JPH07297527A - Printed-circuit board - Google Patents

Abstract

PURPOSE:To provide a printed-circuit board capable of preventing a generation of a bridge due to solder between adjacent pads without being left in an electrode mounting part when the solder is melted. CONSTITUTION:In a printed-circuit board having a mounting pattern 11 that a pad 10 corresponding to each electrode of LCCs is provided in a board 1 and that solder is supplied to the pad 10 to solder the electrode onto the pad 10, an electrode mounting part 10a in an intermediate portion to which the electrode of the pad 10 is attached is formed to be narrow and the both ends are formed in wide parts 10b, 10c.

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 a mounting pattern for mounting electronic parts.

[0002]

2. Description of the Related Art For example, in a leadless chip carrier (hereinafter referred to as LCC), a large number of electrodes are arranged at a predetermined interval on a peripheral portion of a main body. On the other hand, a mounting pattern having pads at intervals corresponding to the electrodes is formed on the upper surface of the printed circuit board on which the LCC is mounted. And
The LCC is mounted on the printed board by supplying solder to the pads and soldering the electrodes of the LCC to the pads.

By the way, the conventional printed circuit board is formed as shown in FIG. That is, the rectangular mounting pattern 3 is formed by arranging a large number of pads 2 on the upper surface of the substrate body 1 at a predetermined interval. The pad 2 is a strip (rectangle) having a constant width, and an electrode attachment portion 2a is provided at an intermediate portion in the longitudinal direction thereof. Also,
As shown in FIGS. 7 and 8, the LCC 4 has a large number of electrodes 6 arranged at predetermined intervals on the peripheral edge of the main body 5.

When mounting the LCC 4 on a printed circuit board, solder 7 is applied to the upper surface of each pad 2 by printing, and then each electrode 6 of the LCC 4 is positioned on the electrode mounting portion 2a of the pad 2 for reflow soldering. By performing the attachment, the solder 7 is melted and the pad 2 and the electrode 6 are brought into an electrically conductive state, and the LCC 4 is mounted on the printed board.

[0005]

[Problems to be Solved by the Invention] However, LCC
The intervals between the electrodes 6 provided on the peripheral portion of the main body 5 of No. 4 are narrow, and accordingly, the pads 2 formed on the substrate main body 1 are also densely packed. Therefore, when the solder 7 is reflowed, the solder 7 supplied to the adjacent pads 2 is melted and the bridge 8 is generated, and the soldering failure is likely to occur. This is a phenomenon that occurs when the solder 7 supplied to the pad 2 melts and accumulates in the electrode mounting portion 2a without flowing.

The present invention has been made in view of the above circumstances, and its purpose is to prevent the solder supplied to the pads from being accumulated in the electrode mounting portion when the solder is melted, and the solder between the adjacent pads. Another object of the present invention is to provide a printed circuit board which can prevent the occurrence of a bridge due to the above and can surely mount electronic components.

[0007]

In order to achieve the above object, the present invention provides a substrate main body with a pad corresponding to each electrode of an electronic component, and supplies solder to the pad. In a printed circuit board in which an electrode is soldered to a pad, another portion of the pad where the electrode is attached is made wider than a portion where the pad is attached. According to a second aspect of the present invention, the pad has a strip shape and both end portions are wider than an intermediate portion to which the electrode is attached, and a third aspect of the present invention is that the pad has a strip shape and an intermediate portion to which the electrode is attached is provided at both ends. It is narrower than the part.

According to a fourth aspect of the present invention, the pad has a gourd shape in which an intermediate portion to which the electrode is attached is constricted. A fifth aspect of the present invention is to form a row on each of two adjacent sides of the electronic component. Among the plurality of pads provided in, the pad in each row provided closest to the corner of the electronic component is shorter than the other pads.

According to a sixth aspect of the present invention, among a plurality of pads provided in a row on each of two adjacent sides of the electronic component, the pad in each column provided closest to a corner of the electronic component is: The corners facing each other are cut diagonally.

[0010]

When mounting the electronic component on the printed circuit board, after supplying solder to the upper surface of each pad, each electrode of the electronic component is positioned at the electrode mounting portion of the pad and reflow soldering is performed. When the solder melts, the solder does not collect in the electrode attachment portion and flows into the wide portions at both ends of the pad, so that a bridge is prevented from being generated due to excess molten solder.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. However, the same components as those of the prior art will be designated by the same reference numerals and description thereof will be omitted. 1 to 3 show the first embodiment, and a rectangular mounting pattern 11 is formed on the upper surface of the substrate body 1 by arranging a large number of pads 10 at predetermined intervals. The pad 10 has a strip shape (rectangle), and an electrode attachment portion 10a is provided at an intermediate portion in the longitudinal direction thereof.
Wide ends 10b and 10c having a width wider than that of the electrode mounting portion 10a are provided at both ends.

That is, each pad 10 has a wide portion except the electrode mounting portion 10a, so that molten solder during soldering does not collect in the electrode mounting portion 10a.
The pad 10 is formed so as to flow to the wide portions 10b and 10c at both ends.

Therefore, when the LCC 4 is mounted on a printed circuit board, after the solder 7 is supplied on the upper surface of each pad 10 by printing, each electrode 6 of the LCC 4 is positioned on the electrode mounting portion 10a of the pad 10 for reflow soldering. By doing so, the solder 7 is melted and the pad 10 and the electrode 6 are brought into electrical conduction, and the LCC 4 is mounted on the printed board.

At this time, when the solder 7 is melted, the solder 7 has a property of flowing to a portion having a large area, so that the solder 7 flows toward the wide portions 10b and 10c of the pad 10 as shown by an arrow, and the solder 7 is attached to the electrode mounting portion 10a. Without accumulating, it is possible to prevent defective soldering such as generation of a bridge due to excessive solder 7 as in the conventional case.

FIG. 4 shows a second embodiment, which is a modification of the pad. That is, the pad 12 shown in (a) is in the shape of a strip (rectangle), and the electrode attachment portion 12a having a width narrower than other portions is provided in the longitudinal middle portion thereof. That is, both ends of the pad 12 result in the electrode mounting portion 12
The wide portions 12b and 12c having a width wider than that of a are formed.

As described above, by forming the electrode mounting portion 12a of each pad 12 to be narrower than the other portions, the molten solder at the time of soldering is accumulated in the electrode mounting portion 12a as in the first embodiment. Instead, it flows to the wide width portions 12b and 12c at both ends of the pad 12, so that the same effect as the first embodiment can be obtained.

The pad 13 shown in (b) has a gourd shape,
An electrode mounting portion 13a having a width narrower than the other portions in the middle portion thereof
Is provided. That is, both ends of the pad 13 are consequently formed into circular wide portions 13b and 13c which are wider than the electrode attachment portion 13a.

As described above, by forming the electrode mounting portion 13a of each pad 13 to be narrower than the other portions, the molten solder at the time of soldering is accumulated in the electrode mounting portion 13a as in the first embodiment. Instead, it flows to the wide width portions 13b and 13c at both ends of the pad 13, so that the same effect as that of the first embodiment can be obtained.

The pad 14 shown in (c) has a substantially elliptical shape, and has a wide portion 14b formed at one end thereof, an electrode attachment portion 14a at the middle portion thereof, and a narrow portion 14c at the other end thereof. That is, one end portion of the pad 14, that is, the portion exposed to the outside from the peripheral portion of the LCC 4 is the electrode mounting portion 14a.
The width is wider, and the portion hidden by the peripheral edge of the LCC 4 is narrow.

As described above, by forming the wide portion 14b wider than the electrode mounting portion 14a at one end of each pad 14, the molten solder at the time of soldering becomes the electrode mounting portion 1.
Wide portion 1 at one end of pad 14 without accumulating in 4a
4b, the same effect as the first embodiment can be obtained.

FIG. 5 shows a third embodiment. In FIG. 5A, a rectangular mounting pattern 16 is formed on the upper surface of the substrate body 1 by arranging a large number of pads 15 at predetermined intervals. However, the pad 15a located at the corner portion 16a of the mounting pattern 16 is formed to be shorter than the other pads 15.

By forming in this way, a sufficient insulating space can be secured between the pads 15a located at the corner portions 16a of the mounting pattern 16 and the pads 15a can be provided up to the corner portions 16a. There is an effect that the pad density can be increased with respect to the area.

In (a), a rectangular mounting pattern 18 is formed on the upper surface of the substrate body 1 by arranging a large number of pads 17 at predetermined intervals, and the corner portion 18a of the mounting pattern 18 is formed. Adjacent to the pad 17a
The end portion 17b is cut diagonally.

By forming in this way, a sufficient insulating space can be secured between the pads 17a located at the corners 18a of the mounting pattern 18, and the pads 17a can be provided up to the corners 18a. There is an effect that the pad density can be increased with respect to the area.

The shape of the pad in the third embodiment is the same as that of the first embodiment, but the length of the pad located at the corner of the mounting pattern in the pad shown in the second embodiment is long. The length of the pad may be shortened or cut diagonally, and the shape of the pad is not limited.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment.
That is, by arbitrarily and selectively combining the constituent elements of each of the above-described embodiments, it is possible to configure a device having a function equivalent to or different from that of each of the embodiments. Therefore, an embodiment in which the constituent elements of the above-described embodiments are arbitrarily and selectively combined may be a new embodiment.

[0027]

As described above, according to the present invention, when the solder supplied to the pads is melted, it is not collected in the electrode mounting portion and flows to one end or both ends of the pads, so that the adjacent pads are adjacent to each other. It is possible to prevent the occurrence of bridging due to soldering between them, and to securely mount electronic components,
There is an effect that the reliability of soldering can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a mounting pattern according to a first embodiment of the present invention.

2A and 2B are a plan view and a side view showing the pad of the embodiment in an enlarged manner.

FIG. 3 is a plan view of a pad for explaining the operation of the same embodiment.

FIG. 4 is a plan view showing a modified example of the pad according to the second embodiment of the present invention.

FIG. 5 is a plan view showing a mounting pattern according to a third embodiment of the present invention.

FIG. 6 is an enlarged plan view showing a conventional mounting pattern and pads.

FIG. 7 is an L for a pad provided on a conventional substrate body.
FIG. 3 is a vertical cross-sectional side view of a state in which a CC electrode is soldered.

FIG. 8 is a plan view of FIG.

FIG. 9 is an L for a pad provided on a conventional substrate body.
The top view which shows the state which the electrode of CC was soldered and the bridge generate | occur | produced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate main body 4 ... LCC 6 ... Electrode 7 ... Solder 10, 12, 13, 14 ... Pad 10a, 12a, 13a, 14a ... Electrode attachment part

Claims (7)

[Claims] 1. A printed circuit board in which a pad corresponding to each electrode of an electronic component is provided on a substrate body, and solder is supplied to the pad to solder the electrode to the pad. A printed circuit board, characterized in that the other part of the part to which is attached is made wider than the part to which the pad is attached. 2. The printed circuit board according to claim 1, wherein the pad has a strip shape and both end portions are wider than an intermediate portion to which the electrode is attached. 3. The printed circuit board according to claim 1, wherein the pad has a strip shape, and an intermediate portion to which the electrode is attached is narrower than both end portions. 4. The printed board according to claim 1, wherein the pad has a gourd shape in which an intermediate portion to which the electrode is attached is constricted. 5. Among the plurality of pads provided in a row on each of two adjacent sides of the electronic component, the pad in each column provided closest to the corner of the electronic component is the other pad. The printed circuit board according to claim 1, wherein the printed circuit board is formed to be shorter. 6. Among a plurality of pads provided in a row on each of two adjacent sides of the electronic component, pads in each column provided closest to a corner of the electronic component face each other. The printed circuit board according to claim 1, wherein the corner portion is obliquely cut. 7. The printed circuit board according to claim 1, wherein the electronic component is a leadless chip carrier having a plurality of electrodes on a peripheral portion of a main body.