JP2002026523A - Through hole structure of multilayer printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a dummy conductive land in a layer where the connection pattern of a multilayer printed circuit board is not formed, to prevent through hole plating from being deformed due to thermal stress by the conductive land, and to secure the continuity between the connection pattern and through hole plating. SOLUTION: In this through hole structure of the multilayer printed circuit board, the conductive land 30 is formed in the layer where the connection pattern 4 is not formed, the through hole 3 is prevented from being deformed by the thermal stress that is generated when the conductive member 10a is connected to the through bole 2 by molten solder 11, and the continuity between the connection pattern 4 and through hole 3 is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a through-hole structure of a multilayer printed circuit board, and more particularly, to the effect of a connection pattern on all or a part of another layer on which a connection pattern conducting with through-hole plating is not formed. A new improvement for forming a conductive land as a dummy having no holes and preventing the occurrence of conduction failure due to cracks between the through-hole plating and the connection pattern due to shrinkage of the through-hole plating due to cooling of the solder during soldering .

[0002]

2. Description of the Related Art Conventionally, a structure shown in FIG. 2 has been generally used as a through-hole structure of a multilayer printed circuit board of this kind. That is, what is indicated by reference numeral 1 in FIG. 2 is a multilayer printed circuit board configured as shown in FIG. 9, which partially shows a part of the multilayer printed circuit board. 1a-1h
It is composed of

As shown in FIG. 9, a large number of through-holes 2 are formed through the multilayer printed circuit board 1, and through-hole plating 3 made of a conductive metal is formed on the inner wall of the through-holes 2 in a film form. Have been. Each of the layers 1a to 1
h is usually formed with a certain connection pattern connected to the through-hole at each position. The connection pattern 4 to be electrically connected to the through-hole plating 3 of the through-hole 2 at this position is the second connection pattern. Layer 1b and seventh layer 1g
And each connection pattern 4 is a through-hole plating 3
And is conductive. For reference, as shown in FIG. 8, this connection pattern 4 is used in the case of four layers or eight layers, and the thickness of the connection pattern 4 is 35 μm.
m, the thickness of the multilayer printed circuit board 1 is 1.6 mm.

As shown in FIG. 2, for example, as shown in FIG. 2, after inserting a pin 10a as a conductive member of the jumper pin 10 between each of the above-described through holes 2, the conductive material of the jumper pin 10 and the through hole 2 is inserted. By simultaneously supplying the solder while heating the land 30 with a soldering hand as shown in FIG. 3, the pin 10a and the conductive land 30 are soldered. When the insertion of the pin 10a is completed and the temperature of the molten solder 11 is lowered and cooled, the pin 10a is fixed in the through hole 2.

[0005]

Since the conventional through-hole structure of a printed circuit board is configured as described above, there are the following problems. That is, a thermal stress occurs due to the heat of the molten solder, a solder shrinkage stress occurs when the solder glove is removed in the direction of arrow X shown in FIG. 3, and a stress of expansion of the substrate occurs due to heating by the solder glove in the direction of arrow Y. appear. Accordingly, the through-hole plating 3 is pulled inward as shown in FIG. 4 due to the shrinkage when the molten solder is cooled and solidified, and as a result, a crack 20 is generated between the connection pattern 4 and the through-hole plating 3, The degree of the crack 20 progresses due to a further thermal change while the encoder or the like using the multilayer printed circuit board 1 is operated after shipping, and changes as shown in FIG. 5 to FIG. , Conduction failure. In such a state, the circuit function of the multilayer printed circuit board 1 is lost, and the operation as originally designed is impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in particular, it is intended to connect all or a part of other layers in which a connection pattern conducting with through-hole plating is not formed. A conductive land as a dummy having no pattern action is formed to prevent the occurrence of conductive failure due to cracks between the through-hole plating and the connection pattern due to shrinkage of the through-hole plating due to cooling of the solder during soldering. An object of the present invention is to provide a through-hole structure for a multilayer printed circuit board.

[0007]

According to the present invention, there is provided a through-hole structure for a multilayer printed circuit board, wherein a conductive member is inserted through a molten solder into a through-hole formed on the multilayer printed circuit board and having through-hole plating. In a through-hole structure of a multilayer printed board in which a connection pattern formed in any of the layers of the printed board and the conductive member are conducted through the molten solder and the through-hole plating, the connection pattern is A conductive land connected to the through-hole plating is formed on all or some of the layers that are not formed, and the conductive land surrounds the through-hole. This is a configuration that is formed all around and parallel to the connection pattern.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a through-hole structure of a multilayer printed board according to the present invention will be described below with reference to the drawings. The same or equivalent parts as those in the conventional example will be described using the same reference numerals. In FIG. 1, a reference numeral 1 denotes a multilayer printed board configured as shown in FIG. 9, which partially shows a part of the multilayer printed board, and the multilayer printed board 1 has first to eighth layers 1a to 1a. 1h.

As shown in FIG. 9, a large number of through-holes 2 are formed through the multilayer printed circuit board 1, and through-hole plating 3 made of a conductive metal is formed on the inner wall of the through-holes 2 in a film form. Have been. Each of the layers 1a to 1
h is usually formed by connecting a certain connection pattern to the through hole at each position. The connection pattern 4 to be electrically connected to the through hole plating 3 of the through hole 2 at this position is the second connection pattern. Layer 1b and seventh layer 1g
And each connection pattern 4 is a through-hole plating 3
And is conductive.

In each of the layers 1a to 1g, the connection pattern 4
Are formed on the remaining layers 1c to 1e and 1g, on which the conductive lands 30 are formed in a ring shape around the entire periphery of the through-hole plating 3, and the connection patterns 4 are formed.
The conductive lands 30 are integrally connected to the through-hole plating 3. Therefore, each of the conductive lands 30 is not connected to a circuit element as in the connection pattern 4 but has only a role as a physical reinforcement for the through hole 3. Also, in FIG. 1, the conductive lands 30 are formed on all the layers other than those having the connection patterns 4. However, when the conductive lands 30 are formed not on all the layers but on some of the layers, it is effective as reinforcement.

Next, when a jumper pin 10 is connected between the through holes 2 in the above-described state, for example, as shown in FIG. 9, the jumper pin 10 is inserted into the through hole 2 as shown in FIG. A pin 10a as a conductive member is inserted through the molten solder 11, and the molten solder 11
As shown in FIG.
Insert In addition, the jumper pin 1 is used as the conductive member.
It is not limited to 0, but may be other means. When the insertion of the pin 10a is completed and the temperature of the molten solder 11 is lowered and cooled, the pin 10a is fixed in the through hole 2.

When the jumper pin 10 is inserted and fixed in the through hole 2 via the molten solder 11, the through hole plating 3 contracts inward of the through hole 2 due to thermal stress, as shown in FIG. The conductive lands 30 formed on each of the layers 1c to 1e and 1g will be described.
Are integrally connected to the through-hole plating 3 (that is, when the through-hole plating 3 is applied, the through-hole plating 3 and the connection pattern 4 are integrally connected). Physical resistance to contraction toward the other side, and from the results of the experiment, it was confirmed that conduction between the connection pattern 4 and the through-hole plating 3 as in the related art can be completely prevented.

[0013]

The through hole structure of the multilayer printed circuit board according to the present invention is configured as described above, so that the following effects can be obtained. In other words, since all or some of the layers having no connection pattern have conductive lands connected to the through-hole plating, the through-hole plating due to thermal stress when fixing the jumper pins with molten solder is performed. Inward shrinkage can be prevented, conduction failure due to cracks between the connection pattern and through-hole plating can be prevented, and reliability of an electronic circuit using a multilayer printed circuit board can be ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a through-hole structure of a multilayer printed circuit board according to the present invention.

FIG. 2 is a sectional view showing the conventional structure of FIG.

FIG. 3 is an explanatory diagram showing stress lines when a through hole is heated with a solder glove and the solder glove is removed.

FIG. 4 is an enlarged explanatory view of a portion A of FIG. 3 showing a crack generated between a connection pattern and through-hole plating by the fixing method of FIG. 3;

FIG. 5 is an explanatory diagram showing cracks in FIG. 4;

FIG. 6 is an explanatory diagram showing the progress of cracks in FIG.

FIG. 7 is an explanatory view showing a state in which a crack progresses in FIG. 6 and a connection pattern and through-hole plating are completely separated;

FIG. 8 is a cross-sectional view showing a conventionally used multilayer printed circuit board.

FIG. 9 is a plan view of a main part of the multilayer printed circuit board of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer printed circuit board 1a-1g layer 2 Through hole 3 Through hole plating 4 Connection pattern 10a Conductive member 30 Conductive land

Claims (2)

[Claims] A conductive member (10a) is inserted through a molten solder (11) into a through hole (2) formed on a multilayer printed board (1) and having a through hole plating (3). The connection pattern (4) formed in any one of the layers (1a to 1g) of the substrate (1) and the conductive member (10a) are melted and soldered.
(11) and in the through-hole structure of the multilayer printed circuit board which is made to conduct through the through-hole plating (3), in each of the layers (1c to 1e, 1g) where the connection pattern (4) is not formed. A through hole structure for a multilayer printed circuit board, wherein a conductive land (30) connected to the through hole plating (3) is formed on all or some of the layers. 2. The conductive land (30) is formed all around the through hole (2), and the conductive land (30)
2. The method according to claim 1, wherein the second member is formed in parallel with (4).
The through-hole structure of the described multilayer printed circuit board.