JPH054105A - Working of hole on printed circuit board - Google Patents

Abstract

PURPOSE:To provide a hole working method on a printed circuit board in which drilling work can be carried out with high precision from the surface layer to the second layer even if a circuit board is warped or the between-layer distance is dispersed, in the method for working a hole on a multilayered printed circuit board for connecting the first layer (surface layer) and the second layer through the hole. CONSTITUTION:In a hole working method on a printed circuit board in which a hole communicating to a second conductor layer 5c on the lower layer from the first conductor layer 5a on the surface of a multilayered printed circuit board 5, by a twist drill 2, a voltage is applied previously between the twist drill 2 and the second conductor layer 5c, and drilling work is carried out on the printed circuit board 5, driving the twist drill 2, and when the electric conduction between the drill 2 and the second conductor layer 5c is detected, the operation of the twist drill 2 is suspended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a hole in a multi-layer printed circuit board, which is mainly a first layer (surface layer) and a second layer, which is a so-called surface layer IVH (Interstitial Via Hole) substrate. Regarding

[0002]

2. Description of the Related Art Conventionally, in a multilayer printed circuit board, a hole leading to a surface layer and a second layer is processed, and the surface layer and the second layer are electrically connected through the hole to increase wiring density. However, in this hole drilling process, the distance from the drill tip to the second layer of the board is set in advance with the printed circuit board mounted on the NC drilling machine, and the drill is moved by this set distance to drill the hole. I'm trying to do.

[0003]

However, in the conventional method of processing a hole as described above, the processed hole does not reach the second layer when the substrate is warped or the interlayer distance varies. In some cases, it may penetrate through the second layer and reach the third layer, which makes it difficult to process holes with a desired depth with high yield. The present invention has been made in consideration of such circumstances, and by electrically detecting the contact of the drill with the conductor layer, even if the substrate is warped or the interlayer distance varies, the surface layer to the second layer It is intended to provide a method of drilling a hole in a printed circuit board, which is capable of making a hole with high accuracy.

[0004]

SUMMARY OF THE INVENTION The present invention is a method for drilling holes in a printed circuit board, wherein a hole communicating from a first conductor layer on the surface of a multilayer printed circuit board to a second conductor layer below the same is drilled. A voltage is applied between the second conductor layer and the printed circuit board while driving the drill, and the drill is stopped when electrical continuity is detected between the drill and the second conductor layer. The present invention provides a method for drilling holes in a printed circuit board.

[0005]

Since the voltage is applied between the drill and the second conductor layer in advance, when the tip of the drill comes into contact with the second conductor layer when the printed board is drilled by the drill, the drill and the second conductor layer are contacted. Electrical conduction occurs between the layers. Therefore, if the drill is stopped when this continuity is detected, a hole just reaching the second conductor layer can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. This does not limit the invention. FIG. 1 is a structural explanatory view showing an embodiment of the present invention, in which 1 is an NC drilling machine, 2 is a drill mounted on the NC drilling machine, 3 is driving of the drill of the NC drilling machine, and a moving distance in a drilling direction (Z-axis direction). A controller to control the
4 is a fixed table on which the material for drilling is installed
Is a multilayer printed circuit board fixed on the table 4 for drilling, and the multilayer printed circuit board 5 includes a surface conductor layer (first conductor layer) 5a, an insulating layer 5b, a second conductive layer 5c, an insulating layer 5d, a It is composed of three conductor layers 5e and an insulating layer 5f.

Further, 6 is a power source for applying a voltage between the drill 2 and the second conductor layer 5c, and 7 is a current detector for detecting and outputting a current when a current is passed from the power source 6 to the drill 2. Yes, the controller 3 receives the output from the current detector 7 while the NC drill is drilling with the drill 2,
The driving of the drill 2 is stopped on the NC drilling machine 1. FIG. 2 is a top view showing an example of the conductor pattern of the second conductor layer 5c, L is a land connected to the surface conductor layer 5a through a hole processed by the drill 2,
The shaded portion of the conductor layer 5c is a power source connecting conductor pattern provided for connecting the power source 6 to each pattern of the second conductor layer 5c. The power source connecting conductor patterns are gathered at the end of the substrate and connected to the power source 6. Further, in FIG. 2, a portion surrounded by a broken line is an effective use area of the printed circuit board, and a portion outside the broken line is a portion which is removed when the board is completed.

In such a structure, the NC drilling machine 1
Moves the drill 2 to the position of a preset coordinate position (one land L), and then lowers it in the Z-axis direction while rotating the drill 2. Thereby, the drill 2 starts drilling in the multilayer printed circuit board 5. And
When the tip of the drill 2 reaches the second conductor layer 5c, the drill 2 and the second conductor layer 5c are electrically conducted, and the current detector 7
Is output, the controller 3 causes the NC drill 1 to stop the drill 2.

As a result, a hole just reaching the second conductor layer 5c from the surface layer 5a is processed. At this stage, the surface conductor layer 5a is formed over the entire surface of the multilayer printed board 5, and is processed into a desired pattern after the processing of the holes is completed.

[0010]

According to the present invention, even if the multilayer printed circuit board is warped or the interlayer distance varies, it is possible to always accurately and accurately form a hole from the surface conductor layer to the second conductor layer thereunder. ..

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is a top view showing a main part of a substrate applied to an embodiment of the present invention.

[Explanation of symbols]

 1 NC Drilling Machine 2 Drill 3 Controller 4 Fixed Table 5 Multilayer Printed Circuit Board 5a Surface Conductor Layer 5b Insulating Layer 5c Second Conductor Layer 6 Power Supply 7 Current Detector

Claims (1)

Claim: What is claimed is: 1. A method for drilling holes in a printed circuit board, wherein a hole is drilled from the first conductor layer (5a) on the surface of the multilayer printed circuit board (5) to the second conductor layer (5c) below it.
A voltage is applied between the drill (2) and the second conductor layer 5c in advance, and the printed board (5) is driven while driving the drill (2).
A method for drilling holes in a printed circuit board, characterized in that the drill (2) is stopped when electric conduction is detected between the drill (2) and the second conductor layer (5c). ..