JPS6347268B2 - - Google Patents

Description

[Detailed description of the invention]

OBJECT OF THE INVENTION [Field of Industrial Application] The present invention relates to lead frame materials for semiconductor devices such as ICs and LSIs. [Conventional technology] In the past, many ICs and LSIs were manufactured using ceramic packages, but as a result of constant price competition, more and more products are being manufactured using lower-cost plastic molds, and this trend will continue in the future. It is thought that it will become even stronger. Of course, lead frame materials are also required to be as inexpensive as possible. Kovar alloy (29Ni-16Co-Fe) was preferred as a lead frame for ceramic packages due to its thermal expansion coefficient and sealing properties, but as the price of Co increased, 42Ni-Fe alloy was increasingly used. I started to do that. However, since Ni is also expensive,
There was a strong demand for the emergence of inexpensive materials. Proposals that meet this demand include, for example (34-
40) Use of Ni-(2~10)Cu-Fe alloy (JP-A-Sho
56-33457) and (25-50)Ni-(1-25)Cu-
There are Fe alloy leads (Japanese Unexamined Patent Publication No. 56-50550), but these have been developed by replacing some of the Ni with Cu, as long as the thermal expansion coefficient and corrosion resistance of the 42Ni-Fe alloy are not significantly changed.
The idea is to change your clothes. Lead frame materials used in the manufacture of electronic devices using plastic molds are required to have minimum required characteristics and be as inexpensive as possible. [Problems to be Solved by the Invention] The purpose of the present invention is to meet the above requirements by using pure iron, which is the most common low-cost material, as a base material, and by improving the insufficient properties with a minimum amount of alloy components. An object of the present invention is to provide a lead frame material improved by the addition of. Arrangement of the Invention [Means for Solving the Problems] The lead frame material of the present invention includes Cu and Ni.
In the case of two types, the total amount is 1% or more and less than 5%, and the remainder is substantially
It is characterized by being made of an alloy of Fe. In manufacturing the lead frame material of the present invention,
There is virtually no problem with impurities when alloying components are added to pure iron, but even when impurities are difficult to avoid when using other manufacturing methods, it has been confirmed that the following components can be tolerated up to the limits listed. ing. C: up to 0.1%. Si and Mn: up to 2% in total amount. [Function] Apart from price, the properties required for lead frame materials used in plastic molds include corrosion resistance, plating and solderability, punching workability, strength and bendability, thermal conductivity, and silicon resistance. It has a similar thermal expansion coefficient as well as heat resistance strength. Looking at pure iron, it has excellent punching properties, sufficient strength and bendability. Thermal conductivity and heat resistance strength are not bad, and the coefficient of thermal expansion is generally satisfactory. Therefore, it is only necessary to slightly improve corrosion resistance, plating properties, and soldering properties. The above-mentioned alloy components were selected from this viewpoint, and the lower limit of the amount added is determined as the limit at which the desired effect can be obtained. On the other hand, the upper limit for Ni is mainly due to price constraints, and for Cu, if it exceeds 5%, the hot workability of the material decreases and cracks are more likely to occur during forging and blooming. This is based on the fact that it would be difficult to manufacture the plate material. [Example] A material having the alloy composition shown in the table below (the remainder is essentially Fe) was melted, rolled into a 5 mm thick sheet, and the surface was cleaned by pickling.
A test piece measuring cm x 10 cm was prepared. To examine the plating properties, we first plated a Cu base (thickness: 1μ), and then plated Ag (thickness:
4μ) was applied. This plating test piece was heated to 300℃.
The samples were placed in an air bath for 10 minutes, taken out, and the number and presence of blisters on the front and back sides were counted. Corrosion resistance is determined by placing the test piece in a humid atmosphere at 96℃ for 10
After leaving it for a while, the number of rusts was counted and used as a scale. For comparison, the same test was also conducted on a test piece prepared in the same manner using pure iron. The results are also shown in the table.

[Table] Effects of the Invention According to the present invention, by keeping Fe as the main component and alloy components at a low level, it is possible to obtain a lead frame material that is inexpensive but comparable in performance to conventional materials with high alloy compositions. This material is particularly useful in lead frames for plastic molded semiconductor devices.

Claims (1)

[Claims] 1 Any one or two of Cu and Ni,
In the case of two types, the total content is 1% or more and less than 5%,
A lead frame material consisting of an alloy in which the balance is essentially Fe. 2 The content of impurities is C: 0.1% or less, respectively.
The lead frame material according to claim 1, comprising an alloy in which the total amount of Si and Mn is regulated to 2% or less.