JPS6215627B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention uses Fe, which is inexpensive and has excellent adhesion to plastic, in plastic molded ICs.
- Concerning Cr-based alloy IC lead frame materials. [Prior art] Conventionally, this type of lead frame material has been made of 42 alloy (41Ni-), which has excellent compatibility with semiconductor elements (Si chips) and excellent sealing properties with ceramics and glass.
Fe) is widely used. However, it has the disadvantage of high cost because it contains a large amount of Ni, which is an expensive raw material. However, in recent years, with the strict demand for reducing the cost of products, there has been a growing demand for materials that are cheaper than before and have the minimum necessary characteristics, leading to consideration of pure iron and stainless steel (SUS430, SUS410). However, the former easily rusts in the atmosphere, so it has poor corrosion resistance, and the latter has excellent corrosion resistance, but the general plating process used for current 42 alloys does not provide good plating adhesion. First, it has the disadvantage that the plating process such as activation treatment is complicated. The present inventor has developed 6 to 6 materials as materials that meet this requirement.
Lead frame material made of 10% Cr-Fe alloy with excellent corrosion resistance without impairing plating properties
50457). [Problem to be solved by the invention] ICs are sealed with ceramic or plastic to protect their elements from the outside, but plastic-sealed types are less reliable in a moisture-resistant environment than ceramic types. This is a drawback. However, in recent years, there has been a trend toward smaller and thinner packages due to the demand for higher density packaging, and there is a stronger desire for improved moisture resistance than ever before. However, since conventional materials have poor adhesion to plastic, water can enter through gaps between the leads and the plastic, causing problems such as corrosion and disconnection of the Al wiring on the element. [Means and effects for solving the problems] From the above points of view, the present invention aims to improve the shortcomings of conventional Fe-Cr alloys, improve adhesion to plastics, and prevent water from entering through gaps. As a result of investigating the correlation with the surface morphology of the material, it was found that the surface roughness
This is based on the discovery that the adhesion to the resin was significantly improved and the plating property was also good at a thickness of 0.4 to 10μ. In other words, in this application, Cr6~10%, C0.1% or less balance Fe
and impurities, and the alloy contains Ni,
One or more of Cu and Mo alone or in combination
The present invention provides a lead frame material characterized by containing an alloy of 0.2 to 3.5% and having a surface roughness of 0.4 to 10μ. The reasons for the limitations of the present invention will be described below. Cr is effective for corrosion resistance, but if its amount exceeds 10%, it will not be possible to obtain plating with good adhesion.
When the amount of Cr decreases, good plating can be obtained, but corrosion resistance deteriorates. If it is less than 6%, the corrosion resistance will be extremely poor and it will not be practical as a lead frame, so it is limited to 6 to 10%. If a large amount of C is contained, it forms carbides and causes corrosion, so the content is set to 0.1% or less. Furthermore, in the present invention, in order to obtain even better corrosion resistance without impairing the plating adhesion of the above-mentioned basic alloy, one or more of Ni, Cu, and Mo may be contained, and the amount thereof may be If it is less than 0.2% in the composite, it has no effect on corrosion resistance, while if it exceeds 3.5%, the plating properties and moldability of the frame will be significantly deteriorated, which is not practical, so it is limited to 0.2 to 3.5%. Although it is desirable that the present alloy contains fewer impurities,
Impurities contained in industrially used raw materials such as Fe and Cr and small amounts of Mn, Si, Al, Mg, Ca, etc. added for the purpose of deoxidation and desulfurization during melting are substantially eliminated by the present invention. does not affect the characteristics of the A feature of the present invention is that high plastic adhesion is obtained by roughening the surface of the final strip in the process of forming the desired plate thickness using an alloy having the composition range described above, and the surface roughness is less than 0.4μ. That doesn't have that effect. If the thickness exceeds 10μ, the adhesion to the plastic will be high, but the plating tends to blister, which is not practical for use as a lead frame, so it is set at 0.4 to 10μ. [Example] The following is an explanation based on an example. After melting and casting the alloy shown in the table in a high frequency induction furnace,
Forged and hot rolled at temperatures above ℃, thickness 3
Rolled into a mm plate. Furthermore, cold rolling and annealing were repeated to obtain a thin plate material with a thickness of 0.25 mm.

〔effect〕

As is clear from the table, alloys 1 to 6 of the present invention have significantly improved adhesion strength and surface roughness compared to comparison alloy 8, general SUS410, and pure iron.
Even Alloy 1 with a thickness of 0.45μ had approximately twice the strength, and excellent plating properties were obtained when the surface roughness was 10μ or less. It is also clear that all of the alloys of the present invention have better plating properties and corrosion resistance that are more suitable for use as lead frames than pure iron and general stainless steel. The surface roughness of the present invention can be obtained by any of the commonly used polishing methods (shot blasting, sandblasting, etc.) other than the belt grinding and pickling methods described in the examples. surface roughness of 0.4μ even in
Similar effects were observed above. As described above, the lead frame material of the present invention is an inexpensive material that has both good plating properties and adhesion to plastic, and greatly improves the reliability of plastic molded packages, and has industrial effects. big.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of plastic adhesion strength testing. 1: sample, 2: thin plate jig for plastic mold, 3: hot plate, 4: plastic.

Claims (1)

[Claims] 1. In an IC lead frame material molded with plastic, the weight ratio is Cr6 to 10% and C0.1.
Fe-Cr alloy with a balance of less than % Fe and unavoidably mixed impurity elements with a surface roughness of 0.4 to 10μ
An IC lead frame material having excellent adhesion to the above-mentioned plastic, characterized in that: m. 2 In the IC lead frame material molded with plastic, the weight ratio is Cr6-10%, C0.1
% or less and one or two of Ni, Cu, and Mo
Contains 0.2 to 3.5% of species or more, singly or in combination, with the remainder
Contains Fe and unavoidably mixed impurity elements
An IC lead frame material having excellent adhesion to plastic, characterized by being made of an Fe-Cr alloy and having a surface roughness of 0.4 to 10 μm.