the lead frame material, colocated grain boundaries below Σ 5 occupy all the grain boundaries of the aforementioned roughened layer present in the aforementioned roughened layer The ratio is above 90.0%. The lead frame material according to claim 1 or 2, wherein the conductive substrate is made of a metal or alloy selected from the group consisting of copper, copper alloy, iron, iron alloy, aluminum and aluminum alloy. The lead frame material according to claim 1 or 2, wherein the roughened layer contains at least one element of copper and nickel. The lead frame material according to Claim 1 or 2, further comprising one or more of the following layers: formed on the aforementioned rough layer, having a composition different from that of the aforementioned rough layer, and containing nickel, palladium, rhodium One or more elements selected from the group of , ruthenium, platinum, iridium, gold, silver and tin. A method for manufacturing a lead frame material, which is the method for manufacturing a lead frame material according to any one of Claims 1 to 7, wherein the method is characterized in that: the roughened layer is formed by electroplating. A semiconductor package made of the lead frame material described in any one of Claims 1-7.

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