JP2000183109A - Manufacture of wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify works by a method, wherein a space enclosed with a soft sheet and a mounting tool is decompressed, and by making use of a pressing force of the soft sheet due to compression, apexes of a plurality of bump-like connection terminals exposed through transparent holes are flattened. SOLUTION: The entire surface on the upper face of a plurality of wiring boards is coated with a soft sheet 14 composed of silicon rubber, and a reinforcing plate 2 and a wiring substrate main body 6 overlaid via an adhesive sheet 10A are enclosed with the soft sheet 14 and a mounting tool 11. Next, a space enclosed by the soft sheet 14 and the mounting tool 11 and surrounded by an exhaust pipe 12 is decompressed. After a preliminary heating is performed under the decompression, the adhesive sheet 10A is heated at 170 deg.C for 60 min and is cured, and pressure from the soft sheet 14 due to compression is exploited, while the reinforcing plate 2 is adhered to the wiring substrate main body 6. Here at the same time, after the apex of a solder bump 8 is flattened under a pressure from the soft sheet 14, the soft sheet 14 is removed to complete a wiring substrate.

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 wiring board having a wiring board main body and a reinforcing plate, and more particularly to a method for applying pressure to a flexible sheet generated by decompression and applying pressure to a top of a bump-shaped connection terminal. Or a method of manufacturing a wiring board including a step of flattening a top portion of a bump-shaped connection terminal and a step of bonding a wiring board body and a reinforcing plate.

[0002]

2. Description of the Related Art Hitherto, there has been known a wiring board having a reinforcing plate adhered to a main surface of a wiring board main body. This reinforcement plate,
The so-called stiffener improves the rigidity of the wiring board,
It is used to maintain its flatness.

FIG. 6 is a cross-sectional view of a wiring board 101 on which a flip-chip type integrated circuit chip is mounted. This wiring board 101
A reinforcing plate 102 in which a through-hole 103 corresponding to the integrated circuit chip 111 is formed, a wiring board main body 106 in which a plurality of electrode pads 109 and a plurality of connection pads 107 corresponding to the terminals 112 of the integrated circuit chip 111 are arranged, And an integrated circuit chip 111. The reinforcing plate 102 and the wiring board main body 106 are bonded via an adhesive layer 110.
The integrated circuit chip 111 includes a connection pad 107 of the wiring board body 106 and a terminal 112 of the integrated circuit chip 111.
Are connected to each other via the solder 108A, and thus are mounted on the wiring board main body 106.

[0004] Such a wiring board 101 is manufactured as follows. That is, as shown in FIG. 7A, the wiring board main body 106 is prepared, and the adhesive sheet 1 is placed at a predetermined position.
10A is placed, and the reinforcing plate 102 is placed thereon with positioning. Next, as shown in FIG.
The weight WT is placed on the reinforcing plate 102, and is heated and pressed to bond the reinforcing plate 102 to the wiring board main body 106 via the adhesive layer 110. Next, after removing the weight WT, as shown in FIG. 7C, the flattening jig PT is placed on the bump-like connection terminals (hereinafter, also simply referred to as solder bumps) 108 of the wiring board body 106, Pressing with a press, solder bump 1
08 are flattened. Next, when the flattening jig PT is removed, the wiring board shown in FIG. further,
When the integrated circuit chip 111 is placed on the solder bumps 108 and heated to melt the solder and connect the integrated circuit chip 111 and the wiring board body 106, the wiring board 101 shown in FIG. 6 is completed.

[0005]

However, when the wiring board 101 is manufactured in this manner, when mass-producing a large number of wiring boards, the flattening jig PT is inserted into the through-hole of each wiring board. It is necessary to dispose while positioning, and to collect the flattening jig PT after the flattening step of the solder bumps 108, which is very troublesome and raises the manufacturing cost.

In the above-described conventional method, the reinforcing plate 1
Air bubbles remain in the adhesive layer 110 for adhering the substrate 02 to the wiring board main body 106, and adhesion reliability and airtightness are reduced, and adhesion reliability is low. In addition, the work of bonding the reinforcing plate 102 to the wiring board 106 and the work of flattening the wiring board main body 106 are separately performed, which is troublesome. Furthermore, the weight WT
When the flattening jig PT is pressed and flattened by placing the flattening jig PT on the flattening jig PT, the load is not necessarily uniformly applied, and a large warpage or distortion occurs in the wiring board 101 or the top of the solder bump 108 Sometimes, the coporanality that was created was increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and a method of flattening bump-like connection terminals (solder bumps) of a wiring board without using a flattening jig for each wiring board. Provided is a method of manufacturing a wiring board that can simplify the operation by simultaneously flattening the connection terminals, and also reduce the warpage of the wiring substrate and the coplanarity of the tops of the bump connection terminals. The purpose is to:

[0008]

According to a first aspect of the present invention, there is provided a semiconductor device having a first main surface and a second main surface, on which an electronic component is mounted. A first main surface of the wiring substrate body having a plurality of bump-shaped connection terminals;
The second reinforcing plate main surface of a reinforcing plate having a reinforcing plate main surface and a second reinforcing plate main surface and having a through-hole was bonded by exposing the plurality of bump-shaped connection terminals through the through-hole. A method for manufacturing a wiring board, comprising: a mounting step of mounting the wiring board main body and the reinforcing plate on a plane of a mounting jig; and covering the wiring board main body and the reinforcing plate with a flexible sheet. An enclosing step of enclosing the wiring board body and the reinforcing plate with the mounting jig, and a space surrounded by the flexible sheet and the mounting jig is depressurized and pressurized by the flexible sheet, And a flattening step of flattening the tops of the plurality of bump-shaped connection terminals exposed from the through-holes.

According to the present invention, the wiring board main body and the reinforcing plate are arranged in the space surrounded by the flexible sheet and the mounting jig, and the space is reduced in pressure, and the pressure of the flexible sheet generated by the reduced pressure is used. Since the tops of the plurality of bump-shaped connection terminals exposed from the through holes are flattened, the tops of the bump-shaped connection terminals of many wiring boards can be simultaneously flattened with a common flexible sheet. Therefore, there is no need to dispose a flattening jig on each wiring substrate, and it is not necessary to collect the flattening jigs after the flattening step, thereby simplifying the work.

[0010] Further, since the pressure is reduced to uniformly apply a pressure to the entire flexible sheet, the wiring board main body and the reinforcing member are required as compared with the conventional method in which a flattening jig is placed on each wiring board and pressurized. The plate can be pressed uniformly. For this reason, the coplanarity formed by the tops of the bump-shaped connection terminals after the flattening step can be reduced.

Here, the wiring board body may be any one having an insulating layer and a wiring layer. For example, the insulating layer and the wiring layer are alternately formed on one or both sides of a core substrate made of a metal substrate or an insulating substrate. Although a multilayer wiring board or the like in which a plurality of layers are laminated may be mentioned, a single-layer wiring board may be used. Also, on the second main surface of the wiring board body, for example,
Terminals such as connection pads, solder bumps, and pins for connecting to another printed wiring board such as a motherboard may be formed.

The material of the reinforcing plate may be appropriately selected in consideration of the rigidity, the coefficient of thermal expansion, and the like. For example, in addition to a metal plate such as copper, copper alloy, aluminum, and stainless steel, a resin having increased rigidity may be used. Plates and the like. Also, the reinforcing plate
In addition to the through hole corresponding to the integrated circuit chip, a through hole corresponding to that may be formed in a wiring board on which another electronic component (such as a chip capacitor) is mounted. Further, a plating layer may be formed on the surface of the reinforcing plate as necessary, for example, a nickel plating layer, a gold plating layer, or the like may be formed.

The adhesive may be selected in consideration of the adhesiveness to the reinforcing plate and the wiring board body, the coefficient of thermal expansion, and the like, and a paste-like adhesive such as an epoxy resin or a polyimide resin may be used. Alternatively, an adhesive sheet obtained by processing these into a film shape in advance may be used. As the adhesive sheet, for example, epoxy resin or the like may be made of glass fiber or continuous porous PTFE.
A three-dimensional network-like fluororesin substrate impregnated with a film may be used. In this specification, bonding means such as a paste-like adhesive and a film-like adhesive sheet are collectively referred to as an adhesive.

The mounting jig has a flat surface on which the wiring board body and the reinforcing plate overlapped with an adhesive are arranged, and a space capable of being decompressed by being surrounded by the flexible sheet and the mounting jig is formed. Anything should do. The flexible sheet may be made of a flexible material such as rubber or resin. When such a flexible sheet is used, when the space surrounded by the flexible sheet and the mounting jig is depressurized, the airtightness of the space is easily increased, so that the bonding step is performed easily and securely. be able to.

Further, the invention according to claim 2 has a first main surface and a second main surface, and a plurality of bump-shaped connection terminals for mounting electronic components on the first main surface. A first main surface of the wiring board body, a second main surface of the reinforcing plate having a first main surface of the reinforcing plate and a second main surface of the second reinforcing plate, and having a through hole;
A method for manufacturing a wiring board, wherein the plurality of bump-shaped connection terminals are exposed from the through holes and bonded, wherein the wiring board body and the reinforcing plate are bonded to the first main surface and the second reinforcing plate main surface. And placing the wiring board body and the reinforcing plate with a flexible sheet, and placing the flexible sheet and the above-described mounting jig And an enclosing step for enclosing the wiring board body and the reinforcing plate, and the space surrounded by the flexible sheet and the mounting jig is decompressed and heated while being pressurized by the flexible sheet. A flattening and bonding step of flattening the tops of the plurality of bump-shaped connection terminals exposed from the through holes and bonding the first main surface of the wiring board main body and the second reinforcing plate main surface of the reinforcing plate; The gist of the present invention is a method for manufacturing a wiring board, comprising:

According to the present invention, the wiring board main body and the reinforcing plate are arranged in the space surrounded by the flexible sheet and the mounting jig, and the space is reduced in pressure. Along with the flattening of the bump-shaped connection terminals, the wiring board body and the reinforcing plate are bonded. As described above, the step of flattening the bump-shaped connection terminals and the step of bonding the wiring board body and the reinforcing plate, which have been conventionally separated, can be performed simultaneously, so that the steps can be simplified and the manufacturing cost can be reduced.

Further, in the invention according to claim 3, in the mounting step, the reinforcing plate, in which an adhesive sheet is pasted on the wiring substrate main body and the second reinforcing plate main surface in advance, is attached to the first main surface. A gist of the present invention is a method for manufacturing a wiring board, wherein the mounting jig is mounted on a plane of the mounting jig in a state where the main surface faces the second reinforcing plate.

According to the present invention, since the adhesive sheet is attached to the reinforcing plate in advance, the adhesive sheet is less likely to wrinkle or break, and can maintain a flat and uniform thickness. Is good.

Further, the invention according to a fourth aspect of the present invention provides a method of manufacturing a wiring board, characterized in that an adhesive sheet previously attached to the reinforcing plate is formed smaller than an outer shape of the reinforcing plate. And

According to the present invention, since the outer shape of the adhesive sheet is formed smaller than the outer shape of the reinforcing plate, the amount of the adhesive that sticks out at the time of pressure bonding can be reduced. In this case, the surface of the bump-shaped connection terminal in the through-hole can be covered, and the occurrence of connection failure with the integrated circuit chip can be effectively prevented.

More preferably, the adhesive is cured after being preheated to a temperature lower than the temperature at which curing of the adhesive starts, after the pressure is reduced. This is because it is possible to prevent discoloration of plating such as gold plating applied to the surface of the reinforcing plate or the like due to outgas such as a solvent coming out of the adhesive material.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A shows an enlarged cross-sectional view of a wiring board 1 manufactured in the present embodiment.
(B) is a plan view of the reinforcing plate 2 as seen from the first reinforcing plate main surface 2A side. The wiring board 1 has a substantially rectangular plate shape of 40 × 40 mm in plan view and includes a reinforcing plate 2 and a wiring board body 6. The reinforcing plate 2 and the wiring board body 6 are made of a composite material in which the second main surface of the reinforcing plate 2 and the first main surface of the wiring board body 6 are made by impregnating a continuous porous PTFE base material with an epoxy resin. Are adhered through an adhesive layer 10.

The reinforcing plate 2 is made of a copper plate having a thickness of 0.7 mm, and has a first reinforcing plate main surface 2A and a second reinforcing plate main surface 2B.
And a substantially square plate shape of 40 × 40 mm having
In the approximate center thereof, a portion extending between the first reinforcing plate main surface 2A and the reinforcing plate main surface 2B corresponding to a flip-chip connection type integrated circuit chip (not shown) to be mounted is formed in a size of 15 × 15.
A substantially square through hole 3 of mm is formed. Further, nickel plating and gold plating (not shown) are formed on the surface of the reinforcing plate 2.

On the other hand, the wiring board body 6 is a substantially square plate of 40 × 40 mm having a first main surface 6A and a second main surface 6B, and an integrated circuit to be mounted is provided on the first main surface 6A side. A large number of connection pads 7 having a diameter of 115 μm are arranged in a substantially lattice shape corresponding to the terminals of the chip, and solder bumps 8 made of eutectic solder are formed on each connection pad 7. These solder bumps 8 are arranged so as to be exposed in the through holes 3 of the reinforcing plate 2 as shown in FIG. The tops 8A of the solder bumps 8 are flattened by a flexible sheet 14 described later. A large number of electrode pads 9 are formed on the second main surface 6B side. The wiring substrate body 6 is made of a continuous porous P
A resin insulation layer made of a composite material in which a TFE base material is impregnated with an epoxy resin, and a plurality of wiring layers (not shown) are laminated.

Next, a method of manufacturing the wiring board 1 will be described with reference to FIGS. First, a film-like adhesive sheet 10A is temporarily bonded at a predetermined position of the second reinforcing plate main surface 2B of the reinforcing plate 2 at 100 to 120 ° C., and in the mounting step, as shown in FIG. The reinforcing plate 2 to which the adhesive sheet 10A has been attached is positioned and placed on the first main surface 6A of the wiring board body 6 manufactured by a known method.

Next, as shown in FIG. 3, the reinforcing plate 2 and the wiring board main body 6 stacked via the adhesive sheet 10A are placed on the second main surface 6B of the wiring board main body 6 so that the mounting jig 11 is placed thereon. It is mounted on the mounting surface 11A so as to be in contact with the surface 11A. The mounting jig 11 has a concave portion 11R having a mounting surface 11A as a bottom surface, and has an adhesive /
In the flattening step, an exhaust pipe 12 for reducing the pressure of the space surrounded by the mounting jig 11 and the flexible sheet 14 is formed.

Next, in the surrounding step, as shown in FIG. 4, the entire upper surface of the plurality of wiring boards 1 is covered with a flexible sheet 14 made of silicon rubber and having a thickness of 1.0 mm. Adhesive sheet 10A
Surrounding the reinforcing plate 2 and the wiring board main body 6 which are overlapped with each other.

Next, in the bonding / flattening step, as shown in FIG. 5, the space surrounded by the flexible sheet 14 and the mounting jig 11 is reduced in pressure from the exhaust pipe 12. Under reduced pressure, 1
After preheating at 00 ° C for 30 minutes,
The adhesive sheet 10A is cured by heating for 0 minutes, and the reinforcing plate 2 and the wiring board main body 6 are adhered while utilizing the pressure from the flexible sheet due to the reduced pressure. At this time, at the same time, the top of the solder bumps 8 is flattened by the lower surface 14B of the flexible sheet by pressing from the flexible sheet 14, and then the flexible sheet 14 is removed to complete the wiring board 1 shown in FIG.

In this embodiment, preheating under reduced pressure (vacuum) was performed before curing by heating at 170 ° C.
This is because it is possible to prevent the discoloration of the gold plating layer applied to the wiring and the like on the surface of the reinforcing plate 2 and the wiring board main body 6 due to outgas such as a solvent generated from the adhesive. The temperature of the preheating under reduced pressure is lower than the temperature at which the curing of the adhesive starts, and more preferably, it may be appropriately performed at a higher temperature, but the adhesive of the present embodiment starts curing at 140 ° C or higher. The temperature of the preheating was set to 100 ° C.

In the wiring board 1 manufactured by the manufacturing method of this embodiment, the coplanarity formed by the tops of the solder bumps 8 can be reduced, and a flattening jig is provided in each through hole of the reinforcing plate 2. There is no need to dispose, and there is no need to collect this flattening jig after the flattening step. Therefore, the plurality of wiring boards 1 can be flattened at once with high accuracy.

Further, the generation of bubbles in the adhesive layer 10 for bonding the reinforcing plate 2 and the wiring board body 6 is suppressed, and the bonding reliability is high. Further, since this bonding and the flattening of the top of the solder bump 8 can be performed at the same time, the operation can be simplified.

In this embodiment, in the mounting step,
The temporary bonding of the adhesive sheet 10A to the reinforcing plate 2
Although placed on the wiring board main body 6, the adhesive sheet 10A and the reinforcing plate 2 may be sequentially stacked on the wiring board main body 6. However, this embodiment is preferable because the positioning of the reinforcing plate 2, the adhesive sheet 10A, and the wiring board main body 6 is facilitated. Further, in order to prevent the adhesive from protruding, it is preferable to use an adhesive sheet 10A having a shape slightly lower than the outer shape of the reinforcing plate 2. further,
It is preferable to use an adhesive sheet 10A made of a material similar to that of the insulating layer of the wiring board body 6 as in the present embodiment, since the thermal expansion coefficient and the like are compatible between them. Further, the adhesive sheet 10
A paste adhesive may be used instead of A.

In the present embodiment, the flexible sheet 14 made of silicon rubber is used in the surrounding step, but the present invention is not limited to this, and a flexible resin or another material may be used.

Although the above has been described with reference to the embodiment of the present invention, the present invention is not limited to the above embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist of the present invention. Nor.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a wiring board according to an embodiment of the present invention, wherein FIG. 1A is an enlarged cross-sectional view and FIG. 1B is a plan view of a reinforcing plate viewed from a first main surface of the first reinforcing plate. .

FIG. 2 is a view illustrating a method for manufacturing a wiring board according to an embodiment of the present invention, and shows a state in which an adhesive sheet is overlaid on the wiring board main body.

FIG. 3 is a view showing a method of manufacturing a wiring board according to the embodiment of the present invention, and shows a state in which a plurality of wiring board bodies and reinforcing plates are arranged on a mounting jig in a mounting step.

FIG. 4 is a diagram showing a method of manufacturing the wiring board according to the embodiment of the present invention, showing a state where the wiring board is covered with a flexible sheet in a surrounding step and is surrounded by a mounting jig.

FIG. 5 is a view showing a method of manufacturing the wiring board according to the embodiment of the present invention, in which the tops of the solder bumps of the plurality of wiring boards are flattened by a flexible sheet in a bonding / flattening step, and the reinforcing plate, the wiring board body and Shows a state in which is adhered.

FIG. 6 is an enlarged cross-sectional view of a wiring board having a reinforcing plate according to the related art.

FIG. 7 is a diagram showing a conventional method for manufacturing a wiring board;
(A) is a diagram showing a state in which a reinforcing plate is placed on the wiring board body via an adhesive sheet, (b) is a diagram showing a state in which a weight is placed on the reinforcing plate and the adhesive sheet is heated and cured, and (c) is a diagram showing () Shows a state in which a bump flattening jig is placed on the solder bumps, and (d) shows a wiring board in which the tops of the solder bumps are flattened.

[Explanation of symbols]

 1: wiring board 2: reinforcing plate 2A: first reinforcing plate main surface 2B: second reinforcing plate main surface 3: through hole 6: wiring substrate body 6A: first main surface 6B: second main surface 7: connection pad 8 : Solder bump (bump-shaped connection terminal) 8A: top of solder bump 10A: adhesive sheet 10: adhesive layer 11: mounting jig 11A: mounting surface 14: flexible sheet

[Reference number] 99-0354

Claims (4)

[Claims] 1. The first main surface of a wiring board body having a first main surface and a second main surface, and having a plurality of bump-like connection terminals for mounting electronic components on the first main surface. And a second reinforcing plate main surface of a reinforcing plate having a first reinforcing plate main surface and a second reinforcing plate main surface and having a through hole, exposing the plurality of bump-shaped connection terminals from the through hole. A method of manufacturing a wiring board bonded and adhered, comprising: a mounting step of mounting the wiring board main body and the reinforcing plate on a plane of a mounting jig; and covering the wiring substrate main body and the reinforcing plate with a flexible sheet; An enclosing step of enclosing the wiring board body and the reinforcing plate with the flexible sheet and the mounting jig, and reducing the pressure of the space surrounded by the flexible sheet and the mounting jig, using the flexible sheet. Pressurizing, a flattening step of flattening the tops of the plurality of bump-shaped connection terminals exposed from the through holes; Method for manufacturing a wiring board, which comprises a. 2. The first main surface of a wiring board body having a first main surface and a second main surface, and having a plurality of bump-shaped connection terminals for mounting electronic components on the first main surface. And a second reinforcing plate main surface of a reinforcing plate having a first reinforcing plate main surface and a second reinforcing plate main surface and having a through hole, exposing the plurality of bump-shaped connection terminals from the through hole. A method for manufacturing a wiring board, wherein the wiring board body and the reinforcing plate are placed in a state where the first main surface and the second reinforcing plate main surface are overlapped with an adhesive. A mounting step of mounting on the plane of the jig; and covering the wiring board body and the reinforcing plate with the flexible sheet, and surrounding the wiring board body and the reinforcing plate with the flexible sheet and the mounting jig. And a step of reducing the pressure in the space surrounded by the flexible sheet and the mounting jig and applying pressure while applying pressure to the flexible sheet. Then, the tops of the plurality of bump-shaped connection terminals exposed from the through holes are flattened, and the first main surface of the wiring board body and the second main surface of the second reinforcing plate of the reinforcing plate are bonded. A method for manufacturing a wiring board, comprising: a bonding step. 3. The mounting step according to claim 1, wherein the reinforcing board, in which an adhesive sheet is pasted on the wiring board main body and the second reinforcing board main face, is attached to the first main face and the second reinforcing board main face. A method of manufacturing a wiring board, comprising mounting the mounting jig on a flat surface of the mounting jig in an opposed state. 4. The method for manufacturing a wiring board according to claim 1, wherein the adhesive sheet previously attached to the reinforcing plate is formed smaller than an outer shape of the reinforcing plate.