JPH04261054A - Lead of semiconductor package - Google Patents

Abstract

PURPOSE:To obtain a lead of a semiconductor package whose lead tip does not float up even if load is applied in such a fashion that every lead may come into contact with a pattern on a substrate definitely when joining said substrate. CONSTITUTION:A Z-shaped semiconductor's lead is constituted by forming an acute angle between a lead base end section 2a and a lead central part 2b and between the lead central part 32b and a lead tip section 2c.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to leads for semiconductor packages, and more particularly to the shape of leads in semiconductor packages that connect a semiconductor and a pattern on a substrate via the leads.

0002

2. Description of the Related Art FIG.
1 is a side view showing a lead of a conventional semiconductor package disclosed in the publication; in the figure, 1 is a semiconductor package, and 2 is a lead protruding from the side surface of the semiconductor package 1. FIG. The leads 2 include, from the semiconductor package 1 side, a lead base end portion 2a, a lead center portion 2b, and a lead tip portion 2c.
It consists of 4(a) and 4(b) are side views showing deformation of the lead due to load during bonding, respectively, in which numeral 3 represents a substrate, and 4 represents a pattern formed on the substrate 3.

The leads of a conventional semiconductor package are constructed as described above. For example, as shown in FIG. 4, after positioning the leads 2 and patterns 4, a load is applied to ensure that the leads 2 and patterns 4 are in contact with each other. The solder is heated to melt the solder and achieve the bond.

0004

[Problems to be Solved by the Invention] As electronic devices become smaller and more sophisticated, lead pitches in semiconductor packages are becoming increasingly finer. Therefore, even though higher precision is required in the lead forming process for bending the leads into a predetermined shape, it is still not sufficient. A load is applied to the semiconductor package 1 in the direction of arrow A in order to bring it into contact with the semiconductor package 1 . As described above, in the lead shape of a conventional semiconductor package, the lead base end portion 2a and the lead center portion 2b intersect at an obtuse angle, and the lead center portion 2b and the lead tip end portion 2c intersect at an obtuse angle. Therefore, if a load is applied to bring the lead on the right side into contact with the pattern 4 when facing the diagram in FIG.
Since the lead tip 2c on the left side in the figure (a) was already in contact with the pattern 4, the lead tip 2c slides on the pattern. As a result, the lead tip portion 2c is lifted up, resulting in a situation as shown in FIG. 4(b). If soldering is performed in such a state, there is a problem in that sufficient reliability cannot be obtained.

This invention was made to solve the above-mentioned conventional problems, and even when a load is applied to ensure that all the leads are in contact with the pattern on the substrate, the tips of the leads do not lift up. The aim is to obtain leads for semiconductor packages that are not available.

[0006]

[Means for Solving the Problems] A lead of a semiconductor package according to the present invention is composed of a lead base end, a lead center, and a lead tip from the semiconductor package side, and the lead base end is placed against the bonding surface. In addition to being formed substantially horizontally, the lead center portion has a straight line shape making an acute angle with respect to the lead base end portion, and furthermore, the lead tip portion makes an acute angle with respect to the lead center portion.

[0007]

[Operation] The lead of the semiconductor package according to the present invention is
The base end of the lead, the center of the lead, and the tip of the lead form a Z-shape, and even when multiple lead shapes vary, even if a load is applied to ensure that all the leads are in contact with the pattern on the board, The Z-shaped lead acts as a spring to absorb excess load. Therefore, the vicinity of the lead tip does not slide on the pattern, and the lead tip can be prevented from lifting up.

[0008]

[Example] Example 1. FIG. 1 is a side view showing the leads of a semiconductor package according to an embodiment of the present invention, and FIG.
a) and (b) show the deformation of the lead due to the load during bonding when the lead shown in FIG. 1 is used. 1 to 4 are the same as those of the above conventional example. In this example, T.A.
A resin molded B tape was used. TAB tape is made of 125 μm thick polyimide tape with a thickness of 35 μm.
240 leads each having a width of 100 μm were formed in the outer lead portion by etching. After the inner lead part is bonded to the semiconductor electrode, it is molded with resin, and a lead forming device is used to form the Z as shown in Figure 1.
It was formed into a mold lead shape. Here, the bending angles were θa=45° and θb=50° from the lead base end side.

In order to bring the leads of varying shapes into contact with the pattern 4 on the substrate 3, a load is applied to the semiconductor package 1, but according to the lead shape shown in FIG.
Even if a load is applied in the direction of the arrow so that the lead on the right side in the figure contacts the pattern 4 as shown in FIG. 2(a),
The tip of the lead that was in contact with the pattern on the left side as viewed in the figure does not lift up. This is because the Z-shaped leads act as a spring, and all the leads 2 are securely in contact with the pattern 4 on the substrate 3, as shown in FIG. 2(b).
It can be joined like this.

0010

As described above, according to the present invention, in a lead of a semiconductor package that is provided protruding from the side surface of the semiconductor package, from the semiconductor package side to the lead base end, the lead center part, and the lead tip end. The base end of the lead is formed substantially horizontally with respect to the bonding surface, the central part of the lead is formed in a linear shape forming an acute angle with respect to the base end of the lead, and the tip end of the lead is formed into By making an acute angle with respect to the center, even if a load is applied to ensure that all the leads are in contact with the pattern on the board when the lead shape varies, the lead tips will not lift up, ensuring reliability. This has the effect of providing semiconductor package leads that can form a bonding portion with high properties.

[Brief explanation of the drawing]

FIG. 1 is a side view showing leads of a semiconductor package according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing deformation due to load during bonding of the lead according to Example 1.

FIG. 3 is a side view showing leads of a conventional semiconductor package.

FIG. 4 is an explanatory diagram showing deformation due to load during bonding of a conventional lead.

[Explanation of symbols]

1 Semiconductor package 2 Lead 2a Lead base end 2b Lead center part 2c Lead tip

Claims (1)

[Claims] 1. A lead of a semiconductor package that is provided protruding from a side surface of the semiconductor package, which is composed of a lead base end, a lead center, and a lead tip from the semiconductor package side, and the lead base end is connected to a bonding surface. The leads are formed substantially horizontally with respect to each other, and the central portions of the leads are formed in a linear shape forming an acute angle with respect to the base end portions of the leads, and the leading ends of the leads are formed at an acute angle with respect to the central portions of the leads. A lead in semiconductor packages characterized by: