JP2507970B2 - Method for manufacturing multilayer printed wiring board - Google Patents

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 multilayer printed wiring board.

[0002]

2. Description of the Related Art As electronic devices have become more sophisticated in recent years, the external size of electronic parts has become smaller, and the density of printed wiring boards for mounting and holding the electronic parts and connecting the parts has increased. It is progressing. In particular, multi-layer printed wiring boards are being adopted as a method for increasing the density of printed wiring boards. This multilayer printed wiring board is manufactured by, for example, a plurality of inner-layer boards and outer-layer copper foil in which conductor circuits are formed by etching a double-sided copper-clad laminate in which copper foil is formed on both sides of an insulating board made of glass fiber reinforced polyimide board. Between each of the layers, for example, sandwich a prepreg made by impregnating glass cloth with uncured polyimide resin, which is a thermosetting resin, and heat and pressurize the thermosetting resin to integrate them, and then to form an inner layer circuit. A through hole for connecting an outer layer copper foil is formed by drilling a through hole by drilling, copper plating in the through hole using electrolytic plating, and then an outer layer circuit is formed by a subtractive method.

FIG. 3 is a cross-sectional view of an example of a multilayer printed wiring board immediately after drilling through holes by drilling in the procedure of a conventional manufacturing method. As shown in FIG. 3, each inner layer plate 4 in which the copper foil 2 is attached to the insulating plate 1 and the conductor circuit 3 is formed is bonded by the cured prepreg layer 7 made of the glass cloth 6 impregnated with the thermosetting resin 5. There is. In this state, the through hole 8 is drilled by drilling, but the stress generated at the time of drilling causes peeling 9 between the resin and the conductor circuit and a crack 10 in the resin at the interface between the conductor circuit 3 and the thermosetting resin 5 of the prepreg.

The following has been devised as a method of manufacturing a multilayer printed wiring board having a means for preventing the resin 9 from separating from the conductor circuit and the resin crack 10 as a manufacturing method. First, as a method for preventing peeling 9 between the conductor circuit 3 and the resin of the prepreg and the conductor circuit, in JP-A-64-53495, a triazine thiol compound layer is formed on the surface of the conductor circuit 3 of the inner layer plate 4 to form a conductor circuit. 3 has been devised to improve the wettability between 3 and the resin of the prepreg to improve the adhesion strength. In JP-A-1-255297, the chlorine content on the surface of the conductor circuit 3 of the inner layer plate 4 is 0 to 0.
Applying 05% by weight of synthetic resin, the conductor circuit 3 of the inner layer plate 4
A method for improving the adhesive strength between the prepreg layer and the prepreg layer has been devised. As a method for preventing resin cracking 10, Japanese Patent Laid-Open No. Sho 5
In Japanese Patent Laid-Open No. 7-186396, the conductor layer of the inner layer plate 4 is coated with a resin by an electrophoretic method to break the resin 10.
A method has been devised to block the progress of the coating with a coating layer. Further, in Japanese Patent Laid-Open No. 3-50795,
A method has been devised in which the inner layer plate 4 is coated with a resin paste containing glass fibers, which is obtained by mixing the same kind of resin as the prepreg and pulverized into a powder to maintain the glass, and the resin cracks 10 are blocked by the glass fibers. Various methods have been devised in this way, and all of these methods include peeling 9 between the resin and the conductor circuit and cracking 1 of the resin.
Although a means for preventing the generation of 0 has been disclosed, at present, in the method for manufacturing a multilayer printed wiring board, the stress generated at the time of drilling the through hole 8 tends to increase in order to improve the productivity. Therefore, it is not always possible to prevent the peeling 9 between the resin and the conductor circuit and the crack 10 in the resin by the method devised conventionally.

[0005]

In this conventional method for manufacturing a multilayer printed wiring board, the adhesive layer (prepreg) for adhering each inner layer board and outer layer board is composed only of thermosetting resin and glass cloth. , It is not able to withstand the stress of the drill that occurs when drilling after stacking, and the resin cracks or peels between the resin and the conductor circuit at the resin part or the boundary between the resin and the glass cloth, and the plating solution in the subsequent plating process. There is a drawback in that the penetration causes the deterioration of the insulation between the through hole and the inner layer circuit, resulting in a decrease in reliability.

An object of the present invention is to provide a highly reliable method for manufacturing a multilayer printed wiring board which does not cause deterioration of insulation between a through hole and an inner layer circuit due to peeling of the resin from a conductor circuit or cracking of the resin. Especially.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an outer layer plate and a plurality of inner layer plates on which conductor circuits are formed in advance are made of a thermosetting resin between each of the plurality of inner layer plates and the outer layer plate. In the method for manufacturing a multilayer printed wiring board including a step of forming a through hole and an outer layer wiring circuit after laminating with sandwiching the prepreg, heating and pressurizing to integrate, and each of the plurality of inner layer boards. The method further includes the steps of arranging and laminating a thermoplastic resin on at least a part of an adhesive layer region for adhering the outer layer plate, punching the through holes, and then heating and pressing.

[0008]

With the above-described means, the thermoplastic resin is used for cracking the resin and for separating the resin from the conductor circuit at the resin portion or the boundary between the resin and the glass cloth caused by the stress of the drill at the time of drilling the multilayer printed wiring board. The cracks of the filled resin and the separation between the resin and the conductor circuit are filled. As a result, a multilayer printed wiring board free from defects such as cracking and peeling can be obtained.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIGS. 1 (a) and 1 (b) are sectional views showing a first embodiment of the present invention in the order of steps for explaining the same. In the first embodiment, first, as shown in FIG. 1A, the thickness is 100 μm.
Glass fiber reinforced polyimide resin insulation plate 1 with a thickness of 35
Each inner layer board 4 on which a conductor circuit 3 is formed by attaching a copper foil 2 of μm
Is coated with a thermoplastic resin 11 such as polyphenylsulfite (PPS) resin with an average thickness of 5 μm.
Next, the inner layer plate 4 is adhered to each other by forming a prepreg layer 7 in which a thermosetting resin of a prepreg having a thickness of 200 μm made of a glass cloth 6 impregnated with a polyimide resin is cured to be cured. In this state, the through hole 8 is drilled by drilling, but due to the stress generated during this drilling, the conductor circuit 3 and the thermoplastic resin 11 coated thereon are
Delamination 9 between the resin and the conductor circuit and a crack 10 of the resin reaching the portion of the coated thermoplastic resin 11 occur at the interface.

Next, as shown in FIG.
The multilayer printed wiring board in the state of (a) is subjected to a surface pressure of 10 ° C at 210 ° C.
Heat and pressurize at kg / cm ² . At this time, the thermoplastic resin 11 is remelted by heating to separate the resin from the conductor circuit 9
The portion where the resin crack 10 has occurred is filled by pressure. As a result, defects such as peeling 9 and resin cracks 10 between the resin and the conductor circuit are removed.

FIGS. 2A and 2B are sectional views showing the second embodiment of the present invention in the order of steps. In the second embodiment, first, as shown in FIG. 2A, the thickness is 100 μm.
Insulating plate 1 of glass fiber reinforced polyimide resin plate of thickness 3
10% by weight of fine powder of thermoplastic resin 11 such as polyphenylsulfite (PPS) having a particle size of about 3 μm is attached to each inner layer plate 4 on which a copper foil 2 of 5 μm is attached and a conductor circuit 3 is formed.
Resin 1 containing so-called fine powder of thermoplastic resin
The glass cloth 6 impregnated with a thermosetting resin of polyimide containing 2 is hardened with a thermosetting resin of a prepreg having a thickness of 200 μm to form a hardened prepreg layer 7 for adhesion. In this state, the through hole 8 is drilled by drilling, but due to the stress generated at the time of drilling, peeling 9 between the resin and the conductor circuit at the interface between the conductor circuit 3 and the resin 12 containing the fine powder of the thermoplastic resin of the prepreg and the resin A crack 10 occurs.

Next, as shown in FIG.
The multilayer printed wiring board in the state of (a) is heated and pressed at a temperature of 210 ° C. and a surface pressure of 10 kg / cm ² . At this time, the fine powder of the resin 12 containing the fine powder of the thermoplastic resin is re-melted by heating to fill the portion where the peeling 9 between the resin and the conductor circuit and the crack 10 of the resin are caused by pressure. This allows
Defects such as peeling 9 between the resin and the conductor circuit and cracks 10 in the resin are removed.

In the second embodiment, unlike the first embodiment, even a small thing such that the resin crack 10 does not reach the conductor circuit 3 in the inner layer is always in contact with the fine powder of the resin 12 containing the fine powder of the thermoplastic resin. Therefore, there is an advantage that the peeling 9 between the resin and the conductor circuit and the crack 10 of the resin generated in the resin portion are all filled.

[0015]

As described above, according to the present invention, an outer layer plate and a plurality of inner layer plates on which conductor circuits are formed in advance are laminated by sandwiching a thermosetting resin prepreg between each layer, and heated. In a method for manufacturing a multilayer printed wiring board including a step of forming a through hole and a through hole after being pressed and integrated to form a through hole, at least a part of an adhesive layer area for adhering each inner layer board and outer layer board. After placing and stacking the thermoplastic resin, it includes a step of punching and then heating and pressing, so even if peeling between the resin and the conductor circuit or cracking of the resin occurs during drilling, the subsequent heating and pressing step By peeling and refilling the resin and the conductor circuit with the thermoplastic resin in step 1, there is an effect that a defect that affects reliability can be repaired.

In order to prevent the resin from cracking or peeling, the conditions for drilling the through holes of the multilayer printed wiring board prepared by the conventional method are, for example, drilling a 0.4 mm diameter hole in a 12-layer multilayer printed wiring board having a thickness of 3 mm. When carrying out, it was necessary to carry out step processing three times. However, in this embodiment, the hole quality was sufficiently satisfied by performing the step machining twice, and the machining speed was improved by about 40%.

[Brief description of drawings]

FIGS. 1A and 1B are cross-sectional views illustrating a first embodiment of the present invention in a process order.

2A and 2B are cross-sectional views showing a second embodiment of the present invention in the order of steps.

FIG. 3 is a cross-sectional view of an example of a multilayer printed wiring board immediately after drilling through holes by drilling in the procedure of a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation plate 2 Copper foil 3 Conductor circuit 4 Inner layer plate 5 Thermosetting resin 6 Glass cloth 7 Cured prepreg layer 8 Through hole 9 Peeling of resin and conductor circuit 10 Cracking of resin 11 Thermoplastic resin 12 Fine thermoplastic resin Resin containing powder

Claims (1)

(57) [Claims] 1. An outer layer plate and a plurality of inner layer plates on which a conductor circuit is formed in advance are laminated by sandwiching a thermosetting resin prepreg between each of the plurality of inner layer plates and the outer layer plate and heating. In a method for manufacturing a multilayer printed wiring board including a step of forming a through hole after pressurizing and integrating to form a through hole, an adhesive layer that bonds each of the plurality of inner layer boards to the outer layer board A method for manufacturing a multilayer printed wiring board, which comprises the steps of arranging and laminating a thermoplastic resin on at least a part of a region, punching the through holes, and then heating and pressing.