JP3187206B2 - Terminal structure and connection method of printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal structure and a connection method for electrically connecting printed wiring boards.

[0002]

2. Description of the Related Art In a case where printed wiring boards are directly soldered to each other, a method shown in FIG. 6 is generally used. That is,
On one surface (hereinafter, connection surface) 18a of the base material 17 of the first printed wiring board 1a, a plurality of electrodes 11a for electrical connection are provided.
An electrode group 111a composed of
a is a back surface (hereinafter referred to as a back surface) through a through hole (not shown)
It is connected to the wiring pattern 19a. Although not shown, the connection surface 18b of the second printed wiring board 1b is omitted.
Electrode group 111a on connection surface 18a of first printed wiring board 1a
An electrode group having a shape and arrangement corresponding to and corresponding to
Each electrode is connected to a wiring pattern (not shown) on the back surface 19b via a through hole, as in the case of the printed wiring board 1a.

When the printed wiring boards 1 having such a structure are connected to each other, at least one of the electrode groups of the printed wiring boards is coated with a preliminary solder 2 in an amount required for soldering, and the first printed wiring board is first coated. The electrode group 111a of the wiring board 1a and the electrode group of the second printed wiring board 1b are overlapped, and the connection portion is heated by means such as thermocompression bonding (heating direction: X) to connect the electrode groups.

[0004]

However, when soldering is performed as described above, the connected electrode group is exposed to air, so that under high temperature and high humidity, the base material and flux residue between the electrodes are removed. However, it is very easy to absorb moisture, and there is a problem that the reliability is deteriorated due to deterioration of insulation between adjacent electrodes due to moisture absorption. In particular, in recent years, since the connection pitch has become finer, the distance between adjacent electrodes has become extremely narrow,
The above problem is more likely to occur. Also,
Since the area of the electrode itself is reduced due to the miniaturization of the connection pitch, the connection strength per electrode is reduced, and a problem that the connection portion is easily broken due to external force or environmental fluctuations also arises.

[0005] The present invention solves the above problems,
An object of the present invention is to provide a terminal structure of a printed wiring board capable of obtaining a highly reliable connection portion and a connection method.

[0006]

According to the terminal structure of a printed wiring board according to the present invention, in order to achieve the above object, a terminal portion for connecting the printed wiring boards is electrically connected to both printed wiring boards. A pattern having a shape surrounding the connection electrode group is provided on the outer periphery of the connection electrode group for connection, and the connection electrode group is configured to be connected to a signal line on the back surface of the printed wiring board via a through hole.

In the terminal structure of a printed wiring board according to the present invention, at least one or more through-holes are provided in a base portion inside a pattern surrounding a connection electrode group for electrical connection, and the through-holes are formed after soldering is completed. A configuration that closes the hole may be employed.

In order to achieve the above object, a method of connecting terminals of a printed wiring board according to the present invention is to connect a printed wiring board having any of the above terminal structures by soldering in a vacuum atmosphere. .

In the method for connecting terminals of a printed wiring board according to the present invention, the printed wiring board having any of the above terminal structures can be soldered in a dry atmosphere.

[0010]

An embodiment of the present invention will be described with reference to the drawings.
In the following, description will be made by assigning common reference numerals to parts common to the related art.

FIGS. 1A to 1D are views showing a first embodiment of the terminal structure of a printed wiring board according to the present invention. An electrode group 111a for electrical connection is formed on the connection surface 18a of the base member 17 of the first printed wiring board 1a.
1a is connected to the wiring pattern 14a on the back surface 19a via the through hole 12a, and the electrode group 111a is connected to the through hole 1a.
A pattern (hereinafter referred to as an outer peripheral pattern) 13a which completely surrounds 2a is formed around 2a. The through hole 12a is formed within the range of the electrode 11a, but may be formed outside the range of the electrode 11a and connected to the electrode 11a by a wiring pattern as shown in FIG.

The electrode group 11 of the connection surface 18a of the first printed wiring board 1a is provided on the connection surface 18b of the second printed wiring board 11b.
An electrode group 111b and an outer peripheral pattern 13b having shapes and arrangements corresponding to and corresponding to the outer peripheral pattern 13a and the outer peripheral pattern 13a are formed. Like the first printed wiring board 1a, each electrode 11b is formed on the back surface 19b via a through hole 12a. Wiring pattern 14
b. Through hole 12b of first printed wiring board 1a and through hole 12b of second printed wiring board 2b
Are formed at positions facing each other, but the through holes 12 may be arranged at positions not facing each other.

When connecting the printed wiring boards 1 having the above structure, first, the electrode group 111a and the outer peripheral pattern 13a of the first printed wiring board 1a and the electrode group 111b and the outer peripheral pattern 13a of the second printed wiring board 1b are connected. 13b is overlapped. At this time, the electrode group 11 and the outer peripheral pattern 13 of at least one of the printed wiring boards 1 are coated in advance with the necessary amount of preliminary solder 2 for soldering. Next, the connection portion is heated by means such as thermocompression bonding to connect the electrode group 11 and the outer peripheral pattern 13 to each other. At this time, the preliminary solder 2 is also coated on the through hole 12, and the solder 2 is filled so that the through hole 12 is completely closed.

If the connection is made by the above-described method, the electrode group 11 for the electrical connection becomes the outer peripheral pattern 13a, 1
3b, a completely sealed state is achieved. Even under a high-temperature and high-humidity environment, the inside of the outer peripheral patterns 13a and 13b, that is, the periphery of the electrode groups 11a and 11b, does not absorb moisture. Is improved. Also,
Since the connection portions of the outer peripheral patterns 13a and 13b serve as reinforcement, even if an external force is applied, no stress is applied to the electrode groups 11a and 11b, and the connection reliability is improved.

By the way, through holes 12a and 12b are exposed on the back surfaces 19a and 19b of both printed wiring boards 1a and 1b, and the distance between adjacent through holes 12a and 12b is wider than the distance between electrodes 11a and 11b. Group 11
Although the reliability is improved as compared with the case where 1a and 111b are exposed, as the connection pitch becomes finer, insulation deterioration due to moisture absorption becomes a problem.

Therefore, when the through holes 12 are arranged in a zigzag pattern and the wiring pattern 14 is formed on the back surface 19 as in the printed wiring board 1 of the second embodiment of the present invention shown in FIG. 3, the pitch of the electrodes 11 does not change. Also, since the distance between the adjacent through holes 12 is widened, even if moisture is absorbed, deterioration of the insulating property hardly occurs, and reliability is improved. Of course, the arrangement of the through holes 12 is two-stage staggered in FIG.

If the outer peripheral pattern is not connected to another pattern and is in an electrically floating state, noise is likely to be generated, and it is difficult to increase the speed of the signal. Therefore, if the outer peripheral pattern 13 is connected to the power supply line 15 on the connection surface 18 and the outer peripheral pattern 13 is always stabilized at the power supply potential as in the third embodiment of the present invention shown in FIG. Can be speeded up. In the present embodiment, the outer peripheral pattern 13 is connected to the power supply line. However, even when the outer peripheral pattern 13 is connected to the ground line, the same effect can be obtained because the outer peripheral pattern 13 is stabilized at the ground potential.

When a flux containing a large amount of a solvent component is used at the time of soldering, the solvent component volatilizes when the electrode group is sealed with the outer peripheral pattern, and the internal pressure of the area sealed by the outer peripheral pattern increases. A stress is applied to the connection portion of the electrode, and the connection reliability is reduced. Therefore, as in the fourth embodiment of the present invention shown in FIG. 5, an appropriate number of through holes 16 for degassing are provided in a range surrounded by the outer peripheral patterns 13a and 13b of the printed wiring board 1, and the solvent volatilized during soldering is formed. The components are allowed to pass through the through holes 16. Then, the internal pressure of the area sealed by the outer peripheral patterns 13a and 13b is not increased, and the connection reliability is improved. Furthermore, if the through holes 16 are closed with the adhesive 3 or the like after the soldering, the periphery of the electrode group 111 does not absorb moisture even in a high-temperature and high-humidity environment, so that there is no deterioration in insulation and reliability is improved. . The through-hole 16 is not provided, and the solvent component volatilized from the through-hole 12 is removed, and after the connection is completed, the adhesive 3 or the solder 2
For example, the through hole 12 may be closed. Also, the through holes 16 may be provided in at least one of the printed wiring boards.

Further, when the atmosphere around the soldering portion is high in humidity, high humidity air is also drawn into the area surrounded by the outer peripheral pattern 13 during soldering, and the electrode group 111 is formed.
Since the periphery absorbs moisture, reliability may be reduced due to insulation deterioration. In order to solve this, a vacuum atmosphere is applied around the welded portion when soldering. Accordingly, high-humidity air is not trapped in the area surrounded by the outer peripheral pattern 13 and the periphery of the electrode portion 111 does not absorb moisture, so that there is no deterioration in insulation and reliability is improved. The same applies to the case where the atmosphere around the soldering portion is set to a dry atmosphere.

[0020]

As described above, the terminal structure of the printed wiring board according to the first aspect of the present invention has a pattern on both sides of the printed wiring board to be connected, the pattern having a shape surrounding the outer periphery of the connection electrode group for electrical connection. Since the connection electrode group is connected to the signal line on the back surface of the printed wiring board via the through hole,
The electrode group is completely sealed by the outer peripheral pattern,
Even under a high humidity condition, the base material and the like around the electrode do not absorb moisture, and the effect of improving insulation reliability is exhibited. Also, by connecting the outer peripheral pattern,
Even if external force is applied, no direct stress is applied to the electrode group,
The effect that connection reliability improves is also produced.

According to a third aspect of the present invention, there is provided a method of connecting a printed wiring board.
When connecting the printed wiring board having the terminal structure according to claim 1 or 2, the soldering is performed in a vacuum atmosphere, so that the solvent component of the flux is not involved in the inner side of the outer peripheral pattern, so that the connection portion is formed. Since no stress is applied to the wire, the effect of improving the reliability of the connection is achieved.

According to a fourth aspect of the present invention, there is provided a method for connecting a printed wiring board.
When connecting the printed wiring board having the terminal structure according to claim 1 or 2, since the soldering is performed in a dry atmosphere, high humidity air is involved in the outer peripheral pattern during the soldering operation. Therefore, there is an effect that the insulation reliability is improved without absorbing moisture around the electrode group.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of a terminal structure of a printed wiring board according to the present invention, wherein (A) is a plan view of a connection surface, (B) is a plan view of a back surface, and (C) is (A). ) Central section before connection,
(D) is a center sectional view after connection.

FIG. 2 shows an example in which a through hole is formed outside an electrode range.
It is a connection surface top view corresponding to (A).

3A and 3B are diagrams showing a second embodiment of the present invention, wherein FIG. 3A is a plan view of a connection surface, and FIG. 3B is a plan view of a back surface.

FIG. 4 is a plan view of a connection surface showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention after connection, which corresponds to FIG. 1D.

FIG. 6 is a perspective view showing a conventional structure and method for directly soldering printed wiring boards to each other.

[Explanation of symbols]

 1a first printed wiring board 11a electrode 111a electrode group 12a through hole 13a outer peripheral pattern 18a connection surface 19a back surface 1b second printed wiring board 11b electrode 111b electrode group 13b outer peripheral pattern 14b wiring pattern 18b connection surface 19b back surface 1 printed wiring board 2 Spare solder 3 Adhesive 14 Wiring pattern 15 Power supply line 16 Through hole 17 Base material 18 Connection surface 19 Back surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 1-268087 (JP, A) JP-A 54-25248 (JP, A) JP-A 50-9560 (JP, A) 92680 (JP, U) Japanese Utility Model Showa Sho 62-10471 (JP, U) Japanese Utility Model Showa 63-73971 (JP, U) Japanese Patent Publication No. Sho 43-29515 (JP, B1) (58) Fields surveyed (Int. ⁷ , DB name) H05K 1/14 H05K 3/36

Claims (4)

(57) [Claims] In a terminal portion for connecting printed wiring boards, a pattern having a shape surrounding the connection electrode group is provided on an outer periphery of a connection electrode group for electrical connection with both printed wiring boards. A terminal structure for a printed wiring board, wherein the connection electrode group is connected to a signal line on the back surface of the printed wiring board via a through hole. 2. The terminal structure for a printed wiring board according to claim 1, wherein at least one or more through-holes are provided in a base portion inside the pattern surrounding the connection electrode group for electrical connection, and soldering is performed. A terminal structure for a printed wiring board, wherein the through hole is closed after completion. 3. A method for connecting a printed wiring board having the terminal structure according to claim 1 or 2, wherein soldering is performed in a vacuum atmosphere. 4. A method for connecting a printed wiring board having a terminal structure according to claim 1 or 2, wherein the soldering is performed in a dry atmosphere.