JPH04261087A - Printed board and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a thermal stress from being concentrated by a method wherein a through hole is formed in an insulating substrate having conductor parts on its surface and chamfering parts are formed on the opening part of the hole by a chamfering processing. CONSTITUTION:A through hole 5 is formed in an insulating substrate 2 formed with such conductor parts 3 and 4 as a copper-clad laminated board on its whole surface by an NC drilling machine or the like and thereafter or simultaneously with the formation of the hole 5, chamfering parts 9 are formed by a chamfering processing. A conductor plated part 6 is formed on the inner peripheral part of the hole 5, the parts 9 and in the vicinity of the opening part of the hole 5 by copper plating. After that, a circuit pattern is formed on the parts 3 and 4 and conductor parts 7 by an exposure, a developing, an etching and the like. Thereby, as corner parts 8 of the opening part of the hole 5 are removed by a chamfering processing, a thermal stress due to a difference in thermal expansion is dispersed even in the case there is heat input, such as soldering or the like, and the generation of a crack in the conductor plated part 6 is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board having through holes and a method for manufacturing the same.

0002

2. Description of the Related Art FIG. 2 is a sectional view showing a through hole portion of a conventional printed circuit board. In the figure, 1 is a printed circuit board, and conductor parts 3 and 4 such as copper foil are formed on the surface of an insulating board 2 made of glass fiber reinforced epoxy resin, etc.
A through hole 5 is formed through the through hole 5, and a conductor plating portion 6 such as copper plating is formed on the inner circumference of the through hole 5, and a land portion 7 is formed near the opening of the through hole 5, and the conductor portion 3,
It is connected to 4.

The method for manufacturing the printed circuit board 1 described above includes forming through holes 5 using an NC drilling machine or the like on an insulating substrate 2 on which conductor parts 3 and 4 are formed on the entire surface, such as a copper-clad laminate.
A conductor plated portion 6 is formed on the inner periphery of the through hole 5 and near the opening by copper plating. Thereafter, a circuit pattern is formed on the conductor parts 3, 4, 7 by exposure, development, etching, etc.

However, in such a conventional printed circuit board 1, since the opening of the through hole 5 is a corner portion 8, when there is heat input due to soldering or the like, the insulating substrate 2 and the conductor plating portion 6 There was a problem in that thermal stress due to the difference in coefficient of thermal expansion was concentrated at the corner portion 8, causing cracks to occur in the conductor plating portion 6 at the corner portion 8, leading to a deterioration in quality.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a highly reliable printed circuit board that eliminates the concentration of thermal stress, prevents the occurrence of cracks in conductor plating parts, and a method for manufacturing the same. It's about getting.

[0006]

[Means for Solving the Problems] The present invention provides the following printed circuit board and method for manufacturing the same.

(1) An insulating substrate, a conductor portion formed on the surface of the insulating substrate, a through hole formed in the insulating substrate through the conductor portion, and a chamfer formed at the opening of the through hole. and a conductor plating portion formed on the inner periphery of the through hole and the chamfered portion so as to be connected to the conductor portion.

(2) A through hole is formed in an insulating substrate having a conductor on its surface, a chamfer is formed at the opening of the through hole, and the through hole and chamfer are connected to the conductor. A method for manufacturing a printed circuit board in which a conductor plating part is formed on the inner circumference of the board.

[0009]

[Function] In the printed circuit board of the present invention, a through hole is formed by drilling in an insulating substrate having a conductor portion on the surface, and a chamfered portion is formed by chamfering at the opening of the through hole. It is manufactured by forming a conductor plating part on the inner peripheral part of the cut-out part by conductor plating.

[0010] In such a printed circuit board, the corners of the through-hole openings are removed by chamfering, so even when there is heat input from soldering etc., the thermal stress due to the difference in thermal expansion is dispersed. This prevents cracks from forming in the plating area.

Furthermore, since the opening of the through hole is widened by forming the chamfered portion, the plating solution can easily enter during conductor plating, and the reliability of the plating is increased. Furthermore, when a component is mounted in a through-hole and soldered, the solder is retained in the chamfered portion, which increases the reliability of soldering.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a through-hole portion of a printed circuit board according to an embodiment, and in the figure, the same reference numerals as in FIG. 2 indicate the same or corresponding parts.

The printed circuit board 1 includes a conductor portion 3 such as copper foil on the upper and lower surfaces of an insulating substrate 2 made of glass fiber reinforced epoxy resin or the like.
. The connection with the conductor parts 3 and 4 is the same as the conventional one, but the corner part 8 of the opening of the through hole 5 is removed to form a chamfered part 9, and the conductor plated part 6 is removed. is also formed on the chamfered portion 9.

The method for manufacturing the printed circuit board 1 described above includes forming through holes 5 using an NC drilling machine or the like on an insulating substrate 2, such as a copper-clad laminate, on which conductor parts 3 and 4 are formed on the entire surface, or at the same time. A chamfered portion 9 is formed by chamfering. Then, conductor plating portions 6 are formed by copper plating on the inner peripheries of the through holes 5 and the chamfered portions 9, and near the openings. After that, the conductor portion 3 is exposed to light, developed, etched, etc.
, 4 and 7 to form circuit patterns.

Printed circuit board 1 manufactured in this way
Since the corner part 8 of the opening of the through hole 5 is removed by chamfering, even when there is heat input from soldering etc., the thermal stress due to the difference in thermal expansion is dispersed, and the conductor plating part 6 is Cracks are prevented from forming.

Furthermore, by forming the chamfered portion 9, the through hole 5
Since the opening is wide, the plating solution can easily enter when forming the conductor plated part 6, and the reliability of the conductor plated part 6 is increased. Furthermore, when a component is mounted in the through hole 5 and soldered, the solder is retained in the chamfered portion 9, so that the reliability of soldering is also increased.

In the above embodiment, the chamfered portion 9 is formed in a cone shape, but by forming it in a trumpet shape (rounded shape), thermal stress can be more uniformly distributed.

The through hole forming the chamfered portion 9 may be a through hole for mounting a component, a through hole for simply connecting upper and lower conductor sections without mounting a component, or a through hole for simply connecting upper and lower conductor sections without mounting a component. A through hole that connects only the inner layer and does not open to the outer layer may be used.

[0019]

[Effects of the Invention] According to the present invention, since the chamfered portion is formed at the opening of the through-hole, the concentration of thermal stress at the opening of the through-hole is prevented, and the occurrence of cracks in the conductor-plated portion is prevented. Furthermore, it is possible to easily allow the plating solution to enter during plating, thereby increasing the reliability of the conductor-plated portion, as well as improving solder adhesion, thereby obtaining a highly reliable printed circuit board.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a through-hole portion of a printed circuit board according to an embodiment.

FIG. 2 is a cross-sectional view of a through-hole portion of a conventional printed circuit board.

[Explanation of symbols]

1 Printed circuit board 2 Insulating substrate 3, 4 Conductor part 5 Through hole 6 Conductor plating part 7 Land part 8 Corner part 9 Chamfered part

Claims (2)

[Claims] 1. An insulating substrate, a conductor portion formed on the surface of the insulating substrate, a through hole formed in the insulating substrate through the conductor portion, and a chamfer formed at the opening of the through hole. and a conductor plating portion formed on the inner periphery of the through hole and the chamfered portion so as to be connected to the conductor portion. 2. A through hole is formed in an insulating substrate having a conductor on its surface, a chamfer is formed at the opening of the through hole, and the through hole and the chamfer are connected to the conductor. A method for manufacturing a printed circuit board, characterized by forming a conductor plating part on the inner periphery.