JP2010225761A - Member for holding electronic component, and printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve soldering by a reflow soldering capable of reducing soldering defects. <P>SOLUTION: In this member for holding an electronic component in a reflow soldering process of applying solder cream to a surface of a metal plate, and mounting the electronic component on this printed board to solder the electronic component by reflow soldering, a central part thereof holds the electronic component in the own weight direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to reflow soldering of electronic components, and more particularly to a technique for simultaneously soldering a printed board and electronic components to a metal plate.

  Conventionally, a reflow soldering technique has been used to solder an electronic component to a printed circuit board (see, for example, Patent Document 1). Further, when a heat-generating component such as a power amplifier is soldered to a printed board, a metal plate is often soldered under the printed board for the purpose of heat dissipation.

  Conventional reflow soldering will be described with reference to FIGS. 1 and 2. FIG. 1 is an exploded perspective view for explaining an assembly procedure before conventional reflow soldering. 2 is a result of the assembly of FIG. 1, FIG. 2 (a) is a perspective view showing an appearance just before reflow soldering, and FIG. 2 (b) is a cross-sectional view (a part) taken along the line AA after assembly. . 10 is an arrow indicating the direction in which the weight is applied, 11 is a metal plate, 12 is a cream solder applied to the surface of the metal plate 11, 13 is a printed circuit board, 14 is a through hole provided in the printed circuit board 13, 15 is an electronic component, Reference numerals 16 and 17 denote connection terminals of the electronic component 15, and reference numerals 18 and 19 denote connection patterns provided on the upper surface of the printed board 13. In addition to the connection terminals 17 and 18, there are connection patterns and electric circuit wiring patterns on the upper surface (front surface) of the printed circuit board 13, but they are omitted. Further, a connection pattern (solid pattern) for electrically and mechanically connecting the metal plate 11 and the back surface of the printed circuit board 13 is also provided on the back surface (the surface in contact with the cream solder 12) of the printed circuit board 13.

  The electronic component 15 is, for example, a power amplifier, and the printed board 13 is, for example, a two-layer glass epoxy board. For example, the pattern of the printed circuit board 13 is a copper foil. Further, the connection pattern on the back surface of the printed circuit board 13 is a substantially solid pattern for grounding, and there are many through holes (not shown) for electrical connection between the grounding pattern on the back surface and the surface. The through holes and solid patterns are omitted and not shown.

In FIG. 1, cream solder 12 is applied to the upper surface of the metal plate 11 in order to assemble the metal plate 11, the printed circuit board 13, and the electronic component 15.
As a method of applying the cream solder 12 to the upper surface of the metal plate 11, a known technique is used. For example, there are a solder printing method, a dispensing method, and the like. Further, as another method, there is a method of sandwiching a solder sheet between them.

Thereafter, the printed circuit board 13 is placed on the metal plate 11 as shown in the perspective view of FIG. Next, the body part of the electronic component 15 enters the through hole 14 of the printed circuit board 13 so that the connection terminal 16 of the electronic component 15 is aligned with the connection pattern 18 and the connection terminal 17 is aligned with the connection pattern 19. To place. Note that the electronic component 15 may be first placed on the printed board 13 and then placed on the metal plate 11.
As a result, they are assembled as shown in a partial cross-sectional view shown in FIG. 2 (b), and their own weight is applied in the direction of arrow 10, and they are in contact with each other by their own weight and the adhesive force of the solder cream 12.

As described above, when the printed circuit board 13 and the electronic component 15 are assembled on the metal plate 11 via the cream solder 12, the perspective view shown in FIG.
After completion of the operations up to FIG. 2, a soldering operation is performed by a reflow soldering method, and the upper surface of the metal plate 11 and the back surface of the printed board 13, and the upper surface of the metal plate 11 and the lower surface of the electronic component 15 are soldered.
Note that cream solder may be applied to the connection patterns 18 and 19, and the connection terminals 16 and 17 may be soldered simultaneously with the reflow soldering. Further, the connection terminals 16 and 17 and the connection patterns 18 and 19 may be soldered in separate processes.

JP 2005-286099 A

In general, when assembling a metal plate, a printed circuit board, and an electronic component, a jig or the like is used for soldering by the reflow soldering method in order to maintain alignment accuracy.
However, when soldering using the reflow soldering method described above, the printed circuit board and the electronic components are pressed downward (in the direction of their own weight) only by the adhesive force and gravity of the cream solder, so the solder on the metal plate melts. Until it solidifies (during reflow soldering work), it is easily affected by defects.
For example, due to variations in the thickness of applied cream solder, variations in density (distribution distribution of contents such as flux), differences in weight due to the location of printed circuit boards and electronic components, etc., misalignment and bubbles in the solder layer of the connection part Occurs.
For this reason, it is easy to be affected by the variation of the molten state of the solder due to the vibration and inclination of the conveying belt during reflow soldering and the variation of the temperature distribution, and the soldering position shift is likely to occur. In addition, bubbles generated when the cream solder is melted remain, and the electrical connection force and heat conduction characteristics between the printed board or electronic component and the metal plate are reduced, and the electrical performance and reliability may be deteriorated.
In view of the above problems, an object of the present invention is to realize soldering by a reflow soldering method that can reduce soldering defects.

In order to solve the above problems, the present invention uses a pressing member for an electronic component.
That is, the present invention is a pressing member for an electronic component in a reflow soldering process in which a solder cream is applied on a metal plate, the printed circuit board and the electronic component are mounted, and the electronic component is soldered by reflow soldering. When a force in the inner direction is applied to the part, the center part bends in the lower direction, and is a pressing member for an electronic component.
In the printed circuit board on which the electronic component is mounted and has a solid pattern on the back surface and the back surface is bonded to the metal plate by soldering, there are through holes on both sides of the position where the electronic component is mounted. A printed circuit board characterized by the above.

  According to the present invention, it is possible to realize soldering by a reflow soldering method that can reduce soldering defects.

It is a disassembled perspective view for demonstrating the assembly procedure before the conventional reflow soldering. It is a figure for demonstrating the external appearance just before the conventional reflow soldering. It is a disassembled perspective view for demonstrating the assembly procedure before the reflow soldering of one Example of this invention. It is a perspective view of the result of having combined the metal plate 11, the printed circuit board 13, and the electronic component 15 of one Example of this invention. It is a perspective view which shows one Example of the holding member of this invention. It is a perspective view which shows one Example of the holding member of this invention. It is a perspective view which shows the external appearance just before reflow soldering of one Example of this invention. It is a perspective view which shows the external appearance just before reflow soldering of one Example of this invention. It is a partial cross section figure which shows the structure of FET mounted in the printed circuit board as a result of one Example of this invention. It is a perspective view for demonstrating one Example of the printed circuit board of this invention.

An embodiment of the present invention will be described below. In the description of each figure, components having the same function are given the same reference numerals, including those in FIGS. 1 and 2 describing the prior art, and the description will be omitted as much as possible to avoid duplication.
The embodiments described below are for explanation, and do not limit the scope of the present invention. Accordingly, those skilled in the art can employ embodiments in which these elements or all of the elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is an exploded perspective view for explaining an assembly procedure before reflow soldering according to an embodiment of the present invention. Reference numeral 31 denotes a metal plate, 32 denotes a through hole provided in the metal plate 31, 33 denotes a printed board, 34 denotes a through hole provided in the printed board 33, and 12 'denotes cream solder. FIG. 4 is a view for explaining a result of assembling the metal plate 31, the printed circuit board 33, and the electronic component 15. FIG. 4A is a perspective view showing an appearance just before reflow soldering, and FIG. 4B is a cross-sectional view (partial) taken along BB after assembly. FIG. 5 is a perspective view showing an embodiment for explaining a pressing member for an electronic component of the present invention. Reference numeral 51 denotes an electronic component pressing member for pressing the electronic component 15. In the electronic component pressing member 51 of FIG. 5B, 55 is a component pressing portion, 56 is a buffer portion, 57 is a leg portion, and 58 is a claw portion. FIG. 6 is a perspective view showing an embodiment for attaching the pressing member of the present invention. Reference numeral 61 denotes a pressing member for pressing the printed circuit board 33 in addition to the pressing member 51 shown in FIG. FIG. 7 is a perspective view showing an appearance just before reflow soldering according to an embodiment of the present invention.

In FIG. 3, the point different from the conventional one is that a through hole 34 for passing the end portion of the pressing member 51 shown in FIG. 5 is provided in the printed board 33, and the pressing member is provided on the metal plate 31 corresponding to each of the through holes 34. That is, the through hole 32 for attaching the end portion 51 is provided.
Thereafter, as shown in FIG. 4, the printed circuit board 33 is placed on the metal plate 21 to which the cream solder 12 ′ is applied. Next, the body part of the electronic component 15 is placed in the through hole 34 of the printed circuit board 33 so that the connection terminal 16 of the electronic component 15 matches the connection pattern 18 and the connection terminal 17 matches the connection pattern 19. To do. The electronic component 15 may be first placed on the printed board 33 and then placed on the metal plate 31.

As described above, when the printed circuit board 33 and the electronic component 15 are combined on the metal plate 31 via the cream solder 12 ', a perspective view shown in FIG. In addition, a solid pattern (copper foil, etc .: not shown) for grounding is provided on the surface of the back surface of the printed circuit board 31 on which the solder cream 12 'comes into contact so that the solder can be easily adhered. The metal plate 31 is usually made of a metal having excellent thermal conductivity and electrical conductivity (for example, copper, aluminum, etc.), but its surface is also plated so that the solder cream 12 'can be easily adhered. The surface processing is done.
The cream solder 12 'is also called a solder paste, and is a state in which the solder (brazing material) is mixed to be ready for printing or dispensing.
FIG. 4B is a cross-sectional view (partial) taken along the line BB in FIG. The through hole 34 provided in the printed circuit board 33 continues to the through hole 32 of the metal plate 31 in its own weight direction 10 as it is (the cream solder 12 ′ portion is not shown).

After the operation of FIG. 4, the claw portion 58 of the pressing member 51 shown in FIG. 5 is inserted and attached to the through hole 34 and the through hole 32. That is, in FIG. 5B, the holding member 51 has a height Hu from the back surface (bottom surface) of the metal plate 31 so that the electronic component 15 is pressed in the direction of gravity (arrow 53). The distance is set to be smaller than the distance Hb to the upper surface (or the distance Ha that does not take into account the thickness of the cream solder 12 ′) (see FIG. 4B). As a result, when the pressing member is attached, the buffer unit 56 applies a force for pressing the electronic component 15 against the metal plate 31 and the printed board 33 based on the difference in thickness between the height Hu and the distance Ha or Hb.
The claw portion 58 is provided so as to be parallel to the back surface of the metal plate 31, the back surface of the printed circuit board 33, and the bottom portion of the electronic component 15, and the length Wn to both ends of the pressing member 51 corresponds to two. The distance Wm between the through holes 32 (see FIG. 4B) and the length Wu of the pressing member 51 are provided. Similarly, the length Wu of the pressing member 51 is set longer than the distance Wd between the two pairs of through holes 34 (see FIG. 4B). In the case of the embodiment of FIG. 4, the through hole 32 and the through hole 34 have the same shape and dimensions, so that Wm and wd are equal. As a result, when the pressing member is attached, the pressing member 51 is attached and fixed to the metal plate 31 and the printed board 33 by the buffer portion 56 and the leg portion 57.
As a result, the electronic component 15 is pressed and fixed to the printed circuit board 33 and the metal plate 31 by the pressing member 51. Further, the terminals 16 and 17 of the electronic component 15 are pressed and fixed to the connection patterns 18 and 19 of the printed circuit board 33.
For example, the pressing member 51 is formed by bending a metal bar having a circular cross section, or by processing a synthetic resin. At that time, the shape is such that the force as described above is applied.

  Next, as shown in FIG. 6, the pressing member 61 is attached so as to sandwich both ends of the printed board 33 and the metal plate 31. At this time, when the pressing member 61 is sandwiched between both ends of the metal plate 31, a force is applied in the direction parallel to the metal plate 31 and the printed board 33 (the direction indicated by the arrow 62) and outward. At this time, the central portion of the pressing member 61 pushes the upper part of the electronic component 15 downward in the direction indicated by the arrow 63. With this force, the printed circuit board 33 is fixed to the metal plate 31 by the pressing member 61.

  After the work up to FIG. 6, the configuration as shown in FIG. 7 is obtained. In this state, soldering is performed by the reflow soldering method. As a result, the surface of the metal plate 31 and the back surface of the printed circuit board 33 and the surface of the metal plate 31 and the back surface of the electronic component 15 can be soldered. Thereafter, the pressing members 51 and 61 are removed.

  According to the first embodiment, the electronic component and the printed circuit board, the electronic component and the metal plate, and the printed circuit board and the metal plate are mechanically and electrically aligned in a parallel direction with a small positioning angle and a small inclination angle. Can be securely connected.

  A second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a perspective view showing an appearance just before reflow soldering according to an embodiment of the present invention. 81 is a metal plate, 83 is a printed circuit board, 12 ″ is cream solder, 83 is a printed circuit board, 84 is a through hole provided in the printed circuit board 83, 85 is a pressing member for pressing the electronic component 15, and 86 is a printed circuit board. A pressing member for pressing 83.

In FIG. 8, the difference from the first embodiment is that instead of the pressing members 51 and 61 having a circular cross section, rectangular pressing members 85 and 86 having a rectangular cross section are used. For this reason, a through hole 84 for passing the end of the pressing member 85 is provided in the printed circuit board 33 and formed in the metal plate 81 for attaching the end of the pressing member 85 to the metal plate 81 corresponding to each of the through holes 84. Through-holes (not shown) are provided.
The through hole formed in the through hole 84 and the metal plate 81 is a rectangular hole in accordance with the cross-sectional shape of the pressing member 85.

The metal plate 81, the solder 12 ″, the printed circuit board 83, and the electronic component 15 that are overlapped by the operation steps of FIGS. 1 to 4 are fixed to the back surface of the metal plate 81 through the through hole 84 at the end of the pressing member 85. By doing so, the operation described in FIG. 5 is obtained.
That is, the pressing member 85 of the electronic component receives a force applied to the inner side in the lateral (parallel) direction and is fixed to the printed board 83. At this time, the electronic component 15 is pressed and fixed to the metal plate 81 with the central portion of the pressing member 85 downward, and at the same time, the terminals 16 and 17 are pressed and fixed to the connection patterns 18 and 19 of the printed board 83. .

  Similarly to FIG. 6, the printed board 83 and the metal plate 81 are combined and fixed by sandwiching both ends of the metal plate 85 with the end portions of the pressing member 86 interposed therebetween. Then, at that time, the central portion of the pressing member 86 applies a force downward, and presses and fixes the printed board 83 to the metal plate 81.

  According to the embodiment of FIG. 8 above, since the shape of the pressing member is a flat plate and the contact surface is wide, a force is stably applied to the end portion, and the force is stably transmitted to the central portion. Moreover, the force which hold | suppresses an electronic component and a printed circuit board is also widely applied.

FIG. 9 is a partial cross-sectional view showing the structure of an FET (Field Effect Transistor) mounted on a printed circuit board after reflow soldering as a result of an embodiment of the present invention. 91 is a metal plate, 93 is a printed circuit board, 95 is an FET, 92 is solder, 94 is a through hole in which the body of the FET 95 provided on the printed circuit board 93 is disposed, and 98 and 99 are provided on the printed circuit board 93. A connection pattern, D is a drain terminal of the FET 95, S is a source terminal of the FET 95, and G is a gate terminal of the FET 95. The solid pattern on the back surface of the printed circuit board 93 is omitted and not shown.
As shown in FIG. 9, the printed circuit board 93 is mechanically and electrically connected to the printed circuit board 91 by the solder 92, and DrainD is mechanically and electrically connected by the metal plate 91 and the solder 92. The pattern 98 and the solder 92 are mechanically and electrically connected, and the GateG is mechanically and electrically connected by the pattern 99 and the solder 92.

FIG. 10 is a perspective view for explaining another embodiment of the printed circuit board of the present invention. Reference numeral 133 denotes a printed board, 114 denotes a through hole in which a body portion of an electronic component provided on the printed board 133 is disposed, and 134 denotes a through hole.
In the embodiment of FIG. 10, the circular through hole 34 of the embodiment of FIG. 4 is provided at the end of the through hole 114 in which the body portion of the electronic component is disposed.

In Example 1 or Example 2, the pressing member of the electronic component had a circular or flat cross section. However, any cross-sectional shape may be used, and of course, the shape and dimensions may be different at the central portion, the end portion, and the like.
Moreover, in the said Example, the pressing member which hold | suppresses an electronic component was attached previously. However, the pressing member that holds the printed circuit board may be attached first or may be attached at the same time. In some cases, there may be no pressing member for pressing the printed circuit board.
Also, the number of electronic component pressing members for pressing the electronic components and the number of pressing members for pressing the printed circuit board need not be limited to the embodiment, and may be any number.
Further, the electronic component pressing member for pressing the electronic component and the pressing member for pressing the printed circuit board may be integrally manufactured and attached at a time.
Moreover, the shape of a groove part and a through-hole is also arbitrary. Furthermore, a groove, a recess, or a protrusion may be provided on the end of the metal plate so that the pressing member can be easily fixed or positioned.

As described above, the present invention is a pressing member for an electronic component in a reflow soldering process in which a solder cream is applied on a metal plate, the printed circuit board and the electronic component are mounted, and the electronic component is soldered by reflow soldering. The electronic component holding member includes a central portion that holds the electronic component, a leg portion that extends downward, and a claw portion that engages with the metal plate.
Preferably, the pressing member of the electronic component is inserted into the groove portion through a through hole provided in the printed board and a groove portion of a metal plate provided at a position corresponding to the through hole, and the central portion is the electronic part. The reflow soldering is performed by pressing the electronic component against the metal plate and the printed board by pressing the component.
Preferably, the printed circuit board has an electronic component mounted thereon, has a solid pattern on the back surface, and is bonded to the metal plate and the back surface by soldering on both sides of the position where the electronic component is mounted. It has a hole, and attaches the pressing member for the electronic component.
More preferably, a groove portion is provided at a position corresponding to a through hole provided in the printed board in the metal plate, and the pressing member for the electronic component is attached.

  10: Arrow indicating own weight direction, 11: Metal plate, 12, 12 ′, 12 ″: Cream solder, 13: Printed circuit board, 14: Through hole, 15: Electronic component, 16, 17: Connection terminal, 18, 19 : Connection pattern, 31: Metal plate, 32: Through hole, 33: Printed circuit board, 34: Through hole, 51: Pressing part, 55: Component pressing part, 56: Buffer part, 57: Leg part, 58: Claw part 61: Pressing member, 81: Metal plate, 83: Printed board, 84: Through hole, 85: Pressing member, 86: Pressing member, 91: Metal plate, 92: Solder, 93: Printed board, 94: Through hole, 95: FET, 98, 99: Connection pattern, D: Drain terminal, S: Source terminal, G: Gate terminal.

Claims (2)

An electronic component holding member in a reflow soldering process in which a solder cream is applied on a metal plate, a printed circuit board and an electronic component are mounted, and the electronic component is soldered by reflow soldering,
A pressing member for an electronic component, comprising: a central portion for pressing the electronic component downward; a leg portion extending downward; and a claw portion that engages with the metal plate. In a printed circuit board on which electronic parts are mounted, having a solid pattern on the back surface, and bonding the back surface by soldering with a metal plate,
A printed circuit board having through holes on both sides of a position where the electronic component is mounted.

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