JP2727697B2 - Method for manufacturing multilayer printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] Regarding a method for manufacturing a multilayer printed circuit board, a surface IVH (Interstitial Via Hole) connecting an inner layer conductor and a conductor layer on the surface of the multilayer printed circuit board can accurately control the depth. A method of forming a surface IVH on a multi-layer printed circuit board, in which a monitoring conductor layer is previously formed on an intermediate layer base material in an area other than a product area of the multi-layer printed circuit board. A plurality of holes having different depths from the surface of the multilayer printed board are provided, and a tip end in the depth direction of the opened hole detects a limit point (point Z) at the time of cutting the monitor conductor layer. A surface IVH is formed in the product area based on the detection information.

[Industrial applications]

The present invention relates to a method for manufacturing a multilayer printed circuit board,
The present invention relates to a method for accurately obtaining the depth of a hole when drilling a surface H (Interstitial Via Hole).

When manufacturing a multilayer printed circuit board, as shown in FIG. 4, a copper foil 2 having a pattern formed on both sides or one side of a thermosetting resin substrate 1 such as an epoxy resin is provided and an intermediate layer is formed. A base material 3 is formed, and a surface layer copper foil 5 is provided with a prepreg 4 interposed on both surfaces of the intermediate layer base material,
After laminating these intermediate layer base material, prepreg and surface layer copper foil by pressing, the surface from the surface of these surface layer copper foils to the inner layer conductor composed of the copper foil pattern provided on the intermediate layer base material
After drilling a via hole 7 or the like penetrating the IVH6 or the laminated base material, the prepreg, and the surface layer copper foil, an electroless copper plating layer, It is formed by providing a conductor made of a copper plating layer.

Thereafter, as shown in FIG. 5, the formed multilayer printed circuit board 8 is then cut into a predetermined size to make the product area 8A.

[Conventional technology]

By the way, conventionally, when drilling a hole on the surface IVH, after drilling a shallow hole so as not to reach the inner layer conductor from the surface in a region of the printed circuit board where the inner layer conductor is formed, gradually. A hole is formed with a drill while the depth of the hole is deepened, and the state of the tip of the hole is observed by visually checking the opening of the printed circuit board with the hole. And the tip of the perforated hole reaches the inner layer copper foil,
Observe the state where the copper foil of the inner layer conductor is cut by a drill, determine whether the tip of the hole has reached the inner layer conductor and determine the depth of the hole to be drilled. I have.

Then, the time when the tip of the drill cuts the inner layer conductor is set as the limit point of the movement of the drill, and the movement size of the drill is set, and the surface IVH is perforated with the set size.

[Problems to be solved by the invention]

However, in such a conventional method, the hole is repeatedly drilled while gradually increasing the depth of the hole, and the predetermined hole depth is determined. There are difficulties that require a lot of effort to make a decision.

Further, since such a trial hole is formed in the product area 8A of the multilayer printed circuit board as shown in FIG. 5, there is a problem that the product area is damaged and the product yield is reduced.

The present invention is directed to a method of perforating the surface IVH so as to eliminate the above-mentioned problems and not damage the product area.

In addition, the surface IVH of a predetermined depth can be easily formed by a single drilling operation.
It is an object of the present invention to provide a method for manufacturing a multilayer printed circuit board in which the depth of the hole can be determined.

[Means for solving the problem]

A method of manufacturing a multilayer printed board according to the present invention that achieves the above object is a method of forming a surface IVH on a multilayer printed board, wherein a monitoring conductor layer is previously formed in an intermediate layer in an area other than a product area of the multilayer printed board. A plurality of holes having different depths from the surface of the multilayer printed circuit board are formed on the base material, and the tip of the opened hole in the depth direction is a critical point at the time of cutting the monitoring conductor layer. (Z point) is detected, and a surface IVH is perforated in the product area based on the detection information.

(Operation)

The method of the present invention comprises, before forming a monitor conductor layer in a peripheral region of an intermediate layer base material other than a product region of a printed circuit board, and using a drill to form a plurality of surfaces IVH on a peripheral portion of the printed circuit board. Are drilled for each hole with the depth of each hole being different.

In this way, the limit point of the drill when the tip of the drill cuts the monitoring conductor layer provided on the surface of the intermediate layer base material is detected. Then, a hole is drilled in the surface IVH of the product area based on the detected limit point of the drill. In this way, a large number of test holes are not formed in the product area, and a product with a high yield can be obtained.

Further, when drilling the surface IVH, a plurality of drills are provided on the drilling machine, and each of the plurality of drills is
If the holes having different depths are formed at once by using the NC control device, the hole forming operation can be performed only once, and the process can be further shortened.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1 (a) and a cross-sectional view taken along the line II ′ of FIG. 1 (a), a region other than the product region 8A of the intermediate layer base material 3, that is, the intermediate layer base material Surface IV in the surrounding area 3A in advance
A monitor conductor layer 11 serving as a monitor for drilling H is formed and placed. This monitoring conductor layer is preferably formed by etching the copper foil 2A into a predetermined pattern on the periphery of the base material shown in FIG.

Then, as shown in FIG. 4, after the surface layer copper foil is placed up and down with the prepreg sandwiched on both surfaces of the intermediate layer base material 3 having the monitor conductor layer 11, the intermediate layer base material 3, the prepreg Then, the surface layer copper foil is laminated under pressure to form a multilayer printed circuit board 8.

The peripheral portion of the multilayer substrate thus laminated is monitored at a position corresponding to 1 at a depth up to the position where the inner layer conductor (copper foil 2 of a predetermined pattern) is formed in the product area. Conductor layer 11 is formed.

Next, FIG. 2 (a) and II-II 'of FIG. 2 (a)
As shown by the line, a drill is used from above the monitor conductor layer 11 is formed, the size of the drill in the downward moving direction is sequentially increased, and the depth from the surface to the tip of the hole is sequentially reduced. Holes 12A, 12B,
12C .... perforated, and visually observed the portion perforated with this hole or using a microscope, to detect the position of the depth of the optimal state where the tip of the drill cut the monitoring conductor layer, At this time, the movement limit point of the drill, that is, the Z point is detected.

Then, a hole is made in the multilayer substrate in the product area by using a drill in which the direction of movement of the drill is set so as to move to the Z point.

In this way, it is not necessary to form a large number of test holes as in the conventional method, and the disadvantage that the product area is lost due to the formation of the test holes can be eliminated, and the product yield of the printed circuit board is improved. .

FIG. 3 (a) and FIG.
As shown in FIG. 3 (b) in a sectional view taken along the line III-III 'in FIG. 3 (a) and FIG. 3 (c) in a sectional view taken along the line IV-IV' in FIG. Is the depth from the surface
l _1, conductor layer 11A which different allowed formed as l _2, two rows at different 11B forming location, or more when such a plurality of rows provided, different inner conductor depths from the surface in the product region of Can be applied to a multilayer substrate having

In addition, a plurality of the drills are provided on a drilling machine, and each of the drills is controlled by using an NC control device or the like so as to have different depths, and when the holes are opened, the drills should be more efficiently drilled up to the inner conductor. The size of the hole in the depth direction can be determined in a short time.

[Effects of the Invention] As is clear from the above description, according to the present invention, the surface IVH from the surface layer to the inner layer conductor can be accurately drilled to a predetermined depth to form a hole. The problem that the product area becomes defective due to the perforation is eliminated, and the production yield of the multilayer printed circuit board is improved.

[Brief description of the drawings]

1 (a) and 1 (b) are a plan view and a sectional view of a multilayer printed board used in the method of the present invention, and FIGS. 2 (a) and 2 (b) are steps of the present invention. FIGS. 3 (a), 3 (b) and 3 (c) are plan and sectional views showing another embodiment of the method of the present invention, and FIG. FIG. 5 is an explanatory view of a method for manufacturing a multilayer printed circuit board, and FIG. 5 is a plan view of a printed circuit board in a conventional method. In the figure, 1 is a substrate, 2, 2A is a copper foil, 3 is an intermediate layer substrate, 3A is a peripheral region, 4 is a prepreg, 5 is a surface layer copper foil, and 6 is a surface IVH
(Intermediate layer via hole), 7 is a via hole, 8 is a multilayer printed circuit board, 8A is a product area, 11, 11A and 11B are monitor conductor layers, and 12A, 12B, 12C and 12D are holes.

Claims (1)

(57) [Claims] 1. A method for forming a surface IVH on a multilayer printed circuit board, the method comprising: forming a monitor conductor layer (11) in an area other than a product area (8A) of the multilayer printed circuit board (8) in advance; (3), a plurality of holes (12A, 12B, 12C, 12D...) Having different depths from the surface of the multilayer printed circuit board (8) are provided. Detecting a limit point (Z point) at the time of cutting the monitor conductor layer (11), and forming a hole on the surface IVH in the product area (8A) based on the detected information. Manufacturing method of printed circuit board.