JPH051618B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a lead frame material used as a material for a lead frame, which is an electronic component that connects a semiconductor chip and an external terminal.
For more details, C of low chromium iron-chromium alloy,
In addition to stipulating the upper limits of Si, Mn, and Al,
This relates to a lead frame material with excellent corrosion resistance and improved plating and solderability, which is made by cladding Ni or Ni alloy as a cladding material to a base material containing Ni, Cu, Mo or Nb, Ti, Ta, or Zr. . [Prior Art] Conventionally, Fe-Ni42 alloy has been mainly used as a lead frame material due to its strength and thermal expansion characteristics. Since this Fe-Ni42 alloy is expensive, a cheaper material is desired, and copper alloys are also used from the viewpoint of cost merit and conductivity. However, although this copper alloy also has excellent conductivity and heat dissipation, it lacks strength compared to Fe-Ni42 alloy, and this is especially true when outer leads are inserted into components in the automatic IC assembly process. There are inconveniences such as bending. Pure iron and low carbon steel are the cheapest in terms of cost, but cannot be used because they are prone to rust and have poor corrosion resistance. Therefore, it is considered to use stainless steel from the viewpoint of corrosion resistance and strength. However, lead frame materials are required to have good solderability and plating properties because they are soldered to a plating base in order to increase the reliability of the contacts and chip mounting parts. Poor attachment and plating properties. Therefore, the inventor tried to improve this point, and with low Cr, C, Si, Mn, Al
proposed a lead frame material made of an iron-chromium alloy with a specified upper limit value (Japanese Patent Laid-Open No. 59-9149). [Problems to be solved by the invention] The low chromium iron alloy proposed by this inventor still has insufficient plating and soldering properties,
Au, Ag
It was necessary to perform strike plating of Cu and Ni before plating. The present invention was made to solve the above-mentioned problems of the previously proposed lead frame material made of a low chromium iron alloy, and provides a lead frame material with excellent plating and soldering properties. The purpose is to [Means for solving the problem] Therefore, the inventor used the previously proposed low chromium iron alloy as a base material and clad this with Ni or Ni alloy as a cladding material, thereby improving plating and soldering properties. This new finding led to the completion of the present invention. The lead frame material of the first invention of the present invention has 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 remainder substantially consists of Fe, and Ni or a Ni alloy is clad as a cladding material. The lead frame material of the second invention is, in weight%,
Contains 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,
The gist is that the base material further contains 0.6% or less of one or more of Nb, Ti, Ta, and Zr, and the remainder is substantially Fe, and is clad with Ni or Ni alloy Ni alloy. . The lead frame material of the third invention is, in weight%,
Contains 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,
Furthermore, Ni: 3.0% or less, Cu: 2.0% or less, Mo: 4.0
The main feature is that Ni or Ni alloy is clad as a cladding material on a base material containing one or more of the following. The lead frame material of the fourth invention is, in weight%,
Contains 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,
Furthermore, Ni: 3.0% or less, Cu: 2.0% or less, Mo: 4.0
% or less and Nb, Ti,
The gist is that the base material contains 0.6% or less of one or more of Ta and Zr, and the remainder is substantially Fe, and Ni or Ni alloy is clad as the clad material. The lead frame material according to the present invention specifies the upper limit values of C, Si, Mn, and Al of the low chromium iron alloy, and also contains Ni, Cu, Mo, or Nb as necessary.
The base material is one containing one or more of Ti, Ta, and Zr, and the reasons for limiting the range of the components (wt%) will be explained below. Cr; 5.0 to 10.5% Cr is an element that improves the plating properties, heat resistance, and corrosion resistance of the base material, and in order to obtain such effects, it is necessary to contain it in an amount of 5.0% or more. However, if it is too large, it will impair plating and soldering properties, so it must be kept at 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 too much C deteriorates corrosion resistance and solderability, so it is necessary to suppress it to 0.10% or less. Si: 2.0% or less Si is an effective element that acts as a deoxidizing agent during melting and slightly increases corrosion resistance, but if it is too much, it impairs solderability and the toughness of the base material. % or less. Mn: 2.0% or less Mn is an element that acts as a deoxidizing and desulfurizing agent during melting, but if it is too large, it deteriorates the toughness of the base material, so it must be kept at 2.0% or less. Al: 0.10% or less Al acts as a deoxidizing agent, but too much Al impairs solderability, so it must be kept at 0.10% or less. One or more of the following: Ni: 3.0% or less, Cu: 2.0% or less, Mo: 4.0% or less Ni, Cu, and Mo are elements that contribute to improving corrosion resistance, so one or more of these elements However, too much will damage the toughness of the base material.
Ni needs to be 3.0% or less, Cu 2.0% or less, and Mo 4.0% or less. 0.6% or less of one or more of Nb, Ti, Ta, and Zr Since Nb, Ti, Ta, and Zr are all elements that contribute to increasing the strength of the base material, one or more of these Although more than 100% of the content is added, too much will actually harm the toughness, so the total content should be 0.6% or less. In order to obtain the desired corrosion resistance, solderability, and plating properties, it is sufficient that the Ni of the clad material, which is clad in the base material consisting of the above-mentioned components, contains 40% or more of Ni, with the balance being iron. High purity Ni is not required. Further, in some cases, other Ni alloys such as alloys of Ni and Cu containing 40% or more of Ni may be used. When cladding the above-mentioned base material with a cladding material made of Ni, the cladding material may be clad on the entire front and back surfaces of the base material, the cladding material may be clad only on one side of the base material, or one or both sides of the base material. a part of (e.g. central part)
There is a mode in which the cladding material is clad only in the case of cladding. Further, the thickness ratio between the base material and the cladding material, the area ratio in the case of partial cladding, etc. are appropriately selected depending on the required specifications of the lead frame material. Furthermore, as a means of cladding the cladding material to the base material, the most mass-producible method is to overlap the base material and the cladding material, roll them, and press them together.
Moreover, it can be manufactured at low cost. [Example] Examples of the present invention will be described to clarify the effects of the present invention. Table 1 shows the chemical components (% by weight) of the base material used in this example.

【table】

[Table] In Table 1, No. 1 and No. 2 are comparative examples, where No. 1 is equivalent to SUS304 and No. 2 is equivalent to SUS430. No. 3 to No. 12 are invention examples, No. 3 is a base material containing Cr, C, Si, Mn, and Al within the composition range of the present invention, and No. 4 to No. 5 are examples of the invention. This is a base material with one or more of Nb, Ti, Ta, and Zr added to the above basic composition, and No.6 to No.7 have the above basic composition.
Added Ni, Mo and Cu. Also, No.
8 to 12 have the above basic composition plus Ni, Cu, Mo and
A base material containing one or more of Nb, Ti, Ta, and Zr. A strip material (thickness 0.35 mm) made of the components shown in Table 1 was used as the base material, and a strip material (thickness 0.05 mm) made of 70% Ni or more and the balance Fe was applied as the cladding material to both the front and back sides of the base material. As shown in FIG. 1, a lead frame material 14 was produced by cold rolling, in which cladding materials 12 were clad on the entire front and back sides of a base material 10. The final thickness of the lead frame material 14 obtained here was 0.25 mm, and the thickness of the surface clad layer in the final clad state was about 25 μm. The lead frame material thus obtained was further strain-relieved annealed at 650° C. for 3 minutes in ammonia decomposition gas, and tested for corrosion resistance, plating properties, and solderability. Corrosion resistance was evaluated by performing a humidity test in which the product was left in a humid atmosphere at a temperature of 49° and a humidity of 98% for 96 hours, and the presence or absence of rust was examined at that point. The results are shown in Table 2, where the samples with no rust generation are marked with a circle, and the samples with rust are marked with an x mark. To evaluate the plating property, we applied Ag spot plating (approximately 5 μm) directly to the Ni surface, and then
This was done by examining the surface condition after heating for a minute. The results are shown in Table 2, and those that did not blister due to heating are marked with a circle, and those that did blister due to heating are marked with an x. Solderability was evaluated using non-halogen flux by immersing it in solder consisting of 60% Sn to 40% Pb for 10 seconds at a temperature of 230°C. These results are also shown in Table 2, where the cases where the solder adhesion was good are marked with a circle, and the cases where the solder adhesion was not good, that is, there was poor twisting to the center of the clad material. Those that occurred are marked with an x.

[Table] As is clear from Table 2, No. 1 is a comparative example.
and No. 2 have no problem with corrosion resistance, but are inferior in plating and soldering properties, whereas Nos. 3 to 12, which are examples of the invention, have no problems in corrosion resistance, plating properties, and soldering properties. It was confirmed that it was excellent. Note that no significant difference in plating and soldering properties was observed between those that were subjected to strain relief annealing and those that were not. [Effects of the Invention] As explained above, the present invention has Cr:
5.0 to 10.5%, C: 0.10% or less, Si: 2.0% or less,
The basic composition is Mn: 2.0% or less, Al: 0.10% or less, and Ni: 3.0% or less, Cu;
2.0% or less, Mo; 1 or 2 of 4.0% or less
0.6% or less of one or more of Nb, Ti, Ta, and Zr is added, and the remainder is substantially
Since the lead frame material is made by cladding Ni as a cladding material to a base material made of Fe, it has significantly improved plating and soldering properties compared to the previous low chromium iron alloy developed by the inventor. Therefore, there is no need to perform Ni strike plating before plating Au and Ag as in the past.
Even if this step is omitted and Au or Ag is directly plated, sufficient plating and solderability can be obtained, which is an excellent effect. Furthermore, it is possible to provide a lead frame material that has better plating and soldering properties than lead frame materials made of ferrite or austenitic stainless steel.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of a lead frame material manufactured in an embodiment of the present invention. 10... Base material, 12... Clad material, 14... Lead frame material.

Claims (1)

[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%
1. A lead frame material comprising: a base material containing the following, the remainder substantially consisting of Fe, and cladding with Ni or a Ni alloy as a cladding material. 2 In 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%
The base material contains the following and further contains 0.6% or less of one or more of Nb, Ti, Ta, and Zr, and the remainder is substantially Fe, and Ni or Ni alloy is clad as a cladding material. Made of lead frame material. 3 In 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%
Contains the following, plus Ni; 3.0% or less, Cu; 2.0%
Hereinafter, a base material containing one or more of Mo; 4.0% or less, and the remainder substantially consisting of Fe,
A lead frame material characterized by being made of Ni or Ni alloy as a cladding material. 4 In 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%
Contains the following, plus Ni; 3.0% or less, Cu; 2.0%
Hereinafter, a base material containing one or more of Mo; 4.0% or less and one or more of Nb, Ti, Ta, and Zr of 0.6% or less, and the remainder substantially Fe is used. A lead frame material characterized by being made of Ni or Ni alloy as a cladding material.