JP2011192668A - Electronic circuit unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic circuit unit which is always mounted on a mother board in a stable posture and has a substrate corner portion, where the leg portion of a metallic cover is soldered, securely fixed to the mother board to perform high-reliability mounting. <P>SOLUTION: In the electronic circuit unit 11, a circuit portion 3 provided on the upper surface of a substrate 2 is covered with the metallic cover 4, and the leg portion 4a of the cover 4 is soldered to a solder land 6 adjacent to the upper-end peripheral edge of a through hole 5 and a through hole conductor 12 in the through hole 5, but not soldered on the lower-surface side of a substrate 1, at the corner portion 2a of a substrate 2. To the corner portion 2a on the lower surface of the substrate 1, a first reinforcing land 8 in a C shape substantially surrounding the through hole 5 is provided, but the both through hole 5 and the first reinforcing land 8 are isolated from each other. To the lower surface of the substrate 1, a connection land group 7 group electrically connected to the circuit portion 3 and a second reinforcing land 9 located nearby the corner portion 2a are provided, and lands 7 to 9 are soldered to corresponding land portions of the mother board 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic circuit unit suitable for use as a transmission / reception unit, for example, which is surface-mounted on a mother board of a cellular phone, and in particular, a leg portion of a metal cover covering a circuit portion of a substrate is soldered to a corner portion of the substrate. It is related with the electronic circuit unit.

  As this type of electronic circuit unit, wiring patterns and electronic components are arranged on the upper surface of a rectangular substrate to form a high-frequency circuit unit, and the legs of a metal cover (shield cover) covering the high-frequency circuit unit are formed on the substrate. A configuration of soldering to a through-hole conductor provided at a corner is widely known. On the lower surface of the board, a large number of connection lands electrically connected to the wiring pattern of the high-frequency circuit section are arranged as, for example, LGA (Land Grid Array), and these connection lands are mounted on the corresponding land sections of the motherboard. Then, the electronic circuit unit is surface-mounted on the mother board by soldering.

  In such an electronic circuit unit, the inner wall portion of the through hole 22 formed in the corner portion 21a of the substrate 21 is usually cylindrical as shown in FIG. Through-hole conductor 23. The through-hole conductor 23 is formed so that the upper and lower ends thereof are continuous with the annular solder lands 24 and 25. The leg portion 26 a of the metal cover 26 is inserted into the through hole 22, and the leg portion 26 a is joined to the through-hole conductor 23 and the solder lands 24 and 25 by solder 27. On the upper surface of the substrate 21 is provided a high-frequency circuit unit 28 in which wiring patterns and electronic parts (not shown) are arranged. The high-frequency circuit unit 28 is covered with a metal cover 26 to be electromagnetically shielded. ing. In addition, on the lower surface of the substrate 21, a large number of connection lands 29 electrically connected to the wiring pattern of the high-frequency circuit section 28 and reinforcing lands 30 for increasing the mounting strength to a mother board (not shown) are provided. In FIG. 7, the connection lands 29 are disposed at the peripheral edge of the substrate 21, but may be disposed in a region other than the peripheral edge (such as the central portion). The reinforcing land 30 is relatively large so that it can be firmly soldered to the land portion of the mother board. Therefore, as shown in FIG. 7, if reinforcing lands 30 are provided in the vicinity of the corner 21a of the substrate 21, the corner where stress is likely to concentrate when dropped after being commercialized into a mobile phone or the like. The portion 21a is difficult to peel from the motherboard. Further, as shown in FIG. 6, since the leg portion 26a of the metal cover 26 is soldered not only to the solder land 24 but also to the through-hole conductor 23 and the solder land 25, a large solder land 24 is formed on the upper surface side of the substrate 21. A sufficient soldering strength can be secured to the leg portion 26a even without providing. As a result, since the area occupied by the solder lands 24 on the upper surface of the substrate 21 can be suppressed, the space for the high-frequency circuit section 28 can be expanded to the vicinity of the corner 21a of the substrate 21 (see, for example, Patent Document 1).

  There has also been proposed an electronic circuit unit in which a corner portion of a substrate is chamfered so that a semi-cylindrical through-hole conductor is exposed, and a leg portion of a metal cover is soldered to the through-hole conductor (for example, , See Patent Document 2).

Japanese Patent No. 4249772 JP 2008-53442 A

  When the legs of the metal cover are soldered to the through-hole conductor provided at the corner of the board of the electronic circuit unit as in the conventional example described above, a large space for the high-frequency circuit is secured on the upper surface of the board. Therefore, the electronic circuit unit can be easily reduced in size and functionality. However, as shown in FIG. 6, the solder 27 attached to the solder land 25 on the lower surface side of the substrate 21 continuous with the through-hole conductor 23 tends to protrude greatly downward due to its own weight. When mounted on the top, the protruding solder sometimes tilts, and an improvement has been desired. That is, if the protruding solder is undesirably large, the electronic circuit unit cannot be mounted in a stable posture on the mother board, which tends to cause mounting defects.

  Further, in the conventional electronic circuit unit of this type, as shown in FIG. 7, the reinforcing land 30 is provided at a position slightly away from the corner 21a of the substrate 21 where the through-hole conductor 23 exists. May be warped by an impact such as dropping, and in that case, there is a risk that excessive stress acts on the reinforcing land 30 in the vicinity of the corner portion 21a to cause separation from the motherboard. Patent Document 1 exemplifies an electronic circuit unit in which a through-hole surrounded by a through-hole conductor is exposed in a reinforcing land. However, when such a structure is employed, it should be attached to the through-hole conductor. Problems such as solder wrapping around the reinforcement land and projecting greatly downward, or solder that should adhere to the reinforcement land during mounting escape into the through-hole and the soldering strength of the reinforcement land becomes extremely weak is there.

  The present invention has been made in view of such a state of the art, and an object of the present invention is to always mount the motherboard on a motherboard in a stable posture and to solder the metal cover legs to the corners of the board. It is an object of the present invention to provide an electronic circuit unit that can be securely fixed to a mother board and can be mounted on a surface with high reliability.

  In order to achieve the above object, the present invention is configured such that a circuit portion provided on the upper surface and a connection runt group provided on the lower surface are electrically connected to each other and inserted into a through hole in a corner portion of the substrate. A metal cover attached to the substrate in a state of covering the circuit portion and having a leg portion soldered to the corner portion, and surface-mounted by soldering the connection runt group to a motherboard In the electronic circuit unit, a solder land for soldering the leg portion is provided only at the upper surface of the substrate at the corner of the substrate, and the lower surface of the substrate is separated from the lower peripheral edge of the through hole. On the other hand, at least at the corner edge side of the corner closest to the through-hole, a reinforcing land is provided that surrounds the periphery of the lower end, and the reinforcing land is a part to be soldered to the mother board. At least one of the solder lands and de has a configuration that has a notch for the air vent.

  In the electronic circuit unit configured in this way, there is no possibility that the solder joining the legs of the metal cover to the corners of the board will protrude greatly from the bottom of the board to the motherboard side, so it always has a stable posture on the motherboard. Can be installed. Further, the through hole into which the leg portion of the metal cover is inserted is surrounded by the reinforcing land at least at the corner edge side of the board corner closest to the through hole on the lower surface of the board. By attaching, the corners of the substrate can be firmly fixed to the motherboard. In addition, since the reinforcing land is separated from the lower end periphery of the through hole, the leg portion of the metal cover and the reinforcing land are not soldered, and the solder to be attached to the reinforcing land at the time of mounting is the through hole. There is no escape to the inside.

  For example, if the reinforcing land is formed in a C shape surrounding the lower edge of the through hole and the through hole is located between the notch and the corner edge of the substrate corner, In addition, the reinforcing lands and the through holes can be disposed efficiently.

  In the above configuration, it is preferable that the second reinforcing land is provided in the vicinity of the corner on the lower surface of the substrate, in addition to the reinforcing land, because the mounting strength of the electronic circuit unit to the mother board can be greatly increased.

  In the above configuration, if the leg portion of the metal cover is soldered to the solder land provided on the upper surface of the substrate and the through-hole conductor provided in the through hole, the solder land is not formed large. However, sufficient soldering strength can be secured to the legs of the metal cover. As a result, it is preferable because the area occupied by the solder lands on the upper surface of the substrate can be suppressed and the space for the circuit portion can be expanded to the vicinity of the corner of the substrate. However, even if there is no through-hole conductor in the through-hole and the metal cover legs are soldered only to the solder lands on the top surface of the board, the posture of the electronic circuit unit mounted on the motherboard is stable. In addition, it is possible to increase the mounting strength of the electronic circuit unit to the mother board by providing a reinforcing land around the through hole on the lower surface of the substrate.

  According to the electronic circuit unit of the present invention, there is no possibility that the solder joining the leg portion of the metal cover to the corner of the board will protrude greatly from the lower surface of the board to the motherboard side. It can always be mounted in a stable posture and is less likely to cause mounting defects. Further, the through hole into which the leg portion of the metal cover is inserted is surrounded by the reinforcing land at least at the corner edge side of the board corner closest to the through hole on the lower surface of the board. By attaching, the corners of the substrate can be firmly fixed to the motherboard. Therefore, there is no possibility that the corner portion of the substrate warps due to an impact such as dropping. In addition, since the reinforcing land is separated from the lower end periphery of the through hole, the leg portion of the metal cover and the reinforcing land are not soldered, and the solder to be attached to the reinforcing land at the time of mounting is the through hole. There is no escape to the inside. Therefore, it is possible to obtain a highly reliable electronic circuit unit that has a high mounting strength with respect to the mother board and is difficult to be peeled off from the mother board even when an impact is applied when dropped.

1 is an external view of an electronic circuit unit according to a first embodiment of the present invention. It is principal part sectional drawing of the electronic circuit unit which concerns on the example of 1st Embodiment. It is a bottom view of the principal part of the electronic circuit unit shown in FIG. It is principal part sectional drawing of the electronic circuit unit which concerns on the example of 2nd Embodiment of this invention. It is a bottom view of the principal part of the electronic circuit unit shown in FIG. It is principal part sectional drawing of the electronic circuit unit which concerns on a prior art example. It is a bottom view of the principal part of the electronic circuit unit shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. First, an electronic circuit unit according to a first embodiment of the present invention will be described with reference to FIGS. The electronic circuit unit 1 shown in these figures is surface-mounted on a mother board 20 (see FIG. 2) of a cellular phone and used as a transmission / reception unit.

  This electronic circuit unit 1 is provided with a high frequency circuit section 3 in which wiring patterns and electronic parts (not shown) are arranged on the upper surface of a rectangular substrate 2, and legs of a metal cover 4 covering the high frequency circuit section 3. The part 4 a is soldered to the corner 2 a of the substrate 2. The metal cover 4 is a shield cover formed by bending a flat metal plate, and electromagnetically shields the high-frequency circuit unit 3. A through hole 5 into which the leg portion 4 a of the metal cover 4 is inserted is formed in the corner 2 a of the substrate 2, and an annular solder land 6 adjacent to the upper edge of the through hole 5 is formed on the substrate 2. It is formed on the upper surface. However, in the present embodiment, no through-hole conductor is provided on the inner wall portion of the through-hole 5. Therefore, the leg portion 4 a of the metal cover 4 is joined only to the solder land 6 by the solder 10, and the solder land 6 is electrically connected to a ground pattern which is a part of the wiring pattern of the high frequency circuit portion 3.

  A large number of connection lands 7 electrically connected to the wiring pattern of the high-frequency circuit unit 3 are disposed on the lower surface of the substrate 2. In the present embodiment, these connection lands 7 are arranged on the peripheral edge of the substrate 2, but the connection lands 7 may be arranged in a region other than the peripheral edge of the substrate 2 (such as the central portion). The electronic circuit unit 1 is surface-mounted on the mother board 20 by mounting these connecting lands 7 on the corresponding land portions of the mother board 20 and soldering.

  Further, on the lower surface of the substrate 2, a C-shaped first reinforcing land 8 is provided at the corner 2a, and a plurality of circular second reinforcing lands 9 are disposed in the vicinity of the corner 2a. . The first reinforcement land 8 substantially surrounds the lower edge of the through hole 5 while being separated from the lower edge of the through hole 5, and the through hole 5 is exposed between the notch 8a and the corner edge 2b of the corner 2a. ing. The notch 8a is formed as an air vent for releasing the expanded air in the through hole 5 in the reflow process during mounting. The second reinforcement land 9 is juxtaposed with the first reinforcement land 8. These reinforcing lands 8 and 9 are formed larger than the connecting lands 7 and are mounted on the corresponding land portions of the mother board 20 and soldered in the same manner as the connecting lands 7. By doing so, the corner 2a of the substrate 2 can be firmly fixed to the mother board 20.

  As described above, in the electronic circuit unit 1 according to this embodiment, the leg portion 4 a of the metal cover 4 is soldered only to the solder land 6 on the upper surface of the substrate 2, and the through-hole conductor is provided in the through hole 5. Therefore, there is no possibility that the solder 10 that joins the leg 4a to the corner 2a protrudes greatly from the lower surface of the board 2 to the mother board 20 side. Therefore, the electronic circuit unit 1 can always be mounted on the mother board 20 in a stable posture and is unlikely to cause mounting failure. Further, the through hole 5 into which the leg portion 4a of the metal cover 4 is inserted is surrounded by the first reinforcing land 8 at the corner edge 2b side of the corner portion 2a on the lower surface of the substrate 2, and therefore the first reinforcing land. By soldering 8 to the mother board 20, the corner 2 a can be firmly fixed to the mother board 20. In addition, since the second reinforcement land 9 is arranged in the vicinity of the first reinforcement land 8, the corner portion 2a and the vicinity thereof can be obtained by soldering the first and second reinforcement lands 8 and 9 to the mother board 20. Can be firmly fixed to the mother board 20. Therefore, the electronic circuit unit 1 is less likely to warp the corner 2a of the substrate 2 due to an impact such as when dropped. Further, since the first reinforcing land 8 is separated from the peripheral edge of the lower end of the through-hole 5, the leg portion 4a of the metal cover 4 and the first reinforcing land 8 are not soldered, and the first reinforcing land 8 is mounted at the time of mounting. The solder that should adhere to the reinforcing land 8 does not escape into the through hole 5. Therefore, the mounting strength with respect to the mother board 20 is high, and it is a highly reliable electronic circuit unit that is difficult to peel off from the mother board 20 even when an impact is applied when dropped.

  The first reinforcing land 8 can be formed in an appropriate shape that substantially surrounds the through-hole 5 with a predetermined interval, but the first reinforcing land 8 has a substantially C-shape as in this embodiment. And the 1st reinforcement land 8 and the through-hole 5 can be efficiently arrange | positioned in the corner 2a of the board | substrate 2. FIG. If the solder land 6 is provided with a notched portion for venting air, the notched portion 8a of the first reinforcing land 8 can be omitted. In this case, the first reinforcing land 8 is formed in an annular shape, for example. be able to.

  Next, an electronic circuit unit according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. However, in these FIGS. 4 and 5, since the same reference numerals are given to the portions corresponding to the first embodiment described above, the overlapping description is omitted.

  In the electronic circuit unit 11 according to the second embodiment, the through-hole conductor 12 is provided on the inner wall portion of the through hole 5 of the substrate 2, and the solder land 6 is reduced in diameter accordingly, the first embodiment. It is very different from the example. That is, in this electronic circuit unit 11, the leg 4 a of the metal cover 4 is soldered not only to the solder land 6 on the upper surface of the substrate 2 but also to the through-hole conductor 12 in the through hole 5. A sufficient soldering strength can be secured to the leg portion 4a without forming a large thickness. As a result, since the area occupied by the solder lands 6 on the upper surface of the substrate 2 can be suppressed, the space for the high-frequency circuit unit 3 can be expanded to the vicinity of the corner 2a, and the electronic circuit unit 11 can be reduced in size and functionality. It is easy to promote. In the second embodiment as well, since the land to be soldered to the leg portion 4a is not provided on the lower surface of the substrate 2, there is a possibility that the solder 10 protrudes greatly from the lower surface of the substrate 2 to the mother board 20 side. Absent.

DESCRIPTION OF SYMBOLS 1,11 Electronic circuit unit 2 Board | substrate 2a Corner part 2b Corner edge 3 High frequency circuit part 4 Metal cover 4a Leg part 5 Through-hole 6 Solder land 7 Connection land 8 1st reinforcement land 8a Notch part 9 2nd reinforcement land 10 Solder 12 Through-hole conductor 20 Motherboard

Claims (4)

A circuit board provided on the upper surface and a connection runt group provided on the lower surface are electrically connected to each other, and a leg portion that is inserted into a through hole in the corner portion of the substrate and soldered to the corner portion. An electronic circuit unit comprising a metal cover attached to the substrate in a state of covering the circuit portion, and being surface-mounted by soldering the connection runt group to a motherboard,
Solder lands for soldering the legs are provided only on the upper surface of the substrate at the corners of the substrate, and at least the through holes are separated from the lower peripheral edge of the through holes on the lower surface of the substrate. A reinforcing land surrounding the lower edge is provided on the corner edge side of the corner closest to the corner, and the reinforcing land is a part to be soldered to the motherboard, and at least one of the reinforcing land and the solder land is An electronic circuit unit comprising a notch for venting air.   2. The reinforcing land according to claim 1, wherein the reinforcing land is formed in a C shape surrounding a lower end periphery of the through hole, and the through hole is located between the notch and the corner edge of the substrate corner. An electronic circuit unit characterized by comprising:   3. The electronic circuit unit according to claim 1, wherein a second reinforcing land is provided in the vicinity of the corner portion of the lower surface of the substrate, in addition to the reinforcing land.   4. The method according to claim 1, wherein the leg portion is soldered to the solder land provided on the upper surface of the substrate and the through-hole conductor provided in the through hole. A featured electronic circuit unit.

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