JPH098424A - Printed wiring board and its manufacturing method - Google Patents

Abstract

PURPOSE: To provide the title printed wiring board and its manufacturing method having strong bond properties between a resin filler layer and a packaging pad in a through hole capable of junctioning the packaging pad with an opposite member without fail. CONSTITUTION: A through hole filled with a resin filler layer 1 is covered with a packaging pad 61. The resin filler layer 1 is provided with rosary-like anchor holes 10 formed of continuous particle recessions. The rosary-like anchor holes 10 are formed by chemical roughening process of the resin filler layer 1 so that the lower part of the packaging pad 61 may intrude into the inside of the anchor holes 10. The hole filler resin comprising the resin filler layer 1 is made of the mixture of relatively stable roughening and stabilizing resin to the chemical roughening process and a particle resin filler melting earlier than the roughening and stabilizing resin in the chemical roughening process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having a structure in which a through hole is filled with a filling resin and a mounting pad is provided thereon, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a printed wiring board, as shown in FIG. 8, there is a printed wiring board provided with through holes 93 on both front and back surfaces of an insulating substrate 95 for electrical continuity. Through hole 9
3 has a metal plating film 931 on its inner wall,
Inside thereof, a resin filling layer 932 filled with a filling resin is formed. The lower opening of the through hole 93 is covered with the mounting pad 97. The mounting pad 97 is bonded onto the mating member 96 using solder balls 961.

As shown in FIG. 9, the mounting pad 97 is formed on the surface of the resin filling layer 932 in the through hole 93.
It is formed by polishing with a means such as physical polishing or chemical polishing to form a roughened surface 930, and then applying a copper plating layer. The reason for roughening the surface of the resin-filled layer 932 is as follows.
This is to improve the adhesion between the mounting pad 97 and the resin filling layer 932. As the resin filling layer 932, an epoxy resin or a combination filling resin of acrylic resin and epoxy resin is used.

On the other hand, as shown in FIG.
The upper opening of 3 is electrically connected to the pattern circuit 98.
The pattern circuit 98 is connected to the electronic component 991 mounted on the mounting portion 99 via a wire 992. The electronic component 991 and the pattern circuit 98 are sealed with a sealing resin 995 to prevent moisture.

[0005]

However, in the above-mentioned conventional printed wiring board, only the uniform and shallow roughened surface 930 is formed on the surface of the resin filling layer 932. Therefore, the adhesiveness between the resin filling layer 932 and the mounting pad 97 is still insufficient.

Therefore, as shown in FIG. 10, when the mounting pad 97 is formed by applying a copper plating layer 971 to the surface of the resin-filled layer 932, the resin-filled layer is subjected to a high temperature environment in reflow, soldering, and heat resistance tests. 932
The air 970 that has entered between the copper plating layer 971 and the copper plating layer 971 expands, and the mounting pad 97 is warped and deformed. Therefore, as shown in FIG.
When the solder ball 961 is placed under the mounting pad 97 in soldering to the No. 6, there is a possibility that a positional deviation occurs between the mounting pad 97 and the mating member 96, resulting in a defective joint.

In view of the above conventional problems, the present invention has a strong adhesion between the resin filling layer in the through hole and the mounting pad, and the mounting pad can be reliably bonded to the mating member. A wiring board and a manufacturing method thereof are provided.

[0008]

The present invention comprises an insulating substrate, a pattern circuit provided on the surface of the insulating substrate, and a through hole penetrating the insulating substrate and having a metal plating layer on its inner wall. A resin filling layer filled with a hole filling resin is provided inside, and a mounting pad is formed by metal plating so as to cover the through hole by contacting the resin filling layer at the opening of the through hole. In the printed wiring board according to the present invention, the resin-filled layer has a bead-shaped anchor hole formed on the surface facing the mounting pad, the bead-shaped anchor hole being formed by continuous granular recesses toward the inside of the resin-filled layer. The printed wiring board is characterized in that the lower part of the mounting pad penetrates into the bead-shaped anchor hole.

The resin-filled layer in the through hole has a beaded anchor hole on its surface. The beaded anchor holes are formed from the surface of the resin-filled layer toward the inside. The bead-shaped anchor hole has a plurality of protrusions protruding therein, and has a granular recess having a shape as if several beads are continuously connected.

The beaded anchor holes preferably have a depth of 5 to 20 μm. If it is less than 5 μm,
The mounting pad may come out of the beaded anchor hole, and the adhesion between the resin-filled layer and the mounting pad may be reduced. On the other hand, if it exceeds 20 μm, the resin thickness between the adjacent bead-shaped anchor holes becomes thin,
The strength of the resin-filled layer may decrease.

The metal plating layer on the inner wall of the through hole preferably has a roughened uneven surface. As a result, the hole-filling resin bites into the uneven surface of the metal plating layer, and the adhesion between the metal plating layer and the resin filling layer is improved. Therefore, the tightness of the through hole can be ensured. Examples of the above-mentioned roughening method include blackening treatment and soft etching.

Next, as a method of manufacturing the above-mentioned printed wiring board, for example, through holes are formed in the insulating substrate so as to penetrate therethrough, and the entire surface of the insulating substrate including the through holes is subjected to panel plating. , A resin filling layer is formed by filling the through hole with a filling resin, then the surface of the resin filling layer is chemically roughened, and then the surface of the resin filling layer is covered with the through hole. In the method of manufacturing a printed wiring board in which a mounting pad is formed by metal plating on the above, the hole filling resin is a roughening stabilizing resin that is relatively stable against the chemical roughening treatment, and There is a method for producing a printed wiring board, which comprises a mixture with a granular resin filler that dissolves faster than the roughening-stabilizing resin.

The hole filling resin is a mixture of a roughening stabilizing resin and a resin filler. The roughening stable resin is a resin that is relatively stable against chemical roughening treatment. An example of such a roughening-stabilizing resin is an epoxy resin when chromic acid, a chromic acid mixed liquid, or permanganic acid is used as the chemical roughening treatment solution. On the other hand, the resin filler is a resin which is more easily dissolved in the chemical roughening treatment than the roughening stable resin. As the resin filler, for example, an epoxy filler is used when the solution of the chemical roughening treatment is used.

The particle size of the resin filler is preferably 1 to 10 μm. If the thickness is less than 1 μm, it may not be possible to form a mounting pad by metal plating on the surface of the resin filling layer. On the other hand, if the thickness exceeds 10 μm, the mounting pad formed by metal plating may peel off from the resin-filled layer.

The filling resin is the roughening stabilizing resin 10
It is preferable to contain 20 to 60 parts by weight of the resin filler with respect to 0 parts by weight. When the amount of the resin filler is less than 20 parts by weight, the amount of the resin filler dissolved by the chemical roughening treatment is small and the beads-shaped anchor hole becomes shallow. Therefore, the adhesion strength of the mounting pad to the resin-filled layer may be reduced. On the other hand, when the amount of the resin filler exceeds 60 parts by weight, the surface of the resin-filled layer is largely corroded, and the strength of the resin-filled layer is rather lowered, and cracks may occur in the resin.

The surface of the resin-filled layer is chemically roughened. Specific examples of such chemical roughening treatment include etching of the resin filling layer with chromic acid, a chromic acid mixture, or permanganate.

[0017]

In the printed wiring board of the present invention,
Bead-shaped anchor holes are formed on the surface of the resin-filled layer that fills the through holes. The beaded anchor hole has a plurality of protrusions protruding from its inner wall. The lower part of the mounting pad penetrates into the beaded anchor hole. The lower part thereof is firmly bited by the above-mentioned plurality of protrusions formed in the beaded anchor hole.

Therefore, the bonding force between the mounting pad and the resin-filled layer is increased, and the adhesion between them is improved. Therefore, even in a high temperature environment, the mounting pad does not peel off from the resin-filled layer and does not deform. Therefore, when joining to the mating member, the misalignment between the mating member and the mounting pad does not occur. Therefore, according to the present invention, the mounting pad can be reliably bonded to the mating member.

Next, in the method of manufacturing a printed wiring board according to the present invention, the filling resin filled in the through holes is a roughening stabilizing resin which is relatively stable against chemical roughening treatment, and the above chemical It is composed of a mixture with a resin filler having a higher solubility in the roughening treatment than that of the roughening stable resin. Therefore, if the above chemical roughening treatment is performed after filling the filling resin into the through holes, the resin filler on the surface of the resin filling layer is dissolved and further eroded toward the inside of the resin filling layer. Therefore, the bead-shaped anchor hole is formed on the surface of the resin-filled layer.

Therefore, when the mounting pad is formed by metal plating, the lower part of the mounting pad enters the bead-shaped anchor hole. The plurality of protrusions in the beaded anchor hole strongly hold down the lower part of the mounting pad.
Therefore, according to the present invention, as described above, it is possible to manufacture a printed wiring board in which the mounting pad and the resin filling layer have high adhesion.

According to the present invention, a printed wiring board having a strong adhesiveness between a resin filling layer in a through hole and a mounting pad and capable of reliably bonding the mounting pad to a mating member, and a manufacturing method thereof. A method can be provided.

[0022]

EXAMPLE A printed wiring board according to an example of the present invention will be described with reference to FIGS. As shown in FIG. 1, the printed wiring board 19 of this example includes a pattern circuit 62 provided on the surface of the insulating substrate 7 and a through hole 60 penetrating the insulating substrate 7 and having a first metal plating layer 5 on its inner wall. Consists of. A resin filling layer 1 filled with a filling resin is provided in the through hole 60. Through hole 6
In the upper opening 0, a mounting pad 61 is formed by metal plating so as to contact the resin filling layer 1 and cover the through hole 60.

As shown in FIGS. 2 and 3, the resin-filled layer 1 has a depth of 5 to 20 μm formed on the surface facing the mounting pad 61 by granular recesses continuous toward the inside of the resin-filled layer 1. It has a beaded anchor hole 10. The lower part of the mounting pad 61 penetrates into the beaded anchor hole 10 and bites into it.

As shown in FIG. 2, the metal plating layer 5 covering the inner wall of the through hole 60 has a roughened uneven surface 50. The pattern circuit 62 is electrically connected to the electronic component mounted on the mounting portion (see FIG. 8).

Next, a method for manufacturing the printed wiring board will be described. First, as shown in FIG. 4, an insulating substrate 7 having copper foils (not shown) attached to both front and back surfaces is prepared. As the insulating substrate 7, for example, glass epoxy resin is used. Next, through holes 60 are formed in the insulating substrate 7 so as to penetrate therethrough vertically. Next, the entire surface of the insulating substrate 7 including the through holes 60 is subjected to panel plating of copper to form the first metal plating layer 5. Next, the first metal plating layer 5 that covers the inner wall of the through hole 60 is subjected to blackening treatment so that the surface of the first metal plating layer 5 has an uneven surface 50.
(See FIG. 2).

Next, a resin filling layer 1 is formed by filling the through hole 60 with a filling resin. The hole-filling resin used in the resin-filled layer 1 is a roughening-stabilizing resin that is relatively stable against chemical roughening treatment, and a granular resin filler that dissolves faster than the roughening-stabilizing resin in the chemical roughening treatment. A mixture of. The hole-filling resin contains 20 to 60 parts by weight of a resin filler with respect to 100 parts by weight of the roughening-stabilizing resin. An epoxy resin was used as the roughening-stabilizing resin. On the other hand, as the resin filler, an epoxy type filler having a particle size of 1 to 10 μm was used. Next, as shown in FIG. 5, the surface of the resin filling layer 1 is chemically roughened. This chemical roughening treatment is performed by etching using a chromic acid solution.

Next, as shown in FIG. 6, a second metal plating layer 2 made of copper is formed on the surface of the resin-filled layer 1 that has been subjected to the chemical roughening treatment so as to cover the through holes 60.
Next, as shown in FIG. 7, the first metal plating layer 5 and the second metal plating layer 2 are etched by a photoresist method to mount upper and lower openings of the through hole 60, and a mounting pad 61 and a pattern. The circuit 62 and the mounting portion are formed. The pattern circuit 62 is connected to a mounting portion for mounting an electronic component (not shown) (see FIG. 8).

Next, as shown in FIG. 1, the mounting pad 6
1 expose the surface and solder resist 8 around it.
And the solder resist 8 is also applied to the surface of the pattern circuit 62. Next, on the surface of the mounting pad 61,
A third metal plating layer 3 made of Ni / Au is applied. As a result, the printed wiring board 19 is obtained.

Next, the operation and effect of this embodiment will be described.
In the printed wiring board 19 of this example, as shown in FIGS. 1 to 3, beads-shaped anchor holes 10 are formed on the surface of the resin filling layer 1 filled in the through holes 60. This beaded anchor hole 10 is, as shown in FIG.
A plurality of protrusions 11 are projected on the inner wall thereof.

The lower part of the second metal plating layer 2 forming the mounting pad 61 penetrates into the beaded anchor hole 10. The lower part thereof is firmly bited by the plurality of protrusions 11 formed in the beaded anchor hole. Therefore, the bonding force between the mounting pad 61 and the resin-filled layer 1 is increased, and the adhesion between them is improved. Therefore, even under a high temperature environment, the mounting pad 61 does not peel off from the resin filling layer 1 and does not deform. Therefore, at the time of joining to the mating member, there is no displacement between the mating member 96 and the mounting pad 61 (see FIG. 8). Therefore, according to this example, the mounting pad can be reliably bonded to the mating member.

The first wall covering the inner wall of the through hole 60
As shown in FIG. 2, an uneven surface 50 is formed on the metal plating layer 5 by blackening treatment. Therefore, the filling resin enters the concave portion of the uneven surface 50, and the resin filling layer 1 is in close contact with the inner wall of the through hole 60. Therefore, high sealing performance can be obtained in the through hole 60.

Next, in the method of manufacturing a printed wiring board of this example, the hole-filling resin has a roughening-stabilizing resin that is relatively stable to chemical roughening treatment and a solubility to the chemical roughening treatment. It consists of a mixture with a resin filler higher than the roughening-stabilized resin. Therefore, when the chemical filling process is performed after the resin filling layer 1 is formed by filling the hole filling resin in the through holes, the resin filler on the surface of the resin filling layer 1 is dissolved as shown in FIG. Are further eroded toward the inside of the resin-filled layer 1. Therefore, the beaded anchor hole 10 is formed on the surface of the resin filling layer 1.

Therefore, as shown in FIGS. 3 and 6, when the mounting pad 61 is formed by metal plating, the lower portion thereof enters the bead-shaped anchor hole 10. The protrusion 11 in the beaded anchor hole strongly holds down the lower part of the mounting pad 61. Therefore, according to this example, it is possible to manufacture the printed wiring board 19 in which the adhesion between the mounting pad 61 and the resin filling layer 1 is high.

[Brief description of drawings]

FIG. 1 is a sectional view of a printed wiring board according to an embodiment.

FIG. 2 is an enlarged sectional view of a main part of the printed wiring board according to the embodiment.

FIG. 3 is an explanatory diagram showing a surface state of a resin filling layer in a through hole according to the embodiment.

FIG. 4 shows a method for manufacturing a printed wiring board according to an embodiment,
Explanatory drawing of the through hole which provided the resin filling layer.

FIG. 5 is an explanatory view of the resin-filled layer having beaded anchor holes formed on the surface, following FIG. 4;

FIG. 6 is an explanatory view of an insulating substrate plated with a panel, following FIG. 5;

FIG. 7 is an explanatory view of the mounting pad and the pattern circuit formed on the surface of the insulating substrate, following FIG. 6;

FIG. 8 is an explanatory diagram of a conventional printed wiring board.

FIG. 9 is an explanatory diagram showing a surface state of a resin-filled layer in a conventional example.

FIG. 10 is an explanatory diagram showing a problem in the conventional example.

[Explanation of symbols]

 1. . . Resin-filled layer, 10. . . Beaded anchor hole, 11. . . Protrusions, 19. . . Printed wiring board, 2. . . Second metal plating layer, 3. . . Third metal plating layer, 5. . . First metal plating layer, 60. . . Through-hole, 61. . . Mounting pad, 62. . . Pattern circuit, 7. . . Insulating substrate,

Claims (6)

[Claims] 1. An insulating substrate, a pattern circuit provided on the surface of the insulating substrate, a through hole penetrating the insulating substrate and having a metal plating layer on the inner wall thereof, and a resin filling the inside of the through hole. In a printed wiring board, a resin-filled layer filled with is provided, and a mounting pad made of metal plating is formed in the opening of the through-hole so as to contact the resin-filled layer and cover the through-hole. , The resin-filled layer has a bead-shaped anchor hole formed on the surface facing the mounting pad, the bead-shaped anchor hole being formed continuously toward the inside of the resin-filled layer. A printed wiring board characterized in that the lower part of the above-mentioned mounting pad penetrates inside. 2. The printed wiring board according to claim 1, wherein the beaded anchor hole has a depth of 5 to 20 μm. 3. The printed wiring board according to claim 1, wherein the metal plating layer on the inner wall of the through hole has a roughened uneven surface. 4. An insulating substrate is provided with through holes extending therethrough vertically, panel plating is performed on the entire surface of the insulating substrate including the through holes, and resin is filled by filling a hole filling resin into the through holes. Of a printed wiring board in which a layer is formed, then the surface of the resin-filled layer is chemically roughened, and then a mounting pad is formed on the surface of the resin-filled layer by metal plating so as to cover the through holes. In the manufacturing method, the hole-filling resin is a roughening-stabilizing resin that is relatively stable to the chemical roughening treatment, and a granular resin filler that dissolves faster than the roughening-stabilizing resin in the chemical roughening treatment. A method for producing a printed wiring board, which comprises a mixture of 5. The filling resin according to claim 4,
Resin filler 20 to 100 parts by weight of roughening stable resin
The manufacturing method of the printed wiring board characterized by including ~ 60 weight part. 6. The method for manufacturing a printed wiring board according to claim 4, wherein the resin filler has a particle size of 1 to 10 μm.