Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Patent
1999-07-21
2000-09-12
Jones, Deborah
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
205271, 205291, 428680, 428687, 428926, 428929, 428935, B32B 1520
Patent
active
061175668
DESCRIPTION:
BRIEF SUMMARY
TECHENICAL FIELD
The present invention relates to a lead frame material useful for the production of lead frames, such as those for semiconductor devices.
BACKGROUND ART
As the integration of IC's and LSI's is increasing, the required pin-count is increasing, necessitating fine patterning of leads. Etching is suited to the production of lead frames having leads of fine patterns from lead frame materials. For example, Japanese Patent Application Unexamined Publication No. 3-148856 (1991) discloses production of lead frames by etching a three-layered lead frame material comprising two metal layers of different thicknesses and an aluminum etching stop layer sandwiched therebetween.
In the method, the etching stop layer enables selective etching of one of the two metal layers of different thicknesses. The thicker metal layer is to be the base material of the lead frame and is thick enough to afford the required mechanical strength. The thinner metal layer is to be the bonding areas for connection with IC's and is thin enough to form finely patterned bonding areas. Thus lead frames having both fine bonding areas for connection with IC's and sufficient mechanical strength can be produced by the selective etching.
The etching stop layer of the three-layered lead frame material used in the method, however, is an aluminum layer formed by vapor deposition. The vapor deposition for forming the aluminum layer disadvantageously requires a complicated process, which increases the production cost of the lead frame material.
Further, in the course of producing lead frame by the above-described method, the three-layered lead frame material is exposed to high temperatures when, for example, polyimide films are bonded as an insulating protective films to the surfaces of the lead areas with polyamic acid adhesives by curing the adhesives at 350.degree. C. or higher. The etching stop layer therefore requires a good heat-resistance enough to withstand such a high temperature. For example, nickel layers, which are readily formed by electroplating, cannot act as etching stop layers, because copper diffuses from metal layers into the nickel layers at high temperatures of 350.degree. C. or higher.
In Japanese Patent Application Unexamined Publication No. 5-121617 (1993) is disclosed the production of lead frames from a two-layered lead frame material comprising a first copper layer of 80 to 150 .mu.m thickness and a second aluminum layer of 10 to 50 .mu.m thickness, by selectively plating a third copper layer on the second aluminum layer, and then patterning the first copper layer to form inner leads. Having the aluminum layer as an etching stop layer, the two-layered lead frame material used in the method also involves the same problem as that with the three-layered lead frame material.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a three-layered lead frame material and a two-layered lead frame material, which have an etching stop layer being able to formed readily by electroplating without requiring a troublesome process such as vapor deposition and having excellent heat-resistance.
As the results of studies to solve the above-described problems, the inventors have found that a specific alloy layer of a specific thickness is useful as the etching stop layer of three-layered and two-layered lead frame materials because it can be formed readily by electroplating without requiring a troublesome process such as vapor deposition and contributes excellent heat-resistance to the three-layered and two-layered lead frame materials. They have completed the present invention on the basis of the finding.
That is, the present invention provides a lead frame material, comprising formed on the copper or copper alloy layer (A) and contains 0.3 to 1.0 wt % of phosphorus; and nickel-phosphorus layer (B).
The present invention further provides a lead frame material, comprising formed on the copper or copper alloy layer (A) and contains 0.3 to 1.0 wt % of phosphorus.
BEST MODE FOR CARRYING OUT THE INVENTION
The
REFERENCES:
patent: 4935310 (1990-06-01), Nakatsugawa
patent: 5403672 (1995-04-01), Urasaki, et al.
Aso Kazuyoshi
Matsumoto Tatsunori
Noguchi Masami
Jones Deborah
Koehler Kobert R.
Nippon Denkai Ltd.
North Corporation
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