JPH04307796A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To prevent remaining of non-etchant part by providing through holes at four corners of an inner layer board, further providing copper foil patterns for printing pilots at the same positions as those of the holes on front and rear surfaces, and using a distance between the circumference of the hole and the outer periphery of the pattern as an index of aligning front and rear inner layer patterns on, the front and rear surfaces. CONSTITUTION:Through holes 5 are formed at four corners of an inner layer board 1 as printing pilots by drilling. Pilot patterns 6 or an inner layer pattern film in which a circuit pattern region 4 corresponding to the center of the board 1, a plurality of dot patterns 3 corresponding to peripheral edge regions 2 and the patterns 6 are arranged, are provided on the surface of the board 1 to match the holes 5. The film is so aligned that the holes 4 formed at the four corners fall within the inner circumference of the patterns 6 to align the front and rear surfaces. Thus, remaining of non-etchant part is eliminated to prevent a short-circuit between wirings.

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 multilayer printed wiring boards.

0002

[Prior Art] A conventional multilayer printed wiring board is shown in FIG.
As shown in (b), the peripheral region 2 surrounding the circuit pattern region 4 of the inner layer substrate 1 with the circuit pattern region 4 provided in the center improves the thickness accuracy after multilayer molding and prevents the occurrence of lamination voids. A dot pattern 3 of copper foil is arranged in order to prevent warpage and reduce warpage.

[0003] In such an inner layer substrate 1, when a circuit is formed in the circuit pattern area 4, there is no index to confirm the alignment accuracy (amount of deviation) between the front and back sides, so the alignment accuracy between the front and back sides of the circuit pattern decreases. However, there is a problem in that the overall pattern position accuracy after multilayer molding is reduced. Therefore, some dot patterns 3 provided in the peripheral area 2 of the inner layer substrate 1
It has been proposed that a through hole 5 smaller than the dot pattern 3 be provided in advance by drilling in accordance with the center of the pattern. In this case, when providing the dot pattern 3 of the etching resist film in alignment with the through hole 5, the alignment accuracy of the circuit patterns on the front and back sides of the inner layer substrate is controlled by the distance between the circumference of the through hole 5 and the circumference of the dot pattern 3. Therefore, the positional accuracy of the inner layer pattern can be improved.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional multilayer printed wiring board, the dot pattern is as shown in FIG.
As shown in b), the dot patterns 3a on the front side of the inner layer substrate 1 and the dot patterns 3b on the back side are alternately provided,
Since the dot patterns do not overlap at the same location on the front and back sides of the inner layer substrate 1, when forming the circuit, the etching resist film in the area without the dot pattern is exposed from the back side through the through hole, and a pattern of the size of the through hole is exposed through the through hole. There is a drawback that the etching resist film that has barely adhered to the surrounding area peels off in the next etching process, becomes floating chips of the etching resist film, and adheres to unnecessary locations, resulting in etching residue.

[0005]

[Means for Solving the Problems] The method for manufacturing a multilayer printed wiring board of the present invention includes the steps of forming through holes as printing pilots in an inner layer substrate, and forming pilots for positional alignment corresponding to the positions of the through holes. A step of aligning the pilot pattern of the inner layer pattern film having a pattern with the through hole and forming it on both the front and back surfaces of the inner layer substrate, and patterning the conductive layer of the inner layer substrate using the inner layer pattern film as a mask, and patterning the conductive layer of the inner layer substrate to form circuit wiring and forming a dot pattern around the circuit wiring.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are a schematic plan view and an enlarged view of part A of an inner layer substrate for explaining one embodiment of the present invention.

First, through holes 5 are formed as printing pilots at the four corners of the inner layer substrate 1 by drilling. The through hole 5 has a perfect circle with a diameter of 1.5 mm. next,
a circuit pattern area 4 corresponding to the center of the inner layer substrate 1;
A pilot pattern 6 of an inner layer pattern film (not shown) in which a plurality of dot patterns 3 corresponding to the peripheral area 2 and a printing pilot pattern 6 are arranged is provided on the surface of the inner layer substrate 1 in alignment with the through hole 5.

[0009] Here, dot pattern 3 has a diameter of 2.4 m.
m dots are arranged at a diagonal distance of 2.54 mm and alternately on the front and back sides of each inner layer substrate 1. The printing pilot patterns 6 are perfect circles with a diameter of 1.8 mm, and are arranged on the front and back sides of the inner layer substrate 1 at positions corresponding to the through holes 5, respectively.

By aligning the inner layer pattern film so that the through holes 5 provided at the four corners are within the circumference of the pilot pattern 6, the front and back sides of the inner layer pattern can be aligned with an accuracy of within 150 μm. In this way, a plurality of inner layer substrates 1 on which the inner layer patterns are aligned, a circuit is formed by etching, and a plurality of inner layer substrates 1 are stacked together via a plurality of prepregs, and multilayer molding is performed using a lamination press to form a multilayer printed wiring board. Configure.

In addition, a plurality of through holes 5 are provided at each corner in the four corners of the peripheral area 2 of the inner layer substrate 1 of the multilayer printed wiring board, and two corresponding pilot patterns 6 are formed, one with a diameter of 1.8 mm and the other with a diameter of 1.6 mm. By providing different types, it is possible to improve the positional accuracy of the front and back alignment of the inner layer pattern to within 50 μm.

0012

As explained above, the present invention provides through holes at the four corners of the inner layer substrate, and further provides copper foil patterns for printing pilots on the front and back surfaces at the same position as the through holes, respectively.
By using the distance between the circumference of the through hole and the outer periphery of the copper foil pattern as an indicator of the accuracy of front-to-back alignment of the inner layer pattern, the inner layer pattern position accuracy is improved, and furthermore, the distance between the circumference of the through hole and the outer circumference of the copper foil pattern is improved. This has the effect of preventing etching residue and preventing short circuits between wirings.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view and an enlarged view of part A of an inner layer substrate for explaining an embodiment of the present invention.

FIG. 2 is a schematic plan view and an enlarged view of part B of an inner layer substrate for explaining an example of a conventional multilayer printed wiring board.

[Explanation of symbols]

1 Inner layer substrate 2 Peripheral area 3, 3a, 3b Dot pattern 4 Circuit pattern area 5 Through hole 6 Pilot pattern

Claims (1)

[Claims] 1. A step of forming a through hole as a printing pilot in an inner layer substrate, and aligning the pilot pattern of an inner layer pattern film having a pilot pattern for positional alignment corresponding to the position of the through hole with the through hole. and forming a conductive layer on the inner layer substrate using the inner layer pattern film as a mask to form a circuit wiring and a dot pattern around the circuit wiring. A method for manufacturing a multilayer printed wiring board characterized by: