JP4872736B2 - How to connect electronic devices - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity as compared with a method using a dispenser, and to coat a compound ball having a small diameter with a very small amount of paste stably. <P>SOLUTION: First, the compound ball 5 is fixed to all electrodes 4 for connecting each electronic device on a lower substrate 1 where a plurality of electronic devices are formed. Then, a print mask 6 having an opening 61 at the positions of all fixed compound balls 5 is arranged so that the upper parts of all compound balls 5 are brought into contact with each opening 61. Then, solder paste printing is performed, a recess is formed at a part in contact with the opening 61 of a surface layer 52 in the compound ball 5, and at the same time, solder paste 7 is stuck to the upper part of the compound ball 5. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a method for connecting between opposing electrodes of upper and lower electronic devices (packages, etc.) with a plurality of composite balls comprising a core and a surface layer.

Electronic components with a package-on-package structure have upper and lower packages connected by a plurality of solder balls. Instead of solder balls made entirely of solder, solder is applied to the surface of a metal or plated heat-resistant resin core. In some cases, a composite ball having a layer is used. Also,
The external terminal of the upper package may not be a ball terminal. In that case, after fixing the composite ball on the electrode of the substrate of the lower package, it is necessary to apply a solder paste on each composite ball and place the upper package thereon to perform reflow heating. .

Conventionally, since this solder paste is applied using a dispenser, there is a problem that productivity is low and it is difficult to stably apply a small amount of paste to a small-diameter composite ball.
In addition, as a conventional document relating to a connection method using a solder ball, the following Patent Document 1 can be cited, but this document does not describe a method using a composite ball composed of a core and a surface solder layer. .
JP-A-10-233574

An object of the present invention is to provide a plurality of composite balls each having a core and a surface layer, and upper and lower electronic devices (
As a method for connecting electrodes facing each other in a package or the like, the method is to provide a method that is more productive than the above-described method and can stably apply a small amount of paste to a small-diameter composite ball.

In order to solve the above-mentioned problem, the electronic device connection method of the invention 1 is a method of connecting the opposing electrodes of the first and second electronic devices with a composite ball comprising a core and a surface layer, a) on the electrode of the first electronic device, comprising: a substrate; an electronic component provided on the substrate; and an electrode electrically connected to the electronic component and provided on the substrate. A step of fixing the composite ball; and (b) after the step (a), a printing mask having an opening is disposed so that the composite ball is in contact with the opening. And a step of attaching a solder paste to the upper part of the composite ball while forming a dent in a portion in contact with the opening.

A method of connecting an electronic device according to a second aspect of the present invention is a method of connecting electrodes facing the upper and lower electronic devices with a plurality of composite balls comprising a core and a surface layer, wherein the lower substrate has a plurality of electronic devices formed thereon. After the composite ball is fixed to all the electrodes for connecting each electronic device above, a print mask having openings at the positions of all the fixed composite balls is provided, and the upper part of all the composite balls is connected to each of the openings. By placing it in contact with the solder paste printing,
The method includes a step of attaching a solder paste to an upper portion of the composite ball while forming a dent in a portion of the surface layer of the composite ball that is in contact with the opening.

According to the methods of the inventions 1 and 2, solder paste printing is employed to form a dent in the surface layer of the composite ball, and the solder paste is attached to the top of the composite ball so that the solder paste attached to the top is It is held in the recess and is prevented from flowing down from the composite ball. Therefore, compared with the method using a dispenser, the productivity is high, and a small amount of paste can be stably applied onto a small-diameter composite ball.

According to a third aspect of the present invention, there is provided the electronic device connecting method according to the first or second aspect, wherein the printing mask in which the diameter of the opening is formed to be smaller than the diameter of the composite ball is the center of the opening at the fixed position of the composite ball. It is installed according to the center.
According to the method of the invention 3, a ring-shaped recess concentric with the composite ball is formed on the upper surface layer of the composite ball.

According to a fourth aspect of the present invention, there is provided the electronic device connection method according to the first or second aspect, wherein the printing mask includes:
The opening is formed with its center shifted outward from the center of the composite ball fixing position, and the printing mask is installed with the center of the opening shifted outward from the center of the composite ball fixing position. It is characterized by doing.
According to the method of the invention 4, a crescent-shaped depression is formed inside the upper portion of the surface layer of the composite ball.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a diagram for explaining an embodiment of an electronic device connection method according to the present invention.
In this embodiment, a method for fixing an upper package on a plurality of packages formed on a lower substrate when manufacturing an electronic component having a package-on-package structure will be described.

First, as shown in FIG. 1A, a plurality of lower packages in which chips 2 are bonded by wires 3 are formed on a lower substrate 1. On the lower substrate 1, connection electrodes 4 for the respective packages are formed. The connection electrode 4 of each package includes at least one of the chips 2 provided on the lower substrate 1 and wiring provided on the lower substrate 1 (
(Not shown). A composite ball 5 including a core 51 and a solder layer 52 on the surface is fixed on all the connection electrodes 4. Also, a printing mask 6 having openings 61 at all positions of the fixed composite ball 5 is prepared.

2A, the diameter A of the opening 61 is smaller than the diameter of the composite ball 5, and the center of each opening 61 is fixed to the composite ball 5 as shown in FIG. It is formed according to the center of the position. FIG. 3 is a plan view of one package region 11 of the lower substrate, and the printing mask 6 is drawn on the two-dot chain line to indicate the positional relationship between the two.

Next, as shown in FIG. 1B, the print mask 6 is aligned with the center of the opening 61 at the center of the fixed position of the composite ball 5, and the upper parts of all the composite balls 5 are placed in the openings 61. Place it in contact. At that time, a spacer S for supporting the printing mask 6 may be disposed between the lower substrate 1 and the printing mask 6.
In this state, the solder paste 7 placed on the printing mask 6 is moved while being scraped from the right to the left in FIG.
1 is filled with solder paste 7. At that time, the pressure applied to the printing mask 6 (printing pressure) is shown in FIG.
As shown in (b), the peripheral corner portion of the opening 61 of the printing mask 6 may bite into the surface layer 52 of the composite ball 5. In this state, the solder paste 7 is filled in the opening 61 while the printing pressure moves from right to left.

Next, the solder paste 7 adheres to the top of each composite ball 5 by removing the printing mask 6. FIG. 2C is a cross-sectional view of the composite ball 5 immediately after the print mask 6 is removed, and FIG.
Is a plan view thereof.
As shown in these drawings, immediately after the print mask 6 is removed, a ring-shaped recess 53 concentric with the composite ball 5 is formed on the composite ball 5, and the solder paste 7 is attached to the upper part. When the print mask 6 is removed and a little time passes, the solder paste 7 adhering to the upper portion of the composite ball 5 spreads outward as shown in FIG. Is held in a state where it is difficult for the composite ball 5 to flow down.

Next, as shown in FIG. 1D, the connection electrodes 81 of the upper package 8 are placed on the corresponding composite balls 5 of the lower package. Next, as shown in FIG.
Reflow heating is performed to melt the solder paste 7 and the solder layer 52 of the composite ball 5, thereby connecting the upper and lower packages.
According to the method of this embodiment, the surface layer 5 of the composite ball 5 is adopted by using solder paste printing.
2, the solder paste 7 is attached to the upper portion of the concave portion 53, so that the solder paste 7 is held in the concave portion 53 and prevented from flowing down from the composite ball 5. Therefore, compared with the method using a dispenser, the productivity is high, and a small amount of paste can be stably applied onto a small-diameter composite ball.

An example in which a printing mask to be used is different from that in the above embodiment will be described with reference to FIG.
FIG. 4A is a plan view of one package region 11 of the lower substrate, and a printing mask 60 is drawn on the lower substrate by a two-dot chain line to show the positional relationship between the two. FIG. 4B is a cross-sectional view showing the positional relationship between the opening 61 and the composite ball 5. FIG. 4C is a cross-sectional view showing the state of the composite ball 5 immediately after the solder paste printing, and FIG. 4D is a plan view thereof.

In this example, the diameter A of the opening 61 is the same as the diameter of the composite ball 5, and the center C6 of each opening 61 is outside the center C5 of the fixed position of the composite ball 5 (the chip 2 closest to each composite ball 5).
The printing mask 60 is formed so as to be shifted to the side away from the printing plate. The printing mask 60 is installed by shifting the center C6 of the opening 61 outward from the center C5 of the fixed position of the composite ball 5 (the side away from the chip 2 closest to each composite ball).

In this state, as described above, solder paste printing is performed to put the solder paste 7 in all the openings 61. At that time, the pressure (printing pressure) applied to the printing mask 60 is arranged inside the surface layer 52 of the composite ball 5 (the side closest to the chip 2 closest to each composite ball) as shown in FIG. The peripheral corner portion of the opening 61 of the printing mask 60 bites into the portion that is formed. In this state, the solder paste 7 is filled in the opening 61 while the printing pressure moves from right to left.
Thus, the composite ball 5 immediately after the print mask 60 is removed is shown in FIGS. 4 (c) and 4 (d).
As shown in FIG. 4, a crescent-shaped dent 53 is formed in a portion disposed on the inner side of the surface layer 52 of the composite ball 5 (the side closest to the chip 2 closest to each composite ball), and the dent is formed from the top of the composite ball 5. The solder paste 7 is attached to the side opposite to 53.

A little time passes after the printing mask 60 is removed, and the solder paste 7 adhering to the upper part of the composite ball 5 spreads outward, but this solder paste 7 is recessed 53 on the side of the composite ball 5 that is close to the chip 2. Is held in a state where it is difficult for the composite ball 5 to flow down. On the other hand, the solder paste 7 tends to flow down on the side away from the chip 2.
Therefore, in the example of FIG. 4, since the solder paste 7 flows down to the side away from the chip 2, problems such as adhesion of the solder paste 7 that has flowed down to the wire 3 hardly occur.

Sectional drawing explaining the method of embodiment. Sectional drawing which shows the relationship between the opening part of a printing mask, and a composite ball. The top view which shows the positional relationship of the opening part of a printing mask, and a composite ball. Sectional drawing explaining the example which uses the printing mask different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lower substrate, 2 ... Chip | tip, 3 ... Wire, 4 ... Electrode for connection of lower package, 5 ... Composite ball, 51 ... Core, 52 ... Surface solder layer, 53 ... Depression, 6 ... Printing mask, 60 ... Print mask, 61 ... Opening, 7 ... Solder paste, 71 ... Squeegee, 8 ... Upper package, 81
... Connecting electrode for upper package, S ... Spacer.

Claims (4)

A method of connecting the opposing electrodes of the first and second electronic devices with a composite ball comprising a core and a surface layer,
(A) a substrate, an electronic component provided on the substrate, and electrically connected to the electronic component;
Fixing the composite ball on the electrode of the first electronic device having an electrode provided on the substrate;
(B) After the step (a), a print mask having an opening is disposed so that the composite ball is in contact with the opening, so that the surface of the surface of the composite ball is in contact with the opening. Attaching a solder paste to the top of the composite ball while forming a recess;
A method for connecting an electronic device, comprising: A method of connecting the opposing electrodes of the upper and lower electronic devices with a plurality of composite balls comprising a core and a surface layer,
After fixing the composite ball to all the electrodes for connecting each electronic device on the lower substrate on which a plurality of electronic devices are formed, a printing mask having openings at the positions of all the fixed composite balls, The upper part of all the composite balls is arranged so as to be in contact with each opening, and by performing solder paste printing, while forming a dent in the part of the surface layer of the composite ball that is in contact with the opening, A method for connecting an electronic device, comprising a step of attaching a solder paste to an upper portion of a composite ball. 3. The printing mask in which the diameter of the opening is formed smaller than the diameter of the composite ball is placed with the center of the opening aligned with the center of the fixed position of the composite ball.
The connection method of the electronic device of description. In the printing mask, the opening is formed by shifting the center thereof outward from the center of the fixed position of the composite ball,
The method for connecting electronic devices according to claim 1, wherein the printing mask is installed by shifting the center of the opening to the outside of the center of the fixed position of the composite ball.

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