JPH07116555B2 - Lead frame material and manufacturing method thereof - Google Patents

Description

The present invention relates to a lead frame material used as a material of a lead frame which is an electronic component for connecting a semiconductor chip and an external terminal, and a manufacturing method thereof. More specifically, low chromium iron-chromium alloys such as C, Si, Mn, Al
In addition to specifying the upper limit of, Ni, Cu, Mo or Nb,
Lead frame material with excellent corrosion resistance, which is obtained by plating Ni or Ni alloy or Cu or Cu alloy on the base material added with Ti, Ta, Zr and then cold rolling, and which has improved plating property and solderability. And a method for manufacturing the same.

[Conventional technology]

In terms of strength and expansion resistance, conventional lead frame materials
Fe-Ni42 alloy has been mainly used. Since this Fe-Ni alloy is expensive, a cheaper material is required, and a copper alloy is also used from the viewpoint of cost merit and conductivity. However, this copper alloy is also excellent in terms of conductivity and heat dissipation, but it lacks strength compared to the Fe-Ni42 alloy, and this is especially the case when the outer leads are inserted into parts during IC automatic assembly process. There is an inconvenience such as bending.
Pure iron and low carbon steel are the cheapest in terms of cost,
It cannot be used because it easily rusts and has poor corrosion resistance. Therefore, it is possible to use stainless steel from the viewpoint of corrosion resistance and strength. However, the lead frame material is required to have solderability and plating property because it is plated and soldered to improve the reliability of the contact part and chip mounting part. Inferior in plating property and plating property. Therefore, the inventor tried to improve this point,
A lead frame material made of an iron-chromium alloy in which the upper limits of C, Si, Mn, and Al are defined by Cr has been proposed (Japanese Patent Laid-Open No. 59-91).
49).

[Problems to be solved by the invention]

In the low chromium iron alloy proposed by the present inventor, the plating property and the solderability are still insufficient, and the adhesion of Au and Ag is improved to improve the adhesion of the undercoat.
It was necessary to perform strike plating of Ni and Ni.

The present invention has been made to solve the above-mentioned problems of the lead frame material made of the low chromium iron alloy proposed previously, and provides a lead frame material excellent in plating property and solderability. The purpose is to

[Means for solving problems]

Therefore, the inventor of the present invention newly found that the plating property and the solderability were improved by performing the cold rolling after applying the previously proposed low chromium iron alloy as the base material and completed the present invention. It has come to do.

The lead frame material according to the first aspect of the present invention is C, in weight%.
r; 5.0 to 10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0
% Or less, Al; 0.10% or less, and the balance consisting essentially of Fe, and a plated layer of Ni or Ni alloy or Cu or Cu alloy whose surface is smoothed by cold rolling. That is the summary.

The lead frame material of the second invention is Cr; 5.0-
10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less,
Al; 0.10% or less, and 0.6% or less of one or more of Nb, Ti, Ta, and Zr, and the balance is substantially F.
The gist of the invention is that it comprises a base material made of e and a plating layer made of Ni or Ni alloy or Cu or Cu alloy whose surface is smoothed by cold rolling.

The third leadframe material is Cr; 5.0 to 10.5% by weight.
%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al;
A base material containing 0.10% or less, 0.6% or less of Ni; 3.0% or less, Cu; 2.0% or less, Mo: 4.0% or less, 0.6% or less of one or more, and the remainder being substantially Fe. , Ni or Ni alloy or Cu or Cu with smooth surface by cold rolling
The gist is that the plating layer is made of an alloy.

The lead frame material of the fourth invention is Cr; 5.0-
10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less,
Al: 0.10% or less, Ni: 3.0% or less, Cu; 2.0
% Or less, Mo; 4.0% or less, and one or more kinds and
A base material containing 0.6% or less of one or two or more of Nb, Ti, Ta, and Zr, and the balance being substantially Fe, and Ni or Ni alloy or Cu or whose surface is smoothed by cold rolling. Is characterized in that it is composed of a Cu alloy plating layer.

The manufacturing method of the lead frame material of the fifth invention is
, Cr; 5.0 to 10.5%, C; 0.10% or less, Si; 2.0% or less, M
Containing n; 2.0% or less, Al; 0.10% or less, and the balance substantially Fe
The base material is made of Ni or Ni alloy plating or Cu or Cu alloy plating, cold rolled, and then strain relief annealed.

The alloy used as the Ni alloy or Cu alloy plating may contain Ni or Cu in a proportion of 1 to 50% in total of one or more of P, B, W, Mo, Cr and Ti.

The lead frame material according to the present invention defines the upper limits of C, Si, Mn, and Al of the low chromium iron alloy and, if necessary, one of Ni, Cu, Mo or Nb, Ti, Ta, and Zr, or A material containing two or more kinds is used as the base material, and the reason for limiting the component range (% by weight) will be described below.

Cr; 5.0 to 10.5% Cr is an element that improves the plating property, heat resistance and corrosion resistance of the base material, and 5.0% is required to obtain such effects.
It is necessary to contain the above. However, if it is too large, the solderability is impaired, so it is necessary to set it to 10.5% or less.

C: 0.10% or less It is necessary to contain C to some extent in order to obtain strength as a base material, but if it is too much, corrosion resistance and solderability deteriorate, so it is necessary to suppress C to 0.10% or less.

Si; 2.0% or less Si acts as a deoxidizer during melting and is an element effective in slightly increasing the corrosion resistance, but if it is too much, it impairs the toughness of the base material, so it should be 2.0% or less. .

Mn: 2.0% or less Mn is an element used as a deoxidizing agent and a desulfurizing agent during melting, but if it is too much, the toughness of the base material deteriorates.
It must be less than or equal to%.

Al; 0.10% or less Al acts as a deoxidizing agent, but if it is too much, it hinders solderability, so it must be 0.10% or less.

Ni: 3.0% or less, Cu: 2.0% or less, Mo: 4.0% or less One or more of Ni, Cu, and Mo are elements that contribute to the improvement of corrosion resistance.
One or more of these are added, but if too much is added, the toughness of the base material is impaired, so Ni is 3.0% or less, Cu is 2.0% or less.
Below, Mo must be 4.0% or less.

0.6% or less of one or more of Nb, Ti, Ta, and Zr Nb, Ti, Ta, and Zr are elements that contribute to increasing the strength of the base material. Although more than one kind is added, if the amount is too large, the toughness is rather adversely affected, so it is necessary to make these total 0.6% or less.

The lead frame material of the present invention comprises a base material having the composition as described above and a plating layer made of Ni or Ni alloy or Cu or Cu alloy whose surface is smoothed by cold rolling. As a result, the dimensional accuracy of the thickness of the material is improved, the surface of the material becomes smooth, surface flaws are controlled, and the surface condition is remarkably improved, so that the Au or Ag plating property and solderability are improved.

Further, the lead frame material of the present invention is plated with Ni or Ni alloy or Cu or Cu alloy, and then cold-rolled to smooth the surface of the plating to improve the strength of the base material. Can be improved. Next, strain relief annealing improves the flatness required for the lead frame material.

〔Example〕

Examples of the present invention will be described to clarify the effects of the present invention. Table 1 shows the chemical composition (% by weight) of the base material used in this example.

In Table 1, No. 1 and No. 2 are comparative examples, and No. 1 is
SUS304 equivalent, No.2 is SUS430 equivalent. No. 3 to No. 13 are examples of the invention, and No. 3 is Cr, C within the composition range of the present invention,
It is a first invention example containing Si, Mn and Al, and Nos. 4 to 6 are second invention examples containing one or more of Nb, Ti, Ta and Zr in this basic composition. Nos. 7 to 10 are third invention examples containing one or more of Ni, Cu and Mo in the above basic composition, and Nos. 11 to 14 are N in the above basic composition.
One or more of b, Ti, Ta and Zr and Ni, Cu and M
It is a fourth invention example containing one or more of o.

Using a cold rolled material having a thickness of 0.35 mm consisting of the components shown in Table 1, No. 1 and No. 2 which are comparative examples were not plated,
Inventive examples Nos. 3 to 14 are plated with Ni or Ni alloy plating or Cu plating with 3 to 5 μm as shown in Table 2, respectively.
m, and then cold-rolled to a plate thickness of 0.25 mm. Among the lead frame materials thus obtained, No. 4 to No. 14 were further annealed in ammonia decomposition gas at 650 ° C for 3 minutes for strain relief, and the corrosion resistance, plating property, solderability and strain of each material were investigated. The test was conducted.

Corrosion resistance is evaluated in a humid atmosphere with a temperature of 49 ° C and a humidity of 98%.
A wet test was carried out for 96 hours, and the presence or absence of rust at that time was examined. The results are shown in Table 2. When no rust was generated, the mark was marked with a circle, and when rust was generated, it was marked with a cross.

The plating property was evaluated by directly spot-plating Ag (about 5 μm) on the Ni surface, and then examining the surface condition after heating at 450 ° C. for 5 minutes. The result is the second
As shown in the table, the ones that did not have blisters due to heating are indicated by a circle, and those that did not have blisters due to heating were indicated by a cross.

The solderability was evaluated by using a non-halogen flux and immersing it in a solder composed of 60% Sn to 40% Pb at a temperature of 230 ° C for 10 seconds. The results are also shown in Table 2, but those having good solder adhesion are indicated by a circle, and those having poor solder adhesion, that is, the twisting failure to the central part of the clad material The generated ones are indicated by x.

As shown in Fig. 1, the strain test is performed on the lead frame material 10
At a width of 2 mm from the end 12 of the, a 150 mm distortion-free cutting is made by photoetching to make a cutting portion 14, and a separating portion 16
It was performed by measuring the warp height h (mm) of the tip 16a of the.

As is clear from Table 2, No. 1 and No. 2 which are comparative examples.
Has no problem in corrosion resistance but is inferior in plating property and solderability, which is an invention example of the present invention No. 3 to
It was confirmed that No. 14 is excellent in both corrosion resistance, plating property and solderability, and No. 4 to No. 14 which were subjected to strain relief annealing were No. 1 which were not subjected to strain relief annealing. ~ N
It was shown that the amount of strain was significantly lower than that of O.3, and it was confirmed that the strain relief annealing improves the flatness as one of the properties required for the lead frame material. In addition, no significant difference was observed in the plating property and the solderability between those that were subjected to strain relief annealing and those that were not.

[Advantages of the Invention] The present invention, as described above, is in the range of Cr: 5.0 to 10.5% by weight.
%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al;
0.10% or less is the basic composition, and if necessary,
Ni: 3.0% or less, Cu: 2.0% or less, Mo: 4.0% or less, 1 or 2 or more, or Nb, Ti, Ta, Zr 1 or 2 or more, 0.6% or less is added, and the balance is substantially Base material consisting of Fe and Ni or Ni with a smooth surface by cold rolling
Since it is a lead frame material consisting of a plating layer consisting of Ni alloy or Cu or Cu alloy, it has significantly improved plating property and solderability as compared with the conventional low chromium iron alloy developed by the inventor. , It is not necessary to perform Ni strike plating prior to Au and Ag plating as in the past,
Even if this step is omitted and Au or Ag is directly plated, there is an excellent effect that sufficient plating properties and solderability can be obtained. Further, the flatness required for the lead frame material can be improved by performing strain relief annealing after cold rolling after plating if necessary.
Further, it is possible to provide a lead frame material which is more excellent in plating property and solderability than the lead frame material made of ferritic or austenitic stainless steel.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a strain relief test of a lead frame material. 10 …… Lead frame material, 12 …… End, 14 …… Cut, 16 …… Separate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 23/50 D

Claims (5)

[Claims] 1. By weight%, Cr; 5.0 to 10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al; 0.10% or less, and the balance substantially consisting of Fe. A lead frame material comprising a base material and a plating layer made of Ni or Ni alloy or Cu or Cu alloy having a smooth surface by cold rolling. 2. By weight%, Cr; 5.0 to 10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al; 0.10% or less, further containing Nb, Ti, Ta, Plating consisting of a base material containing 0.6% or less of one or more kinds of Zr and the balance being substantially Fe, and Ni or Ni alloy or Cu or Cu alloy whose surface is smoothed by cold rolling. Leadframe material consisting of layers. 3. By weight%, Cr; 5.0 to 10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al; 0.10% or less, and further Ni; 3.0% or less, Cu; 2.0% or less, Mo: 4.0% or less, 0.6% or less of 1 type or 2 types or more, and the balance consisting essentially of Fe, and Ni or Ni whose surface is smoothed by cold rolling. Lead frame material consisting of alloy or Cu or plating layer consisting of Cu alloy. 4. By weight%, Cr: 5.0% to 10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al; 0.10% or less, and further Ni: 3.0% or less. , Cu; 2.0% or less, Mo; 4.0% or less, one or more kinds, and Nb, Ti, Ta, Zr, one or more kinds, 0.6% or less, and the balance substantially F
A lead frame material comprising a base material made of e and a plating layer made of Ni or Ni alloy or Cu or Cu alloy whose surface is smoothed by cold rolling. 5. By weight%, Cr; 5.0 to 10.5%, C; 0.10% or less, Si; 2.0% or less, Mn; 2.0% or less, Al; 0.10% or less, and the balance consists essentially of Fe. A method for producing a lead frame material, which comprises subjecting a base material to Ni or Ni alloy plating or Cu or Cu alloy plating, cold rolling, and then strain relief annealing.