JPH0365894B2 - - Google Patents

Abstract

PURPOSE:To unnecessitate or sharply reduce the correction by hand works by a method wherein the first bonding is performed on the column located outside the boundary line of the first and the second regions, and the second bonding is performed on the column located inside the boundary line. CONSTITUTION:The first ball bonding is performed on the wire pads 4a and 5a of the column located outside the boundary line 9 of substrates 2 and 3, and the second wedge bonding is performed on the wire pads 4b and 5b of the column located inside the boundary line 9. Consequently, as bonding wires 6a and 6b do not come in contact with each other because they are separated in upward direction from the pads 4b and 5b of the inside column on the side they are connected to the pads 4a and 4b of the outside column, the wires 6a and 6b can be made short in length. On the other hand, the wires 6a and 6b are moved in close to the surface of the substrates 2 and 3 on the side where they are connected to the pads 4b and 5b of the inside column, but as there is no other pad in the vicinity of them, they intersect only at the point P located in the neighborhood of the boundary line 9. Accordingly, the wire which is used to correct the contact of the wires and the pads and the correcting work are unnecessitated, or those processes can be reduced substantially.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a wire bonding method using staggered wire bonding.

[Technical background of the invention and its problems]

Wire bonding is often used to connect wiring patterns in different areas or to connect wiring patterns and input/output wire bonding pads of chip components such as IC chips. In recent years, with the increase in wiring density on substrates and the degree of integration of IC chips, higher density wire bonding has been required, and one of the wire bonding methods suitable for higher density is staggered wire bonding. There is wire bonding.

Staggered wire bonding is a technique that enables high-density wire bonding by arranging bonding positions in a staggered manner so that the distance between adjacent bonding positions is greater than the interval between wiring patterns.

FIG. 4 shows a specific example of staggered wire bonding according to the prior art, in which one ends of bonding wires 6a, 6b are first bonded to two rows of bonding pads 4a, 4b on a first region, and bonding wires 6a,
The other end of 6b is second bonded. Generally, first bonding involves pressing a ball formed at the tip of the bonding wire to the bonding position, so-called ball bonding, and second bonding involves pressing the middle part of the bonding wire to the bonding position. So-called wedge bonding is used, in which a wedge-shaped bond is formed and the wire is cut after bonding is performed.

However, in conventional staggered bonding, second bonding, which is wedge-shaped bonding, is performed on wire bonding pads 5a and 5b on the same area (second area), so bonding wires are parallel to the substrate surface. Due to the nature of wedge bonding, which tends to be in a state close to There was a problem. In order to avoid this problem, conventionally it has been necessary to provide a sufficient distance between the wire bonding pads 5a and 5b on which second bonding is performed, resulting in an increase in the wire length of the bonding wire. Since gold wire is generally used for bonding wire,
The increase in wire length poses a major problem from the viewpoint of cost and resource conservation.

In addition, with conventional staggered wire bonding,
Adjacent bonding wire 6 as shown in the figure
Since a and 6b intersect at two points P ₁ and P ₂ when viewed from the front, these intersection points P ₁ ,
There is also the problem of contact between the bonding wires 6a and 6b at _P2 . Furthermore, even if the second bonding positions of the bonding wires 6a and 6b with respect to the bonding pads 5a and 5b are swapped in FIG. 4 and the wire 6a is connected to the pad 5b and the wire 6b is connected to the pad 5a, the bonding wires 6a, A similar problem arises as the length over which 6b exists in a near-parallel state increases. For this reason, conventionally, after the wire bonding process, there are a large number of wires, and when the density is particularly high, almost all the wires are
It was necessary to manually correct the positions of a and 6b.

[Purpose of the invention]

An object of the present invention is to connect a plurality of wiring patterns on a first region or bonding pads connected to them or a bonding pad of a chip component, and a plurality of wiring patterns on a second region or a bonding pad connected to them. When connecting bonding pads that have been bonded or bonding pads of chip components using staggered wire bonding,
This prevents the bonding wire from coming into contact with nearby wiring patterns or bonding pads without making the wire length longer than necessary, and also reduces contact between the bonding wires, eliminating the need for manual corrections after the bonding process. Alternatively, it is an object of the present invention to provide a wire bonding method that can significantly reduce the amount of wire bonding.

[Summary of the invention]

In order to achieve the above object, the wire bonding method according to the present invention has two rows of wire bonding positions on the first and second regions.
It is characterized in that first bonding is performed on the outer rows of the boundary line of each region, and second bonding is performed on the inner rows. Here, the first bonding and the second bonding are preferably ball bonding and wedge bonding, respectively, as in the past, but the first bonding is not necessarily ball bonding and may be wedge bonding.

〔Effect of the invention〕

In the wire bonding method according to the present invention, second bonding by wedge bonding, in which the angle of the bonding wire tends to be nearly parallel to the substrate surface, is performed at the wire bonding position in the inner row, and first bonding is performed at the wire bonding position in the outer row. By applying it to the wire bonding locations, the problem of the prior art where bonding wires connected to the outer row of wire bonding locations contact the inner row of wire bonding locations is eliminated. Therefore, the distance between the wire bonding positions in the outer row and the wire bonding positions in the inner row can be minimized, and the wire length of the bonding wire can be shortened. Also,
This also contributes to reducing the area occupied for forming wire bonding pads on wiring boards and chip components.

Furthermore, in the present invention, adjacent bonding wires intersect only on the boundary line between the first and second regions, and are sufficiently separated elsewhere, so there is almost no problem of wires contacting each other, and complicated procedures are avoided. It is possible to eliminate or minimize the need for manual modifications.

[Embodiments of the invention]

FIGS. 1a and 1b are a plan view and a sectional view for explaining a wire bonding method according to an embodiment of the present invention.

In the figure, a first substrate 2, which is a first region, and a second substrate 3, which is a second region, are fixed on a support substrate 1, and these first and second substrates 2,
3, two rows of wire bonding pads 4a, 4b and 5a, 5b are arranged in a staggered manner. Further, one end of the wiring patterns 7a, 7b, 8a, 8b is connected to each wire bonding pad 4a, 4b, 5a, 5b. For example, wire bonding pads are similarly formed at the other ends of the wiring patterns 7a, 7b, 8a, and 8b, and are connected to chip components (not shown).

Of the two rows of wire bonding pads 4a and 4b on the first substrate 2, the wire bonding pads 4a and 4b in the outer row with respect to the boundary line 9 between the first substrate 2 and the second substrate 3 are Of the two rows of wire bonding pads 5a, 5b on the second substrate 3, the wire bonding pads 5b in the inner row with respect to the boundary line 9 are connected by bonding wires 6b, and similarly, the wire bonding pads 5b in the inner row are connected to the boundary line 9. Wire bonding pads 4b in the inner row with respect to the boundary line 9 on the substrate 2
and the wire bonding pads 5a in the outer row with respect to the boundary line 9 on the second substrate 3 are connected by bonding wires 6b.

Here, on both the first and second substrates 2 and 3, the first wire bonding step, that is, the first bonding, is performed on the wire bonding pads 4a,
5a, and a second wire bonding step, ie, second bonding, is performed on the wire bonding pads 4b, 5b in the inner row with respect to the boundary line 9. In the figure, the first bonding is performed by ball bonding, and the second bonding is performed by wedge bonding.

According to the wire bonding method according to the present invention, since the bonding wires 6a and 6b are first bonded on the side connected to the wire bonding pads 4a and 5a in the outer row, the bonding wires 6a and 6b are connected to the wire bonding pads in the inner row. Padded 4
Since the pads are sufficiently spaced upward from the pads 4b, 5b on the pads 4b, 5b, there is almost no possibility of contacting the pads 4b, 5b. Therefore, the distance between the wire bonding pads 4a, 5a in the outer row and the wire bonding pads 4b, 5b in the inner row can be reduced, and the length of the bonding wires 6a, 6b can be minimized. can.

On the other hand, the side of the bonding wires 6a and 6b connected to the bonding pads 4b and 5b in the inner row is second bonded by wedge bonding, so they are in a state close to the substrates 2 and 3. Since there are no other wire bonding pads, there is no problem.

Furthermore, the bonding wires 6a and 6b are
Since the first substrate 2 and the second substrate 3 intersect only at one point P near the boundary line 9 when viewed from the front, the possibility that they will come into contact with each other is extremely small.

Therefore, according to the present invention, after the bonding process,
Wire modification work for correcting the contact between the bonding wire and the bonding pad or the contact between the bonding pads is unnecessary or can be minimized, resulting in a significant improvement in productivity.

Also. In the above embodiment, since the first bonding is ball bonding, it is advantageous in the following points. In other words, compared to wedge bonding, ball bonding has the advantage that there is less protrusion in the lateral direction (direction perpendicular to the wire) due to the collapse of the wire material. The dimensions of the wire bonding pads 4a and 5a (especially the dimension in the direction perpendicular to the wire) can be reduced, and the distance from the inner row of wire bonding pads 4b and 5b passing between the wire bonding pads 4a and 5a can be reduced. wiring pattern 7b,
The risk of contact with 8b is also reduced. Therefore, the density of the wire bonding pads 4a, 5a in the outer row is changed from that of the wire bonding pads 4 in the inner row.
It is possible to increase the bonding density to the same level as b and 5b, and the bonding density can be increased.

The wire bonding method of the present invention is applied to a functional device in which staggered wire bonding is performed over a long area, for example, an element array 21 on a first substrate 2 and a second substrate 3 as shown in FIG. and electronic circuit 2 to drive it
2 (IC chip, etc.) is provided separately, and both substrates 2,
3 is fixed on a common support substrate 1, and then the wiring patterns on each substrate 2 and 3 are connected by wire bonding (long image sensor, split type thermal head, etc.). It is. In such devices, element arrays (photoelectric conversion element arrays in the case of image sensors, heating element arrays in the case of thermal heads) with an array density of 8/mm or more have been put into practical use, and wire bonding However, the present invention can meet the demand for high-density wire bonding with high yield and high mass productivity.

FIG. 3 shows another embodiment of the present invention,
Wire bonding pads 32a and 32b formed on the substrate 31 and wire bonding pads 32a and 32b mounted on the substrate 31
This figure shows a state in which the present invention is applied when connecting input/output wire bonding pads 34a and 34b on a chip component 33 such as an IC chip using bonding wires 35a and 35b in a staggered bonding manner. Wiring patterns 36a, 3 are formed on the bonding pads 32a, 32b on the substrate 31.
6b is connected. In the figure, of the bonding wires 35a and 35b, the side connected to the wire bonding pads 32a and 34a is the first bonding, and the side connected to the wire bonding pads 32b and 34b is the second bonding. It is clear that this embodiment also provides the same effects as the previous embodiment. The same effect can be obtained even if the IC chip 33 in FIG. 3 is replaced with a simple board other than the board 31.

The present invention can be modified in various other ways without departing from the scope of the invention. For example, in the embodiments, wire bonding pads on a board may be connected, or wire bonding pads on a board and wire bonding pads on a chip component may be As described above, the wiring pattern does not have a wire bonding pad, and the wiring pattern is connected to another wiring pattern, a wire bonding pad formed at the end of the wiring pattern, or a wire bonding pad on a chip component. It goes without saying that the present invention can also be applied to cases where connections are made using staggered bonding.

Furthermore, although the first bonding was explained as ball bonding in the above embodiments, the present invention is also effective when the first bonding is wedge bonding.

[Brief explanation of drawings]

1A and 1B are a plan view and a sectional view for explaining a wire bonding method according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of an example of a functional device to which the wire bonding method of the embodiment is applied. 3 is a sectional view for explaining a wire bonding method according to another embodiment of the present invention, and FIGS. 4a and 4 b are cross-sectional views for explaining a wire bonding method using conventional staggered bonding. FIG. 2 is a plan view and a sectional view. DESCRIPTION OF SYMBOLS 1... Supporting substrate, 2... First substrate (first region), 3... Second substrate (second region), 4a,
4b, 5a, 5b... bonding pad, 6
a, 6b...bonding wire, 7a, 7b,
8a, 8b... Wiring pattern, 9... Boundary line between the first region and the second region, 21... Element array,
22... Chip parts, 31... Board, 32a, 3
2b...34a, 34b...bonding pad,
33... Chip parts, 35a, 35b... Bonding wire, 36a, 36b... Wiring pattern.

Claims (1)

[Claims] 1 A plurality of wiring patterns on a first region or a bonding pad connected to them or a bonding pad of a chip component, and a plurality of wiring patterns on a second region or a bonding pad connected to them. In a wire bonding method in which connected bonding pads or bonding pads of chip components are connected by staggered wire bonding, each of the two rows of wire bonding positions on the first and second regions is A wire bonding method characterized by performing first bonding on the outer rows and performing second bonding on the inner rows with respect to the boundary line of the area. 2. The wire bonding method according to claim 1, wherein the first bonding is ball bonding and the second bonding is wedge bonding. 3. Claim 1, wherein the first area is a substrate on which a predetermined element array is formed, and the second area is a substrate on which an electronic circuit connected to this element array is formed. Wire bonding method described in section.