JPH0878842A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of a printed wiring board wherein exfoliation between a metal plating film in a through hole and electrically insulating material buried in the through hole is not generated, and permeation of moisture can be prevented. CONSTITUTION: A metal plating film 3 is formed on the surface of an insulating board 9 and the inner wall of a through hole 90. A roughened surface layer 30 is formed on the surface of the metal plating film 3 by chemical surface treatment. The inside of the through hole 90 and its peripheral part are filled with electrically insulating material 1 as filler, which is cured. The electrically insulating material 1 and the roughened surface layer which protrude on the insulating board 9 surface are polished and eliminated. Pattern circuits 61, 62 are formed on the insulating board 9. As the chemical surface treatment, the following are quoted; a method wherein blacking treatment only is performed, a method wherein blacking treatment and blacking reducing treatment are performed in order, and a method wherein blacking treatment, blacking reducing treatment, and acid treatment are performed in order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a printed wiring board having a through hole penetrating an insulating substrate, and more particularly to a method of filling the inside of the through hole with a filler.

[0002]

2. Description of the Related Art For example, a ball grid type printed wiring board is provided with through holes in order to electrically connect each pattern circuit provided on the front and back sides or to dissipate heat. As shown in FIG. 16, the through hole 90 is provided so as to penetrate the insulating substrate 9 that constitutes the printed wiring board. A metal plating film 93 is applied to the inner wall of the through hole 90.

Then, in the through hole 90,
Filling material 91 using an epoxy resin is filled. The filler 91 prevents the flux, the solder cleaning liquid, and the like from seeping out through the through holes 90 when the printed wiring board is soldered to the mother board, and the pattern circuit 961 or the semiconductor chip 5 provided on the front surface of the insulating substrate 9. Alternatively, it plays the role of preventing contamination of the die pad 963 on which it is mounted.

[0004]

However, in the above-mentioned printed wiring board, the peeling portion between the metal plating film 93 in the through hole 90 and the filling material 91 is caused by the temperature when the soldering is performed on the motherboard. 991 (FIG. 16). When using a printed wiring board,
Moisture may infiltrate through the peeled portion 991 and accumulate as moisture 995 between the insulating substrate 9 and the adhesive 990. The moisture 995 is generated by the pattern circuit 961, the semiconductor chip 5, or the die pad 9 provided on the front surface of the insulating substrate 9.
It may corrode 63.

Further, when the printed wiring board is soldered to the mother board as described above, the heat causes the moisture 995 to be rapidly heated, so that the insulating substrate 9 and the semiconductor chip 5 are separated from each other as shown in FIG. In some cases, a peeled portion 992 may be generated. Further, the pattern circuit 961, the semiconductor chip 5, and the die pad 963 may be damaged.

In view of the above conventional problems, the present invention prevents the infiltration of moisture without causing separation between the metal plating film in the through hole and the filling material filled in the through hole. The present invention intends to provide a method for manufacturing a printed wiring board that can be manufactured.

[0007]

According to the present invention, a through hole is formed in an insulating substrate so as to penetrate the insulating substrate, and then a metal plating film is applied to the surface of the insulating substrate and the inner wall of the through hole. Surface treatment to form a roughened surface layer on the surface of the metal plating film, and then supply a filler to the inside of the through hole and the periphery of the opening to cure it, and then to the surface of the insulating substrate. A method for manufacturing a printed wiring board is characterized in that the protruding filler and the roughened surface layer are removed by polishing, and then a pattern circuit is formed on the surface of the insulating substrate.

What is most noticeable in the present invention is that a roughened surface layer is formed on the surface of the insulating substrate and the surface of the metal plating film provided on the inner wall of the through hole by chemical surface treatment, and After the filler is supplied into the hole and cured, the filler and the roughened surface layer protruding on the surface of the insulating substrate are removed by polishing.

The surface of the metal plating film is subjected to a chemical surface treatment to form a roughened surface layer. Examples of the chemical surface treatment include a method of performing only blackening treatment, a method of sequentially performing blackening treatment and blackening reduction treatment, a method of sequentially performing blackening treatment, blackening reduction treatment, and acid treatment.

As a method of performing only the blackening treatment, for example, the insulating substrate is immersed in a blackening treatment liquid obtained by dissolving sodium chlorite, trisodium phosphate, sodium hydroxide or the like in water. . As a result, needle-like crystals are generated on the surface of the metal plating film. This crystal
A roughened surface layer is formed in the through holes and on the surface of the insulating substrate.

As a method for sequentially performing the blackening treatment and the blackening reduction treatment, for example, the insulating substrate is immersed in the blackening treatment solution, and then sodium borohydride, sodium hydroxide, etc. are dissolved in water. The insulating substrate is immersed in the first reduction treatment liquid. Further, this is immersed in a second reduction treatment liquid in which sodium hydroxide, formaldehyde, methanol, etc. are dissolved in water. As a result, needle-like crystals are generated on the surface of the metal plating film, and the crystals are reduced.

As a method for sequentially performing the blackening treatment, the blackening reduction treatment and the acid treatment, for example, the insulating substrate is sequentially immersed in the blackening treatment liquid and the reduction treatment liquid, and then this is subjected to acid treatment. It is immersed in an acid treatment solution such as sulfuric acid. As a result, needle crystals are formed on the surface of the metal plating film, and the crystals are once reduced and then oxidized.

Next, a filling material is filled in the inside of the through hole forming the roughened surface layer and the peripheral portion of the opening, and is hardened. Next, the filler protruding from the surface of the insulating substrate is polished and removed together with the roughened surface layer of the metal plating film on the surface of the insulating substrate by using a buff, a brush or the like. As a result, the surfaces of the metal plating film and the filler become smooth,
The entire surface of the insulating substrate becomes a smooth surface. Next, a pattern circuit is formed on the surface of the smooth insulating substrate.

The filler is an electrically insulating material or a conductive material. The electrically insulating material is, for example, epoxy resin,
One or more synthetic resins selected from polyimide resins. The metal plating film is made of one or more selected from copper, nickel and gold. On the other hand, examples of the conductive material include carbon paste. As the insulating substrate, for example, a glass / epoxy substrate, a glass / polyimide substrate, a glass maleimide triazine substrate or the like is used.

The through holes are used to electrically connect the pattern circuits provided on the front side surface and the back side surface of the insulating substrate. The through hole can also be used as a heat dissipation hole for dissipating heat from the semiconductor chip or the pattern circuit. A semiconductor chip, for example, can be mounted on the printed wiring board.
The printed wiring board is mounted on a separate motherboard. The printed wiring board is, for example, a ball grid array or a pin grid array.

[0016]

In the method of manufacturing a printed wiring board according to the present invention, the metal plating film is formed on the inner wall of the through hole, and the surface of the metal plating film is chemically surface-treated to form the roughened surface layer. Is forming. A filling material is filled inside the through hole. The filler adheres to the inner wall of the through hole due to the unevenness of the roughened surface layer. Therefore, even if a thermal shock is applied, the filling material does not peel off from the inner wall of the through hole. Therefore, it is possible to prevent moisture from entering through the through holes.

Further, in the present invention, the filler is supplied not only inside the through hole but also around the opening. Therefore, even if the filler contracts when the filler is cured, the entire interior of the through hole can be filled with the filler.

The metal plating on the surface of the insulating substrate forms a roughened surface layer, which is then polished and removed to form a uniform smooth surface. Therefore, even when the metal plating surface is further covered with a plating film, a plating film having a uniform thickness can be formed. Therefore, it is possible to form a smooth pattern circuit having a uniform layer thickness on the surface of the insulating substrate.

Therefore, even when this pattern circuit is used as a die pad and an electronic component such as a semiconductor chip is mounted on the die pad by using an adhesive, the pattern circuit and the adhesive can be brought into close contact with each other. . Therefore, even if it is subjected to a thermal shock, the adhesive does not separate from the circuit pattern and moisture does not enter. As a result, it is possible to suppress damage to electronic components and pattern circuits.

According to the present invention, there is no peeling between the metal plating film in the through hole and the filling material filled in the through hole, and it is possible to prevent the infiltration of moisture. It is intended to provide a method for manufacturing a plate.

[0021]

【Example】

Example 1 A method for manufacturing a printed wiring board according to an example of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the printed wiring board 10 manufactured by this example has through holes 90 penetrating the insulating substrate 9. The inner wall of the through hole 90 has a roughened surface layer 30.
It is covered with a metal plating film 3 having. The inside of the through hole 90 is filled with the electric insulating material 1 as a filling material.

The pattern circuit 6 is formed on the front surface of the insulating substrate 9.
1 and a die pad 63 for mounting a semiconductor chip are provided. A pattern circuit 62 and a heat dissipation pad 64 are provided on the back side surface of the insulating substrate 9. The die pad 63 and the heat radiation pad 64 are connected by the through hole 90 provided in the substantially central portion of the insulating substrate 9. As shown in FIG. 2, the space between the pattern circuits 61 and 62 on the front and back surfaces is the through hole 9 provided in the peripheral portion of the insulating substrate 9.
Connected by 0.

The semiconductor chip 5 is mounted on the die pad 63 with an adhesive 59. The semiconductor chip 5 has a bonding pad 610 at the tip of the pattern circuit 61.
Are connected by a wire 50. The semiconductor chip 5 and the wires 50 are sealed with resin 55. The adhesive 59 is a die attach resin, an epoxy resin, an epoxy resin containing a filler, or the like. The printed wiring board 10 of this example is a system in which the semiconductor chip 5 and the pattern circuit 61 are connected by a wire 50.

A pattern circuit 62 and a heat radiation pad 64 are provided on the back side surface of the insulating substrate 9. On the pattern circuit 62, a plurality of pads 620 for joining the pads 82 of the motherboard 8 with the solder 81 are provided.

Next, a method for manufacturing the printed wiring board will be described with reference to FIGS. First, as shown in FIG. 3, an insulating substrate 9 whose front and back surfaces are covered with the copper foil 2 is prepared. Next, as shown in FIG. 4, a through hole 90 is formed in the insulating substrate 9 so as to penetrate the insulating substrate 9. Next, as shown in FIG. 5, the metal plating film 3 is applied to the surface of the insulating substrate 9 and the inner wall of the through hole 90. The metal plating film 3 is copper.

Next, as shown in FIG. 6, a roughened surface layer 30 is formed on the surface of the metal plating film 3 by chemical surface treatment. The chemical surface treatment is performed by blackening treatment. The blackening treatment is performed by immersing the insulating substrate 9 in the following blackening treatment liquid for 0.3 to 15 minutes. By this blackening treatment, copper needle crystals are formed on the surface of the metal plating film 3.

Blackening treatment liquid-ingredient (concentration in water) sodium chlorite. ． ． ． ． ． ． 20-70 g / liter, trisodium phosphate 12 water. ． ． ． 10 to 30 g / liter, sodium hydroxide. ． ． ． ． ． ． ． 10 to 30 g / liter, temperature. ． ． ． ． ． ． ． 70-98 ° C,

Next, as shown in FIG.
Electrically insulating material 1 made of epoxy resin is supplied to the inside of 0 and the peripheral portion of the opening by means such as screen printing. At this time, the electrically insulating material 1 is projected from the surface of the insulating substrate 9. Next, this electrical insulating material 1 is heated to 150 ° C.
Heat to cure. Next, as shown in FIG. 8, the electrically insulating material 1 and the roughened surface layer 30 protruding on the surface of the insulating substrate 9 are polished and removed by a buff to form a smooth surface.

Next, as shown in FIGS. 9 to 13, a pattern circuit, a die pad, and a heat dissipation pad are formed on the surface of the insulating substrate 9 by an etching resist method. That is, first, as shown in FIG. 9, the front surface and the back surface of the insulating substrate 9 are covered with a resist film 71 having a desired pattern. Next, the insulating substrate 9 is etched to remove unnecessary portions of the copper foil 2 and the metal plating film 3. Then, the resist film 71 is peeled off.

As a result, as shown in FIG. 10, the pattern circuit 61, the bonding pad 610, and the die pad 63 are formed on the front surface of the insulating substrate 9. Further, on the back side of the insulating substrate 9, the pattern circuit 62 and the heat dissipation pad 6 are provided.
4 is formed.

Next, as shown in FIG. 11, the metal plating film 3 in the pattern forming portion is partially exposed on the front and back surfaces of the insulating substrate 9 to form a solder resist film 72.
To cover. Next, as shown in FIG. 12, the surface of the metal plating film 3 is partially covered with the Ni / Au plating film 4 by plating.

As a result, as shown in FIG. 13, the die pad 63 and the bonding pad 610 are covered with the Ni / Au plating film 4. In addition, a pad 620 for bonding to the mother board is formed on the back surface of the insulating substrate 9. As a result, the printed wiring board 10 is obtained.

Die pad 63 of the printed wiring board 10
As shown in FIG. 14, using an adhesive 59,
The semiconductor chip 5 is mounted. The semiconductor chip 5 is electrically connected to the bonding pad 610 by the wire 50. The semiconductor chip 5 and the wires 50 are sealed with resin 55.

The pad 620 on the back side of the printed wiring board 10 is arranged on the pad 82 of the mother board 8 via the ball-shaped solder 81 as shown in FIG. By heating this, the pad 620 of the printed wiring board
And the pad 82 of the motherboard 8 are soldered.

Next, the function and effect of this example will be described.
In the method for manufacturing a printed wiring board according to this example, as shown in FIGS. 6 and 7, the surface of the metal plating film 3 formed on the inner wall of the through hole 90 is chemically surface-treated to give a roughened surface layer. Forming 30. Therefore, the electrically insulating material 1 adheres to the inner wall of the through hole 90 due to the unevenness of the roughened surface layer 30. Therefore, even if a thermal shock is applied, the electrically insulating material 1 does not peel off from the inner wall of the through hole 90. Therefore, it is possible to prevent moisture from entering through the through hole 90.

Therefore, even when the printed wiring board is mounted on the mother board by soldering, peeling does not occur between the metal plating film in the through hole and the electrically insulating material due to the melting temperature of the solder.

The electrical insulating material 1 is supplied not only to the inside of the through hole 90 but also to the peripheral portion of the opening. Therefore, even if the electric insulating material 1 contracts when the electric insulating material 1 is cured, the entire inside of the through hole 90 can be filled with the electric insulating material 1.

A roughened surface layer is formed on the metal plating 3 on the surface of the insulating substrate 9, which is then polished to form a uniform smooth surface. Therefore, even when the surface of the metal plating 3 is further covered with a plating film, a plating film having a uniform thickness can be formed. Therefore, the insulating substrate 9
It is possible to form the pattern circuit 61 and the die pad 63 on the surface of which are smooth and have a uniform layer thickness.

Therefore, when the semiconductor chip 5 is mounted on the die pad 63 by using the adhesive 59, the die pad 63
And the adhesive 59 can be closely attached. Therefore, the adhesive 59 does not separate from the die pad 63 even when it is subjected to a thermal shock, and the moisture does not enter. As a result, damage to the semiconductor chip 5, die pad 63, and pattern circuit 61 can be suppressed.

In the above description, the example in which the semiconductor chip 5 and the wiring pattern 61 on the insulating substrate 9 are connected by the wire 50 via the bonding pad 610 has been shown. However, the connection between the semiconductor chip 5 and the wiring pattern 61 can also be performed by a method in which the solder bump 500 is provided on the bonding pad 610 of the wiring pattern 61 and the semiconductor chip 5 is connected, as shown in FIG.

Example 2 In this example, a blackening treatment and a blackening reduction treatment were sequentially carried out as a chemical surface treatment to form a roughened surface layer on the surface of the metal plating film. That is, first, the blackening treatment shown in Example 1 was performed. Next, the above-mentioned insulating substrate was sequentially immersed in the following first reduction treatment liquid and second reduction treatment liquid to perform blackening reduction treatment. The immersion time in the first reduction treatment liquid and the immersion time in the second reduction treatment liquid are 0.1 to 15 minutes.

First Reduction Treatment Liquid-Component Sodium Hydrogen Boron. ． ． ． ． 0.1-5.0 g / liter, sodium hydroxide. ． ． ． ． ． ． 0.1-5.0 g / liter, temperature. ． ． ． ． ． ． ． ． ． ． ． ． 30-60 ° C,

Second reduction treatment liquid-Component sodium hydroxide. ． ． ． ． ． ． 1.0-10 g / liter, formaldehyde. ． ． ． ． ． ． 1.0 to 20 g / liter, methanol. ． ． ． ． ． ． ． ． ． 1.0 to 30 g / liter, temperature. ． ． ． ． ． ． ． ． ． ． ． ． 30-60 ° C,

By the blackening reduction treatment, reduced copper needle crystals are formed on the surface of the metal plating film. Others are the same as in the first embodiment. In this example, since the above treatment is performed, the acid resistance is further improved as compared with the case of Example 1. In addition, also in this example, the same effect as that of the first embodiment can be obtained.

Example 3 In this example, a blackening treatment, a blackening reduction and an acid treatment were sequentially carried out as a chemical surface treatment to form a roughened surface layer on the surface of the metal plating film. That is, in performing the process of this example, first, the blackening process shown in Example 1 was performed, and then the blackening reduction process shown in Example 2 was performed. Next, the above insulating substrate was immersed in an acid treatment liquid containing the following components.
The immersion time in the acid treatment solution is 0.1 to 10 minutes.

Acid treatment liquid / component Sulfuric acid. ． ． ． ． 30-300 g / liter, temperature. ． ． ． ． ． 5-40 ° C,

By the above chemical surface treatment, oxidized copper needle crystals were formed on the surface of the metal plating film. Others are the same as those in the second embodiment. Also in this example, the same effect as that of the second embodiment can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a printed wiring board of Example 1 mounted on a motherboard.

FIG. 2 is an explanatory view showing the front and side surfaces of the printed wiring board of Example 1.

FIG. 3 is a cross-sectional view of an insulating substrate having a surface coated with a copper foil in the method for manufacturing a printed wiring board according to the first embodiment.

FIG. 4 is a cross-sectional view of an insulating substrate having through holes, which is continued from FIG. 3;

5 is a cross-sectional view of an insulating substrate provided with a metal plating film, following FIG.

FIG. 6 is a cross-sectional view of the insulating substrate on which a roughened surface layer is formed, following FIG.

FIG. 7 is a cross-sectional view of an insulating substrate in which through holes are filled with an electrically insulating material, following FIG. 6;

8 is a cross-sectional view of the insulating substrate whose surface is polished, following FIG.

9 is a sectional view of the insulating substrate coated with a resist film, following FIG.

FIG. 10 is a cross-sectional view of the patterned insulating substrate following FIG. 9.

11 is a cross-sectional view of the insulating substrate coated with the solder resist film, following FIG.

FIG. 12 is a cross-sectional view of an insulating substrate having a Ni / Au plating film, following FIG. 11.

13 is a cross-sectional view of the insulating substrate from which the solder resist film has been removed, following FIG.

FIG. 14 is a sectional view of a printed wiring board on which a semiconductor chip is mounted.

FIG. 15 is a cross-sectional view of a printed wiring board of Example 1, which is electrically connected to a semiconductor chip using bumps.

FIG. 16 is an explanatory diagram showing an internal state of a through hole in a conventional example.

FIG. 17 is an explanatory diagram showing an internal state of a through hole when a thermal shock is applied in a conventional example.

[Explanation of symbols] 1. ． ． Electrical insulating material, 10. ． ． Printed wiring board, 2. ． ． Copper foil, 3. ． ． Metal plating film, 30. ． ． Roughened surface layer, 4. ． ． Ni / Au plating film, 5. ． ． Semiconductor chip, 61, 62. ． ． Pattern circuit, 63. ． ． Die pad, 64. ． ． Heat dissipation pad, 8. ． ． Motherboard, 9. ． ． Insulating substrate, 90. ． ． Through hole,

Claims (6)

[Claims] 1. A through hole is formed in an insulating substrate so as to penetrate the insulating substrate, and then a metal plating film is applied to the surface of the insulating substrate and the inner wall of the through hole.
By a chemical surface treatment, a roughened surface layer is formed on the surface of the metal plating film, and then a filler is supplied to the inside of the through hole and the peripheral portion of the through hole to cure, and then,
A method for manufacturing a printed wiring board, comprising polishing and removing the filler and the roughened surface layer protruding from the surface of the insulating substrate, and then forming a pattern circuit on the surface of the insulating substrate. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the chemical surface treatment is blackening treatment. 3. The method for manufacturing a printed wiring board according to claim 1, wherein the chemical surface treatment is a blackening treatment and a blackening reduction treatment in sequence. 4. The method of manufacturing a printed wiring board according to claim 1, wherein the chemical surface treatment is performed by sequentially performing a blackening treatment, a blackening reduction treatment, and an acid treatment. 5. The method according to any one of claims 1 to 4,
The said roughened surface layer has a needle-shaped surface, The manufacturing method of the printed wiring board characterized by the above-mentioned. 6. The method according to any one of claims 1 to 5,
A method for manufacturing a printed wiring board, wherein the roughened surface layer is polished with a buff or a brush.