JPS58141546A - Leadframe material - Google Patents

Abstract

PURPOSE:To obtain a lead frame material having excellent punching productivity and plating characteristic. CONSTITUTION:A lead frame material is composed of an alloy containing 15- 25% Ni, 1-30% Cu and Fe which is substantially a remainder. If Ni is not added exceeding 15%, metal organization becomes unstable. Accordingly transformation occurs at the heating and cooling after formation of a lead frame, for example, at the plastic mold temperature and thereby dimensions change, or if Ni is added exceeding 25%, a thermal conductivity is deteriorated and economical manufacturing is no longer possible. Moreover, if Cu is not added exceeding 1%, any improvement in plating characteristic and solderability can not be realized. On the other hand, if it is added too much, a hot producibility is deteriorated and crack may be generated at the time of rolling into a sheet. There is no substantial problem of impurity in case of adding an allow to the pure iron during manufacturing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an abrasive for lead frames of semiconductor devices such as ICs and LSIs.

Traditionally, many ICs and LSIs have been 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 we believe that this trend will become even stronger in the future. It will be done. Of course, there was also a demand for lower monthly lead frame rates.

Kovar alloy (29Ni) is used as a lead frame for ceramic packages due to its thermal expansion coefficient and sealing properties.
-i 6Co -Fe) was favorable - & rt, but as Co 1111i price soared, 42Ni-Fe
Alloys have come into widespread use. However, since Ni is also expensive, there has been a strong demand for a cheaper feed.

Proposals that meet this demand include, for example, (34”-4(
1) Use of Ni-(2~I(1)Cu-Fe alloy (JP-A-56-33457 +3') or (25~50)N
There are leads of j-(1-25) Cu-F'e alloy (Japanese Patent Application Laid-Open No. 50-50550), but these are il, 2
Attach the thermal expansion coefficient and corrosion resistance of N i -1+' e alloy.
We are facing the torture of replacing part of N1 with CIJ as long as it does not change anything.

Did the inventor use plastic mold? Pi, lead frame mounting plate used for manufacturing child devices: ・t &,
1: % Ceramic package materials have characteristics that are appropriately selected from a different perspective, and considering that they should also serve as layer 1, the idea is not to replace the conventional N1 with CLI, but to We researched the balance between desired properties and price by adding a certain amount of alloying ingredients, and arrived at the Kinoe 191.

The lead frame material of the present invention has a Ni content exceeding 15%2.
It is characterized by being made of an alloy containing less than 5% Cu and less than 30% Cu: 1 to 10%, with the remainder being substantially Fe.

Apart from price, the properties required of the sheet frame material used in plastic molds are strong corrosion resistance, plating and solderability, a coefficient of thermal expansion close to that of chipping, and side heat strength.

The Fe-Ni-Cu alloy having the above composition has a good balance of these properties. That is, the feeding properties are considerably high due to the presence of Ni, the plating properties and solder resistance I11 are significantly improved by the addition of Cu, and the strong adhesion and bending properties are also high.

Thermal conductivity and ini-I thermal strength are not bad, and the thermal expansion coefficient also shows a satisfactory value. Punching workability is 42Ni-
It is far superior to high Ni content materials such as Fe alloys. Ease of punching is an important factor because it makes the processing process into lead frames advantageous and greatly contributes to reducing the manufacturing cost of the entire electronic equipment.

The alloy components mentioned above were selected from this point of view, but to add to the explanation, if Nl is not added in an amount exceeding 15%, the metal structure will become unstable, making it difficult to heat and cool the lead frame after forming it. , for example, transformation occurs at the temperature of the plastic mold and the dimensions change, and 25
Addition of more than 1% decreases thermal conductivity, which goes against the purpose of manufacturing at low cost. Moreover, Cu is 1%
If the amount is less than the above, it will not be possible to improve the plating properties and solderability, and on the other hand, if the amount is too large, the hot workability will be reduced and cracks may occur during rolling into a sheet.

When 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 other manufacturing methods are used and impurities are unavoidable, the following It has been determined that the components of

C: up to 0.3%.

S] and Mn: up to 3%. Ta, the combination d1 is 3
Must not exceed %.

The suitability of the lead frame material of the present invention for plastic molded semiconductor devices is shown by data on improved punching workability and plating performance.

EXAMPLES Old materials having the compositions shown in the table below (the remainder being essentially Fe) were made into a bath, rolled into sheets of 5 mm thick, and the surfaces cleaned by pickling.

Punching workability was evaluated by the length of the sheared surface and the size of the burr when a thin plate with a thickness of 0.25 mm was punched using a carbide die with a clearance set to 7% of the plate thickness.

The plating properties are as follows: 3 cm
The specimen was cut into test pieces, plated with a Cu undercoat (1 μm thick) without being separated, and then plated with Ag (4 μm thick) thereon. This plated test piece was placed on a hot plate at 450° C. for 5 minutes, taken out, and the presence or absence of blisters on the front and back sides was counted.

For comparison, similar tests were conducted on 42Ni-Fe alloy and other particles outside the scope of the present invention.

The results are also shown in the table.

Patent applicant: Daido Steel Co., Ltd.

Claims (2)

[Claims] (1) A lead frame material comprising an alloy containing more than 15% Ni and less than 25% of Cu, 21% to 30% of Cu, and the remainder being substantially I'e. (2) The alloy further contains C: 0.3% or less, Si: 3% or less, and Mn 23% or less. However, the total amount of Si and Mn is limited to 3%. ) The lead frame material according to claim 1, which contains the following.