JPH11193429A - Copper alloy for multipin lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy having excellent strength, electrical conductivity, solderability, bendability, platability, moldability and resin adhesion property by specifying the contents of Ni, Zn and Sn of the essential components to be incorporated into the copper alloy. SOLUTION: Ni is incorporated at 16 to 30% by weight %, Zn at 5 to 30% and Sn at 1 to 4% as essential components into the copper alloy. Further, one kind or >=2 kinds of Mn, Mg and Si are incorporated at 0.05 to 2% in total therein. If one kind or >=2 kinds of Mn, Mg and Si are incorporated into the copper alloy consisting of Ni, Zn and Sn as essential alloy elements, the workability is improved. Namely, the rim cracks at the time of cold or hot rolling of an ingot are decreased and the yield in a rolling stage is improved. Further, elements which are effective in improving characteristics or impurity elements which do not impair the characteristics may be incorporated into the alloy if their contents are below about 2%. The adhesion to a resin package to a large-sized die pad may be well executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of a copper alloy for a multi-pin lead frame.

[0002]

2. Description of the Related Art Heretofore, as a lead frame material for mounting a semiconductor element, an Fe-30 to 45% Ni alloy having excellent airtightness with a ceramic package has been used. However, in recent years, inexpensive resin packages have been frequently used, and at the same time, inexpensive copper alloys having good conductivity (heat dissipation properties) have been used for lead frame materials (for example, Japanese Patent Laid-Open No. 4-66629, JP-A-6-184
No. 675, etc.). Furthermore, recently, the speeding up and integration of semiconductor elements have been advanced, and the QFP type lead frame 5 in which the lead pins 2 are densely arranged on all sides of the die pad 4 as shown in FIG. 1 or the lead pins 2 as shown in FIG. More than 100 multi-pin lead frames 1 have been developed. In the multi-pin lead frame 1, the tip 3 of the inner lead has a narrow (fine pitch) interval of the lead pins 2 of about 0.5 to 0.05 mm, and the die pad 4 on which a semiconductor element is mounted.
Are also large.

[0003]

When such a multi-pin lead frame having a narrow lead pin interval is formed by using a conventional copper alloy, the lead pins are likely to be defective in shape, and the die pad area is large. Between the resin and the lead frame, the resin may peel or break during use due to the difference in thermal expansion between the resin and the lead frame. These troubles occur in the same manner when the lead frame is formed by punching a die or by etching. From such a fact, the present inventors,
Research on copper alloys with excellent moldability of lead pins and excellent adhesion with resin package (resin adhesion), and copper alloys containing a large amount of Ni and Sn of conventional Cu-Ni-Zn-Sn-based alloys Have found that both of the above properties can be improved, and have conducted further studies to complete the present invention. An object of the present invention is to provide a copper alloy for a multi-pin lead frame which is excellent in lead pin moldability and resin adhesion in addition to the strength, conductivity, solderability, bending workability, plating property, etc. required for a lead frame. And

[0004]

According to the first aspect of the present invention,
16 to 30% by weight (hereinafter referred to as "%") of Ni as a main component;
, And 5 to 30% of Sn and 1 to 4% of Sn.

[0005] The invention according to claim 2 is characterized in that Mn, Mg, Si
2. The copper alloy for a multi-pin lead frame according to claim 1, wherein one or more of the above are contained in a total amount of 0.05 to 2%. 3.

[0006]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, Ni, Zn, S
Each alloy element n improves the properties such as strength, conductivity, solderability, bending workability, and plating properties, and also functions to improve the formability of fine pitch lead pins and the adhesion to the resin package. . The Ni, Zn,
The contents of Sn alloy elements are 16 to 30%,
The reason for specifying 30% and 1 to 4% is that even if any element falls below the lower limit, the above-mentioned properties are not sufficiently improved,
Further, when any one of the elements exceeds the upper limit, the workability is reduced. The effect of improving the moldability and resin adhesion of the lead pin is exhibited by the synergistic effect of Ni, Zn, and Sn contained in appropriate amounts.

In the present invention, the copper alloy according to claim 1 wherein Ni, Zn and Sn are the main alloying elements,
Workability is improved by including one or more selected from the group consisting of n, Mg, and Si. That is, edge cracking during cold or hot rolling of the ingot is reduced, and the processing yield in these rolling steps is improved.
If the content of the selective element is less than 0.05%, the effect cannot be sufficiently obtained, and if it exceeds 2%, the workability of the ingot decreases. Therefore, the content of the selected element is 0.0
It is defined as 5 to 2%. In the copper alloy of the present invention, an element other than the above, which is effective for improving the characteristics, or an impurity element which does not impair the characteristics, may be contained as long as the amount is about 2% or less. If it exceeds 2%, the workability of the ingot may be reduced, which is not preferable.

[0008]

The present invention will be described below in detail with reference to examples. (Example 1) Copper alloys of the present invention composition shown in Table 1 (Nos. 1 to 1)
Was melted and cast by a conventional method to form a 10 mm thick ingot, and the ingot was subjected to face milling to remove oxide scale, and then annealed in the middle to perform cold working to a thickness of 0.1 mm. It was processed into a 12 mm copper alloy plate.

(Comparative Example 1) Copper alloys (Nos. 11 to 15) other than the composition of the present invention shown in Table 1 were processed into a copper alloy plate having a thickness of 0.12 mm in the same manner as in Example 1.

(Conventional Example 1) Copper alloys (Nos. 16 and 17) having the conventional compositions shown in Table 2 were each processed into a copper alloy plate having a thickness of 0.12 mm in the same manner as in Example 1.

Each of the copper alloy plates obtained in Example 1, Comparative Example 1, and Conventional Example 1 was formed into a multi-pin lead frame shown in FIG. 2 and the shape of the lead pin was investigated. The molding was performed by a die punching method or an etching method. Epoxy resin was molded over the entire die pad portion of the well-punched multi-pin lead frame, and the adhesion between the resin and the multi-pin lead frame after the thermal cycle test was investigated. Both lead pin moldability and resin adhesion are 10
The test was carried out every 00 pieces. Tables 1 and 2 show the number of each defect.

[0012]

[Table 1] (Note) * The number of defects per 1000 lead frames. * Example 1

[0013]

[Table 2] (Note) * The number of defects per 1000 lead frames.

As is clear from Tables 1 and 2,
Nos. 1 to 10 were all excellent in lead pin moldability and resin adhesion. This is due to a synergistic effect of alloying elements of Ni, Zn, and Sn contained in appropriate amounts. The shape of the lead pin was good even at the tip of the inner lead at a narrow interval. In addition, Mg, Mn,
A material containing an appropriate amount of at least one type of Si (No. 6-1
Also in 0), the shape of the lead pin was extremely good. On the other hand, No. 11 of the comparative example has less Ni and Zn and does not contain Sn, and No. 12 has more Ni and Sn,
No. 13 has a large amount of Zn and a small amount of Sn, and No. 14 has no Sn, and No. 15 has a small amount of Zn.
Nos. 16 and 17 each had a small amount of Ni or Sn, so both were inferior in lead pin moldability and resin adhesion.

The lead pin moldability and resin adhesion have been described above. However, the copper alloy sheet of the present invention has other properties (strength, conductivity, solderability, bending work) required as a lead frame material. Properties, plating properties, etc.) were also investigated. As a result, all of them exhibited characteristics that were not problematic in practical use. The copper alloy of the present invention is not limited to a multi-pin lead frame, but can provide the same effect when used for a normal lead frame.

[0016]

As described above, in the copper alloy of the present invention, fine pitch lead pins can be favorably formed by the synergistic effect of Ni, Zn, and Sn contained in appropriate amounts. Further, since the adhesiveness to the resin package is good even for a large die pad, peeling and breakage of the resin package are suppressed. Further, by containing one or more of Mn, Mg, and Si, the yield at the time of rolling the ingot is improved. Therefore, the copper alloy of the present invention is extremely useful for a multi-pin lead frame and has a remarkable industrial effect.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a QFP type lead frame.

FIG. 2 is a partial explanatory view of a multi-pin lead frame.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-pin lead frame 2 Lead pin 3 Tip part of inner lead 4 Die pad 5 QFP type lead frame

Claims (2)

[Claims] 1. Ni is 16 to 30% by weight as a main component.
(Hereinafter referred to as%), 5 to 30% of Zn, and 1 to 4% of Sn. 2. The copper alloy for a multi-pin lead frame according to claim 1, wherein one or more of Mn, Mg, and Si are contained in a total amount of 0.05 to 2%.