JPS6257106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a lead frame for an integrated circuit, and more particularly to a lead frame having an aluminum coating layer spotted in the longitudinal direction.

Conventionally, this type of lead frame has a base material made of Kovar or Fe-42%Ni alloy,
Lead frames made of vapor-deposited or clad aluminum are known as inexpensive and practical lead frames, but lead frames made of vapor-deposited or clad aluminum have the following problems in manufacturing.

In other words, since aluminum cannot be plated using normal methods, the only means of covering it are vapor deposition or cladding, but these methods require the first step.
As shown in the figure, the aluminum layer 2' can be provided in stripes at best on the base material 1', and it is extremely difficult to provide the aluminum layer 2' only in spots where necessary.

For this reason, as shown in Figure 2, the punched product can only be used in relatively simple products with a small number of pins, in which the lead leg 3' can only be protruded in the width direction where the aluminum coating layer is present. Ta.

On the other hand, as shown in FIG. 3, gold, gold,
A method of spot plating precious metals such as silver is known, but this method uses a mechanical mask and a plating liquid spray nozzle, so the direction of the lead leg 6' is not limited to the width direction, so it is complicated. lead frames can be manufactured. However, such lead frames have the disadvantage that they are expensive because they use precious metals such as gold and silver.

In addition, the lead frame is bonded with an IC chip on the required surface, and then packaged with resin or the like after wire bonding. However, the lead frame and the package material do not fit well, so it is difficult to ensure sufficient adhesion during the packaging process. This will reduce the reliability of the IC product.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to economically advantageously fabricate a lead frame having a complex structure having aluminum coating layers spotted in the longitudinal direction in a short time by an etching method using a mechanical mask. The objective is to provide a method that can produce

That is, the gist of the present invention is to coat at least one entire surface or a part of one surface of a base material consisting of a long strip with aluminum in a striped manner by cladding or vapor deposition, and then remove unnecessary materials from the base material. In a method for manufacturing a lead frame having a necessary aluminum coating layer in spots in the longitudinal direction by selectively removing the aluminum coating layer, a hollow chamber into which an etching solution is introduced when removing the unnecessary aluminum coating layer. The hollow chamber is provided with a plurality of small holes for injecting the etching solution from the inside toward the unnecessary aluminum coating layer. Aluminum coating in the longitudinal direction, characterized in that the etching process is performed by setting an etching liquid supply device provided with a masking protrusion for mechanically masking the necessary aluminum coating layer in contact with the base material. A method of manufacturing a lead frame having a layer in spots is provided.

The time to remove the unnecessary aluminum coating layer by etching from the aluminum coating layer which is coated on the entire surface or a part of one side of the base material by cladding or vapor deposition in the form of stripes is immediately after the aluminum coating layer is coated on the base material by cladding or vapor deposition. Alternatively, aluminum may be clad or vapor-deposited on the base material, and then punched.

Generally, there are various methods for selectively removing unnecessary aluminum, such as the following.

Dissolution removal method using chemicals - 1 Masking method (1) Mechanical masking method (2) Paint resist method a Spray coating method b Offset printing method c Photo resist method d Screen printing method I-2 Dissolution method (1) Chemical etching Example, Caustic soda aqueous solution (concentration 1% to saturated aqueous solution), hydrochloric acid aqueous solution (concentration 1 to 35%) (2) Electrolytic etching Example, hydrochloric acid aqueous solution (concentration 1 to 35%) Mechanical removal method By grinder, wire brush, shotplast method Removal FIG. 4 of the accompanying drawings shows a method of etching and removing an aluminum coating layer by mechanical masking, as an embodiment of the method of the present invention.

In the figure, a base material 1 consisting of a long strip-shaped body
A material made of Fe-42%Ni alloy and having aluminum 2 deposited on the entire surface of one side was used.

3 is a base for supporting the base material 1; 4 is an etching liquid supply device having a masking protrusion 5; a hollow chamber 6 filled with etching liquid; a plurality of small holes 7; and a liquid inlet 8. Arrows indicate the flow direction of the etching solution.

As a method for removing multiple unnecessary aluminum layers, the base material 1 is fixed to the base 3, the masking protrusion 5 is brought into close contact with the surface of the base material 1 on which the necessary aluminum coating layer is deposited, and the etching liquid supply device 4 is turned on. Set.

Then, in this state, the etching liquid is sent into the hollow chamber 6 from the liquid inlet 8, and is injected through the plurality of small holes 7 onto the unnecessary aluminum coating layer deposition surface of the base material 1, thereby etching the unnecessary aluminum coating layer. Remove.

The portion that is mechanically masked by the masking protrusion 5 and remains as the necessary aluminum coating layer deposition surface is in the form of a spot.

In FIG. 4, unnecessary aluminum is removed by arranging the base material 1 vertically, but it is of course also possible to remove unnecessary aluminum by arranging the base material horizontally.

According to the lead frame manufacturing method of this embodiment carried out as described above, the following effects can be obtained.

(1) When removing an unnecessary aluminum coating layer, a hollow chamber is provided for introducing an etching liquid into the hollow chamber, and a plurality of small holes are used to spray the etching liquid from inside the hollow chamber toward the unnecessary aluminum coating layer. and a masking protrusion for mechanically masking the necessary aluminum coating layer by contacting the necessary aluminum coating layer during etching in the hollow chamber. By setting it on the material and performing the etching process, the unnecessary aluminum coating layer can be continuously removed by using a mechanical mask etching liquid spray method, which is the opposite of spot plating. It can be efficiently removed in a short time (high-speed removal), and at the same time, the necessary aluminum coating layer can be left in spots. As a result, an aluminum-coated lead frame with a complicated structure can be obtained economically, and the range of use of the aluminum-coated lead frame can be significantly expanded.

(2) After the aluminum coating layer coated by cladding or vapor deposition using the above method is removed by etching, a satin-like slightly uneven surface remains, and the existence of this uneven surface makes it difficult to package. At this time, the lead frame and package material become more compatible, and the gripping force between them is significantly improved. As a result, it is possible to reliably prevent moisture from entering the package,
By being able to prevent corrosion of bonding wires due to moisture intrusion, the reliability of IC products can be significantly improved.

Moreover, such an uneven surface has the effect of being very easily compatible with solder during soldering.

As described above, the present invention employs an etching method using a mechanical mask to economically advantageously manufacture a lead frame having a complex structure having an aluminum coating layer spotted in the longitudinal direction in a short time. It can be said that the industrial value of this method is extremely large.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams of a conventional example, and FIG. 4 is an explanatory diagram of an embodiment of a lead frame manufacturing method according to the present invention. 1: Base material, 2: Aluminum, 3: Base, 4: Etching liquid supply device, 5: Masking protrusion, 6: Hollow chamber, 7: Small hole, 8: Liquid inlet.

Claims (1)

[Claims] 1. After coating at least one entire surface or a part of one surface of a base material consisting of a long strip with aluminum in a striped manner by cladding or vapor deposition, selectively removing an unnecessary aluminum coating layer from the base material. In the method for manufacturing a lead frame having a necessary aluminum coating layer in spots in the longitudinal direction, the lead frame has a hollow chamber into which an etching solution is introduced when removing the unnecessary aluminum coating layer, and the inside of the lead frame is A plurality of small holes are provided in the hollow chamber for injecting the etching solution toward the unnecessary aluminum coating layer, and the hollow chamber is further provided with a plurality of small holes for spraying the etching solution onto the unnecessary aluminum coating layer during etching. A lead frame having an aluminum coating layer spotted in the longitudinal direction, characterized in that an etching liquid supply device provided with masking protrusions for mechanical masking is set on the base material to perform the etching process. Production method.