JPH07307543A - Printed wiring board - Google Patents

Abstract

PURPOSE:To protect a connection pattern against discontinuity caused by the warpage of a printed wiring board when an external force is applied onto a discrete component. CONSTITUTION:A discrete component 15 such as a connector is fixed to a printed wiring board 41 through such a manner that its leads 16 are inserted into through-holes 42 provided on the wiring board 41 and soldered. A connection pattern 44 led out from a land 43 is arranged extending from the land 43 by a certain distance vertical to the direction of a force applied to the discrete component 15. By this setup, the connection pattern 44 is kept free from the influence of the warpage of the board 41 and hardly discontinued. The connection part 44A of the connection pattern 44 is locally thick and hardly discontinued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board, and more particularly to a printed wiring board suitable for mounting discrete components such as connectors and switches under external force.

[0002]

2. Description of the Related Art Discrete parts such as connectors and switches are mounted on many printed wiring boards for electronic parts.

FIG. 7 is a top view of the essential parts of a conventional printed wiring board. Further, FIG. 8 shows a cross section of the main part of the printed wiring board as seen from the line segment BB 'in this figure. The printed wiring board 11 is composed of a planar insulating base material, and a conductive circuit pattern is formed on the surface thereof. As the insulating base material, a glass epoxy material or a polyimide base material is generally used. Through holes 12 for mounting discrete components such as connectors and switches are provided at predetermined positions of such a printed wiring board 11.

The through hole 12 has a land 13. A connection pattern 14 is drawn out from these lands 13 and an arbitrary electric circuit is formed. In the discrete component 15 mounted on the printed wiring board 11, the ends of the lead portions 16 are inserted into the through holes 12 and fixed with solder 17. This discrete component 15
Is a structure in which an external force is applied from outside to the fixed direction 18.

The connection pattern 14 drawn out from the land 13 of the through hole 12 can be originally wired in any direction. However, in general, the connection pattern 14 is often wired in parallel with the leads of the discrete component 15 according to the wiring rule that it is preferable to connect the components at the shortest distance.

[0006]

To simplify the explanation, consider the case where the discrete component 15 is a connector. A case where a male connector as one of the connectors is mounted on the printed wiring board 11 and a female connector is attached to and detached from the female connector will be described as an example, and the problems occurring in this case will be described below.

9 to 11 sequentially show the process of attaching and detaching the connector. In these drawings, the same reference numerals are used except for the discrete component 15 shown in FIGS. 7 and 7. On the printed wiring board 11, a male connector 21 has ends of leads 22 fixed to the through holes 12 with solder 17. The male connector 21 has a male contact 24, which is electrically connected to the lead 22, in a housing 23 thereof. The female connector 26 has a female contact 28 arranged in its housing 27, which is electrically connected to a cable wire 29.

When the female connector 26 is advanced in the direction of the arrow 31 and fitted into the male connector 24, the male contact 28 is inserted into the female contact 28 as shown in FIG. As a result, the two are electrically connected, but at the time of this insertion, 0.1 to 0.1 per pair of contacts 24 and 28 is inserted.
Insertion force of about 0.5 kg is generated. A part of this insertion force acts as an external force through the male contact 24 and is applied to the lead 22 of the male connector 21. Since the lead 22 is soldered to the through hole 12 of the printed wiring board 11, this external force is applied to this soldering portion and the through hole 1.
It is added to the land 13 of No. 2 in the direction of the arrow 31.

As a result, the female connector 26 on the land 13 of the through hole 12 of the printed wiring board 11 is formed.
A local force is generated at a position opposite to the insertion direction of (1) (position on the side far from the female connector 26). The printed wiring board 11 is generally made of a soft material such as a glass epoxy material or a polyimide base material as described above. Therefore, the external force causes the printed wiring board 11 itself to be distorted and warped, as exaggeratedly shown in FIG. This warp is applied to the connection pattern 14 drawn out from the land 13 of the through hole 12 in the front and back layers of the printed wiring board 11.

FIG. 11 shows the case where the female connector is removed from the male connector. In this case, the female connector 26
Is pulled in the direction of arrow 33 opposite to the direction of arrow 31 and is removed from the male connector 21. At this time, a force in the opposite direction acts on the portion warped by the distortion shown in FIG.

Each time the connectors 21 and 26 are attached / detached in this manner, a force acts on the connection pattern 14, which induces metal fatigue, and finally the connection pattern 14 is formed.
There was a problem that there might be a disconnection.

According to Japanese Patent Laid-Open No. 3-12987, when inserting the connection terminals of the card edge connector, an extremely large force is required due to the large number of terminals, and this causes disconnection. It has been pointed out. In this publication, an excessive load at the time of insertion is reduced by forming a plurality of conductor end portions of the card edge connector into uneven shapes. However, due to this, the force applied to the discrete component cannot be significantly reduced, and the problem of disconnection of the connection pattern similarly occurs depending on the usage mode.

Further, in JP-A-64-363, a slit extending in the longitudinal direction of the land portion is formed in a wide land portion of a conductive foil for a common electrode in a connector connecting portion of a flexible printed circuit board. This part of the conductive foil is strip-shaped. And I try not to force the transformation. However, such a method cannot be applied to a normal connection pattern that is relatively narrow and not flexible.

Therefore, it is an object of the present invention to prevent disconnection of a connection pattern for connection with discrete components even when external components are applied from a predetermined direction to the discrete components mounted on the substrate and the substrate portion is warped. It is to provide a printed wiring board.

[0015]

According to a first aspect of the present invention, there are provided: (a) a through hole to which a lead portion of a discrete component such as a connector and a switch is fixed; and (b) a lead portion from a land of the through hole to a substrate. A printed wiring board is provided with a connection pattern that is drawn out along an insulating surface that constitutes the board for at least a predetermined distance in a direction substantially perpendicular to the direction of the external force exerted on the surface.

That is, according to the first aspect of the present invention, the connection pattern is drawn out at least a predetermined distance in a direction substantially perpendicular to the direction of the external force exerted on the substrate surface through the through hole, and the portion where the warp occurs is generated. The connection pattern can be avoided and the disconnection due to metal fatigue of the connection pattern is prevented.

According to the second aspect of the invention, the base of the connection pattern drawn out from the land of the through hole is locally thicker than the rest of the pattern portion,
We have reinforced the parts that are prone to disconnection.

According to the third aspect of the present invention, the connection pattern is wired in a direction substantially perpendicular to the main direction of the external force by the above-mentioned predetermined distance, and then the connection pattern is also formed in the main direction of the external force along the insulating surface which constitutes the substrate. By arranging wires in parallel directions, the requirements for general efficiency of wiring and prevention of disconnection are harmonized.

Further, in the invention according to claim 4, the connection pattern has its wiring direction changing at a right angle, and in the invention according to claim 5, the portion where the wiring direction changes has a curvature. By doing so, it is possible to support various wiring pattern designs.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 is a top view of the essential parts of a printed wiring board according to an embodiment of the present invention. Further, FIG. 2 shows a cross section of a main part of the printed wiring board as seen from a line segment AA 'in FIG. In these figures, the same parts as those in FIGS. 7 and 8 are designated by the same reference numerals, and the description thereof will be appropriately omitted. In the printed wiring board 41, an adhesive layer is unfolded on the surface of an insulating base material, metal foils are laminated, and unnecessary portions of these metal foils are removed by etching to form an arbitrary electric circuit pattern. As the insulating base material, a glass epoxy material or
A polyimide base material is used. Copper foil is generally used as the metal foil.

In recent years, an OA on which a printed wiring board is mounted
With the downsizing and weight reduction of devices such as (office automation) devices, printed wiring boards have become thinner and lighter. For example, the plate thickness is 0.6mm or 0.4m
A very thin printed wiring board of m has been adopted. The printed wiring board 41 of this embodiment is also made of such a thin board, and through holes 42 for mounting discrete components such as connectors and switches are provided at predetermined positions thereof.

The through hole 42 of the printed wiring board 41 of the present embodiment has an inner wall plated with copper and has a diameter of about 0.3 mm to 0.5 mm larger than the diameter of the lead portion 16 of the discrete component 15 inserted therein. It has a diameter. Discrete component 1 mounted on printed wiring board 41
In No. 5, the end portions of the lead portions 16 are inserted into the through holes 42 and soldered, thereby enabling electrical connection and fixing onto the printed wiring board 41.

The through hole 42 is formed in the printed wiring board 4
No. 1 to No. 1 is 0.4 mm to 1.
It has a copper foil land 43 that is as large as 0 mm. A connection pattern 44 for forming an electric circuit is wired from the land 43. The discrete component 15 mounted on the printed wiring board 41 is also the same in that it has a structure in which an external force is applied in the fixed direction 18 from the outside.

However, as is apparent from FIG. 1, in the printed wiring board 41 of the present embodiment, the connection pattern 44 is not arranged so as to extend in the direction 18 from the through hole 12 as a starting point as it is, but rather the through hole. 12 is a starting point and extends in a direction orthogonal to the direction 18 by a predetermined length, and is bent 90 degrees from here to extend in the direction 18. In addition, this connection pattern 44 is a land 43.
The width of the pattern is locally thicker at the connecting portion 44A with respect to the other portions.

The case where the discrete component 15 is composed of a connector in the printed wiring board of this embodiment will be described below as a representative example.

3 to 5 sequentially show the steps of attaching and detaching the connector of this embodiment. In these figures, components other than the discrete component 15 shown in FIGS. 1 and 2 are designated by the same reference numerals as those of the first or second discrete component, and the description thereof will be omitted as appropriate.

The male connector 21 has a male contact 24, which is electrically connected to a lead 22 in a housing 23 thereof.
Are arranged. In this embodiment, the lead 22 and the male contact 24 have an integrated structure. The female connector 26 has a female contact 28 arranged in its housing 27, which is electrically connected to a cable wire 29.

The male connector 21 is mounted at an arbitrary position on the printed wiring board 41. Then, the ends of the leads 22 of the male connector 21 are inserted into the through holes 42, and the solder 1
It is electrically connected and fixed at 7. When fitting the female connector 26 into the male connector 21, insert the female connector 26 into the arrow 3
The male contact 24 is first inserted into the female contact 28 by moving in one direction. The insertion force in this case is somewhat different depending on the structure of the contacts 24 and 28 of both connectors 21 and 26, but in general, one set of contacts 2
A force of 0.1 to 0.5 kg per 4, 28 is required.

FIG. 4 shows a state in which the male contact 24 is inserted into the female contact 28. At this time, a part of this inserting force is applied to the lead portion 16 of the male connector 21 through the male contact 24. become. The lead portion 16 is formed in the through hole 42 of the printed wiring board 41.
The lead portion 16 is fixed here. Therefore, this external force is applied to the portion of the lead portion 16 to which the solder 17 is attached and the land 43 of the through hole 42 in the same direction as the fitting direction of the connector shown by the arrow 31.

As a result, as in the case described with reference to FIG. 10, a local force is generated on the side of the land 43 farthest from the female connector 26. Since the printed wiring board 41 is made of a material such as a glass epoxy material or a polyimide material, the periphery 45 of the board is distorted and warped as shown in FIG. This warp occurs at the same position as the local force generated when the connectors 21 and 26 are fitted together. The warp caused by this force becomes more remarkable as the printed wiring board 41 becomes thinner. Further, as shown in FIG. 5, when the female connector 26 is pulled out from the male connector 21, a force is applied in the opposite direction, so that a warp occurs at the opposite position.

However, in the printed wiring board according to the present embodiment, as is clear from FIG. 1, the connection pattern 44 is provided with the land 4 so as to avoid a portion where these warps occur remarkably.
The wiring is wired on the printed wiring board 41 along a direction perpendicular to the double-headed arrows 31, 33 for a predetermined distance from 3. Therefore, the warp generated on the printed wiring board 41 is hardly affected. In addition, the connection pattern 44 has a structure in which disconnection is unlikely to occur because the connection portion 44A with the land 43 is locally thicker than the other portions. For the above reasons, in the printed wiring board 41 of the present embodiment, even if the female connector 26 is repeatedly inserted into the male connector 21 and vice versa, disconnection of the connection pattern 44 caused by this occurs. Does not occur.

The part of the printed wiring board on which the connector is mounted has been described above, but it goes without saying that the present invention can be applied to discrete components other than the connector. For example, with respect to a switch, even with respect to the force generated when the switch is pushed down or the contact is switched by sliding the switching piece, the connection pattern is arranged in the direction orthogonal to the direction of those forces. Similarly, it is possible to prevent disconnection by locally widening the width of the connection pattern at the connection portion with the land.

FIG. 6 shows another example of the connection pattern on the printed wiring board. The discrete component 52 of the printed wiring board 51 is soldered by inserting the lead portion (not shown) into the through hole 53. The connection pattern 55 drawn from the land is drawn from the outside in a direction substantially orthogonal to the direction 56 of the force applied to the discrete component 52, and after changing its direction so as to rotate with a predetermined curvature, it becomes a linear pattern. Are wired in the direction of other circuit components not shown. The connection pattern portion 55A of the portion pulled out from the land is thicker than the other pattern portions.

As shown in this modified example, the connection pattern does not necessarily have to have a pattern shape bent at a right angle, and may have a shape having a predetermined R. Also in this case, since the pattern is arranged so as to avoid the portion where the printed wiring board is warped, it is possible to effectively prevent the disconnection together with the thick connection pattern portion 55A as the sub-brand.

Although the connection patterns arranged on one surface of the printed wiring board have been described in the embodiments and the modifications, the connection patterns are formed not only on the front surface of the board but also on the back surface or an intermediate surface therebetween. Of course, those are also effective, and it is natural that the present invention can be applied to them.

[0037]

As described above, according to the first aspect of the present invention, the connection pattern is drawn out at least a predetermined distance in the direction substantially perpendicular to the direction of the external force exerted on the substrate surface through the through hole. It is possible to prevent the connection pattern from avoiding a portion where warpage occurs, and prevent disconnection due to metal fatigue of the connection pattern. Therefore, even if the printed wiring board becomes thin, the reliability is maintained,
The usage period can be extended.

According to the second aspect of the invention, since the base of the connection pattern drawn out from the land of the through hole is locally thicker than the rest of the pattern, the disconnection is less likely to occur. There is an effect that.

Further, in the invention according to claim 3, after the connection pattern is laid out in the direction substantially perpendicular to the main direction of the external force by the above-mentioned predetermined distance, the connection pattern is parallel to the main direction of the external force along the insulating surface which also constitutes the substrate. Since wiring is performed in the direction in which wiring is performed, it is possible to prevent disconnection while improving the efficiency of general wiring.

In the invention according to claim 4, the wiring direction of the connection pattern is changed at a right angle, and in the invention according to claim 5, the portion where the wiring direction is changed is provided with a curvature. The wiring pattern can be taken without impairing the freedom of design.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a printed wiring board according to an embodiment of the present invention.

FIG. 2 shows a main part of the printed wiring board shown in FIG.
It is sectional drawing seen from the A'direction.

FIG. 3 is a cross-sectional view showing the main part of the printed wiring board before inserting the female connector into the male connector in the present embodiment.

4 is a cross-sectional view showing a main part of the printed wiring board in a state where a female connector is inserted into the male connector shown in FIG.

FIG. 5 is a cross-sectional view showing a main part of the printed wiring board when the female connector is removed from the male connector in the present embodiment.

FIG. 6 is a plan view showing a connection pattern of a printed wiring board according to a modified example of the present invention.

FIG. 7 is a plan view of a main part of a conventional printed wiring board.

FIG. 8 shows a main part of the printed wiring board shown in FIG.
It is sectional drawing seen from the B'direction.

FIG. 9 is a cross-sectional view showing a main part of a printed wiring board before inserting a female connector into a conventional male connector.

10 is a cross-sectional view showing a main part of the printed wiring board in a state where a female connector is inserted in the male connector shown in FIG.

FIG. 11 is a cross-sectional view showing a main part of a printed wiring board when a conventional female connector is removed from a male connector.

[Explanation of symbols]

 14, 44 Connection pattern 15 Discrete part 16 Lead part 21 Male connector 26 Female connector 41 Printed wiring board 42 Through hole 43 Land 44A Connection part with land 45 Periphery (as part where warpage occurs)

Claims (5)

[Claims] 1. A through hole to which a lead part of a discrete component such as a connector or a switch is fixed, and a board extending from a land of the through hole at least a predetermined distance in a direction substantially perpendicular to a direction of an external force mainly exerted on the board surface by the lead part. And a connection pattern drawn out along the insulating surface that constitutes the printed wiring board. 2. The printed wiring board according to claim 1, wherein the base portion of the connection pattern drawn out from the land of the through hole is locally thicker in width than the remaining pattern portion. 3. The connection pattern is wired in the direction substantially perpendicular to the main direction of the external force by the predetermined distance, and then is wired in the direction parallel to the main direction of the external force along the insulating surface which also constitutes the substrate. The printed wiring board according to claim 1, wherein: 4. The printed wiring board according to claim 3, wherein the connection pattern has its wiring direction changed at a right angle. 5. The printed wiring board according to claim 3, wherein the wiring pattern of the connection pattern changes smoothly along a predetermined curvature.