JPH0645497A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To realize lead frames of a narrow pitch by providing upper and lower steps in a zigzag manner by a space of at least a thickness of a lead plate at its end in order to obtain an insulating space of adjacent inner leads of the frames. CONSTITUTION:Openings 10 of parts B, C are punched by pressing, and then ends 11 of inner leads of a part A are cut by shearing or laser beam machining. Thus, the inner leads are separated. Then, a plastically processed part 12 is bent by plastically deforming by a press to form an oblique part 9 to a horizontal plane 8 of leads, ends of the leads are alternately changed in different heights, and disposed in a zigzag manner. As a result, the inner leads an be disposed at narrow pitch. Even if the leads are brought into contact when the leads are resin-sealed, a sufficient insulation interval can be obtained at upper and lower rows, and hence an irregular standard of inner lead positions can be alleviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and particularly to a semiconductor device having a narrow bonding pad pitch of a semiconductor chip and a relatively small chip size and requiring a large number of external leads. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, lead frames for semiconductor devices are
It is made by pressing or etching. Since the press method has a low manufacturing cost, it is widely used as a manufacturing method for mass-produced lead frames. However, as semiconductor chip manufacturing technology advances and the chip wiring rules fall below 1 micron, the chip size becomes
If the pitch of the bonding pads is not reduced, the effect of the technique for reducing the chip size and improving the yield cannot be sufficiently obtained. Corresponding to this, the inner lead of the lead frame has become slender because it is necessary to realize a narrow pitch.

The current lead frame production capacity is that in a progressive feed method in which a plurality of molds are arranged and the leads are partially pressed, a plate thickness of 150 μm and a lead width of 120 μm / space 120 μm. A pitch of 240 microns is possible. For the etching method, a 220 micron pitch with 110 micron lead width / 110 micron space is possible. On the other hand, the pad pitch on the chip side is 130 to 150 μm, and recently, a narrow pitch of 110 μm has been considered. Considering the above spacing, it can be seen that it has become impossible to extend the inner leads to the vicinity of the island periphery for wiring.

[0004]

If the punch width of the press die is narrowed in order to realize the narrow pitch, the desired press die for narrow pitch cannot be manufactured due to the strength and manufacturing restrictions. It becomes impossible to punch. At the current level of technology, the limit is about 80% of the thickness of the lead frame.

This is also the case with the etching method. Due to the etching rate, etching becomes extremely difficult at a pitch narrower than the thickness of the lead frame.

Therefore, if the pressing method, which is the conventional manufacturing method, is adopted, the internal leads cannot be brought sufficiently close to the vicinity of the island, and the length of the bonding wire must be compensated for. If the wire length is long, not only the deformation of the wire itself such as twisting but also the resin filled at the time of resin sealing causes a short circuit, an edge touch, etc., which causes a quality problem.

When the method of reducing the plate thickness of the lead frame is adopted, the lead frame can be formed, but the strength of the external lead of the completed product is not sufficient, and the lead bending and flatness cannot be satisfied.

An object of the present invention is to refine a current technology such as a press working method to realize a lead frame with a narrow pitch and to cope with the tendency of increasing the number of pins.

[0009]

The lead frame of the present invention has a zigzag arrangement in which the inner leads adjacent to each other are provided with a step at the top and bottom thereof at a space of at least the lead plate thickness in order to secure an insulation interval. There is. Therefore, in the press working method, the punch width of the press die can be set to be the same as the width of the internal leads, and thus the internal lead pitch can also be set to the same dimension as the lead width.

In the case of press working, if the thickness of the plate is 150 μm, the pitch can be 120 μm of lead width / 240 of space 120 from the current mass production technology level, so the pitch is 120 μm of 1/2 of that. Is fully possible.

[0011]

1 is a perspective view of an embodiment of the present invention.
The semiconductor chip 1 is mounted on the island 4 of the lead frame 2 and the relative positional relationship of each part is shown. (The state used for sealing is transparent and not shown.) A part of the internal lead to be bonded and the B part that widens the space between each lead are separated by shearing and are sufficient for punching with a die. There is a C portion that can be spaced at various intervals, and these are punched and separated with a mold as in the conventional case. Although each lead is connected to the external lead, this portion can be dealt with by a conventional technique, so that the illustration is omitted.

[0012] Two modes are exemplified for the up and down bending. Island 4 to lead frame horizontal surface 8
The inner lead 9 is bent downward every other piece at the same time as the inner lead 9 is shifted and the dimple processing is performed (FIG. 2 (a)). There is a mode (FIG. 2 (b)) in which every other part of the part 9 is bent and shifted every other part.

Here, an example of a method for manufacturing a lead frame will be described. Regarding the outer shape of the lead frame 2, first, the lead frames of the C portion are punched by press working, and subsequently, the lead frames of the A and B portions are separated by shearing working. At this time, at the same time, every other lead may be bent to shift each other or the islands may be bent, or this bending may be performed in another step. Before plating, there is an etching process as a pretreatment process to clean the plated surface. At this time, etching is performed excessively to etch the sheared side surface. By doing so, adjacent leads do not get entangled by burrs or the like and cause a problem in the assembly process. When a light beam having a high energy density such as a laser beam is used for the processing of the A and B portions, the cutting margin can be slightly formed, so that the above-mentioned entanglement does not occur and the surface of the lead frame can be smoothed by etching.

When the internal leads are elastically deformed and fixed by a lead pressing jig (not shown) at the time of bonding, all the internal leads can be aligned and bonded on the same plane. After bonding, if the lead pressing jig is released and the leads are opened, the bending shape can be restored by the elasticity of the lead material, and it is possible to prevent a short circuit between adjacent leads.

When a part of the inner lead is bent, the entire length of the lead 9 is clogged. Therefore, the bent lead 9 and the tip of the unbent lead inevitably have different lengths. The wires 3 do not contact each other. If the leads after elastic deformation are not sufficiently pulled back and forth, the bonding can be performed in a staggered manner for each pin.

FIG. 1 shows a partially bonded wire 3
Is illustrated.

Further, the width of the inner lead capable of wire bonding is 100 μm, and if the pad pitch on the chip side is also 100 μm, it is possible to bond without tilting along the chip and the possibility of contact between wires is minimized. Can be limited.

As the lead frame material, Fe / Ni alloy or copper alloy can be used, and basically there is no limitation as long as it is an elastic metal material. Further, as the plating metal, a conventionally known metal can be used.

FIG. 3 is a plan view of a lead according to another embodiment of the present invention. First, as shown in FIG. 3A, the openings 10 in the B and C portions are punched out by press working, and then the gap 11 between the inner lead tips of the A portion is cut by shearing or laser beam working. This separates each internal lead. Next, as shown in FIG.
As shown in (c) and (d), the textured portion 12 is bent to form an inclined surface 9 with respect to the horizontal surface 8 of the lead, and the height of the lead tip is changed by misalignment. That is, the arrangement of the tips is staggered as shown in FIG.

FIG. 4 shows another embodiment of the hollow type. The lead frame 2 is mounted on the base 7 with Ag paste as the adhesive 5 using alumina ceramics as the base material of the cap 2 and the base 7, and is sealed with the low melting point glass 13 or resin. It is effective for quick delivery and evaluation of initial characteristics.

In one embodiment or another embodiment, a heat dissipation member may be adhered to the back surface of the island 4 for resin sealing in order to improve heat dissipation characteristics.

[0022]

As described above, according to the present invention, since the internal leads can have a narrow pitch, in the conventional structure, in the case of a small chip, the internal leads do not reach the inside sufficiently and become a long wire. Wiring can be done by reference.
In addition, even if the leads touch the left and right during resin encapsulation, a sufficient insulation interval can be secured in the upper and lower rows, so that the standard of uneven internal lead positions can be loosened and the cost increase such as taping to fix the leads with resin tape is possible. This has the effect of increasing the number of pins adopting the above structure.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a semiconductor chip of the present invention.

FIG. 2 is a sectional view of an embodiment of a semiconductor chip of the present invention.

3A and 3B are plan views of manufacturing steps according to another embodiment of the present invention, and FIG. 3C is a sectional view taken along the line AA ′ in FIG. Figure 3 of the staggered array
It is (d).

FIG. 4 is a sectional view of still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Lead frame 3 Bonding wire 4 Island 5 Adhesive 6 Cap 7 Base 8 Horizontal surface 9 Sloping surface 10 Opening hole 11 Between 12 Soft processing part 13 Low melting point glass

Claims (2)

[Claims] 1. A semiconductor device, wherein tip portions of inner leads adjacent to each other provided on a lead frame are vertically arranged in a zigzag pattern. 2. A method of manufacturing a semiconductor device, characterized in that the leading end portions of the inner leads of the lead frame are separated by shearing and the roots of the inner leads are perforated.