JPH10107176A - Method and structure for connecting electronic part and substrate, and solder bump forming method in them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate poor connection by, even an electronic part is bent, perfectly and electrically connecting the wiring pad of the electronic part and the wiring pattern of a substrate, individually, through a solder. SOLUTION: In order that a wiring pad 2 and a wiring pattern 10 are individually perfectly connected each other, a solder 16 is supplied whose amount is almost proportional to the curvature of a BGA(ball grid array) 8 and/or substrate 9, and the wed area of the solder 16 when the wiring pad 2 and/or wiring pattern 10 are heated and melted. As a result, poor connection is eliminated while the wiring pad 2 of the BGA 8 and the wiring pattern 10 of the substrate 9 are, through the solder 16, perfectly, electrically, and individually connected together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure between an electronic component and a substrate, a method of connecting the same, and a method of forming a solder bump in the connection structure and the connection method, and more particularly to an electronic component (BGA (Ball Grid Array)). And CSP (Chip Si)
Wiring pads of package-type surface-mounted electronic components such as ze Package) and the wiring pattern of the board (eg, printed wiring board on which electronic components are mounted) are electrically and completely connected individually via solder. The present invention relates to a connection structure between an electronic component and a substrate having no connection failure and a connection method thereof, and a method of forming a solder bump in the connection structure and the connection method.

[0002]

2. Description of the Related Art Recently, an increase in the number of connection points of electronic parts has been desired due to a demand for higher performance of electronic equipment. For this reason, a BGA type or CSP type surface mount type electronic device that uses the entire one main surface of the package of the electronic component is better than a surface mount type electronic component in which leads are arranged on the package side surface of the electronic component. Parts are in the limelight. CSP type is package
The package size of the BGA type is larger than that of the CSP type. The configuration of a plurality of wiring pads provided on the main surface of the base material which is one main surface of the package is CS
The same applies to both P-type and BGA-type. Therefore, BGA
A description will be given by taking a surface-mount type electronic component as a representative. In addition,
Abbreviated as BGA for simplicity.

FIG. 7 shows a connection structure between a BGA and a substrate.
A description will be given with reference to (a), (b), (c), and (d). FIG.
In (a), 1 is a base material of BGA8. A plurality of wiring pads 2 are provided on the main surface of the substrate 1.
Similarly, in FIG. 7A, reference numeral 3 denotes a mold portion, and the inside of the mold portion 3 includes an IC chip, a conductor pattern for connecting the IC chip to the wiring pad 2, a bonding wire, and the like. In FIG. 7B, reference numeral 9 denotes a substrate such as a printed wiring board (hereinafter abbreviated as a substrate). A wiring pattern 10 is provided on a surface of the substrate 9 on which the BGA 8 is mounted. This wiring pattern 10
For example, as shown in FIG. 7C, it is composed of a circular portion 10b and a routing portion 10a. Also, if necessary,
In some cases, a solder resist layer 12 for preventing spread of the solder is provided except for a circular portion around the circular portion 10b. Then, as shown in FIG. 7D, the above-mentioned wiring pads 2 of the BGA 8 and the above-mentioned wiring patterns 10 of the substrate 9 are individually electrically connected via solder 16, and the BGA 8 is mounted on the substrate 9. The Rukoto.

Next, a process of mounting the above BGA 8 on the substrate 9 will be described with reference to FIGS. 8 (a), 8 (b), 8 (c), 8 (d) and 8 (e). First, a metal screen mask (hereinafter abbreviated as a metal mask) 4 is provided on the main surface of the substrate 1.
The metal mask 4 is provided with a plurality of openings 4 a having a constant capacity corresponding to the positions and shapes of the wiring pads 2. The solder paste 6 placed on the upper surface of the metal mask 4 is pressed into the opening 4a by the squeegee 5.
When the squeegee 5 moves from the left side to the right side (in the direction of arrow A), the solder paste 6 placed on the upper surface of the metal mask 4 in the moving direction of the squeegee 5 moves from the squeegee 5 to the surface of the metal mask 4. The opening 4a is filled with a certain amount of solder paste 6a under the action force in the direction toward the base material 1 and the rotational force on the surface (see FIG. 8A). Next, by separating the metal mask 4 from the base material 1, a certain amount of the solder paste 6a remains on the wiring pads 2 and printing is performed (see FIG. 8B). Further, the base material 1 on which the fixed amount of the solder paste 6a is printed is passed through a reflow device, so that the solder is melted, and a chipped solder bump 7 is formed by the surface tension of the solder. 8 (c)). In addition,
Japanese Patent Application Laid-Open No.
2018869 and JP-A-7-202401.

Then, a certain amount of solder paste 11 is applied on the wiring pattern 10 on the substrate 9 to
Place BGA8 upside down on top. That is, the substrate 9
Side solder paste 11 and BGA 8 side solder bump 7
Are opposed to each other (see FIG. 8D). 8D, the solder bumps 7 and the solder paste 11 are reflowed, and the solder 16 wets the wiring pads 2 and the wiring patterns 10, and the base material 1 is cooled. Thereby, the solder 16 is solidified, and the wiring pads 2 of the BGA 8 and the wiring patterns 10 of the substrate 9 are individually electrically connected via the solder 16, and the BGA 8 is mounted on the substrate 9. (Fig. 8
(E)).

[0006]

However, the above-described conventional connection structure between an electronic component and a substrate has the following problems. That is, as shown in FIGS. 7 and 8, residual stress when a wiring pattern (not shown) is manufactured on the surface of the base 1 on the side of the wiring pad 2 and the surface of the mold 3 side, The portion 3 tends to have a curved shape in which the substrate 1 side is convex due to a difference in the amount of thermal contraction during molding (bimetal effect) based on a difference in the coefficient of thermal expansion of the material. As a result, the solder 16 (BG
When the supply amount of the solder paste 6 to be the solder bump 7 on the A8 side and / or the solder paste 11) on the substrate 9 side is constant, the warpage (curvature) of the base material 1 causes the wiring pad 2 of the BGA 8 and the The wiring pattern 10 is connected via the solder 16 on the inner side, but is separated on the outer side into the BGA 8 side 16a and the substrate 9 side 16b and is not connected via the solder 16. That is, a connection failure may occur.

More specifically, FIG. 7 and FIG.
As shown in FIG. 8, the substrate 1 is warped (curved), and in this state, a certain amount of the vertices of the solder bumps 7 are not on the same plane (indicated by the dashed line in FIG. 8C). . For this purpose, as shown in FIG. 8D, when the BGA 8 which is turned upside down is placed on the substrate 9, most of the solder bumps 7 come into contact with the solder paste 11, but the outer solder bumps 7 May not come into contact with. When reflow is performed in this state, the bimetal effect is weakened, and all the solder bumps 7 reflow with the solder paste 11 and are once mounted. However, when the substrate 1 is bent again by cooling after the reflow, the BGA 8 can be mounted on the substrate 9 with the solder 16 on the inside, but FIG.
As shown in (e), the outer solder 16 is the BGA 8 side 1
6a and the substrate 9 side 16b, the wiring pads 2 of the BGA 8 and the wiring pattern 10 of the substrate 9 may not be connected via the solder 16.

[0008] The above-mentioned poor connection depends not only on the degree of curvature of the base material 1 but also on the wiring pattern 10 composed of the routing portion 10a and the circular portion 10b on the substrate 9. That is, since the region other than the wiring pattern 10 has low wettability with the solder, if the individual solder bumps 7 have a fixed amount (the amount of the solder is equal), the more the wiring portions 10a, the more the solder 16
Is spread to the routing part 10a, and the degree of swelling at the circular part 10b becomes small, and the above-mentioned connection failure increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a connection structure between an electronic component and a substrate in which the wiring pads of the electronic component and the wiring pattern of the substrate are electrically and completely connected individually via solder, and there is no poor connection. An object of the present invention is to provide a connection method, a connection structure thereof, and a solder bump forming method in the connection method.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device, comprising the steps of: providing a wiring pad and a wiring pattern so as to completely and individually connect a wiring pad and a wiring pattern to each other; The method is characterized in that a solder is supplied in an amount substantially proportional to the degree of soldering and the wet area of the solder when the wiring pad and / or the wiring pattern is heated and melted.

As a result, the connection structure of the electronic component and the substrate according to the present invention and the method of connecting the same, and the method of forming the solder bumps in the connection structure and the connection method, require that the wiring pad of the electronic component and the wiring pattern of the substrate form a solder. Are completely electrically connected to each other through the connection and there is no connection failure.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, four examples of embodiments of a connection structure between an electronic component and a substrate of the present invention, a connection method thereof, and a solder bump forming method in the connection structure and the connection method will be described with reference to FIGS. This will be described in detail with reference to FIG. In FIGS. 1 to 6, the same or corresponding parts as those shown in FIGS. 7 and 8 are denoted by the same reference numerals, and the description will not be repeated.

1 (a), 1 (b), 1 (c), 1 (d), and 1 (e) show a connection structure between an electronic component and a substrate according to the present invention and a connection method thereof.
FIG. 4 is an explanatory diagram showing a first embodiment of a solder bump forming method in the connection structure and the connection method, and showing a process of mounting a BGA on a substrate. In the first embodiment, the supply amount of the solder 16 is adjusted with respect to the curvature of the substrate 1 while keeping the wet area of the wiring pad 2 and the wiring pattern 10 constant. This adjustment is performed by the capacity of the opening 4a of the metal mask 4 when the solder paste 6 is printed and supplied on the wiring pad 2, and the base 1 and the substrate 9 having the upward convex shape are formed. This is performed in consideration of the gap.

That is, the wiring pads 2 of the substrate 1 and the substrate 9
In consideration of the curvature of the base material 1, the wiring patterns 10 of the present embodiment are made equivalent to each other, using a metal mask 4 in which the opening degree of the outer opening 4a is larger than that of the opening 4a near the center. Printing solder paste 6 on material 1 (FIG. 1 (a))
reference). Then, the supply amount of the printed solder paste 6a increases toward the outside (see FIG. 1B). When the reflow is performed in this state, the bump height of the outer solder bump 7 is larger (bump diameter is larger) than the solder bump 7 near the center (inner side), and the vertices of the solder bumps 7 in the BGA 8 are on the same plane (FIG. 1 (c)) (refer to FIG. 1 (c)). On the other hand, the same amount of solder paste is placed on each wiring pattern 10 of the substrate 9.
The strike 11 is printed, and the above-mentioned BGA 8 is turned upside down so that the solder bumps 7 of the BGA 8 and the solder paste 11 of the substrate 9 are combined (see FIG. 1D). When reflow is performed in the above-described state, the outer solder 1
6 is larger than the supply amount of the inner solder 16, even if the base material 1 is curved, the wiring pattern 2 of the base material 1 and the wiring pattern 10 of the The BGA 8 is mounted on the substrate 9 without any connection failure, particularly on the outside, through the electrical connection via the reference numeral 16 (see FIG. 1E).

FIGS. 2A and 2B are explanatory views showing a modified example of the metal mask 4 in the above-described first embodiment. The metal mask 4 shown in FIG. 2A is obtained by adjusting the capacity of the opening 4 a by providing a step-like step according to the curvature of the base material 1. The metal mask 4 shown in FIG. 2 (b) is obtained by adjusting the capacity of the opening 4a with a gentle inclination (three-dimensionally forming a curved surface).

FIGS. 3 (a), 3 (b) and 3 (c) show a connection structure between an electronic component and a substrate according to the present invention, a connection method therefor, and a solder bump formation method in the connection structure and connection method.
It is explanatory drawing which showed embodiment of FIG. The second embodiment is a modification of the above-described first embodiment, and uses a metal mask 4 having a thickness smaller than that of the metal mask 4 used in the above-described first embodiment. It is. That is, the supply amount of the solder 16 in the second embodiment is adjusted by printing the solder paste 6 on the wiring pad 2 and supplying the solder paste 6 to the opening 4 a of the thin metal mask 4.
(See FIG. 3A). Then, based on using this thin metal mask 4,
Solder balls 1 of the same diameter (same amount) are provided on each solder paste 6a after printing to compensate for the decrease in the amount of supplied solder.
3 is supplied by a vacuum suction jig 14 (see FIG. 3B).
Since it is difficult to selectively suck the solder ball 13 on the outside with the suction hole 14a of the vacuum suction jig 14 so as to be large, it is necessary to adjust the amount of the solder paste 6a to be printed in advance. This is advantageous in actual work.

Then, for each wiring pad 2, the sum of the printed solder paste 6a and the supplied solder ball 13 is equal to the printed solder paste as shown in FIG. 1B of the first embodiment. If the amount corresponds to the amount of the strike 6a, the bump height of the outer solder bump 7 is higher (bump diameter is larger) than the solder bump 7 near the center after reflow, and the apex of each solder bump 7 is the same. Plane (Fig. 3
(See (c) in FIG. 3 (c).) As a result, the arrangement is made as shown in FIGS. 1 (d) and (e) of the first embodiment. As shown in FIG.
By mounting the BGA 8 on the substrate 9, even if the substrate 1 is curved, the wiring pads 2 of the substrate 1 and the wiring patterns 10 of the substrate 9 are individually electrically connected via the solder 16. Therefore, there is no connection failure especially on the outside.

FIGS. 4 (a), 4 (b) and 4 (c) show a third embodiment of a connection structure between an electronic component and a substrate according to the present invention, a connection method thereof, and a solder bump forming method in the connection structure and connection method.
It is explanatory drawing which showed embodiment of FIG. The third embodiment is a modification of the first and second embodiments described above. The supply amount of the solder 16 in the third embodiment is adjusted around the wiring pad 2. When the solder resist layer 15 is provided and the solder paste 6 is printed and supplied on the wiring pad 2, the opening 15 of the solder resist layer 15 is provided.
This is performed with the capacity of a. That is, the solder resist layer 15 is provided on the substrate 1. This solder resist layer 1
The opening 15a of No. 5 is smaller on the center side and larger on the outer side in consideration of the degree of curvature of the base material 1. A metal mask 4 is placed thereon, and a solder paste 6 is printed on the wiring pads 2 with a squeegee 5. Opening 4a of this metal mask 4
Are the same (see FIG. 4A). As a result of the screen printing, the wiring pads 2 and the solder resist layer 15 are formed.
The solder paste 6a spreads out from the gap, and the amount of the printed solder paste 6a is as shown in FIG. 1 (b) of the above-described first embodiment and FIG. 3 (b) of the second embodiment. In the same manner as in FIG.
(B)). Then, when this is reflowed, the solder does not wet the base material 1, so that the BGA 8 in which the height of the solder bumps 7 of each wiring pad 2 is uniform is obtained. After the reflow, the solder resist layer 15 is removed (FIG. 4).
See (c). As a result, the first embodiment and the second
Similarly to the embodiment, when the BGA 8 is mounted on the substrate 9, there is no connection failure even if the base material 1 is curved.

FIGS. 5 (a), 5 (b) and 5 (c) show a fourth embodiment of a connection structure between an electronic component and a substrate according to the present invention, a connection method thereof, and a solder bump forming method in the connection structure and connection method.
It is explanatory drawing which showed embodiment of FIG. FIG. 6 is a graph (graph) showing the relationship between the wiring pad diameter and the bump height when the amount of supplied solder is constant. In this fourth embodiment,
The supply amount of the solder 16 is fixed, and the wet area of the wiring pad 2 and the wiring pattern 10 is adjusted with respect to the curvature of the substrate 1. That is, assuming that the amount of the solder bumps (solder paste) is the same, the diameter (pad diameter) of the circular wiring pad is the same as the bump height (diameter) of the solder bumps after the reflow of the solder paste, as shown in FIG. The larger the value, the lower (small) the trade-off relationship.
Therefore, in the fourth embodiment, the shape of the wiring pad 2 is adjusted. As an adjustment method, the wiring pads 2 on the outer side compared to the wiring pads 2 near the center are determined based on the curvature of the base material 1.
(See FIG. 5A). Next, a solder paste 6a is printed on the above-mentioned wiring pad 2 using a metal mask having a constant opening capacity. The volume (capacity) of the printed solder paste 6a is the same on any of the wiring pads 2 (see FIG. 5B). When reflow is performed in this state, the bump height of the outer solder bump 7 becomes higher than that of the solder bump 7 near the center, and the apex of each solder bump 7 is arranged on the same plane. As a result, when the BGA 8 is mounted on the substrate 9, there is no connection failure even if the substrate 1 is curved.

In this embodiment, by adjusting the pad diameter of the wiring pads 2 in consideration of the characteristic curve of FIG. It is relatively proportional.

The methods of making the solder bump vertices flush with each other in the individual embodiments described above may be implemented in combination.
The same effect can be obtained even if the direction of warpage is reversed or a gap occurs between the apex of the solder bump and the substrate due to other causes. Similar effects (no connection failure) can be obtained even when solder bumps are formed on the substrate.

[0022]

As described above, according to the present invention, the degree of curvature of an electronic component and / or a substrate, and the degree of curvature of a wiring pad and / or a wiring so that a wiring pad and a wiring pattern are individually and completely connected in the supply of solder. Since the solder is supplied in an amount approximately proportional to the wet area of the solder when the pattern is heated and melted, the wiring pads of the electronic component and the wiring pattern of the board are electrically and completely connected individually via the solder There is no connection failure.

[Brief description of the drawings]

1 (a), (b), (c), (d) and (e) show a connection structure between an electronic component and a substrate according to the present invention, a connection method thereof, and a solder bump formation method in the connection structure and connection method. 1A and 1B show a first embodiment, wherein a BGA manufacturing process and BGA
FIG. 4 is a diagram schematically illustrating a process of mounting a GA on a substrate.

FIGS. 2A and 2B are explanatory views showing a modification of an opening of a metal mask.

FIGS. 3A, 3B, and 3C are diagrams showing a connection structure between an electronic component and a substrate according to the present invention, a connection method thereof, and a solder bump formation method in the connection structure and connection method; FIG. FIG. 17 is a diagram schematically illustrating a manufacturing process of a BGA according to the embodiment.

FIGS. 4 (a), (b) and (c) show a third embodiment of a connection structure between an electronic component and a substrate of the present invention, a connection method thereof, and a solder bump forming method in the connection structure and connection method; FIG. 3 is a simplified diagram showing a manufacturing process of a BGA showing the above.

FIGS. 5A, 5B, and 5C show a third embodiment of a connection structure between an electronic component and a substrate according to the present invention, a connection method thereof, and a solder bump forming method in the connection structure and the connection method; It is a figure which shows the manufacturing process of the shown BGA in a simplified form.

FIG. 6 is a graph (graph) showing a relationship between a wiring pad diameter and a bump height when a supplied amount of solder is constant.

7A is a schematic view of a BGA, FIG. 7B is a schematic view of a substrate, FIG. 7C is a view taken along a line cc in FIG. 7B, and FIG. It is the schematic of the state in which it was mounted.

8 (a), (b), (c), (d), and (e) show conventional B
It is a figure which shows the manufacturing process of GA, and the process which mounts a BGA on a board in simplified form.

[Description of Signs] 1 ... Base material 2 ... Wiring pad 3 ... Mold part 4 ... Metal mask 4a ... Opening of metal mask 5 ... Squeegee 6, 11 ... Solder paste 7 ... Solder bump 8 ... BGA 9 ... Substrate 10 ... Wiring Pattern 10a: routing portion 10b: circular portion 12, 15: solder resist layer 13: solder ball 14: vacuum suction jig 16: solder

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hideo Nakamura 5-2-2 Koyodai, Ryugasaki-shi, Ibaraki Pref. Hitachi Techno Engineering Co., Ltd.

Claims (7)

[Claims] 1. A connection structure between an electronic component and a substrate, wherein a wiring pad of the electronic component and a wiring pattern of the substrate are individually electrically connected via solder, wherein the supply amount of the solder is The degree of curvature of the electronic component and / or the substrate and the wet area of the solder when the wiring pad and / or the wiring pattern is heated and melted are substantially proportional so that the wiring pad and the wiring pattern are completely connected individually. A connection structure between an electronic component and a substrate, characterized in that the amount is a predetermined amount. 2. The connection structure between an electronic component and a substrate according to claim 1, wherein a supply amount of the solder is constant by adjusting the wetting area with respect to the degree of curvature, and / or A connection structure between an electronic component and a substrate, wherein the degree of curvature is adjusted while keeping the wet area constant. 3. A method of connecting an electronic component and a substrate, wherein the wiring pad of the electronic component and the wiring pattern of the substrate are individually electrically connected via solder, wherein the wiring pad and the wiring pattern are individually Supplying the solder in an amount substantially proportional to the degree of curvature of the electronic component and / or the substrate and the wet area of the solder when the wiring pad and / or the wiring pattern is heated and melted so that the solder is completely connected. Characteristic connection method between electronic components and substrate. 4. The method for connecting an electronic component and a substrate according to claim 3, wherein the supply amount of the solder is constant by adjusting the wetting area with respect to the degree of curvature, and / or A method for connecting an electronic component and a substrate, wherein the degree of curvature is adjusted while keeping the wet area constant. 5. A connection structure between an electronic component and a substrate, wherein a wiring pad of the electronic component and a wiring pattern of the substrate are individually electrically connected via solder, and a wiring pattern between the wiring pad of the electronic component and the substrate. And a method of connecting an electronic component and a substrate to each other electrically via a solder, by supplying solder to the wiring pads of the electronic component and / or the wiring pattern of the substrate, and then heating and melting the solder. A method of forming solder bumps by supplying solder on the wiring pads and / or the wiring patterns so that the wiring pads and the wiring patterns are completely connected individually. Or supplying the solder in an amount substantially proportional to the degree of curvature of the substrate and the wet area of the solder when the wiring pad and / or the wiring pattern is heated and melted. The solder bump forming method according to claim. 6. The solder bump forming method according to claim 5, wherein the supply amount of the solder is constant by adjusting the wetting area with respect to the degree of curvature, and / or A method for forming a solder bump, wherein the curvature is adjusted to be constant. 7. The solder bump forming method according to claim 5, wherein the supply amount of the solder is such that the solder paste is printed on and supplied to the wiring pad and / or the wiring pattern at an opening of a screen mask. Adjusting by capacity,
And or or, by printing a solder paste on the wiring pads and or the wiring pattern and when supplying the solder balls thereon, to adjust by the capacity of the opening of the screen mask, and / or the wiring pads and or A solder bump, wherein a solder resist layer is provided around a wiring pattern, and when the solder paste is printed and supplied on the wiring pad and / or the wiring pattern, the solder paste is adjusted by a capacity of an opening of the solder resist layer. Forming method.