JPH07307568A - Multilayered printed board and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent the bonding of a resin-impregnated base layer from being impeded by copper ions contained in a circuit by a method wherein an adhesion reinforcing layer, a resin-impregnated base layer, and a board foil layer are successively laminated, at least, on the one side of a board equipped with an inner circuit of copper. CONSTITUTION:A board 1 previously subjected to a plating process is introduced into a continuously laminating device, a glass cloth impregnated with unsaturated polyester resin 3 and a copper foil 9 are continuously laminated in this sequence on both sides of the board 1 by pairs of rolls 10 and 14 into a laminate 8 of integral structure. Then, the laminate 8 is subjected to a primary heating process to cure the unsaturated polyester resin 5. The bonding of impregnating resin is not impeded by copper ions contained in a circuit. Therefore, a resin- impregnated base layer is hardly blistered by heat released in a component mounting process and prevented from being separated off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed board used for electronic equipment and the like and a method for manufacturing the same. In this invention, a desired number of resin-impregnated base material layers and metal foil layers are laminated on an inner layer circuit of a substrate provided with an inner layer circuit made of copper on one side or both sides thereof with an adhesive reinforcing layer, and the inner layer circuit and the resin are laminated. The present invention relates to a highly reliable multilayer printed board having improved adhesion with an impregnated base material layer, and a method for efficiently producing the multilayer printed board.

[0002]

2. Description of the Related Art Generally, a multilayer printed circuit board has a structure in which a resin-impregnated base material layer and a metal foil layer are laminated in this order on a substrate provided with a copper inner layer circuit. And has a size of about 500 × 600 mm. Conventionally, a multilayer printed board has been manufactured by hot-pressing and laminating a resin-impregnated base material layer and a metal foil layer on a substrate for forming an inner layer circuit by a molding press.

However, the above-mentioned multilayer printed board is manufactured by a batch method, and it is necessary to apply it to a pressing machine for each hot pressing, resulting in poor productivity. As a method for improving productivity, a method described in Japanese Patent Publication No. 4-3119 can be mentioned. In this method, while continuously supplying a substrate on which an inner layer circuit is formed, a desired number of strip-shaped resin-impregnated base material layers are continuously laminated on the inner layer circuit, and a strip-shaped metal foil layer is continuously formed on the outer side thereof. A multilayer printed board is manufactured by stacking the layers and heating them while continuously transferring them. That is, since the method described in this publication can continuously manufacture a multilayer printed board, it is possible to improve productivity as compared with the batch method.

However, in this method, the circuit of the substrate having the inner layer circuit and the resin impregnated in the resin-impregnated base material layer have poor adhesiveness, and the inner layer circuit is subjected to a mounting step such as soldering after a heating step. There has been a problem that peeling occurs between the formation substrate and the base material. Therefore, the inventors of the present invention, as a result of diligent studies, have found that peeling can be prevented by laminating a base material on a circuit formed on an inner layer circuit forming substrate with an adhesive reinforcing layer interposed therebetween. I arrived.

[0005]

Thus, according to the present invention, a substrate having a conductive inner layer circuit on one or both sides,
Provided is a multilayer printed board comprising a desired number of resin-impregnated base material layers and a metal foil layer formed on the inner layer circuit via an adhesion reinforcing layer. Furthermore, according to the present invention, an adhesive reinforcing layer is coated on a substrate provided with a conductive inner layer circuit on one side or both sides, and this substrate and a desired number of strip-shaped resin-impregnated base material layers are continuously supplied, A metal foil layer is continuously supplied onto the resin-impregnated base material layer, and a desired number of resin-impregnated base material layers and metal foil layers are laminated on the inner layer circuit of the substrate via an adhesion reinforcing layer. A method of manufacturing a multilayer printed board is provided.

First, as the substrate for forming the inner layer circuit used in the present invention, a substrate usually used for a multilayer printed board can be used. For example, paper, glass cloth, glass mat, glass nonwoven fabric, etc. Examples of the base material include a polyester resin, an epoxy resin, a melamine resin, a phenol resin, a silicone resin, or a polyimide resin. The inner layer circuit may be formed on one side or both sides of the substrate. As a material for forming a circuit, conductive copper, an alloy containing copper as a main component, or an aluminum alloy is used. These substrates are formed by a known method. The shape of the substrate is not particularly limited,
A strip or a single plate is preferable for applying the manufacturing method of the present invention.

As a material that can be used for the adhesion reinforcing layer, a material that improves the adhesiveness to the resin-impregnated base material layer described later is used. For example, electroless coatings of dissimilar metals other than copper, such as electroless Sn and electroless Ni, epoxy modified resins whose adhesiveness is not impaired by copper ions, phenol modified resins,
Examples thereof include resin coatings made of polyester modified resin or melamine resin. The layer thickness of the adhesion reinforcing layer varies depending on the raw material used, but is 0.0 for electroless Sn, for example.
5 to 0.5 μm, 0.2 to 10 μm for electroless Ni
m, in the case of a resin coating, it is 1 to 90 μm. Of these, electroless Sn is particularly preferable because it has good adhesion to the resin-impregnated base material layer described below.

The substrate in the resin-impregnated substrate layer is not particularly limited, but paper, glass cloth, glass mat, glass non-woven fabric and the like can be used. As the resin with which the base material is impregnated, a resin that is liquid when impregnated and hardens by heating is used. For example, an unsaturated resin such as an unsaturated polyester resin, a diallyl phthalate resin, or a vinyl ester resin diluted with a vinyl monomer (crosslinking agent) and a polymerization initiator added thereto can be used. In addition,
It is preferable to use a resin having substantially no volatile component (solvent-free resin) because peeling of the resin-impregnated base material layer due to swelling during heat curing can be prevented.

As the metal foil layer, conductive copper, an alloy containing copper as a main component, or an aluminum alloy can be used. Further, the surface of the metal foil layer may be subjected to a roughening treatment in advance. In the multilayer printed board of the present invention, an inner layer circuit, an adhesion reinforcing layer, one or a plurality of belt-shaped resin-impregnated base material layers and a metal foil layer may be laminated on one side, but they may be on both sides. Further, the metal foil layer (one side or both sides) may be further laminated with an adhesion reinforcing layer, one or a plurality of belt-shaped resin-impregnated base material layers, and a metal foil layer.

Next, the multilayer printed board of the present invention can be manufactured by the process as shown in FIG. 1, for example.
Hereinafter, description will be given with reference to FIG. First, the substrate 1 on which a conductive circuit is formed in advance is prepared. An adhesive reinforcement layer is coated on this circuit by way of the adhesive reinforcement layer coating means 2. The adhesive reinforcing layer coating means 2 is preferably a means capable of continuously coating the adhesive reinforcing layer. For example, when performing electroless coating, a dipping method, a spray method, or the like can be used.

FIG. 2 shows an example of the dipping method.
The electroless coating is formed on the circuit by immersing the substrate 21 on which the conductive circuit is formed in the solution tank 22 filled with the solution for electroless coating. Also, FIG.
Shows an example of the spray method, in which the substrate 21 on which the conductive circuit is formed is transferred by the transfer means 32 to the spray device 3
Thus, the electroless coating film is formed on the circuit by the solution for electroless coating that is continuously conveyed to No. 1 and sprayed in the spray device 31.

On the other hand, in the case of a resin coating, an electrostatic coating method, a roll coating method, a screen printing method, a curtain coating method, a spin coating method or the like can be used. Here, FIG. 4 shows an example of the roll coating method. In order to form a resin solution film to be applied on the surface of the roll 42,
Solution tank 4 filled with resin solution between rolls 41 and 42
3 is provided, and the substrate 21 on which the conductive circuit is formed passes between the rolls 42, whereby a resin film is formed on the substrate 21 on which the conductive circuit is formed.
Further, FIG. 5 shows an example of a screen printing method, in which a plate 52 having a predetermined pattern is placed on a substrate 21 having a conductive circuit, and a squeegee 51 is moved to make the conductive pattern conductive. A resin film is formed on the substrate 21 on which the circuit is formed. Next, FIG. 6 shows an example of the curtain coater method, in which a resin solution is dropped by the nozzle 61 to form a resin film on the substrate 21 on which a conductive circuit is formed. Further, FIG. 7 shows an example of the spin coater method, in which the resin solution is dropped by the nozzle 71, and the substrate 21 on which the conductive circuit is formed is rotated, so that the substrate 21 on which the conductive circuit is formed is rotated. A resin film will be formed.

More specifically, in the case of the electroless coating, in the case of electroless Sn, Sn is 10 to 20 g / l and sulfuric acid is 1 in the solvent.
50 to 200 g / l, 10 to 50 g of a solution to which an additive such as thiourea is added at a temperature of 20 to 70 ° C.
It can be used as a concentration of 1 / l. On the other hand, in electroless Ni, Ni sulfate is contained in a solvent such as water at 16 to 24 g /
1, a sodium hypophosphite of 150 to 200 g / l, and a solution to which an additive such as ethylenediamine is added if necessary can be used at a temperature of 20 to 80 ° C. and a pH of 4 to 5. These solutions are subjected to a dipping treatment or a spraying treatment on the substrate on which the inner layer circuit is formed by a known electroless plating method, so that the electroless coating layer is coated on the circuit made of copper.

When a resin coating is used as the adhesion reinforcing layer, the resin is applied under the working temperature of 20 to 60 ° C. and the viscosity of the resin solution is methyl ethyl ketone (MEK),
A solution adjusted to 1 to 800 poise with a solvent such as methyl cellosolve can be applied by the above method. The curing treatment can be performed at 80 to 150 ° C for 1 to 60 minutes. In the case of a resin coating, it is possible to cover the entire surface of the inner layer circuit forming substrate.

As described above, the resin-impregnated base material layer and the metal foil layer are continuously laminated in this order on the substrate 1 having the inner layer circuit whose circuit is covered with the adhesive reinforcing layer. As a method of continuously laminating, for example, Japanese Patent Publication No. 4-311
The method described in Japanese Patent No. 9 can also be used. The continuous laminating step will be described below with reference to FIG.

First, the resin-impregnated base material layer can be formed by passing the strip-shaped base material layer 3 wound around the roll 4 through the impregnation tank 6 filled with the resin 5. The resin-impregnated base material layer is laminated with the substrate 1 on which the inner layer circuit is formed by the roll 10 to form the laminated body 7. The resin-impregnated base material layer does not necessarily have to be a single layer, and a plurality of base material layers 3, rolls 4, resins 5 and impregnation tanks 6 may be provided to stack a plurality of layers.

Next, a strip-shaped metal foil layer 9 wound on a roll 15 is laminated on the laminate 7 by a roll 14 to form a laminate 8.
Becomes Here, before laminating the metal foil layers, an adhesive may be applied to the metal foil layers, if necessary. Further, the surface of the metal foil layer may be previously subjected to a surface roughening treatment for improving the adhesive strength. A multilayer printed board can be obtained by curing the resin while continuously feeding the laminate 8 thus obtained to the primary heating furnace 11. In this heat-curing, since the adhesion-strengthening layer is laminated on at least the circuit on the substrate 1, the resin on the circuit is completely cured without being hindered by the copper ions, and the inner layer circuit due to the swelling of the laminated body Peeling of the resin-impregnated base material layer does not occur.

After that, the cured laminate may be cut off by a cutting device if necessary, and a circuit is further formed on the metal foil layer without cutting it off, and then the adhesion reinforcing layer and the resin are further formed in the same step as above. The impregnated base material layer and the metal foil layer can also be laminated. Moreover, you may secondary-heat a laminated body as needed.

[0019]

The multilayer printed board according to the present invention comprises a substrate having an inner layer circuit made of copper on at least one surface, an adhesive reinforcing layer,
Since the resin-impregnated base material layer and the metal foil layer are formed in this order, the impregnated resin is not hindered from adhering by the copper ions of the circuit. Therefore, blistering due to heat during the component mounting process does not occur, and peeling is prevented.

[0020]

【Example】

Example 1 A circuit was continuously printed with a resist by a screen printing method on a substrate in which a belt-shaped substrate made of a glass cloth was impregnated with a polyester resin and copper was coated on both surfaces thereof. Then
Copper was etched from the substrate to form a circuit, and the resist was removed to form a substrate having an inner layer circuit.

Next, after degreasing the substrate on which the inner layer circuit was formed with an alkali, electroless Sn plating was continuously performed by a spray method. Electroless plating is Sn 120g /
1, a sulfuric acid 100 g / l, and a plating solution having a composition of thiourea as an additive, a temperature of 45 ± 3 ° C., and a speed of 2.
The concentration of the above plating solution is 30 g / l at 0 ± 0.1 m / min.
As a spray on the substrate. By this plating step, electroless Sn having a layer thickness of 0.1 μm was formed on the copper circuit.

Next, in the continuous laminating apparatus as shown in FIG.
The substrate after the plating treatment was carried in. Next, a glass laminate impregnated with the unsaturated polyester resin and a copper foil were successively laminated on both surfaces of the substrate by a continuous laminating apparatus by a pair of rolls to form an integrated laminate.

Next, the laminate was primarily heated to cure the unsaturated polyester resin. This laminate was cut into a desired size by a cutting means to obtain a multilayer printed board. Further, as a comparative example, a multilayer printed board was obtained by a method in which the electroless Sn plating step was omitted from the above steps. The solder heat resistance and thermal shock of the multilayer printed board of the present invention and the multilayer printed board of the comparative example manufactured as described above were tested by the following method.

Solder Heat Resistance Test A multilayer printed board was floated on the molten solder under the conditions shown in the following table to determine whether the board swells or peels. Evaluation Conditions Examples Comparative Examples 260 ° C. for 20 seconds ○ × 260 ° C. for 60 seconds ○ × 288 ° C. for 10 seconds ○ × In the above table, ○ means that no swelling or peeling of the substrate occurs, and × indicates the substrate. Swelling and peeling occurred.

As is clear from the above table, it was found that the multilayer printed board of the present invention did not cause swelling or peeling at all and could be sufficiently used in the actual manufacturing process of the multilayer printed board. Thermal shock test The multilayer printed board is pre-heated at 220 ° C which is a temperature usually applied in the mounting process, and then at 250 ° C for 3 hours.
Solder dip for a second. Furthermore, the surface was coated with a solder resin, and a treatment with a soldering iron was performed for 4 cycles at 235 ° C. for 4 seconds as one cycle. The multi-layer printed board thus treated was stored at -65 ° C for 15 minutes at room temperature (2
5 cycles at 5 ° C., 15 minutes at 125 ° C., and 5 minutes at room temperature as one cycle, and 100 cycles were repeated (MIL: military standard).

As a result, the rate of change in through-hole conductor resistance was less than 10%. In addition, swelling and peeling of the substrate did not occur in appearance. Furthermore, no disconnection occurred in the through-hole conductor. However, the multilayer printed board of the comparative example had swelling and peeling of the board in appearance. Further, when the multilayer printed board is subjected to a glycerin dip treatment and a soldering iron treatment at 250 ° C. for 3 seconds, and the multilayer printed board is subjected to 100 cycles in the same manner as above, the through-hole conductor resistance is the same as above. The rate of change was less than 10%. In addition, swelling and peeling of the substrate did not occur in appearance.
Furthermore, no disconnection occurred in the through-hole conductor. However, the multilayer printed board of the comparative example had swelling and peeling of the board in appearance.

[0027]

EFFECT OF THE INVENTION The method for producing a multilayer printed board of the present invention and the obtained multilayer printed board have an adhesive reinforcing layer, a resin-impregnated base material layer and a metal foil layer on one surface of a circuit board. Therefore, the peeling of the inner layer circuit and the resin-impregnated base material layer due to the swelling can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic process diagram of a continuous stacking apparatus that can be used in the manufacturing method of the present invention.

FIG. 2 is a schematic view of a dipping method which is a means for coating an adhesive reinforcing layer of the present invention.

FIG. 3 is a schematic view of a spray method which is a means for coating an adhesion reinforcing layer of the present invention.

FIG. 4 is a schematic view of a roll coating method which is a means for coating an adhesion reinforcing layer of the present invention.

FIG. 5 is a schematic view of a screen printing method which is a means for coating an adhesion reinforcing layer of the present invention.

FIG. 6 is a schematic view of a curtain coating method which is a means for coating an adhesion reinforcing layer of the present invention.

FIG. 7 is a schematic view of a spin coating method which is a means for coating an adhesion reinforcing layer of the present invention.

[Explanation of symbols]

 1 Inner Layer Circuit Forming Substrate 2 Adhesion Reinforcing Layer 3 Base Material 4, 10, 14, 15, 41, 42 Roll 5 Resin 6 Impregnation Tank 7, 8 Laminated Body 9 Metal Foil Layer 11 Primary Heating 12 Secondary Heating 13 Cutting Device 21 Substrates 22 and 43 on which conductive circuits are formed Solution tank 31 Spray device 32 Conveying means 51 Squeegee 52 Plate 61, 71 Nozzle

Front page continued (72) Inventor Tokio Yoshimitsu 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Shigehiro Okada, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (2)

[Claims] 1. A substrate having a conductive inner layer circuit on one or both sides, and a desired number of resin-impregnated base material layers and metal foil layers formed on the inner layer circuit with an adhesive reinforcing layer interposed therebetween. A multilayer printed board characterized by. 2. A substrate having a conductive inner layer circuit on one or both sides is coated with an adhesion reinforcing layer, and the substrate and a desired number of belt-shaped resin-impregnated base material layers are continuously supplied to obtain the resin-impregnated resin. A multilayer characterized in that a metal foil layer is continuously supplied onto a base material layer, and a desired number of resin-impregnated base material layers and metal foil layers are laminated on an inner layer circuit of a substrate via an adhesion reinforcing layer. Printed board manufacturing method.