JP2001308252A - Lead frame for semiconductor ic and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contact failures from being generated due to foreign matter adhesion to a contact pin that contacts with an IC lead in an IC final test. SOLUTION: A conductive metal 10 hardly solder-plated is fixed on the area A of the lead frame 11 welded by the contact pin 3 of an IC socket.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for a semiconductor IC, and prevents a contact defect from occurring due to foreign matter adhering to a contact pin that comes into contact with an IC lead during a final test of the IC. It is intended to do so.

[0002]

2. Description of the Related Art In a final test of an IC, an IC socket matching the IC is used, and a contact pin of the IC socket is pressed against a lead of the IC to provide electrical continuity and a program of a tester is operated to judge the quality. Is performed. The state in which the contact pin of the IC socket contacts the lead of the IC is roughly classified into a case where the contact pin hits the bottom (back surface) of the lead as shown in FIG. 9 and a case where the contact pin hits the top of the lead as shown in FIG. There is. In these figures, 1 indicates an IC, 2 indicates a lead, 3 indicates a contact pin, 4 indicates a pressing member (latch), and 5 indicates a seating plane. In either case, the solder-plated IC leads usually make contact (press-contact) while sliding over the gold-plated contact pins, so that the solder debris of the leads adheres to the contact pins and the contact resistance value Problems, such as an increase in the number of devices and an opening.

[0003] Therefore, conventionally, a method of removing the solder dust attached to the contact pin, or removing it by washing, polishing or the like has been adopted. The contact pins 3 are usually plated with gold. As shown in FIG. 11A, tin and lead as components of the solder plating 6 (indicated by dotted lines) of the leads 2 of the IC and an intermetallic compound of a nonconductor are used. It is easy to form and is a major cause of contact failure. Reference numeral 7 in FIG. 11B indicates an intermetallic compound of solder and gold adhered on the contact pin 3, which causes a contact failure.

A major cause of the above-mentioned contact failure can be said to be a semiconductor IC manufacturing method.
That is, a conventional semiconductor IC is tested by contacting a contact pin of an IC socket with a solder-plated (overall) lead of an IC using an iron-based or copper-based lead frame. Since the leads are plated with solder as described above, solder dust adheres to the contacting portions, resulting in poor contact. Here, FIG.
The flowchart of the manufacturing and testing process of
In the figure, (1) is a step of die-bonding and wire-bonding an IC chip to a lead frame, (2) is a step of molding a chip, (3) is a step of solder plating, and (4) is a lead. Bending step, (5) is I
This is a test step in which the contact pins of the socket are pressed against the leads of C to test.

[0005]

As described above, since the leads of the conventional IC are entirely plated with solder, the solder is liable to adhere to the gold-plated contact pins, resulting in poor contact.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a conductive metal which is hard to be soldered and electrically good is fixed to a contact portion of a lead of an IC. By doing so, it is possible to prevent foreign matter such as solder dust from causing a contact failure at the time of press contact with the contact pin.

[0007]

According to a first aspect of the present invention, there is provided a lead frame for a semiconductor IC, in which a contact pin of a test IC socket is pressed against a part of a lead which is to be bent later and becomes a lead. Area
In advance, a conductive metal that is difficult to be plated with solder is fixed,
Other parts are plated with solder.

A lead frame of a semiconductor IC according to a second aspect of the present invention is one in which a conductive metal is fixed by using a sputtering (vacuum vapor deposition) method.

According to a third aspect of the present invention, the lead frame of the semiconductor IC is made of tungsten, aluminum or chromium which is hard to be plated with solder and has good conductivity.

According to a fourth aspect of the present invention, there is provided a semiconductor device comprising:
It has a semiconductor IC lead frame.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a flowchart illustrating an embodiment of a method for manufacturing an IC using a lead frame according to the present invention. FIG. 1 (a) shows an IC before or after drilling holes or grooves in a lead frame, and
2 is a step of fixing a conductive metal 10 which is difficult to be plated with solder such as tungsten, aluminum, chromium or the like by a sputtering method or the like on a part to be a lead, and FIG. It is the top view which showed A. Next, (2a) shows a molding step for sealing the chip, and FIG. 3 is a plan view showing details of the molding step, showing a lead region partially sputtered. (3a) is a step of solder plating, and FIG. 4 is a cross-sectional view of a lead frame provided with an IC in this step. Indicates that no solder plating 6 is applied. Since tungsten, aluminum, and the like have a property of not soldering,
These fixing portions 10 are exposed. The step (4) is a step of lead bending (FIG. 5), and the step (5) is a step of pressing a contact pin of a socket against a lead of an IC for testing (FIG. 6). FIG. 7A shows contact pins 3
In the case of an IC using a conventional lead frame showing a state of attachment of a foreign substance causing a contact failure, a solder waste 6a by solder plating is attached to the contact pin. FIG. 7 (b) shows the case of an IC using the lead frame of the present invention, in which no foreign matter such as tungsten, which is not compatible with gold, adheres, not to mention the solder.

In the case of the above embodiment, as in the case of the conventional example, when the IC is soldered to the printed circuit board 8, as shown in FIG. As a result, a good fillet 9 is formed, and there is no mounting problem.

[0013]

As described above, according to the present invention, a metal such as tungsten, aluminum, chromium or the like, which is hard to be plated with solder and has good conductivity, is deposited on a portion of the IC lead to which the contact pin is pressed. There are no contact problems such as increased contact resistance or openness when pressed against pins, and when soldering an IC to a printed circuit board, the back and side surfaces of the leads are plated with solder. There are no implementation issues.

[Brief description of the drawings]

FIG. 1 is a schematic flowchart showing a process of manufacturing an IC according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a region where a metal is fixed to a lead frame according to the first embodiment of the present invention.

FIG. 3 is a plan view in a molding step according to Embodiment 1 of the present invention;

FIG. 4 is a cross-sectional view of a lead frame with an IC in a solder plating step according to Embodiment 1 of the present invention;

FIG. 5 is a front view showing a lead bending step according to the first embodiment of the present invention.

FIG. 6 is a front view showing a test step of the semiconductor IC according to the first embodiment of the present invention;

FIG. 7 shows a conventional example of a contact pin when a contact pin of an IC socket contacts an IC lead (a).
FIG. 4 is a cross-sectional view illustrating a state according to the present embodiment (b).

FIG. 8 is a cross-sectional view showing a state where the IC is soldered to a printed circuit board.

FIG. 9 is a cross-sectional view showing a state in which a contact pin of an IC socket contacts an IC lead.

FIG. 10 is a cross-sectional view showing a state where a contact pin of an IC socket contacts an IC lead.

FIG. 11A is a cross-sectional view showing a conventional contact state between a lead and a contact pin, and FIG.
It is.

FIG. 12 is a flowchart showing a conventional IC manufacturing process and a test process.

[Explanation of symbols]

1 IC, 3 contact pins, 6 solder, 10 metal fixing part, 11 lead frame.

Claims (4)

[Claims] In a lead frame for a semiconductor IC, a part of a lead frame which is later lead bent and becomes a lead is provided.
A semiconductor IC lead characterized in that an area of a lead frame to which a contact pin of a test IC socket is pressed against is fixed in advance with a conductive metal which is difficult to be plated with solder, and the other parts are plated with solder. flame. 2. A conductive metal is sputtered (vacuum deposition).
2. The lead frame of a semiconductor IC according to claim 1, wherein the lead frame is fixed by a method. 3. The semiconductor IC lead frame according to claim 1, wherein tungsten, aluminum, or chromium, which is difficult to be plated with solder and has high conductivity, is used. 4. A semiconductor device comprising the semiconductor IC lead frame according to claim 1.