JP3055285B2 - Intermediate substrate bonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of bonding an intermediate substrate, and more particularly, to a method of forming a spacer for defining the height of a solder portion on an electrode of an intermediate substrate by means of wire bonding means. The electrode is landed and bonded.

[0002]

2. Description of the Related Art Electrodes of a semiconductor chip (hereinafter, simply referred to as a chip) used for electronic components such as ICs and LSIs are:
In recent years, due to the demand for high integration, the number of electrodes has been increasing and the pitch has become narrower. Depending on the chip, the number of electrodes can reach several hundred or more. Is becoming increasingly difficult. In order to solve such a problem, it has been known to bond a chip to a substrate via a plate-like intermediate substrate.

FIG. 12 shows the conventional means, in which 1 is a chip, and an electrode 4 on the lower surface of the chip 1 is shown.
Are bonded to the first electrode 5 on the upper surface of the intermediate substrate 2 via bumps 8a and cream solder 8b formed by wire bonding means. The second electrodes 6 formed in a matrix on the lower surface of the intermediate substrate 2 are bonded to the electrodes 7 formed in a matrix on the upper surface of the substrate 3 via bumps 9a and cream solder 9b. I have. The electrode 5 on the upper surface and the electrode 6 on the lower surface of the intermediate substrate 2 are connected by a conductive material 19.

[0004] The bonding of the intermediate substrate 2 to the substrate 3 is performed by forming bumps 9a on electrodes 7 coated with cream solder 9b.
And then bump 9a and cream solder 9b
Is heated and melted by reflow.

[0005] By the way, the bump 9a and the cream solder 9
b is used in a relatively large amount so that the bonding between the electrodes 6 and 7 is good. Therefore, the bump 9a and the cream solder 9b are heated and melted to be integrated, and easily become the substantially spherical solder portion 9 which bulges outwardly as shown by the solid line in FIG. However, such an outer convex shape has a problem that the adhesive force of the base end portion f of the solder portion 9 is weak and the solder portion 9 is easily peeled off from the electrodes 6 and 7.

Therefore, as a conventional means for solving this,
It is known that a substantially spherical solder portion 9 is shaped into an indented conical shape as shown by a chain line in FIG. 13 so that a base end portion f is firmly fixed to an upper electrode 6 and a lower electrode 7. This shaping is performed as follows. That is, during the reflow, the intermediate substrate 2 is slightly lifted up as shown by the arrow, and the soldered portion 9 in the heated and melted state is stretched into a continuous shape, and the reflow is progressed in this state. After 9 is completely melted, it is cooled and solidified.

[0007]

By the way, the height of the solder portion 9 in the conventional means is determined by the lifting width h of the intermediate substrate 2, and the intermediate substrate 2 is pulled up by a certain width and subjected to heat treatment. It is difficult to maintain the height until the process is completed, and the height of the formed solder portion 9 tends to vary.

Accordingly, an object of the present invention is to provide a method capable of firmly bonding an electrode of an intermediate substrate to an electrode of a substrate at a constant height.

[0009]

To this end, the present invention provides a method for bonding a ball at the lower end of a wire derived from a capillary tool of a wire bonding apparatus to a second electrode of an intermediate base material, forming a spacer of predetermined height by cutting by extending a wire upwardly and then by land the spacer to the solder on the electrode of the board, and to heat treatment to Handa this.

[0010]

According to the above arrangement, a spacer having a fixed height can be easily formed by a wire bonding technique. In addition , when the solder on the electrodes is melted by reflow, the melted solder is sucked up along the spacer, and the electrodes of the intermediate base material and the electrodes of the substrate can be firmly bonded.

[0011]

(Embodiment 1) Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall perspective view of a substrate, an intermediate substrate and a chip bonded to the substrate. 1 is a chip, 2 is an intermediate substrate, and 3 is a substrate. On the lower surface of the chip 1, the electrodes 4 are formed in a zigzag along the side edges. On the upper surface of the intermediate substrate 2, first electrodes 5 are formed in a staggered manner so as to correspond to the electrodes 4 of the chip 1. On the lower surface of the intermediate substrate 2, the second electrodes 6 are formed in a matrix. On the upper surface of the substrate 3, electrodes 7 corresponding to the electrodes 6 are formed in a matrix at the same pitch.

In FIG. 2, reference numeral 8a denotes a bump formed on the electrode 4 of the chip 1, which is bonded to the electrode 5 of the intermediate substrate 2. 8b is cream solder applied to the surface of the electrode 5. In this embodiment, bumps 8 a are formed on the electrodes 4 of the chip 1 by wire bonding, and the bumps 8 a are landed on the electrodes 5 of the intermediate base material 2. Next, the bumps 8a and the cream solder 8b are heated and melted by heating means, and the electrodes 4 and 5 are bonded.

Next, after turning the intermediate substrate 2 upside down as shown in FIG. 3, the second substrate 2 is turned over as shown in FIG.
An arc-shaped spacer 14 ′ is formed on the electrode 6 by the wire 14 led out from the capillary tool 13 of the wire bonding apparatus 10. In FIG. 3, reference numeral 8 denotes a bump 8a which is integrated by heating and melting and a cream solder 8;
b. Reference numeral 11 denotes a driving unit of the wire bonding apparatus 10, and reference numeral 12 denotes a horn having a capillary tool 13 held at a distal end thereof.

FIG. 5 shows a method of forming the spacer 14 '. The spacer 14 'is formed as follows by a method similar to wire bonding performed in a manufacturing process of electronic components such as QFP and SOP. The torch 15 is made to approach below the capillary tool 13 at the position a to generate an electric spark to form a ball 14 a at the lower end of the wire 14. Next, torch 1
5 is retracted to the side, the capillary tool 13 is lowered to the position b, and the ball 14a is bonded to one side of the electrode 6. Next, the capillary tool 13 is slightly raised to a position c, which is diagonally above, to extend the wire 14 upward, and then lowered to a position d, so that the base end 14b of the arched wire 14 is connected to an electrode. 6 is bonded to the other side.

Next, when the capillary tool 13 is pulled up to the position e and the wire 14 is clamped by a clamper (not shown) and pulled up, the wire 14 is pulled up to the base end 14.
b to form the spacers 14 '. As described above, according to the present means to which the wire bonding is applied, the spacer 14 ′ having the predetermined height H can be easily formed by the wire 14. In this embodiment, the electrode 6 is made large, and the ball 14a and the base end 14b of the wire 14 are bonded to the electrode 6. However, the electrode 6 is made small, and only the ball 14a is bonded to this electrode 6. The end 14b may be bonded to the upper surface of the intermediate substrate 2.

After the spacers 14 'have been formed on all the second electrodes 6 of the intermediate substrate 2 as described above, the intermediate substrate 2 is turned upside down as shown in FIG. The spacer 14 ′ is attracted to the nozzle 17 of the mounting head 16 and lands on the electrode 7 of the substrate 3 on which the cream solder 18 is applied. FIG. 7 shows a landing state of the spacer 14 '. As shown, the arched lower end of the spacer 14 'lands on the electrode 7, and the distance D between the substrate 3 and the intermediate substrate 2 is kept constant. For solder, use solder leveler or solder plating
It may be formed by steps or the like.
Land the 4 'arched lower end on the solder on electrode 7
I just need. In FIG. 6, reference numeral 19 denotes a conductive material that connects the electrode 5 on the front surface of the intermediate substrate 2 and the electrode 6 on the rear surface.

After the intermediate substrate 2 is mounted on the substrate 3 as described above, the substrate is heated by a reflow apparatus. FIG. 8 is a side view after reflow. The cream solder 18 heated and melted by the reflow device is sucked up along the spacer 14 ′ composed of the wire 14, and has a substantially continuous shape between the electrode 6 and the electrode 7 as shown in a partially enlarged view of FIG. An inwardly concave solder portion 20 is formed, and the intermediate substrate 2 is
Firmly adhered to. Here, since the height of the solder portion 20 is determined by the height H of the spacer 14 ', the height is higher than that of the conventional method in which the intermediate substrate 2 is slightly lifted and maintained during the heat treatment. The accuracy can be improved.

Further, according to the present means, since the spacer 14 'is embedded in the solder portion 20, the spacer 14'
Therefore, the amount of the cream solder 18 used can be reduced by the above volume, so that it is possible to prevent the cream solder 18 applied to the electrode 7 in a large amount from flowing out in the horizontal direction at the time of reflow and to generate a solder bridge or a solder ball. In FIG. 8, after the reflow, the cream solder 18 and the spacer 14 ′ are completely melted and integrated to form the solder portion 20, but for the sake of explanation, the two are not integrated. I have.

(Embodiment 2) FIG. 9 is a side view during bonding according to another embodiment.
A spacer 14 'is formed. This spacer 14 '
Is formed in the same manner as wire bonding as follows. That is, the capillary tool 13 at the position a is lowered to the position b, the ball 14a is bonded to the electrode 6, and then the capillary tool 13 is raised to the position c to extend the wire 14 straight upward. The wire 14 is cut by forming the spacer 14 ′ by clamping the wire 14 to a position d by clamping it with a clamper.

When the spacers 14 'are formed on all the electrodes 6 of the intermediate substrate 2 as described above, as shown in FIG. 10, the cylinder 20 of the height adjusting device for adjusting the height of the spacers 14' is used. Of the spacer 14 ′ is pressed by the pressing element 22, and the height of all the spacers 14 ′ is adjusted to a predetermined height H.

Next, the intermediate substrate 2 is turned upside down, and FIG.
As shown in FIG. 1, the substrate 3 coated with the cream solder 18
The lower end of the spacer 14 ′ is landed on the electrode 7. Next, when a heat treatment is performed by a reflow device, the melted cream solder 18 is sucked up along the spacer 14 ', and the both 14' and 18 are integrated to form a substantially continuous solder portion 20.

[0022]

As described above, according to the present invention, the electrode of the intermediate substrate can be firmly bonded to the electrode of the substrate at a constant height.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a substrate according to a first embodiment of the present invention, an intermediate base material and a chip mounted on the substrate.

FIG. 2 is a side view of the chip during bonding.

FIG. 3 is a side view during the bonding.

FIG. 4 is a perspective view of the wire bonding apparatus during formation of the spacer.

FIG. 5 is a side view during formation of the spacer.

FIG. 6 is a side view of the intermediate substrate during bonding.

FIG. 7 is a side view of the spacer.

FIG. 8 is a side view of the intermediate substrate after bonding.

FIG. 9 is a side view during spacer formation according to the second embodiment of the present invention.

FIG. 10 is a side view of the spacer during height adjustment.

FIG. 11 is a side view of the spacer.

FIG. 12 is a side view during bonding of an intermediate substrate according to a conventional means.

FIG. 13 is a side view of a main part of the intermediate substrate during bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chip 2 Intermediate base material 3 Substrate 5 1st electrode 6 2nd electrode 10 Wire bonding apparatus 13 Capillary tool 14 Wire 14a Ball 14 'Spacer 18 Cream solder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/12 H01L 21/60

Claims (1)

(57) [Claims] An intermediate substrate having a first electrode to which a chip is bonded on an upper surface and a matrix-like second electrode on a lower surface is formed in a matrix on a substrate. In bonding to the electrode, after bonding the ball at the lower end of the wire led out from the capillary tool of the wire bonding apparatus to the second electrode, the wire is extended upward from the ball and cut to a predetermined value. Form a spacer of height,
Then by landing the spacer in the solder on the upper Symbol substrate electrode, a bonding method of the intermediate base, which comprises heating a semi-field of this.