JP2001308268A - Method for manufacturing small module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the rationalization of production with a single heat process. SOLUTION: The method for manufacturing a small module wherein a chip part 22 and a bearing chip 23 coexist on the same plane of a printed board 21 comprises a flux printing process 111 for printing a flux by means of a metal mask 25 on a land 24 for the bearing chip, a cream solder printing process 112 for printing a cream solder 31 using the metal mask 29 on a land 28 for the chip part, mounting processes 113, 114 for mounting the chip part 22 and the bearing chip 23, and the heat process 115 for heating with a reflow furnace. In the metal screen 29, a recess 32 is formed at a portion corresponding to the land 24 for the bearing chip. As a result, one reflow is enough and the rationalization of production is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a small module used for a portable telephone or the like.

[0002]

2. Description of the Related Art A conventional method of manufacturing a small module has been manufactured by a primary mounting process as shown in FIG. 12 and a secondary mounting process shown in FIG. 13 after the primary mounting process. That is, in the primary mounting step, as shown in FIG. 12, first, a hole 4 is provided at a position corresponding to the land 2 on a printed board 3 on which a land 1 for chip parts and a land 2 for bare chip are provided on the same plane. After the metal mask 5 is placed and the flux 7 is filled in the hole 4 with a squeegee 6, the flux 7 is transferred to the land 2 (hereinafter referred to as printing). ,
A bare chip mounting step 102 in which the solder bumps 9 of the bare chip 8 are placed on the lands 2 so as to be in contact therewith. After this step 102, the solder bumps 9 are heated by a reflow furnace to melt the electrodes of the bare chip 8. And a heating step 103 for electrically and mechanically bonding the lands 2 to each other.

[0003] Next, in a secondary mounting step, as shown in FIG. 13, a bare chip 8 is first fixed on the printed circuit board 3 by reflow soldering in a reflow step 103.
The hole 1 is located at a position corresponding to the land 1 for the chip component 14 above.
0 on which the metal mask 11 provided with the squeegee 1 is placed.
2, a chip component printing step 104 of filling the cream solder 13 into the hole 10 and printing the filled cream solder 13a on the land 1. After this step 104, the electrode 14a of the chip component 14 is placed on the cream solder 13a. And a heating step 106 of heating the reflow solder 13a to solder the electrode 14a and the land 1 after the step 105.

[0004]

However, in such a conventional manufacturing method, the heating step 103 in the primary mounting step is performed.
In the heating step 106 of the secondary mounting step, reflow soldering must be performed again, and the heating step is required twice.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a method for manufacturing a small module in which the heating step is performed once and the production is rationalized.

[0006]

In order to achieve this object, a method of manufacturing a small module according to the present invention is to manufacture a small module in which chip components and bare chips having solder bump electrodes are mixed on the same plane of a printed circuit board. A method, comprising: a first step of printing flux using a first metal mask on lands for bare chips on a printed circuit board;
After the first step, a second step of printing cream solder on a land for chip components of the printed circuit board using a second metal mask, and after the second step, A third step of mounting the chip component on the land for the chip component and mounting the bare chip on the land for the bare chip of the printed circuit board; and after the third step, the chip component and the bare chip are mounted. And a fourth step of heating the printed circuit board in a reflow furnace, wherein a concave portion is formed in a portion corresponding to the land for the bare chip on the printed circuit board surface side of the second metal screen. is there.

[0007] Thus, a small module can be manufactured by using only one reflow heating step, and the production can be rationalized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a method of manufacturing a small module in which chip components and bare chips having solder bump electrodes are mixed on the same plane of a printed circuit board. A first step of printing a flux on a land for bare chips using a first metal mask, and after the first step, using a second metal mask on a land for chip components of the printed circuit board. A second step of printing cream solder, and after this second step, mounting the chip component on the land for the chip component on the printed circuit board and mounting the bare chip on the land for the bare chip on the printed circuit board A third step of heating the printed circuit board, on which the chip components and the bare chip are mounted, in a reflow furnace after the third step. And a method of manufacturing a small module in which a concave portion is formed in a portion corresponding to the land for a bare chip on the printed circuit board surface side of the second metal screen. Since the component and the bare chip can be mounted in the same step, the chip component and the bare chip can be soldered simultaneously in the fourth step, and the production can be rationalized.

Further, at the time of cream solder printing in the second step, since the bare chip is not mounted, the distance between the chip component and the bare chip can be shortened.

According to a second aspect of the present invention, there is provided a method of manufacturing a small module according to the first aspect, wherein the bare chip and the chip component are mounted on a printed circuit board having a distance of 1 mm or less between the land for the bare chip and the land for the chip component. Since the mounting density is increased, a small module can be manufactured.

The first metal mask according to the third aspect of the present invention is the method of manufacturing a small module according to the first aspect, wherein a portion corresponding to a land for a bare chip is meshed, and a net is used. Therefore, it is not necessary to exactly match the land position for the bare chip in the production of the metal mask. Also, flux printing with low viscosity is possible.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a small module in which chip components and bare chips having solderable metal bump electrodes are mixed on the same plane of the printed circuit board. A first step of printing cream solder on a land for the chip and a land for the chip component using a metal mask, and after this first step, mounting the chip component on the land for the chip component of the printed circuit board And a second step of mounting a bare chip on the land for the bare chip of the printed board, and after the second step, heating the printed board on which the chip components and the bare chip are mounted in a reflow furnace. And a step corresponding to the land for bare chips on the side of the metal screen where the squeegee is movable. Parts are provided methods for producing the compact module having a hole at a portion corresponding to the bare land on the bottom of the recess while being formed, since the second step can be mounted to the chip component and the bare chip in the same process,
In the third step, the chip component and the bare chip can be soldered simultaneously. Therefore, the heating process becomes one,
Production can be streamlined.

Further, at the time of cream solder printing in the first step, since the bare chip is not mounted, the distance between the chip component and the bare chip can be shortened.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a small module according to the fourth aspect, wherein the bare chip and the chip part are mounted on a printed circuit board having a distance of 1 mm or less between the land for the bare chip and the land for the chip part. Since the mounting density is high, a small module can be manufactured.

(Embodiment 1) A method for manufacturing a small module according to Embodiment 1 of the present invention will be described below. FIG. 1 shows a method for manufacturing a small module in which a chip component 22 and a bare chip 23 having solder bump electrodes are mixed on the same plane of a printed board 21, wherein a land 24 for the bare chip 23 on the printed board 21 is provided with a metal mask 25. Is placed, and the flux 27 is
Flux printing step 111 for printing
After 1, a metal mask 29 is placed on the land 28 for the chip component 22 of the printed circuit board 21, and the cream solder 31 is printed using the squeegee 30. Substrate 21
A chip component mounting step 113 for mounting the chip component 22 on the cream solder 31a printed on the land 28 for the chip component 22 of the first embodiment;
A bare chip mounting step 114 of mounting the bare chip 23 on the land 24 for one bare chip 23;
Is followed by a heating step 11 of heating the printed circuit board 21 on which the chip component 22 and the bare chip 23 are mounted in a reflow furnace.
5 is provided.

Here, the metal mask 29 has a concave portion 32 formed at a portion corresponding to the land 24 for the bare chip 23.

Here, the mounting step 113 of the chip component 22
Either of the steps 114 and 114 for mounting the chip and the bare chip 23 may be performed first, or the same step may be performed. Whatever it is,
Unlike the conventional case, there is no need to heat separately, and the chip component 22 and the bare chip 23 are mounted.
Heating step 115 for simultaneously heating 2 and bare chip 23
And soldering can be performed. Therefore, production can be rationalized.

Conventionally, as shown in FIG. 13, the metal mask 11 is provided with a convex portion 15 at a position corresponding to the bare chip 8 in order to print the cream solder 13 in a state where the bare chip 8 is mounted. Was. This convex part 1
5, in order to reliably fill the hole 10 with the cream solder 13, an interval 16 of 1 mm or more is absolutely required between the land 1 for the chip component 22 and the land 2 for the bare chip 8. Was.

However, in the present invention, since the bare chip 23 is not mounted in the cream solder printing step 112, the distance between the chip component 22 and the bare chip 23 can be reduced from 0.5 mm to about 0.7 mm, and the mounting density can be reduced. Can be increased.

FIG. 2 is a plan view of one printed circuit board 21. In FIG. 2, reference numeral 22 denotes a chip component;
Is a bare chip. In the present embodiment, the distance 42 between the chip component 22 and the bare chip 23 can be reduced as described above, and the overall size can be reduced, which is a great feature. 33 is a ground electrode formed on the side surface of the printed circuit board 21, and 34 is a signal electrode formed on the other side surface. The five printed circuit boards 21 are connected vertically and horizontally to form a parent board. The image of the parent substrate is similar to the metal mask shown in FIG.

FIG. 3 is a plan view of the parent metal mask 35 mounted on the parent substrate. Five metal masks 29 are connected to the parent metal mask 35 in each of the vertical direction and the horizontal direction. It is not necessary to limit the number to be connected to five. The size of the parent metal mask 35 is 90 m in length.
m, 95 mm in width, and the material is stainless steel. Also, its thickness is 120 microns.

FIG. 4 is an enlarged plan view of one metal mask 29 in the parent metal mask 35. FIG.
In the figure, reference numeral 36 denotes a hole for filling the cream solder 31 in the land 28 for the chip component 22, and is provided at a position corresponding to the land 28. Reference numeral 37 denotes a concave portion provided corresponding to the land 24 for the bare chip 23. In this embodiment, the shape of the recess 37 is substantially the same as the shape of the bare chip 23.

FIG. 5 is a sectional view thereof. In FIG.
The material of the metal mask 29 is stainless steel, and its thickness 38 is 0.12 mm. Also, the depth 39 of the recess 37
Is 0.07 mm, and the thickness 40 of the top surface is 0.05 mm
I have to. Also, a hole 36 for filling the cream solder 31 is provided.
Has a diameter of 0.5 mm. This recess 3
7, the flux 27a printed on the land 24 for the bare chip 23 does not adhere to the metal mask 29. Therefore, the amount of the flux 27a does not become unstable. Further, by providing the concave portion 37 in this manner, the land 28 for the chip component 22 can be brought closer to the limit as compared with the land 28 for the bare chip 23 as compared with the related art. Therefore, the component mounting density can be increased, and the size of the module can be reduced. In the present embodiment, the distance 42 to the land 28 closest to the land 24 is reduced to 0.5 to 0.7 mm.

FIG. 6 is a cross-sectional view of the vicinity of the main part of the bare chip 23. The electrodes 44 of the bare chip 23 are provided with solder bumps 43. On the other hand, a land 24 is provided on the printed circuit board 21, and a flux 27a is printed on the land 24. And this flux 27
The electrodes 44 of the bare chip 23 and the lands 24 are electrically connected by placing the solder bumps 43 on the a and heating them.

FIG. 7 is a sectional view of the printed circuit board 21 and the metal mask 25 for printing the flux 27a on the land 24. The metal mask 25 is used in the flux printing step 111 and is made of stainless steel. The thickness 45 is 0.05 mm. 46
Is a hole provided corresponding to the land 24, and its diameter is 0.12 mm. The holes 46 are filled with the flux 27 to be printed on the lands 24. The flux 27 at this time is preferably a high-viscosity flux.

FIG. 8 is a cross-sectional view of the printed circuit board 21 and the mesh screen 47 for printing the flux 27a on the land 24. The mesh screen 47 is used in the flux printing step 111, and is formed of a stainless mesh in the present embodiment. The thickness 45a is 0.05 mm. 48 is land 24
And is a square that substantially surrounds the entire bare chip 23. The mesh 48 is filled with the flux 27 to be printed on the land 24.
The flux 27 at this time is preferably a low-viscosity flux.

(Embodiment 2) A method of manufacturing a small module according to Embodiment 2 of the present invention will be described below. FIG. 9 shows a method for manufacturing a small module in which a chip component 52 and a bare chip 53 having a solderable metal bump electrode are mixed on the same plane of a printed circuit board 51, and a land for the bare chip 52 on the printed circuit board 51 is provided. 5
4 and metal mask 5 on land 55 for bare chip 53
6 is placed thereon, and a cream solder 58 is
Solder printing step 121 for printing
After 21, a chip component mounting step 122 of mounting the chip component 52 on the cream solder 58 a printed on the land 54 for the chip component 52 of the printed board 51, and after this step 122, the chip component mounting step 122 for the bare chip 53 of the printed board 51. A bare chip mounting step 123 for mounting the bare chip 53 on the cream solder 58b printed on the land 55, and after this step 123, a reflow step 124 for heating the printed circuit board 51 on which the chip components 52 and the bare chip 53 are mounted in a reflow furnace. And

Here, the metal mask 56 is a portion corresponding to the land 55 for the bare chip 53 and has a recess 59 formed on a surface on which the squeegee 57 can move.

Either the step 122 for mounting the chip component 52 or the step 123 for mounting the bare chip 53 may be performed first, or they may be performed in the same step. In any case, it is not necessary to perform reflow separately as in the related art, and the chip component 52 and the bare chip 53 are mounted in the same or different steps, and the chip component 52 and the bare chip 53 are heated simultaneously, and soldering is performed. Can be attached.

As in the first embodiment, conventionally, as shown in FIG. 13, since the cream solder 13 is printed with the bare chip 8 mounted on the metal mask 11, the position corresponding to the bare chip 8 is set. Was provided with a convex portion 15. Since the protrusions 15 are provided, in order to reliably fill the hole 10 with the cream solder 13, an interval 16 of 1 mm or more must be provided between the land 1 for the chip component 22 and the land 2 for the bare chip 8. Was needed.

However, in the present invention, the cream solder printing step 121 for the chip component 52 and the bare chip 53 can be performed by the same process, so that the distance between the chip component 52 and the bare chip 53 is about 0.5 mm to 0.7 mm. In this case, the size of the module can be reduced.

The second embodiment is the same as the first embodiment, and only one module will be described. In practice, however, five modules are connected in the vertical and horizontal directions. is there. Note that this is not limited to five separately. The metal mask 57 is also connected in the same manner.

FIG. 10 is a sectional view of the metal mask 56. In FIG. 10, the material of the metal mask 56 is stainless steel, and its thickness 60 is 0.10 mm. The depth 61 of the recess 59 is 0.05 mm, and the thickness 62 of the bottom surface is 0.05 mm. Reference numeral 63 denotes a hole formed corresponding to the land 54 for the chip component 52 of the printed board 51, and the diameter 64 is a round hole of 0.5 mm. Reference numeral 65 denotes a hole formed on the bottom surface of the concave portion 59, and corresponds to the land 55 for the bare chip 53. The diameter 66 of the hole 65 is 0.12 mm. Then, cream solder 5 is provided in these holes 63 and 65.
8 are filled and printed on lands 54 and 55, respectively.

By forming the recess 59 in this manner, the thickness of the metal mask corresponding to the portion where the bare chip is to be mounted can be reduced.
Since the cream solder can be removed even in the minute hole 65 having a diameter of 50 mm, the land 54 for the chip component 52 and the bare chip 53
Suitable amounts of cream solders 58a, 58
b can be printed.

In addition, since the cream solder 58 can be printed without the bare chip 53 being mounted, the land 55 for the chip component 52 can be brought closer to the land 55 for the bare chip 53 as much as possible. Thus, the component mounting density can be increased. Therefore, the size of the module can be reduced. In the present embodiment, the distance 67 to the land 55 closest to the land 54 is set to 0.5 to
Close to 0.7mm.

FIG. 11 is a cross-sectional view of the vicinity of a main part of the bare chip 53. The electrodes 71 of the bare chip 53 are provided with gold bumps 72 as a solderable metal. On the other hand, a land 55 is provided on the printed board 51, and the cream solder 58b is printed on the land 55. Then, the gold bump 72 is formed on the cream solder 58b.
Is placed and heated, the electrode 7 of the bare chip 53 is heated.
1 and land 55 are electrically connected. In the second embodiment, a conductive adhesive can be used instead of the cream solder 58.

Thereafter, both the first and second embodiments are inspected for the quality of reflow soldering, the mounting of components, and the like. Next, the flux is removed by washing to enhance the adhesion of the underfill. Next, a sealing material is applied to the bare chip to enhance the mechanical strength between the bare chip and the printed board. Next, after drying, an X-ray inspection is performed, and only non-defective products are stored.

[0038]

As described above, according to the present invention, the chip component and the bare chip can be mounted in the same step in the third step, so that the chip part and the bare chip can be soldered simultaneously in the fourth step. It can streamline production.

Further, at the time of printing the cream solder in the second step, since the bare chip is not mounted, the distance between the chip component and the bare chip can be shortened.

[Brief description of the drawings]

FIGS. 1 (1) to 1 (115) are process diagrams of a method for manufacturing a small module according to a first embodiment of the present invention; FIGS.

FIG. 2 is a plan view of the small module.

FIG. 3 is a plan view of the same metal mask.

FIG. 4 is a plan view of a metal mask for one small module.

FIG. 5 is a sectional view of the same.

FIG. 6 is a cross-sectional view of the vicinity of a main part of the bare chip.

FIG. 7 is a sectional view of a metal mask and a printed circuit board.

FIG. 8 is a cross-sectional view of a metal mask and a printed circuit board according to another example.

FIGS. 9A and 9B are process diagrams of a method for manufacturing a small module according to the second embodiment of the present invention;

FIG. 10 is a cross-sectional view of a metal mask and a printed circuit board for one small module.

FIG. 11 is a cross-sectional view of the vicinity of a main part of the bare chip.

12 (101) to (103) are process diagrams of primary mounting of a conventional small module, respectively.

13 (104) to (106) are process diagrams of secondary mounting of a conventional small module, respectively.

[Explanation of symbols]

 111 Flux printing process 112 Cream solder printing process 113 Chip component mounting process 114 Bare chip mounting process 115 Heating process

Claims (5)

[Claims] 1. A method for manufacturing a small module in which chip components and bare chips having solder bump electrodes are mixed on the same plane of a printed circuit board, wherein a land for the bare chips on the printed circuit board is formed using a first metal mask. A first step of printing a flux, and after the first step, a second step of printing cream solder on a land for a chip component of the printed circuit board using a second metal mask;
After the second step, a third step of mounting a chip component on the land for the chip component of the printed circuit board and mounting a bare chip on the land for the bare chip of the printed circuit board; After the step, a fourth step of heating the printed circuit board on which the chip portion and the bare chip are mounted in a reflow furnace, on the printed circuit board surface side of the second metal screen,
A method for manufacturing a small module in which a concave portion is formed in a portion corresponding to the bare chip land. 2. The method for manufacturing a small module according to claim 1, wherein the bare chip and the chip component are mounted on a printed circuit board in which the distance between the land for the bare chip and the land for the chip component is 1 mm or less. 3. The method for manufacturing a small module according to claim 1, wherein the first metal mask has a mesh portion at a portion corresponding to a land for a bare chip. 4. A method for manufacturing a small module in which chip components and bare chips having solderable metal bump electrodes are mixed on the same plane of a printed circuit board, the method comprising the steps of: Of cream solder on metal land using metal mask
And after the first step, a second step of mounting a chip component on the land for the chip component of the printed board, and mounting a bare chip on the land for the bare chip of the printed board, After the second step, a third step of heating the printed circuit board on which the chip components and the bare chip are mounted in a reflow furnace, and the squeegee of the metal screen has a movable surface side, A method of manufacturing a small module, wherein a concave portion is formed in a portion corresponding to a land for a bare chip, and a hole is provided in a portion of the bottom surface of the concave portion corresponding to the land for a bare chip. 5. The method for manufacturing a small module according to claim 4, wherein the bare chip and the chip component are mounted on a printed circuit board having a distance between the land for the bare chip and the land for the chip component of 1 mm or less.