JP3165890B2 - Lay-up method of 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 primary lamination of a prepreg as an adhesive for an insulating plate and an inner layer plate on which a circuit is formed and which has been subjected to a blackening process, for laminating and molding a multilayer printed wiring board by hot pressing or the like. Lay-up method.

[0002]

2. Description of the Related Art In a multilayer printed wiring board (hereinafter referred to as a wiring board), when it is desired to increase the number of pins of ICs or LSIs on one printed wiring board, an inner layer board and an insulating board are laminated in a plurality of layers (layout). Up), and has been rapidly increased in recent years with the demand for high-density mounting on both sides and high speed. The wiring board is arranged so that the insulating board (prepreg) and the inner layer board with the conductor pattern formed on both sides are alternately superimposed,
It is manufactured such that a copper foil layer is polymerized on the front and back of the laminated insulating plate and the inner layer plate, and then heated and pressed by a hot press.
However, in this manufacturing process, before being hot-pressed by a hot press, a multilayer laminated insulating plate or inner layer plate is subjected to primary lamination (hereinafter referred to as a primary laminated plate) in a previous step in advance, and a primary laminated plate is formed. It may be carried in the thermocompression bonding step. In a wiring board in which two or more inner-layer boards (six or more wiring boards) are stacked, the positional accuracy of the through holes formed in the wiring board is a very important factor for determining the value of a product. In the stage of manufacturing a primary laminated board, particularly, in manufacturing a wiring board having six or more layers, it is required to increase the positional accuracy.

[0003] Conventionally, in manufacturing the primary laminated plate 31, a method of fixing it with eyelets or the like has been performed. In the eyelet method, as shown in FIG. 7, the insulating plate 3 and the inner layer plate 5 are overlapped one by one, and a reference pin is inserted into a plurality of reference pin holes (not shown) formed in the peripheral portion, respectively. After the alignment, the eyelets 32 are inserted into a plurality of eyelets formed separately from the reference pin holes, and both ends are fixed by caulking.

[0004]

However, the conventional primary lamination using eyelets has the following problems. For example, as shown in FIG. 8, in a portion where the eyelet 32 is inserted, the eyelet 32 is compressed in a vertical direction by caulking the eyelet 32, so that the interlayer of the eyelet portion becomes narrower than the central layer, and the upper surface and the lower surface are It is formed in a concave shape compared to other surfaces. When performing pressure bonding by a press in this state, if the direction of the pressure is inclined, each layer may be shifted in the lateral direction, so that the accuracy is deteriorated. Further, since both ends of the eyelets 32 project slightly but slightly from the surface of the insulating plate or the inner layer plate disposed at the uppermost end and the lowermost end, when placing another primary stacked one on top of the other, the two ends are separated from each other. They are not placed parallel to each other and cause a positional shift (shift between layers).

[0005] The present invention solves the above-mentioned problems, and provides a method of laying up a printed wiring board in which at least two inner layers are manufactured so that the positional accuracy can be improved during the manufacture of a primary laminate. The purpose is to provide.

[0006]

A lay-up method for a printed wiring board according to the present invention employs the following method to solve the above-mentioned problems. That is, in order to laminate-mold a multilayer printed wiring board, a method of laying up a printed wiring board in which insulating plates and inner layer plates are alternately arranged and primarily laminated, wherein at least one insulating plate and at least one insulating plate are provided. Are positioned alternately in the direction in which they are laminated and positioned, and then fixed by dielectric heating.

[0007] A method of laying up a printed wiring board in which insulating plates and inner layer plates are alternately arranged and primarily laminated in order to laminate-mold a multilayer printed wiring board.
A plurality of the insulating plates and at least one inner layer plate are alternately arranged and positioned in the laminating direction, and then fixed by ultrasonic heating.

It is preferable that the insulating plate is formed of a thermosetting resin.

[0009] Further, a concave or round copper foil defective portion is formed in the copper foil portion provided on the peripheral portion of the inner layer plate, and the defective portion is heated. Is more preferable.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the wiring board is manufactured by a method called mass lamination. In general, the mass lamination method is a method in which an interior circuit is etched and formed by a laminated board maker (inner layer board), and a prepreg is polymerized above and below the circuit layer, and a copper foil is polymerized above and below the prepreg and laminated and formed. There is a distinction from pin lamination in which the inner layer plate, prepreg and copper foil are guided by pins.

FIG. 1 shows a state in which a primary laminate 1 formed in eight layers is dielectrically heated. The primary laminate 1 is 2
Prepregs (insulating plates) 3 and inner plates 5 arranged at the upper, middle and lower stages so as to sandwich the prepreg 3, with reference pin holes formed in the respective prepregs 3 and the inner plate 5. Positioning is performed by guiding a reference pin (not shown) through the guide. An electrode bar 7 for dielectric heating is arranged and set above the upper inner layer plate 5 and below the lower inner layer plate 5.

The prepreg 3 as an insulating plate is an insulating plate made of a sheet-like bonding insulating material formed by impregnating a glass cloth or a glass nonwoven fabric with a thermosetting resin diluted with a solvent to form a semi-cured state. It has the property of starting to melt at about 70 ° C. after heating and hardening at about 170 ° C. The prepreg 3 is formed in a rectangular shape.
A reference pin hole is formed at the corner.

The inner layer plate 5 is provided with a circuit formed thereon and subjected to a blackening treatment. As shown in FIGS.
53, and copper foil portions 54, 54 adhered to the periphery of the prepreg 51 outside the circuit portions 52, 53. The copper foil portion 54 has a plurality of reference pin holes 55 formed at four corners, and a plurality of reference pin holes 55 in the longitudinal direction and the transverse direction of the copper foil portion 54 (in the present embodiment, three in the longitudinal direction and in the transverse direction, respectively). And two (2) copper foil defective portions 56 formed in an elliptical shape. Therefore, the prepreg 51 as a base appears in the copper foil defective portion 56.

The copper foil defective portion 56 may be formed in a concave shape from the circuit portion 52 side to the outside of the copper foil portion 54 as shown in a plan view of FIG. Also,
The reference pin holes 55 of the inner layer plate 5 are formed at positions matching the reference pin holes formed in the prepreg 3. Then, the inner layer plate 5 is formed by bonding a copper foil layer to both surfaces of the prepreg portion 51, printing a wiring drawing, and etching.

The electrode rods 7 for performing dielectric heating on the primary laminate 1 on which the thus formed prepreg 3 and the inner layer plate 5 are superimposed are set in the copper foil defective portions 56 formed on the inner layer plate 5, respectively. They are arranged to face each other. On the side in contact with the primary laminate 1 of the electrode rods 7 arranged vertically,
In order to prevent sparking, an insulator other than the prepreg (for example, silicon rubber or Teflon) 7a is attached, and the electrode rod 7 is preheated in advance so that dielectric heating can be performed in a short time. ing.

In order to prevent sparking, the insulator 7a may not be attached to the electrode rod 7 as in the above embodiment. For example, silicon rubber or the like may be laid on the primary laminate 1 to sandwich an insulator between the electrode bar 7 and the primary laminate 1.

The dielectric heating uses a dielectric loss when a high frequency is applied to a dielectric to heat the dielectric. The dielectric is used for heating an electrical insulator. In the case of normal external heating, for example, when heating with a soldering iron or the like, the heating time is prolonged due to poor heat conduction of the electric insulator, but the dielectric heating is itself heating, so The temperature can be increased irrespective of conduction, and the heating energy density can be increased, so that rapid heating is possible.

The formation of the copper foil deficient portion 56 is to prevent sparks generated at the time of dielectric heating, and causes heat concentration around the electrode rod 7 (heat conduction). This is because the high-rate copper is removed and thermal diffusion is prevented) to enable bonding in a short time.

When heated in this state, when the temperature rises to about 70 ° C., the prepreg 3 begins to melt, the contact surface between the inner layer plate 5 and the prepreg 3 starts to adhere, and the prepreg 3 hardens at about 170 ° C. , Inner layer plate 5 is prepreg 3
Completely adhered and fixed. The portion where the prepreg 3 is melted and fixed is integrated with the prepreg 3 by curing of the prepreg 3, so that even if an oblique force is generated when the prepreg 3 is pressed by a hot press, the inner plate 5 is hardened. Does not shift sideways. Therefore, the positional accuracy of the plurality of inner layer plates 5 can be maintained, and a stable primary laminated plate 1 is formed.

When performing the dielectric heating, the electrode rods disposed below the primary laminate 1 are not limited to those shown in FIG. 1, and the primary laminate 1 is replaced with an iron plate member such as a Teflon plate as an insulating plate. , And may be heated by an electrode rod disposed above the primary laminate 1.

FIG. 5 shows a state in which the primary laminate 1 is manufactured by ultrasonic heating as a method other than the dielectric heating.
The two prepregs 3 arranged on the base 10 and the inner layer plates 5 arranged in the upper, middle, and lower stages so as to sandwich the two prepregs 3 are alternately superposed as in FIG.
An oscillator 11 for transmitting an ultrasonic wave is disposed above the upper inner layer plate 5 so as to face the copper foil defective portion 56 of the inner layer plate 5,
A horn 12 is mounted on the inner layer 5 side of each oscillator 11. The prepreg 3 is melted by heating by oscillating ultrasonic waves, and the prepreg 3 is bonded to the inner layer plate 5 and fixed. In this method, since the bonding time is short, a stable primary laminate 1 is formed in a short time.

The primary laminate 1 formed by each of the above methods
Is carried into the next step, and as shown in FIG.
2 is adhered to the front and back of the primary laminate 1 via the prepreg 21 to manufacture the double-sided copper-clad laminate 20. The double-sided copper-clad laminate 20 is manufactured by hot pressing with a hot press (not shown). As shown in the exploded perspective view of FIG. 6, when hot-pressed by a hot press, the prepregs 21 and 21 and the copper foils 22 and 22 are superimposed on the outside of the prepreg 21 and The jig plates 24 are arranged so as to press the primary laminate 1 from the outer surfaces of the mirror plates 23 via the face plates 23 (this configuration is referred to as a double-sided copper-clad laminate set 25). In this state, the hot plate of the hot press is heat-pressed from both the upper and lower sides of the double-sided copper-clad laminate set 25 for about 2 hours, so that the primary laminate 1 and the prepreg 21 and the copper foil 22 are adhered to each other to form a double-sided copper-clad laminate. The plate 20 is manufactured. Double-sided copper-clad laminate 20
After a variety of steps, a patterned circuit is formed on the surface of the copper foil 26 by etching or the like, and a wiring board is manufactured. Further, when hot-pressing with a hot press, a plurality of double-sided copper-clad laminates 20 can be manufactured together by superposing a plurality of double-sided copper-clad laminates 25 vertically.
Mass production becomes possible.

In the above embodiment, the inner laminated plates 5 are arranged in the upper, middle and lower stages so as to sandwich the prepreg 3 so as to form the primary laminated plate 1 for manufacturing an eight-layer wiring board. However, the prepreg 3
Are arranged in the upper, middle and lower tiers, the primary laminated board 1 for manufacturing a six-layer wiring board can be formed. In this case, when hot pressing by hot press,
The prepreg 21 shown in FIG. 6 can be removed.

[0025]

The method for laying up a printed wiring board according to the present invention comprises the steps of firstly laminating and alternately arranging insulating plates and inner layer plates in order to laminate-mold a multilayer printed wiring board. The insulating plate and the at least one inner layer plate are characterized in that they are alternately arranged and positioned in the laminating direction and then fixed by dielectric heating. When the printed wiring board is heated and press-bonded, even if an oblique component force is applied, a printed wiring board having a stable quality without a risk of lateral displacement of a plurality of inner layers can be manufactured.

If the primary laminate is formed by ultrasonic heating, the bonding time is short, and a stable primary laminate can be manufactured in a short time.

Further, since the insulating plate is formed of a thermosetting resin, the insulating plate is heated and melted at about 70 ° C., cured at about 170 ° C., and the cured state does not change even when the temperature rises. Extremely stable bonding is possible in a short time.

Further, since the copper foil portion provided on the peripheral edge portion of the inner layer plate has a concave or round copper foil defect portion in a plan view, the occurrence of spark is prevented in the case of dielectric heating. At the same time, heat can be concentrated around the electrode rods, and in the case of ultrasonic heating, heat diffusion is prevented and the bonding time is fast, so that a stable primary laminate can be manufactured in an extremely short time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a method of laying up a primary laminate according to one embodiment of the present invention.

FIG. 2 is a plan view showing an inner plate on which a circuit is formed and blackening processing has been performed;

FIG. 3 is a diagram showing a front cross section of the same.

FIG. 4 is a diagram showing another form of the copper foil defect portion of the inner layer plate.

FIG. 5 is a schematic diagram illustrating a method for laying up a primary laminate according to another embodiment of the present invention.

FIG. 6 is a layout diagram for thermocompression bonding of a double-sided copper-clad laminate.

FIG. 7 is a view showing a conventional primary laminated plate.

8 is a schematic diagram showing a part of FIG. 7 in detail.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Primary laminated plate 3 ... Prepreg 5 ... Inner plate 7 ... Electrode rod 54 ... Copper foil part 55 ... Reference pin hole 56 ... Copper foil defective part

Claims (2)

(57) [Claims] 1. A multilayer printed wiring board for laminating and molding.
In the inner layer plate that is alternately arranged with the insulating plate and primary laminated
And a prepreg portion and a circuit portion formed in the prepreg portion.
Contacting the periphery of the prepreg outside the circuit section
And a copper foil portion attached thereto,
Is formed with a concave or round copper foil defect in plan view
An inner layer plate, characterized in that: 2. A method of laying up a printed wiring board in which insulating plates and inner layer plates are alternately arranged and primary laminated in order to laminate-mold a multilayer printed wiring board, wherein the insulating plate is made of a thermosetting resin. Formed at the periphery of the inner layer plate, a copper foil portion is disposed, the copper foil portion
A concave or round copper foil defective portion is formed in the planar view, and at least one insulating plate and at least one inner
The layers are alternately arranged in the direction in which they are
After that, the copper foil defective part is heated by dielectric heating or ultrasonic heating.
It is fixed by heating.
Lay-up method for printed wiring boards.