JPH10242643A - Manufacturing method of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method in which a plurality of inner-layer boards are aligned with good accuracy, and in which especially a thin multilayer wiring board comprising six or more conductor layers is manufactured with high produc tivity and at low costs. SOLUTION: In a manufacturing method for a multilayered printed wiring board, a plurality of inner-layer boards 4 in which wiring patterns are formed respectively on their surfaces, and their back faces are laminated via a prepreg 5a between the boards, and the whole assembly is heated, pressurized and molded integrally. In the manufacturing method, piano wires 9 or thin wires for alignment are sewn in prescribed positions in the inner layers 4 and the prepreg 5a.

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 with improved positional accuracy.

[0002]

2. Description of the Related Art In recent years, with the progress of higher speed and higher density of industrial electronic devices, wiring boards on which electronic components are mounted have been increased in the number of layers and thinned. The demand for multilayer wiring boards is increasing.

Conventionally, such a multilayer wiring board is shown in FIG.
As shown in (Example of Layered Wiring Board), two inner-layer boards 4 each having two wiring patterns 2 and 3 for signal and power supply formed on the front and back surfaces of the insulating board 1, respectively. The prepreg 5a is laminated with the prepreg 5a interposed therebetween, and further, the prepreg 5b and the outer layer copper foil 6 are overlapped on both surfaces thereof, and then the whole is heated and pressurized by a hot press or the like to be integrally molded.

[0004] In such a conventional manufacturing method, the alignment of the wiring pattern between the inner layer plates has been conventionally performed by the following various methods.

(A) Pin lamination method Guide holes are formed at predetermined positions on all the plates to be laminated, such as the outer copper foil 6, the inner plate 4, and the prepregs 5a and 5b, at the same pitch. Metal guide pins are set up on the surface with predetermined pitches, and these pins are pressed into the above-described guide holes to perform positioning.

(B) Multilayer molding method (sequential method) First, after a four-layer plate is formed and a circuit is completed, an inner layer plate is superposed one by one and molded, and this is repeated as necessary.

(C) Adhesive system A plurality of inner layer plates 4 and prepregs 5a are respectively provided with holes for positioning, and these holes are stacked and set on a positioning jig, and then an adhesive such as cyanoacrylate is used. The plates are bonded and fixed to each other using.

(D) Stopper method A stop is used instead of the adhesive, and fixed in an aligned state. That is, as shown in FIG. 5, after the inner slab 4 and the prepreg 5 a are sequentially stacked while being aligned with each other, the stake 7 is driven, and then the tip 7 a of the stake 7 is caulked and mechanically fastened. .

[0009]

However, these alignment and fixing methods have the following problems, respectively.

(A) Pin lamination method Although high-accuracy alignment is possible, only a small press can be used, and productivity is low. Also, it takes time to remove the pin after heating and pressure molding and to remove the resin adhering around the pin.

(B) Multilayer molding method (sequential method) It takes a long time to manufacture a final multilayer wiring board, and cannot meet the market demand for a short delivery time.

(C) Adhesive method Not only the fixing strength is not sufficient, but also the adhesive deteriorates at the time of molding by heating and pressing, and cracks or peels off at the fixing portion.

(D) Stopping method This is a method of precisely aligning a plurality of inner layer boards, and in particular, manufacturing a multi-layer wiring board having six or more conductor layers at high productivity and at low cost. In particular, after laminating a plurality of inner layer plates having a thickness of less than 0.2 mm and a prepreg between the plates, and further laminating the outer layer copper foil on both sides thereof, and then integrally molding by heating and pressing, the outer layer copper foil is formed. Wrinkles occur around the staples.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and to accurately align a plurality of inner layer boards, and particularly to produce a thin multilayer wiring board having six or more conductor layers at a high level. It is an object of the present invention to provide a method for manufacturing the semiconductor device at low cost.

[0015]

According to the method of manufacturing a multilayer printed wiring board of the present invention, a plurality of inner layer boards each having a wiring pattern formed on both front and back sides are laminated with a prepreg interposed between the boards. In a method for manufacturing a multilayer printed wiring board in which an outer layer copper-clad board or a metal foil is laminated on both surfaces thereof, and the whole is heated and pressed to be integrally formed, a piano wire for positioning the inner layer board and a prepreg at predetermined positions is provided. Alternatively, a thin wire is sewn.

Hereinafter, the present invention will be described in detail.

As the inner layer plate, prepreg and outer layer copper foil used in the present invention, the inner layer plate, prepreg and outer layer copper foil generally used in a multilayer printed wiring board can be used. It is not limited.

The piano wire used in the present invention is a high tensile strength steel wire cold-drawn to a uniform thickness, and the fine wire replacing the piano wire is copper, brass, iron, nickel, aluminum, or an alloy or alloy thereof. It is a thin wire other than a metal wire such as a silicon compound or a heat-resistant metal wire such as Teflon. In the case of a piano wire, it is preferable to use a commercially available ultrafine wire of less than 0.3 mm.

Next, an example of sewing a piano wire or a fine wire will be described with reference to the drawings.

FIG. 1 is a sectional view showing the layer structure of a six-layer multilayer printed wiring board according to the present invention. FIG. 2 is an enlarged view of the portion of the ellipse I in FIG. 1, and FIG. 3 is a plan view of FIG.

As shown in FIG. 1, two inner plates 4 having a wiring pattern formed on both front and back sides are aligned and laminated via a prepreg 5a therebetween, and a knot of a piano wire is placed at a predetermined position. A reference hole 8 to be inserted is formed.

As shown in the enlarged view of FIG. 2, the inner layer plate 4 outside the reference hole is made to cross through the reference hole 8.
Then, the piano wire 9 is sewn into the prepreg 5a. As shown in the plan view of FIG. 3, it is desirable to sew the piano wire at four positions a to d in an X shape so as to improve the displacement accuracy. It is desirable to form the knot 9e in the reference hole 8 in order to eliminate dents and scratches on the stainless steel plate (not shown) and to eliminate dents in the outer copper foil 6.

[0023]

The method of manufacturing a multilayer printed wiring board according to the present invention comprises:
By sewing and positioning the inner layer plate and the prepreg of ultra-thin plate with a total thickness of 1.0 mm or less with extra fine piano wire, positioning accuracy similar to the conventional pin lamination method and snap-fit method, and 4-layer plate molding This achieves the same level of molding workability. Also, it is possible to eliminate wrinkles of the outer layer copper foil by the conventional stop method.

[0024]

Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted by such specific Examples.

Example A thickness in which a wiring pattern having a thickness of 35 μm was formed on both front and back surfaces.
Two inner plates having a size of 0.1 mm and a size of 500 × 300 mm were stacked with one 1080 type prepreg interposed therebetween.
A reference hole was made in this, and a piano wire having a diameter of 0.1 mm was sewn into the reference hole as shown in FIGS. 2 and 3 to prepare an inner layer material for a six-layer plate. Then, on both sides of the sewn inner layer material,
One 1080 type prepreg and 18 μm thick outer layer copper foil are laminated in this order, and the whole is 175 ° C., 4 to 40 kg /
It was heated and pressed integrally under the conditions of cm ² for 90 minutes to produce a six-layer multilayer printed wiring board.

Comparative Example 1 The same inner layer plate, prepreg, and outer layer copper foil as those of
A six-layer multilayer printed wiring board was manufactured in the same manner as in Example, except that the alignment was fixed by a normal pin lamination method using 5 mm metal pins.

Comparative Example 2 A prepreg was sandwiched between the same inner layer plates as in the example, and a glass-epoxy plate was further sandwiched as a spacer, and then a gap between the inner layer plate and the inner layer plate was formed using an ordinary cyanoacrylate instant adhesive in an adhesive system. A multilayer printed wiring board having six layers was manufactured under the same conditions as in the example, except that it was fixed.

COMPARATIVE EXAMPLE 3 An inner layer material of an inner layer plate and a prepreg having a diameter of 5
A 6-layer multilayer printed wiring board was manufactured under the same conditions as in the example except that the alignment was fixed by a fitting method using a fitting made of brass having a thickness of 4 mm and a thickness of 4 mm.

As described above, Example and Comparative Example 1
The positional deviation and dimensional stability of the multilayer printed wiring boards obtained in Nos. 1 to 3 were tested by the following methods.
It was shown to.

Positional deviation of each inner layer: The deviation of the dimension between the reference holes between the wiring patterns of the inner layer was measured by a coordinate measuring machine in both the vertical and horizontal directions. Heat resistance: D-4 / 100 wiring board
After the treatment, the plate was immersed in a solder at 260 ° C. for 30 seconds, and the state of the plate (such as warpage) was visually observed. Dimensional stability: MI
According to the L method.

In the item of displacement of the inner layer in Table 1,
L1 and L2 represent the wiring patterns on the front and back of the first inner layer board, and L3 and L4 represent the wiring patterns on the front and back of the second inner layer board. In the table, the mark ○ is not good and the mark △ is not good, but it is practically acceptable, and the mark × is defective.

[0032]

[Table 1]

[0033]

As is clear from the above description and Table 1, the method for manufacturing a multilayer printed wiring board according to the present invention can accurately align a plurality of wiring patterns on an inner layer board, and particularly, a six-layer printed circuit board. The above thin multilayer board can be manufactured with good workability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a layer configuration of a multilayer printed wiring board according to the present invention separately.

FIG. 2 is an enlarged sectional view of an ellipse I in FIG.

FIG. 3 is an enlarged plan view of an ellipse I in FIG. 1;

FIG. 4 is a cross-sectional view showing a layer configuration of a multilayer printed wiring board according to a conventional manufacturing method separately.

FIG. 5 is a cross-sectional view illustrating a stop method of a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 2, 3 Wiring pattern 4 Inner board 5a, 5b Prepreg 6 Outer copper foil 7 Stopper 8 Reference hole 9 Piano wire

Claims (1)

[Claims] 1. After laminating a plurality of inner-layer boards each having a wiring pattern formed on each of the front and back surfaces via a prepreg between the boards, and further laminating an outer-layer copper-clad board or metal foil on both sides thereof, Manufacturing a multilayer printed wiring board by integrally heating and pressing, wherein a piano wire or a fine wire for positioning is sewn to a predetermined position of the inner layer board and the prepreg, and the multilayer printed wiring board is manufactured. Method.