JPS6024585B2 - Manufacturing method of cladding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a lead frame in an IC (integrated circuit) package.

Conventionally, the external lead 2, which serves as a conductive armature of an IC package as shown in Fig. 1, has a low coefficient of thermal expansion.
External lead 1 for guiding plates such as , PC Permanent Oy, Kovar, etc.
, 2, a thin plate for soldering material such as Ag or Ag alloy having good bonding properties is rolled and crimped at the position that will become the bonding part 2' to form cladding materials 10 and 11 as shown in FIG.
After that, it is completely annealed at a temperature of 600 qo or higher for the purpose of diffusion and softening of the crimped metal (brazing material), and further rolling and rolling-rolling are repeated as necessary to obtain a cladding for an IC lead frame. The material used was punched out from materials 10 and 11 using a press machine. Since the bonding parts 2' of the external leads 1 and 2 are the joint parts when connecting the IC chip with wires such as Au or AI in the IC package, defects that may cause wire breakage due to deterioration of adhesive strength are minimized as much as possible. There is a need to. One of the defects mentioned above is a bulging phenomenon that is thought to be caused by gases such as ○ and H at the crimped part of the cladding material, but in the conventional manufacturing method of cladding material for IC lead frames, various rolling conditions are used when crimping the cladding material. Even if the changes were made, it was not possible to prevent blistering from occurring during bran anchoring or rolling after dawn rolling.

The present invention was made in view of the problems in the method of manufacturing a cladding material for an upper C lead frame.

That is, the present invention is a method for producing a cladding material for a lead frame, characterized in that a brazing material of Ag or an Ag alloy is rolled and bonded to an IC lead frame substrate, and then subjected to dawn anchoring at a temperature of 500° C. or less.

The present inventors believed that the cause of blistering in the cladding material for IC lead frames was due to the dawn anchor, and when they investigated the state of blistering by varying the competitive cooling temperature, they found that the blistering occurred around 500 oO as shown in Figure 3, 12. The cladding materials that were phosphorus dulled at higher temperatures had a higher number of blisters.

It was also found that as the number of blisters increases, the size of the blisters also increases. Next, after completing Akatsuki Anchor for the purpose of diffusion of 500 pm or less, 60 pm for the purpose of softening.
If you anchor at 0:00 (Fig. 3, 14), it will become 600 at once.
The number of blisters is much smaller than when using a hot hammer (Fig. 3, 12-a), and there is no problem with the hardness of the lead frame substrate or brazing material. The number of blisters was even smaller when the material was rolled at 600 qo after the post-rolling process (FIG. 3, 13). In addition, when we investigated edge crimping defects (peeling at the crimped boundary) on products that were cold rolled after diffusion annealing at 500 degrees Celsius or less, no defects were observed, as with the conventional Akatsuki temperature of 600 degrees Celsius. There wasn't.

This indicates that a diffusion of 500 oo or less at the rolling crimping part is sufficient. In this way, after rolling and crimping, 500
By dulling at a relatively low temperature below ℃, it was possible to significantly reduce defects (blisters) compared to conventional manufacturing methods. Example 1 IC lead frame substrate where 4 is i and Ag-Cu
A thin plate of alloy brazing material is heated at room temperature using the apparatus shown in Fig. 4.
The cladding material rolled and crimped at a rolling reduction rate of 30% was subjected to a 400qo diffusion hammer, and the number of blisters in the cladding material that had gone through various processes and the presence or absence of peeling at the edges of the brazing material were examined to determine the number of bulges in the brazing material. The results are shown in Table 1.

According to Table 1, it can be seen that the number of blisters that occur in all of the products subjected to 40,000 diffusion sintering after clad rolling as in the production method of the present invention is extremely reduced compared to the conventional production method. .

Furthermore, even after diffusion annealing, rolling, and 60,000-degree softening hammering are repeated, no peeling occurs at the edge of the brazing material, and there is no problem in crimping the brazing material. Table 1 Example 2 An IC lead frame substrate made of Kovar and a thin plate of Ag brazing material were rolled at a temperature of 30,000 using the apparatus shown in FIG.
The clad material that was rolled and crimped at a rolling reduction of 50% was subjected to diffusion phosphorus annealing at 300 CO, and then annealed at 60,000 degrees with the clad material that had gone through the rolling -600 oC sintering process, followed by rolling -6.
The number of blisters in the cladding material of the cladding material after the 00oo stamping process and the presence or absence of peeling of the edges of the brazing material were investigated, and the results are shown in Table 2.

According to Table 2, the number of blisters generated is significantly reduced in the method of the present invention in which 30,000 times of diffusion annealing was performed compared to the conventional method.

Furthermore, peeling of the raw material edges does not occur at all as in the conventional method, and there is no problem with the hardness of the IC lead frame substrate.
As explained in Table 2 and above, according to the manufacturing method of the present invention, the cladding material for IC lead frames, which has strict quality characteristics and has a low lead time, can be made to have a significantly higher lead time by drastically reducing blistering defects. This reduces the cost of IC packages and has a great effect on the industry.

Brief explanation of the drawings Figure 1 shows the cross section of the IC package, Figure 2 shows the IC package.
FIG. 3 is a diagram showing the cladding material for a lead frame, FIG. 3 is a diagram showing the diffusion sintering temperature and the number of blisters, and FIG. 4 is a diagram showing an example of a clad rolling machine.

In the figure, 1: IC lead frame, 2: brazing material (crimped metal), 2': bonding part, 3: brazing material, 4: IC chip, 5: connection wire, 6, 8, 9: ceramic package material, 7: Bonding material, 10:・IC lead frame board, 1
1: Raw material thin plate (crimped metal), 15: Reel for soldering material board, 16: Reel for IC lead frame board, 17:
Guide roll, 18: wire brush, 19: heating device, 2
0: Raw material thin plate, 21: IC lead frame board, 22
: Backup roll, 23: Work roll, 24: Deflector roll, 25: Winding roll. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A method for producing a clad material for an IC lead frame, which comprises rolling and bonding Ag or Ag alloy brazing material to an IC lead frame substrate, and then annealing at 500°C or less.