JPS60251249A - Alloy for lead frame for ic with superior corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain the titled alloy capable of effectively preventing stress corrosion cracking by specifying a composition consisting of Ni, C, Mn, Sn, Pb and Fe. CONSTITUTION:This alloy for a lead frame for IC with superior corrosion resistance consists of, by weight, 35-55% Ni, <=0.05% C, <=2.0% Mn, 0.001-3.0% Sn and/or Pb and the balance essentially Fe or further contains 0.01-4.0% one or more among Cr, Mo, Nb, V, Zr, Ti and Ta. The corrosion resistance is remarkably improved without exerting any unfavorable influence on the thermal expansion characteristics and formability, so stress corrosion cracking is prevented to increase the reliability of a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the corrosion resistance of Fe-Ni alloys used in IC lead frames.

Conventionally, 42@gold (Fe-41%Ni) has been widely used as a material for lead frames of semiconductor devices because of its thermal expansion compatibility with semiconductor elements, glass, ceramics, etc.

However, this alloy does not have sufficient corrosion resistance, and it is known that lead breakage accidents often occur due to stress corrosion cracking during the manufacturing process of semiconductor devices or during use after being incorporated into various electronic devices.

Especially recently, these semiconductor devices are required to have higher reliability than ever before in fields such as aviation and aircraft.
Even 1M manufacturers of semiconductor devices can minimize contamination caused by corrosive substances (for example, residual photoetching liquid, pickling liquid, plating liquid, etc., or impurities in sealing resin), which is one of the causes of stress corrosion cracking. Efforts are being made to keep it to a minimum.

However, it is impossible to eliminate the contamination caused by these corrosive substances, and the industry has been eagerly awaiting the development of an alloy with even better corrosion resistance than the conventional 42 alloy.

The present invention was made to improve the corrosion resistance of 42 alloy and eliminate the above-mentioned drawbacks.
~551S, CD, 05% or less, Mn 2.0
% or less of 8n and Pb in total of 0.
An alloy for an IC lead frame having excellent corrosion resistance, which is characterized by containing a coefficient of 0.001 to 3.0, with the remainder consisting essentially of PE, and the above alloy further containing Cr, Mo, Nb, and V.
, Zr, Ti, and Ta in a total amount of 0.01 to 4.0%.

Next, the reason for limiting the composition of the alloy of the present invention will be described.

Ni is the basic component of this alloy, and if the Ni content is less than 35 or more than 55, the thermal expansion coefficient of the alloy will become too large, making it impossible to maintain compatibility with conductive elements, glass, or ceramics. For this reason, the Ni content was set to 35 to 55 inches.

If too much C is contained, carbides will form in the alloy and the corrosion resistance will deteriorate, so the content is set to 0.054 or less.

Although Mn has the effect of improving the hot workability of the alloy, if it is contained in an excessively large amount, the coefficient of thermal expansion, which is a basic characteristic of this alloy, increases, so it is limited to a coefficient of 2.0 or less.

8n and pb have a great effect on improving corrosion resistance, which is the objective of the present invention, but if either one or the total of the two is less than 0.001%, a sufficient effect cannot be obtained.
On the other hand, if the ratio exceeds 6.0, the effect will be saturated and the moldability will be significantly impaired.
%.

Cr, Mo, Nb, V, Zr, Ti, and Ta are also alloying elements that are included to improve the corrosion resistance of this alloy, but the total amount of one or more of them is 0.01.
If it is less than 4, the effect cannot be obtained, and conversely, if it exceeds 40%, the influence on the thermal expansion characteristics cannot be ignored, so 0.0
The content was set at 1 to 4.0%.

The present invention will be explained below with reference to Examples.

The alloy with the composition shown in the table is melted in a vacuum high-frequency induction furnace and then forged at a temperature of 1000°C to 1100°C.

After hot rolling, repeated cold rolling and softening annealing,
A plate with a thickness of 0.10 m was finished at a final cold rolling rate of 30. After that, samples of 1 ym width and 40 strips in length were cut out from this material by photoetching, and heated at 150°C.
The resin-sealed product in the shape shown in the figure at a temperature of 200°C was placed in a high-temperature, high-humidity environment at a temperature of 85°C and a relative humidity of 95°C.
The sample was left to stand for 1,000 hours, and the frequency of cracking in the sample at that time was investigated. The test was conducted on 50 samples for each alloy. The results are also shown in the table.

As is clear from the results in the table, compared to the conventional alloy (alloy number 1), the alloys of the present invention (alloy numbers 2 to 21) have a lower frequency of cracking (and have better corrosion resistance).

As explained above, according to the present invention, it is possible to significantly improve the thermal expansion characteristics and formability (corrosion resistance) of alloy 42 for IC lead frames, thereby increasing the reliability of semiconductor devices and, by extension, the reliability of electronic products. However, the industrial effects are extremely poor.

[Brief explanation of drawings]

Figure 1 is a perspective view of the sample. 1; Sample 2; Encapsulating resin Name of the person making the first correction Chair Iso+++ 1-R Metal Co., Ltd. No. 8 Nori Kono Osamu Osamu Date of person correction order August 28, 1980 (shipment date ) in the "Detailed Description of the Invention" column of the specification to be amended. (No change in content)

Claims (1)

[Claims] 1. Contains, in weight percent, Ni 35-55%, C 0.05% or less, Mn 2.0 or less, and one or both of Sn and Pb in total of 0.001-6.0. An IC with excellent corrosion resistance characterized in that the remainder is substantially made of Fe.
Alloy for lead frames. 2. Weight% Ni 35-55%, CO, 05%
Hereinafter, Mn is 2.0% or less, Sn% and Pb are contained in a total of 0.001 to 5.0% of one or both of them, and Ic
Cr, Mo, Nb, V. Total of 1 or 2 or more of Zr, Ti, and Ta
An alloy for IC lead frames having excellent corrosion resistance, characterized in that the alloy contains 01 to 4.0% Fe, with the remainder substantially consisting of Fe.