JPH0582960A - Forming method of sectional through-hole in printed wiring board - Google Patents

Abstract

PURPOSE:To provide the forming method of a sectional through-hole in a printed wiring board, in which there is no possibility that a burr is formed to the sectional through-hole and a copper film is peeled. CONSTITUTION:A first through-hole 4 is bored to the section of a land 3 on the side inner than a position as the external shape line 6 of a printed wiring board 1, copper plating is formed while a second through-hole 5 larger than the first through-hole 4 is bored on the side outer than said first through-hole 4 by a drill so as to be crossed over the first through-hole 4, and the external shape line 6 is cut and formed at a position on the side outer than the land 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a through hole having a cross section in a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, the formation of cross-section through holes has been performed as follows. That is, as shown in FIG. 6, a hole is drilled in the portion of the land 13 at the position which becomes the outline 12 of the printed wiring board 11 to form a through hole 14. Next, the through hole 14 is plated with copper to form a copper film.

Next, the printed wiring board 11 is cut at the position of the chain double-dashed line in the same figure by stamping or router cutting so as to cross the through hole 14, and the contour line 12 is formed. .. In this way, as shown in FIG. 7, cross-section through holes are formed.

[0004]

However, as shown in FIG. 8, a burr 15 of a copper film formed by through-hole plating is formed in the outline 12 of the through-hole in section by the rotation of the router during router processing. There is also a problem that the copper film may be partially peeled off.

Further, when punching through-hole plating by press punching to form a through-hole in cross section,
When the thickness of the printed wiring board 11 is 0.5 mm or more, there are problems that the burr 15 of the copper film becomes large and the copper film is easily peeled off.

The present invention has been made to solve the above problems, and an object thereof is to prevent the cross-section through of a printed wiring board in which a burr is formed in the cross-section through hole and the copper film is not peeled off. It is to provide a method for forming holes.

[0007]

In order to achieve the above object, according to the present invention, a first through hole is bored and copper plating is formed in a land portion inside a position which becomes an outline of a printed wiring board. At the same time, a second through hole larger than the first through hole is formed outside the first through hole by a drill so as to cross the first through hole, and then the outline is formed outside the land. The gist is a method of forming a through hole in a cross section in a printed wiring board that is cut and formed at a position.

[0008]

First, the first through hole is formed in the land portion inside the position which becomes the outline of the printed wiring board. Next, after copper plating is formed on the first through hole, a second through hole larger than the first through hole is drilled outside the first through hole so as to cross the first through hole. Finally, the outline is cut and formed at a position outside the land.

Therefore, the second through hole formed so as to cross the first through hole is drilled and the contour line is cut at a position outside the land, so that the drilled portion and the cut portion are formed. No burrs or peeling of the copper film. That is, since the first through-hole conductor has a cross-section through hole that is free from burrs and peeling due to the second through-hole, the cross-section through-hole conductor is not affected by the outer shape processing.

[0010]

Embodiments Embodiments embodying the present invention will be described below with reference to FIGS. As shown in FIG. 1, a circular land 3 is formed at an end of a wiring pattern 2 provided on a printed wiring board 1. A first through hole (cross-section through hole) 4 is provided at the center of the land 3.
And a second through hole (non-through hole) 5 is formed so as to cross the first through hole 4 at the outer position (left side in the drawing). The printed wiring board 1 is cut by router processing so as to cross the second through hole 5 on the outer side of the land 3 to form a contour line 6.

As shown in FIG. 2, a rectangular land 3a is formed at an end of a wiring pattern 2a provided on the back surface of the printed wiring board 1. The first through hole 4 is formed at the center position of the land 3a, and the second through hole 5 is formed at the outer position thereof. On the back surface of this printed wiring board 1, the land 3a is formed so as to have less contact with the second through hole 5 than the front surface. Further, the printed wiring board 1 is cut at the outer side position, and the outline 6
Are formed.

Next, a method of forming a through hole in cross section will be described. As shown in FIG. 3, first, the circular land 3 is formed.
A first through hole 4 having a predetermined diameter is drilled at the center position of the. Then, copper plating is applied by a conventional method to form a copper film on the inner wall surface of the first through hole 4. Then, the second through hole is placed outside the first through hole 4.
The through hole 5 (two-dot chain line in the figure) is drilled so as to cross the first through hole 4. The diameter of the second through hole 5 is equal to that of the first through hole 4.
(1.0 mm in this example), and in this case 1.5
Double, 1.5 mm in this embodiment. When the second through hole 5 is drilled, the land 3 is drilled,
There is no risk of burring or peeling of the copper film in this area due to the drilling.

The diameter of the first through hole 4 is at least 0.
It was possible up to 3 mm. The diameter of the second through hole 5 is 0.
8mm or more is desirable. This is because if the diameter is smaller than 0.8 mm, the drill bends during drilling and it becomes difficult to cut the first through hole 4.

The position where the second through hole 5 crosses the first through hole 4 is the first through hole 4
It is preferable that the straight line passing through the center of is the points P and Q that intersect the circumference. Outside this position, the width of the opening of the first through hole 4 becomes narrower and the printed wiring board 1
When soldering to a motherboard (not shown), it becomes difficult to solder. On the contrary, if it is located inside this position, the connecting portion of the first through hole 4 is reduced, which is not preferable.

When the second through hole 5 is formed by punching in this manner, the state shown in FIG. 4 is reached. In this state, the printed wiring board 1 is cut by router processing so as to cross the second through hole 5 outside the land 3 to form the outline 6. Since the cutting by the router processing is performed at a position outside the land 3, there is no possibility that burrs are generated in the copper film on the inner wall of the first through hole 4 or the copper film is peeled off.

Further, as shown in FIG. 2, on the back surface of the printed wiring board 1 as well as on the front surface of the printed wiring board 1,
The cutting by the router processing is performed at a position outside the land 3a, so that burr does not occur on the copper film on the inner wall of the first through hole 4 and the copper film is not peeled off. As described above, since the land 3a is formed on the back surface of the printed wiring board 1 so that the land 3a is less in contact with the second through hole 5, the second through hole 5 is drilled. The land 3a is more difficult to peel off than the land 3 on the surface when forming a hole. The cutting method for forming the outline 6 may be a cutting method using a mold. In this way, a desired cross-section through hole is formed.

The present invention is not limited to the above embodiment, but may be embodied as follows. That is, FIG.
As shown in, the land 3 may not be circular, but may be formed in a linear shape so that the outer portion of the land 3 is in contact with the circumference of the second through hole. According to this structure, when the second through hole is drilled, the area where the blade of the drill contacts the land 3 is reduced and the land 3 is less likely to come off.

[0018]

As described above in detail, according to the present invention, there is an excellent effect that there is no possibility that a burr is formed in the through hole of the cross section or the copper film is peeled off.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which a first printed wiring board is provided.
FIG. 6 is a plan view of a principal part showing a state in which the outer shape line is cut and formed after forming the second through hole.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a plan view of relevant parts showing a state where a first through hole is formed in a printed wiring board.

FIG. 4 is a plan view of relevant parts showing a state in which a second through hole is drilled from the state of FIG.

FIG. 5 is a plan view of an essential part of a printed wiring board showing another example of the present invention.

FIG. 6 is a plan view of an essential part showing a conventional example and showing a state in which through holes are formed in lands of a printed wiring board.

FIG. 7 is a plan view of relevant parts showing a state after cutting the printed wiring board from the state of FIG. 6;

8 is a perspective view of a main part of the printed wiring board in the state of FIG. 7.

[Explanation of symbols]

1 ... Printed wiring board, 3, 3a ... Land, 4 ... First through hole, 5 ... Second through hole, 6 ... Outline line.

Claims (1)

[Claims] 1. A first through hole (4) is drilled in a portion of a land (3, 3a) inside a position which becomes an outer shape line (6) of a printed wiring board (1) to form copper plating. , A second through hole (5) larger than the first through hole (4) outside the first through hole (4)
Are drilled so as to traverse the first through hole (4), and then the outline (6) is formed on the land (3,
3a) A method of forming a through hole having a cross section in a printed wiring board, which is characterized in that cutting is performed at a position outside of 3a.