JP2001284809A - Multilayer circuit board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayer circuit board, wherein manufacturing processes can be simplified and strength is high. SOLUTION: A printed board 2 is so laminated that an insulating board 4a is arranged on the one uppermost layer of a multilayer circuit board 1. Viaholes 6a which penetrate the insulating board 4a in the width wise direction are arranged, and pins 12 are fixed in the viaholes 6a. In this case, the surface of a copper foil 5a to which base end portions 13 of the pins 12 are bonded is covered with the insulating board 4a, except apertures formed by the viaholes 6a. Consequently, it is unnecessary to previously arrange solder resist before soldering the pins 12. Hence, processes can be simplified, and holding strength of the pins 12 can be improved. The insulating board 4a is formed of glass cloth base material epoxy resin, so that the strength of the whole multilayer circuit board 1 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer circuit board and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a method of manufacturing a multi-layer circuit board, for example, there is a method of laminating a plurality of printed circuit boards on which conductive circuits are formed and pressing them at once. This is a method of laminating a plurality of printed circuit boards on which a predetermined circuit pattern is formed on a copper-clad laminate with an adhesive layer interposed therebetween and by pressing all together. According to such a method of manufacturing a multilayer circuit board of a batch lamination type, there is an advantage that the process can be simplified and the cost can be reduced.

In the multilayer circuit board manufactured as described above, a connection land for forming a circuit pattern and pins is formed on a copper foil exposed on the outermost surface by patterning. Pins for connection to external terminals are mounted by soldering.

[0004]

However, in the above-described method, it is necessary to prevent the solder from flowing between adjacent circuit patterns and causing a short circuit or the like during the soldering operation of the pins. In addition, a step of previously applying a solder resist to the outermost surface has been required. Also, in the above multilayer circuit board, the structure for supporting the soldered pins is
Since the connection lands are formed on the copper foil, a configuration capable of supporting the base end portion of the pin with a stronger force has been required.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a method of manufacturing a multilayer circuit board capable of simplifying the manufacturing process. An object of the present invention is to provide a multilayer circuit board having high supporting strength.

[0006]

According to another aspect of the present invention, there is provided a multilayer circuit board comprising a plurality of printed circuit boards having a conductor layer formed on one of the front and back surfaces of an insulating layer. Wherein the insulating layer is disposed on at least one surface of a pair of outermost surfaces of the front and back surfaces of the multilayer circuit board, and the printed circuit board is provided with the outermost insulating layer. While being laminated, the outermost insulating layer is provided with a hole penetrating in the thickness direction, and a pin for connecting the multilayer circuit board to another member is fixed in the hole. It is characterized by being.

According to a second aspect of the present invention, in the first aspect, the outermost insulating layer is formed of a glass cloth epoxy resin.

According to a third aspect of the present invention, there is provided a method of manufacturing a multilayer circuit board comprising a plurality of printed circuit boards each having a conductor layer formed on one of the front and back surfaces of an insulating layer. The method of (a), wherein the insulating layer is disposed on at least one of the outermost surfaces of the pair of front and back surfaces of the multilayer circuit board so that the outermost insulating layer is provided, and the printed circuit board is provided. Laminating, (b) forming a hole penetrating in the thickness direction of the outermost insulating layer, (c) fixing a pin for connecting the multilayer circuit board to another member in the hole. Performing a process. Here, the step (b) need not always be performed after the step (a), and may be performed in the order of (b) and (a).

[0009]

According to the first aspect of the present invention, the outermost insulating layer is disposed on the outermost surface of the multilayer circuit board, and the hole penetrates the outermost insulating layer in the thickness direction. A pin is fixed inside the unit. For this reason, the conductor layer to which the base end portion of the pin is bonded is covered with the outermost insulating layer, and the holding strength of the pin can be improved.

According to the second aspect of the present invention, the insulating layer is formed of a glass cloth epoxy resin. Thereby, the multilayer circuit board is reinforced by the insulating layer having high strength, and the strength of the entire multilayer circuit board can be improved.

According to the third aspect of the present invention, the outermost insulating layer is provided in advance on the conductor layer to which the base end of the pin is connected. There is no need to provide For this reason, the manufacturing process of the multilayer circuit board can be simplified.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. The multilayer circuit board 1 of the present invention includes a plurality of printed circuit boards 2.
Are laminated, and one outermost surface (in FIG. 3,
An insulating substrate 4a (corresponding to the outermost insulating layer of the present invention) is disposed on the lowermost surface), and a via hole 6a is provided through the insulating substrate 4a in the thickness direction.
The pin 12 is fixed inside.

Printed circuit board 2 forming multilayer circuit board 1
Is a copper-clad laminate 3. The copper-clad laminate 3
For example, it has a known structure in which a copper foil 5 is attached to the entire surface of one surface (the lower surface side in FIG. 1) of an insulating substrate 4 formed of a plate-like glass cloth epoxy resin (FIG. 1).
A).

At a predetermined position on the insulating substrate 4, a surface of the insulating substrate 4 opposite to the copper foil 5 (an upper surface in FIG. 1)
Is applied to form a via hole 6 penetrating in the thickness direction of the insulating substrate 4 and reaching the copper foil 5 (FIG. 1).
B). Laser processing can be performed by, for example, a pulse oscillation type carbon dioxide laser processing apparatus. In this case, the pulse energy is 2.0 to 10.0 mJ, the pulse width is 1 to 100 μs, and the pulse interval is 0.5 ms or more. And the number of shots is desirably 3 to 50.

Thereafter, a desmear process is performed to remove the resin remaining inside the generated via hole 6. The desmear treatment can be performed by, for example, potassium permanganate treatment, oxygen plasma discharge, corona discharge treatment, or the like.

Next, with the copper foil 5 covered with a protective film made of, for example, polyethylene terephthalate (not shown), a plated conductor 7 is formed in the via hole 6 by electroplating using the copper foil 5 as one electrode. (Fig. 1
C). It is preferable that the filling amount of the plated conductor 7 is such that the upper surface thereof is slightly lower than the surface of the insulating substrate 4.
Copper is most preferred as the plating metal, but tin,
Any metal that can be plated, such as silver, solder, copper / tin, or copper / silver, may be used.

A conductive bump 8 made of a low melting point material such as tin is formed by bump plating so as to overlap the plated conductor 7 in the via hole 6. The conductive bumps 8 are filled so as to slightly protrude from the upper surface of the insulating substrate 4 (FIG. 1D). Thereafter, after the protective film is peeled off from the copper foil 5, the copper foil 5 is etched by a well-known etching method to form the conductor circuit 10 (FIG. 1E).

Next, on the surface of the printed circuit board 2 on which the conductive bumps 8 are formed, a thermosetting adhesive 11 (for example, an epoxy resin can be used) is applied by a roll coating method ( (FIG. 1F).

After manufacturing a plurality of printed circuit boards 2 in this manner, the outermost printed circuit board 2a disposed at the lowermost layer
Is formed. The printed circuit board 2a for the outer layer is a copper-clad laminate 3 in which a copper foil 5 is attached to the entire surface of one side of an insulating substrate 4a formed of a plate-like glass cloth epoxy resin.
Is used as a starting material, the copper foil 5a is etched by a well-known etching technique to form a conductor circuit 10a at a predetermined position. At this time, a target mark (not shown) for positioning when forming a via hole 6a to be described later can be distinguished from the front surface side (the lower surface side in FIG. 2) of the insulating substrate 4a. It is provided as follows.

The plurality of printed circuit boards 2 and 2a thus formed are aligned and superposed (FIG. 2).
G). At this time, the uppermost printed circuit board 2 is
0 is directed outward and the conductive bumps 8 are directed inward, and the printed circuit board 2 located therebelow.
Are stacked such that the conductor circuit 10 is located on the upper side. Thus, the conductive bumps 8 of the upper printed circuit board 2 are stacked in a direction connectable to the conductor circuit 10 of the lower printed circuit board 2. The printed circuit board 2a for the outer layer provided on the lowermost layer is arranged so that the insulating substrate 4a faces outward, and the conductor circuit 10a is connected to the conductive bump 8 of the printed circuit board 2 which is directly overlaid. So that they overlap.

The adhesive 11 is cured by, for example, heating and vacuum pressing at 180 ° C. for 70 minutes to form the multilayer circuit board 1 in which the printed boards 2 and 2a are integrated (FIG. 2H). At this time, the tip of the conductive bump 8 of each printed circuit board 2 is connected to a predetermined position of the conductive circuit 10 of the adjacent printed circuit board 2, thereby electrically connecting the conductive circuits 10 of the adjacent printed circuit board 2. Connected.

Next, based on the information on the position of the target mark on the insulating substrate 4a, laser irradiation is performed from the lower surface side of the insulating substrate 4a to penetrate through the insulating substrate 4a in the thickness direction. A via hole 6a (a hole according to the present invention) is formed. Next, the pin 12 formed of a conductive metal is inserted into the via hole 6a,
Is bonded to the conductor circuit 10a by soldering (FIG. 3I).

As described above, according to the present embodiment, the multilayer circuit board 1 has a plurality of printed boards 2 stacked one on top of the other, and the outermost printed board 2a has the insulating board 4a on the outermost surface. Are stacked and adhered so as to be arranged toward. Then, a via hole 6a penetrating in the thickness direction of the insulating substrate 4a is provided, and the pin 12 is fixed in the via hole 6a. At this time, the proximal end 13 of the pin 12
The surface of the copper foil 5a to which is adhered is covered with the insulating substrate 4a except for the surface opened by the via hole 6a. Therefore, it is not necessary to provide a solder resist in advance before the operation of soldering the pins 12. This allows
The manufacturing process of the multilayer circuit board 1 can be simplified.
Further, a copper foil 10a to which the base end 13 of the pin 12 is fixed.
Is protected by the insulating substrate 4a, so that the holding strength of the pins 12 can be improved.

The insulating substrate 4a is formed of a glass cloth base epoxy resin. Thereby, the strength of the entire multilayer circuit board 1 can be improved.

The technical scope of the present invention is not limited to the above-described embodiment, but extends to an equivalent range.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a circuit board according to an embodiment of the present invention. (A) Cross-sectional view of a copper-clad laminate. (B) Cross-sectional view when a via hole is formed in a copper-clad laminate. Sectional view when the via hole is filled with a plated conductor (D) Sectional view when a conductive bump is formed in the via hole (E) Sectional view when a conductive circuit is formed by patterning copper foil (F) Circuit Sectional view when the adhesive layer is applied to the substrate

FIG. 2 is a cross-sectional view showing a circuit board laminating process; (G) a cross-sectional view when circuit boards are stacked; (H) a cross-sectional view of a multilayer circuit board formed by bonding circuit boards.

FIG. 3 is a cross-sectional view of a multilayer circuit board of the present invention. (I) A cross-sectional view of a multilayer circuit board in which a via hole is formed in an outermost insulating substrate and pins are connected in the via hole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Multilayer circuit board 2 ... Printed board 4 ... Insulating board (insulating layer) 4a ... Insulating board (outermost insulating layer) 5 ... Copper foil (conductor layer) 6a ... Via hole (hole part) 10, 10a ... Conductor circuit (Conductor layer) 12 ... pin 13 ... base end

Claims (3)

[Claims] 1. A multilayer circuit board in which a plurality of printed circuit boards each having a conductor layer formed on one of the front and back surfaces of an insulating layer are stacked, wherein: The printed circuit board is laminated on at least one surface by disposing the insulating layer and using it as the outermost insulating layer, and the outermost insulating layer is provided with a hole penetrating in the thickness direction. A pin for connecting the multilayer circuit board to another member is fixed in the hole. 2. The multilayer circuit board according to claim 1, wherein the outermost insulating layer is formed of a glass cloth epoxy resin. 3. A method for manufacturing a multilayer circuit board comprising a plurality of printed circuit boards each having a conductor layer formed on one of the front and back surfaces of an insulating layer, wherein: (a) the multilayer circuit board; A step of arranging the insulating layer on at least one surface of a pair of outermost surfaces of the front and back sides, and using the printed circuit board as an outermost insulating layer, and (b) a thickness of the outermost insulating layer. Forming a hole penetrating in the direction, and (c) fixing a pin for connecting the multilayer circuit board to another member in the hole.