JP2002158426A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board in which the opening of an insertion hole (2) is sustained with no possibility of peeling of a pattern and a lead pattern (7) can be led out in any direction of a land pattern (4). SOLUTION: The land pattern (4) being formed around the insertion hole (2) is formed into a ring shape surrounding the entire circumference of the insertion hole (2) except at least a part (6) of circumferential edge contiguous to the insertion hole (2). Since flow solder fused during flow solder process does not adhere to the part (6) of circumferential edge contiguous to the insertion hole (2), its opening is not closed and the lead part of a component can be inserted later into the opening. Furthermore, since no cut is made in the land pattern (4), adhesion area to an insulating substrate is not decreased and thereby stripping of pattern is prevented and the lead pattern (7) can be led out in any direction.

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 on which electronic components are mounted, and more particularly, to an electronic component soldered by flow soldering,
The present invention relates to a printed wiring board on which both components to be soldered in another process are mounted.

[0002]

[Prior art]

Conventionally, electronic components have been mounted on a printed wiring board by a known flow soldering process in which molten solder flows along the back surface of the printed wiring board from the front side to the back side of the printed wiring board. Was soldered to the surrounding land pattern and electrically connected to the lead pattern drawn from the land pattern.

[0004] However, components to be mounted on the printed wiring board include a connector at a terminal of a cable already connected to another device, a component that cannot withstand the heat of flow solder, and a heat resistance. Due to a problem, some parts cannot be mounted by flow soldering.

To mount these components, after the flow soldering process, a lead portion is inserted from the front side into the insertion hole 101 of the printed wiring board 100 shown in FIGS. On the flow soldering surface 100A side where the soldering by the flow soldering is performed, the land pattern 102 formed around the insertion hole 101 is soldered by hand soldering, and is electrically connected to the lead pattern 103 pulled out from the land pattern 102. are doing.

[0006] Insertion hole 1 for mounting this retrofit component
In the case of the flow solder, the opening may be covered by the solder attached to the land pattern 102 around the solder in the flow soldering. Therefore, as shown in FIG. Land pattern 1 on the upstream side
The notch 104 was formed in a part of No. 02. In the notch portion 104 where the land pattern 102 is not formed, the insulating substrate 106 is exposed at the periphery adjacent to the insertion hole 101, and the insulating substrate 106 is
Since the molten solder has higher water repellency than that of No. 02, the molten solder flowing from the upstream is divided into two by the notch portion 104, so that the insertion hole 101 can be prevented from being blocked.

Further, as shown in FIG. 7, a solder resist 105 lacking in affinity for solder is further laminated on the cutout portion 104 to more effectively repel molten solder.
This prevents solder from adhering to the opening of the insertion hole 101.

[0008]

However, FIG.
In the conventional printed wiring board 100 shown in FIG. 7, since the notch 104 is formed in a part of the land pattern 102, the contact area with the insulating substrate 106 is reduced, and when the lead portion receives some external force, In addition, there has been a problem that the so-called pattern peeling that is peeled off from the insulating substrate 106 easily occurs.

The lead pattern 103 connected to the land pattern 102 is drawn out from the periphery of the land pattern 102 but cannot be drawn out from the notch 104, which causes a problem that the degree of freedom in pattern design is impaired.

[0010] To solve these problems, if the land pattern 112 is formed in a ring shape surrounding the entire periphery of the insertion hole 111 as in a printed wiring board 110 shown in FIG. By applying a solder resist 115 in a band shape on the land pattern 112 on the upstream side in the flow direction (the direction of the arrow), the insertion hole 111 is formed.
It can be considered as a countermeasure against the flow of the molten solder into the opening.

However, on the periphery of the insertion hole 111,
Since the side surface 112a of the land pattern 112 is exposed and a part of the solder flowing around the solder resist 115 is attached to the side surface 112a, a sufficient countermeasure for maintaining the opening of the insertion hole 111 is as follows. did not become.

In view of the above-mentioned problems, the present invention provides a printed wiring board which can maintain the opening of an insertion hole and can lead out a lead pattern in any direction of a land pattern without fear of pattern peeling. The purpose is to:

[0013]

According to a first aspect of the present invention, there is provided a printed circuit board having an insulating substrate having one surface serving as a flow solder surface for soldering a lead portion of an electronic component by flow solder. And on the flow solder side,
And a land pattern formed around the insertion hole formed in the insulating substrate.After soldering the electronic component by flow soldering, the lead of the retrofit component is inserted through the insertion hole and soldered to the land pattern. In the printed wiring board described above, the land pattern is formed in a ring shape surrounding the entire periphery of the insertion hole except for at least a part of a peripheral edge adjacent to the insertion hole.

Since a land pattern is not formed on a part of the periphery adjacent to the insertion hole and the insulating substrate is exposed, molten solder does not adhere during flow soldering. Since a portion where the solder does not adhere is left at a part of the periphery of the insertion hole, the opening is not covered with the solder by the flow solder.

On the other hand, since the land pattern has no notch, the area of contact with the insulating substrate does not decrease, and the pattern does not easily peel off from the insulating substrate.

Further, since the land pattern is formed in a ring shape surrounding the entire circumference of the insertion hole, the lead pattern can be drawn out from any of the peripheral edges.

Further, in the printed wiring board according to the second aspect of the present invention, a part of the periphery where the land pattern is not formed is
A solder resist is applied on the exposed insulating substrate.

Since the periphery of the insertion hole from which the insulating substrate is exposed is further covered with a solder resist lacking in affinity for solder, the adhesion of the molten solder is more effectively prevented, and the opening of the insertion hole is formed of the flow solder. There is no clogging with solder at the time.

Further, in the printed wiring board according to the third aspect of the present invention, the land pattern is formed on a peripheral edge adjacent to the insertion hole.
It is characterized in that it is formed in a ring shape, leaving a part on the upstream side in the flow direction at the time of flow soldering.

Since a part of the peripheral edge of the insertion hole where the land pattern is not formed is the peripheral edge on the upstream side in the flow direction of the molten solder, the molten solder flowing toward the insertion hole is exposed at the portion where the insulating substrate or the solder resist is exposed. Therefore, the opening of the insertion hole can be more effectively maintained without being repelled and flowing into the insertion hole.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A printed wiring board 1 according to a first embodiment of the present invention will be described below with reference to FIGS.
FIGS. 1 to 3 show a main part of the present invention centering on an insertion hole 2 into which a lead part of a not-shown retrofit part is inserted. FIG. 1 is a plan view of a main part of a printed wiring board 1 and FIG.
Is a cross-sectional view taken along line AA of FIG. 1, and FIG. 3 is a plan view of a main part of the printed wiring board 1 excluding a solder resist 3.

The flat side of the printed wiring board 1 shown in FIG. 1 is a flow solder surface 1A through which molten solder flows in the direction of the arrow in the flow soldering process. That is, the other electronic components (not shown) have the lead portions protruding toward the flow solder surface 1A, and are flow-soldered to the land pattern printed around the protruding periphery by a known flow solder.

The insertion hole 2 in the figure is inserted through a lead (not shown) of a retrofitted component that cannot be soldered by flow soldering due to an assembly process or a problem of heat resistance. This is for solder connection to the land pattern 4 on the 1A side, and it is necessary that the opening is not closed by the solder even after the flow soldering process.

The land pattern 4 is a copper foil pattern formed on an insulating substrate 5 serving as a base, and is formed in a horizontally long ring shape surrounding the entire circumference of the insertion hole 2 as shown in FIG. The inside of the ring shape is hollowed out in an oval shape whose longitudinal direction is the direction of the arrow (flow direction) in which the molten solder flows, and the inner diameter on the rear side, which is the downstream side in the flow direction, is substantially equal to the outer diameter of the insertion hole 2. Therefore, the rear side is penetrated along the insertion hole 2.

Since the inside of the land pattern 4 is cut out in an oval shape up to a position in front of the insertion hole 2, the insulating substrate 5 is exposed on the cut-out front side (upstream side in the flow direction). The exposed portion 6 is formed.

A lead pattern 7 also made of copper foil is drawn out from around the land pattern 4, here from the front end. The lead pattern 7 is for electrically connecting a lead part of a retrofit component to be soldered to the land pattern 4 to another circuit of the printed wiring board 1.

On the insulating substrate 5 on which the land pattern 4 and the lead pattern 7 are formed (lower in FIG. 2), FIG.
The solder resist 3 is formed by printing in the area indicated by the diagonal lines. That is, the solder resist 3 includes the lead pattern 7, a part of the front side of the land pattern 4, and the exposed portion 6.
Are formed on these insulating layers so as to cover the insulating substrate 5 including the above.

Printed wiring board 1 thus formed
In the flow soldering process, the flow solder surface 1A is immersed in the solder layer, the substrate 1 is moved toward the upstream in the flow direction (in the direction opposite to the arrow in the drawing), and the molten solder is attached to the leads of the electronic components. Let it.

At this time, the molten solder flowing from the front of the land pattern 4 is
Is repelled by the solder resist 3 covering the substrate.

As a result, no flow solder adheres to the front side peripheral edge of the insertion hole 4 of the printed wiring board 1 pulled up from the solder layer, and the opening is not closed by the flow solder.

The lead portion of the retrofit component is inserted into the insertion hole 4 with the opening kept from the front surface (the upper surface in FIG. 2) of the printed wiring board 1, and the lead portion projecting toward the flow solder surface 1A is surrounded by the lead portion. Is electrically connected to the land pattern 4 by soldering.

In the above-described embodiment, the exposed portion 6 from which the insulating substrate 5 is exposed is covered with the solder resist 3. However, when the flow solder surface 1A of the insulating substrate 5 is subjected to affinity with solder. In this case, the exposed portion 6 does not need to be covered with the solder resist 3 as in the printed wiring board 10 according to the second embodiment shown in FIGS.

The printed wiring board 1 shown in FIGS.
Since 0 is the same as that of the first embodiment except for the difference in the portion covered by the solder resist 13, the same components are given the same numbers.

In this embodiment, since the solder resist 13 is formed by printing except for the land pattern 4 and the inner part thereof, the exposed portion 6 on the front side of the insertion hole 2 is
In this state, the insulating substrate 5 is exposed.

In the flow soldering step, the flow solder flowing from the front in the direction of the arrow goes over the land pattern 4 and goes to the insertion hole 2, but the insulating substrate 5 exposed at the exposed portion 6
It is repelled and does not adhere to the front edge of the insertion hole 2. Therefore, even with the printed wiring board 10, the opening of the insertion hole 2 is not closed by the flow solder.

Also, as in the above-described embodiment, the exposed portion 6 is desirably formed on the peripheral edge adjacent to the insertion hole 2 and on the upstream side in the flow direction.
If a portion where the land pattern 4 is not formed is provided on the periphery of the hole, the flow solder does not adhere. Therefore, even if the exposed portion 6 is formed on a part of the periphery which is not the upstream side, the opening of the insertion hole 2 can be maintained. it can.

Further, since the land pattern 4 is formed in a ring shape covering the entire circumference of the insertion hole 2, the lead pattern 7 is not limited to the front (upstream side in the flow direction) shown in the above-described embodiment. It can be drawn from any area around the pattern 4.

[0038]

As described above, according to the present invention, the insertion hole is not blocked by the melting flow solder.
After the flow soldering process, the lead portion of the retrofit component can be inserted.

Further, since the land pattern has no notch, a contact area with the insulating substrate can be secured, and there is no fear of pattern peeling.

Further, since the land pattern is formed in a ring shape surrounding the entire circumference of the insertion hole, the lead pattern can be drawn out in any direction around the insertion hole, and the degree of freedom in pattern design is not restricted. .

Further, according to the second aspect of the present invention, in addition to the above, the periphery of the insertion hole from which the insulating substrate is exposed is covered with a solder resist having a lower affinity for solder than the insulating substrate. Adhesion of the molten solder to the periphery of the insertion hole can be prevented, and the opening of the insertion hole is not closed by the flow solder.

According to the third aspect of the present invention, in addition to this, a part of the peripheral edge of the insertion hole where the land pattern is not formed is the peripheral edge on the upstream side in the flow direction of the molten solder. The molten solder flowing toward the insulating substrate or the portion where the solder resist is exposed is repelled, does not flow into the insertion hole, and the opening of the insertion hole can be more effectively prevented from being blocked by the molten solder.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view of a main part of the printed wiring board 1 excluding a solder resist 3;

FIG. 4 is a plan view of a main part of a printed wiring board 10 according to a second embodiment of the present invention.

FIG. 5 is a sectional view taken along line BB of FIG. 4;

FIG. 6 is a plan view of a main part of a conventional printed wiring board 100 excluding a solder resist 105.

7A and 7B show a conventional printed wiring board 100, and FIG.
FIG. 2 is a plan view of a main part, and FIG. 2B is a cross-sectional view taken along line CC of FIG.

FIG. 8 shows another conventional printed wiring board 110,
(A) is a plan view of a main part, and (b) is a cross-sectional view taken along line DD of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed wiring board 1A Flow solder surface 2 Insertion hole 3 Solder resist 4 Land pattern 5 Insulating board

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Claims (3)

[Claims] An insulating substrate (5) having one surface serving as a flow solder surface (1A) for soldering a lead portion of an electronic component by flow solder, and an insulating substrate (5) on the flow solder surface (1A) side. And a land pattern (4) formed around the perforated insertion hole (2). After soldering the electronic component by flow soldering, the lead portion of the retrofit component is inserted through the insertion hole (2). In the printed wiring board to be soldered to the land pattern (4), the land pattern (4) has a ring shape surrounding the entire periphery of the insertion hole (2) except for at least a part of a periphery adjacent to the insertion hole (2). A printed wiring board formed on a substrate. 2. A solder resist (3) is applied to a part of the periphery where no land pattern (4) is formed on an exposed insulating substrate (5).
The printed wiring board as described. 3. The land pattern (4) includes an insertion hole (2).
The printed wiring board according to claim 1, wherein the printed wiring board is formed in a ring shape, leaving a part on the peripheral edge adjacent to the upstream side in the flow direction at the time of flow soldering. .