JP2011243879A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board capable of stably connecting an electronic component and a printed circuit board while restraining height of components mounted on the circuit board.SOLUTION: The circuit board comprises a printed circuit boar 11, a dummy component 13 soldered to the printed circuit board 11 on both right and left ends but not constituting an electric circuit constituted by the printed circuit board, and an electronic component 12 mounted between a first straight line L1 on a leftmost end and a second straight line L2 on a rightmost end among upward and downward straight lines passing through a solder 17 connecting the printed circuit board 11 and the dummy component 13, and constituting the electric circuit together with the printed circuit board. The electronic component 12 has a thermal expansion coefficient smaller than that of the printed circuit board 11, and the thermal expansion coefficient of the protection component 13 is set near the thermal expansion coefficient of the electronic component 12.

Description

  The present invention relates to a circuit board.

  Conventionally, there has been provided a circuit board in which an electronic component such as a surface mount LED package having a low thermal expansion coefficient, for example, a ceramic is directly solder-mounted on a printed circuit board having a high thermal expansion coefficient. Since the circuit board has a large difference in thermal tension between electronic components and printed circuit boards, the circuit board can be used by repeated changes in the usage environment of the circuit board (increase and decrease in ambient temperature) and repeated heating and cooling of electronic components. There is a possibility that cracks may occur in the solder connecting the printed circuit board and the electronic component. If a crack occurs in the solder, the connection between the printed board and the electronic component becomes unstable, and the circuit board may not operate normally.

  Therefore, in order to stably connect the printed circuit board and the electronic component, a U-shaped external connection terminal 153 made of an elastic body is provided between the electronic component 151 and the printed circuit board 152 as shown in FIG. An intervening circuit board P is provided (see, for example, Patent Document 1).

  In the circuit board P, when the electronic component 151 and the printed circuit board 152 are thermally expanded or contracted due to a change in the ambient temperature or the like, due to the difference in thermal expansion coefficient between the two components, Shear force is generated. However, the external connection terminal 153 receives the shear force and elastically deforms to absorb the shear ground force. Therefore, the connection between the electronic component 151 and the printed board 152 is stabilized via the external connection terminal 153, and the operation of the circuit board is also stabilized.

  As another circuit board for stabilizing the connection between the electronic component and the printed board, a circuit board Q having a spring member 165 interposed between the electronic component 161 and the printed board 163 is provided (for example, a patent). Reference 2).

  The electronic component 161 includes a plurality of electrodes 162, and the printed circuit board 163 includes a plurality of lands 164 that respectively correspond to the plurality of electrodes 162. The spring member 165 includes a plurality of elastic pieces 166, and the plurality of elastic pieces 166 individually connect the plurality of electrodes 162 and the plurality of lands 164.

  When the electronic component 161 and the printed circuit board 163 are thermally expanded or contracted due to a change in ambient temperature or the like, a shear force is generated between the two members due to the difference in thermal expansion coefficient between the two components. To do. However, the spring member 165 receives the shearing force and elastically deforms to absorb the shearing ground force. Therefore, the connection between the electronic component 161 and the printed board 163 is stabilized via the spring member 165, and the operation of the circuit board is also stabilized.

JP 2006-303396 A JP 2002-353372 A

  However, in the circuit boards P and Q, the circuit boards P and Q are separated from the printed boards 152 and 163 and the electronic components 151 and 161 by separately providing components (external connection terminals 153 and spring members 165). There was a problem that the height of the mounted component would be high.

  The present invention has been made in view of the above reasons, and its object is to provide a circuit board in which the connection between the electronic component and the printed board is stable while suppressing the height of the part mounted on the circuit board. There is to do.

  In order to solve the above-described problems, a circuit board according to the present invention includes a printed circuit board, an electric circuit formed by the printed circuit board, wherein one end side in the first direction and the other end side in the first direction are connected to the printed circuit board. Of the straight line formed in the second direction perpendicular to the first direction and passing through the connecting portion between the printed circuit board and the protective component, the protective component not configured, the first end side in the first direction A protected part that is mounted on the printed circuit board between one straight line and a second straight line on the other end side in the first direction, and that constitutes an electric circuit together with the printed circuit board, and The component has a smaller thermal expansion coefficient than the printed circuit board, and the thermal expansion coefficient of the protection component is set in the vicinity of the thermal expansion coefficient of the protected component.

  In the circuit board, it is preferable that the protected component is mounted on one surface of the printed circuit board, and the protective component is mounted on the other surface.

  In the circuit board, the protected component is preferably opposed to the dummy component via the printed board in the thickness direction of the printed board.

  Also, in this circuit board, the printed circuit board is formed with a wiring pattern constituting the electric circuit, the protected component is connected to a first land formed on the wiring pattern, and the protective component is The printed circuit board is preferably connected to a second land formed independently from the wiring pattern.

  Further, in this circuit board, the printed circuit board is formed with a wiring pattern constituting the electric circuit, and the protection component includes a plurality of terminal portions, and the plurality of terminal portions have the same potential in the wiring pattern. It is preferable to connect to each location.

  In the present invention, there is an effect that it is possible to provide a circuit board in which the connection between the electronic component and the printed board is stable while suppressing the height of the parts mounted on the circuit board.

The principal part enlarged view of the circuit board in Embodiment 1 of this invention is shown. The side view of the circuit board in the same as the above is shown. The schematic of the circuit board of another form in the same as the above is shown. The schematic of the circuit board in Embodiment 2 of this invention is shown. The schematic diagram of the circuit board in Embodiment 3 of the present invention is shown. The schematic of the circuit board of another form in the same as the above is shown. The schematic diagram of the circuit board in a prior art example is shown. The schematic of the circuit board of another form in the same as the above is shown.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The circuit board A of the present embodiment will be described with reference to FIGS. In the following description, the vertical and horizontal directions in FIG. 1 are used as a reference, and the direction perpendicular to the vertical and horizontal directions is the front and rear direction.

  As shown in FIG. 1, the circuit board A of the present embodiment includes a substantially rectangular plate-like printed board 11 on which a wiring pattern 110 is formed, an electronic component (a protected part) 12 mounted on the printed board 11, It consists of a dummy component (protective component) 13 mounted in the vicinity of the electronic component 12.

The printed circuit board 11 is made of, for example, a glass epoxy base body laminated laminate, is formed in a rectangular plate shape that is long in the left-right direction, and has a thermal expansion coefficient of 14 × 10 ⁻⁶ / ° C. A pair of lands 14L, 14R are arranged in the left-right direction on the front surface of the printed circuit board 11, and the pair of lands 14L. 14R is connected to wiring patterns 110 (110L, 110R) having different potentials. The pair of lands 14L and 14R are formed on the printed circuit board 1 when the land 14L is formed on the left side and the land 14R is formed on the right side. The wiring pattern 110 to which the land 14L is connected is referred to as a wiring pattern 110L, the wiring pattern 110 to which the land 14R is connected is referred to as a wiring pattern 110R, and the wiring patterns 110L. When 110R is not distinguished, it is referred to as a wiring pattern 110.

  A pair of lands 14L. Above 14R, a pair of lands 15L and 15R for mounting the dummy component 13 are provided in parallel in the left-right direction, independent (insulated) from the wiring pattern 110. The lands 15L and 15R are referred to as lands 15 when the lands 15L are formed on the left side and the lands 15R are formed on the right side, and the lands 15L and 15R are not distinguished from each other.

  Here, in this embodiment, a pair of lands 14L and 14R are formed between a straight line L11 along the vertical direction passing through the right end of the land 15L and a straight line L21 along the vertical direction passing through the left end of the land 15R. .

The electronic component 12 is a rectangular chip resistor made of alumina and has a thermal expansion coefficient of 7 × 10 ⁻⁶ / ° C. Here, as an example of the electronic component 12, a so-called 1608 size chip resistor having a long side of 1.6 mm and a short side of 0.8 mm is used.

  Terminal portions 121L and 121R are respectively formed on the short sides of the electronic component 12 along the short sides, and the terminal portions 121L and 121R are soldered to the pair of lands 14L and 14R on the printed circuit board 11, respectively. Connected. As a result, the electronic component 12 is mounted on the printed board 11 and constitutes an electric circuit together with the wiring pattern 110.

  Further, the electronic component 12 is mounted on the printed circuit board 11 with its longitudinal direction being along the left-right direction. In FIG. 1, only a part of the circuit board 1 is shown, and only a part of the electric circuit is shown.

The dummy component 13 is formed of a rectangular alumina-based chip jumper having a longitudinal dimension larger than that of the electronic component 12, and has a coefficient of thermal expansion of 7 × 10 ⁻⁶ / ° C. Here, as an example of the dummy component 13, a so-called 3216 size chip jumper having a long side of 3.2 mm and a short side of 1.6 mm is used.

  Terminal portions 131L and 131R are formed on the short sides of the dummy component 13 along the short sides. The dummy component 13 is mounted on the printed circuit board 11 by soldering the terminal portions 131L and 131R to the pair of lands 15L and 15R on the printed circuit board 11, respectively. That is, like the electronic component 12, the dummy component 13 is mounted on the printed circuit board 11 with its longitudinal direction aligned with the left-right direction.

  Thereby, the electronic component 12 and the dummy component 13 are arranged side by side on the printed circuit board 11 along the up-down direction. Here, since the terminal parts 131L and 131R are connected to the pair of lands 15L and 15R that are insulated and independent from the wiring pattern 110, the dummy component 13 does not constitute the electric circuit.

  Here, the electronic component 12 is mounted between the straight lines L1 and L2 along the vertical direction through the solder (connection portion) 17 that connects the terminal portions 131L and 131R of the dummy component 13 and the lands 15L and 15R on the printed circuit board 11. ing.

During energization, the temperature of the circuit board A rises due to the heat generation of the electronic component 12 and the temperature rise in the casing of the device (not shown) including the circuit board A, and the printed board 11 and the electronic component 12 expand thermally. Further, when the energization is interrupted, the temperature of the printed circuit board 11 and the electronic component 12 gradually decreases to normal temperature and thermally contracts. Here, the thermal expansion coefficient (7 × 10 ⁻⁶ / ° C.) of the dummy component 13 is half of the thermal expansion coefficient (14 × 10 ⁻⁶ / ° C.) of the printed circuit board 11, and the thermal expansion coefficient (7 × 10 ⁻⁶ / ° C.) That is, the electronic component 12 and the dummy component 13 are half the amount of expansion or contraction with respect to the temperature change of the printed board 11.

  Here, since the thermal expansion coefficient of the printed circuit board 11 is larger than that of the electronic component 12 (twice), when the dummy component 13 is not mounted, the thermal expansion and the thermal contraction occur continuously. In addition, a shearing force is repeatedly applied to the solder 16. This may cause cracks in the solder 16 that connects the printed circuit board 11 and the electronic component 12.

  However, in the circuit board of the present embodiment, the dummy component 13 is arranged in parallel with the electronic component 12. Therefore, when the thermal expansion or contraction occurs, a part of the thermal stress applied to the solder 16 connecting the electronic component 12 and the printed board 11 by the pair of solders 17 connecting the printed board 11 and the dummy component 13. Is absorbed. The pair of solders 17 absorb thermal stress, so that the amount of expansion or contraction of the printed circuit board 11 between the straight lines L1 and L2 passing through the pair of solders 17 is suppressed. Therefore, the thermal stress acting on the solder 16 connecting the electronic component 12 mounted between the straight lines L1 and L2 and the printed circuit board 11 can be reduced, and the solder 16 can be prevented from cracking. That is, the connection state between the electronic component 12 and the printed board 11 is stabilized, and the operation of the circuit board is stabilized.

  Furthermore, in the circuit board A of the present embodiment, it is not necessary to interpose the external connection terminal 153 shown in FIG. 8 or the spring member 165 shown in FIG. 9 between the printed board 11 and the electronic component 12. The component height of components mounted on the printed circuit board 11 can be suppressed.

  Further, as described above, the dummy component 13 is connected to the independent lands 15L and 15R by being insulated from the electric circuit composed of the printed circuit board 11 and the electronic component 12. Accordingly, when the circuit board A is folded, even if the dummy component 13 is broken due to deformation or the solder 17 that connects the dummy component 13 and the land 15 is cracked, the electric circuit is affected. There is nothing.

  Further, in the above embodiment, the terminals 131L and 131R are formed on the short sides (both left and right ends) of the dummy component 13, respectively, and the terminals 131L and 131R are connected to the printed circuit board 11 by the solder 17. However, as shown in FIG. 3, instead of forming the terminals 131 </ b> L and 131 </ b> R, the terminals 13 a may be formed on each long side (upper and lower ends) of the dummy component 13. In that case, the electronic component 12 should just be mounted between the straight line L3 along the up-down direction passing through the left end of the terminal part 13a, and the straight line L4 along the up-down direction passing through the right end of the terminal part 13a.

  In the present embodiment, the size of the electronic component 12 is a so-called 1608 size, and the size of the dummy component 13 is a so-called 3216 size. However, the size is not limited to this.

(Embodiment 2)
The circuit board B of the present embodiment will be described with reference to FIG.

  The circuit board B of the present embodiment is different from the circuit of the first embodiment in that the dummy component 13 is mounted on the wiring pattern 110L to which one terminal portion (left terminal in the present embodiment) 121L of the electronic component 12 is connected. Different from substrate A. Since other configurations are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

  In the circuit board B of the present embodiment, a wiring pattern 110L to which the left terminal 121L of the electronic component 12 is solder-connected is extended from the connection location toward the dummy component 13 side (upper side). The wiring pattern 110L is extended and then widened in the left-right direction to form a widened portion 110a, and the dummy component 13 is mounted on the widened portion 110a.

  In the dummy component 13, a pair of terminals 131 </ b> L and 131 </ b> R are connected to the widened portion 110 a by soldering 17. That is, the dummy component 13 is short-circuited because the pair of terminals 131 </ b> L and 131 </ b> R are connected to the same potential in the wiring pattern 110.

  Therefore, when the circuit board B is folded, even if cracks occur in the solder 17 that connects the terminal portions 131L and 131R and the printed circuit board 11, an electric circuit composed of the electronic component 12 and the wiring pattern 110 is formed. Does not affect the operation of the circuit.

  Further, since the dummy component 13 is mounted (soldered) on the wiring pattern 110L, it is not necessary to separately provide a land for mounting the dummy component 13 on the circuit substrate 1, so that the size of the circuit substrate 1 is reduced. Can be small. For example, when a land for mounting the dummy component 13 is separately provided on the printed board 11, it is necessary to insulate the wiring pattern 110 to which the electronic component 12 is connected from the land to which the dummy component 13 is connected. For this reason, it is necessary to provide a predetermined creepage distance between the wiring pattern 110 and the land, and the size of the printed circuit board 11 is increased.

  On the other hand, in this embodiment, since the dummy component 13 is mounted on a part of the wiring pattern 110, it is not necessary to provide the creeping distance, and the distance between the electronic component 12 and the dummy component 13 is reduced. And the size of the circuit board 1 can be suppressed.

(Embodiment 3)
The circuit board C of this embodiment will be described with reference to FIG.

  As shown in FIGS. 5A and 5B, the circuit board C of the present embodiment is mounted on a surface (rear surface) opposite to the surface (front surface) on which the electronic component 12 is mounted. This is different from the circuit board A of the first embodiment. Since other configurations are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

  In the circuit board C of the present embodiment, the dummy component 13 is placed at a position (printed circuit board 11) that is reverse to the position where the printed circuit board 11 is sandwiched from the position (the front surface of the printed circuit board 11) mounted on the circuit board A of the first embodiment. Is implemented on the rear side). That is, the lands 15L and 15R are arranged in the left-right direction on the rear surface of the printed circuit board 11, and the terminals 131L and 131R of the dummy component 13 are connected to the pair of lands 15L and 15R by the solder 17, respectively.

  Further, on the front surface of the printed circuit board 11, there is a pair of lands 14L and 14R between a straight line L11 passing through the right end of the land 15L and extending in the vertical direction and a straight line L21 passing through the left end of the land 15R and extending in the vertical direction. Each is formed. The terminals 121L and 121R of the electronic component 12 are connected to the pair of lands 14L and 14R by the solder 16, respectively.

  Here, as in the first embodiment, the electronic component 12 includes the solder L that connects the terminal portion 13L and the printed board 11 through the solder 17 that connects the terminal portion 13L and the printed board 11, and the straight line L1 that extends along the vertical direction. It is mounted between the straight line L2 passing through 17 and extending in the vertical direction.

  Therefore, in the vicinity of the place where the dummy component 13 is mounted on the printed circuit board 11, the expansion or contraction of the printed circuit board 11 that occurs when the temperature of the printed circuit board 11 changes is suppressed by the dummy component 13. In particular, the expansion or contraction of the printed circuit board 11 is suppressed between the straight lines L1 and L2. Therefore, the shearing force acting on the solder 16 connecting the electronic component 12 mounted between the straight lines L1 and L2 and the printed board 11 can be suppressed. It is possible to prevent the solder 16 from cracking.

  Further, the land 14 to which the electronic component 12 is connected is formed on the front surface of the printed circuit board 11, and the land 15 to which the dummy component 13 is connected is formed on the rear surface of the printed circuit board 11, so that the land 14 and the land 15 are vertically aligned. There is no need to provide a creepage distance for insulation. Therefore, the distance between the electronic component 12 and the dummy component 13 can be reduced, and the size of the circuit board 1 in the vertical direction can be suppressed.

  Further, for example, as shown in FIG. 6, the electronic component 12 and the dummy component 13 can be mounted to face each other via the printed board 11, and the vertical direction of the circuit board 11 can be achieved by mounting as described above. The size at can be made smaller.

  Further, for example, as shown in FIG. 5C, when the circuit board 1 is stored in the housing 4, the front surface of the circuit board 1 is close to the inner wall of the housing 4, and the circuit board 1 side from the inner wall. Even if the reinforcing rib 4a protruding to the side is formed, the reinforcing rib 4a does not interfere with the dummy component 13.

A Circuit board 11 Printed circuit board 12 Electronic component (protected component)
13 Dummy parts (protective parts)
14 (14L, 14R) Land (first land)
15 (15L, 15R) Land (second land)
16 Solder (connection part)
17 Solder (connection part)
110 (110L, 110R) wiring pattern 131L. 131R terminal part L1 straight line (first straight line)
L2 straight line (second straight line)

Claims (5)

A printed circuit board,
One end side in the first direction and the other end side in the first direction are connected to the printed board, and a protective component that does not constitute an electrical circuit that the printed board constitutes,
Of the straight lines formed in the second direction orthogonal to the first direction and passing through the connecting portion between the printed circuit board and the protective component, the first straight line on the most end side in the first direction, Mounted on the printed circuit board between the second straight line on the other end side in the first direction and comprising a protected component that constitutes an electric circuit together with the printed circuit board,
The circuit board, wherein the protected component has a smaller thermal expansion coefficient than the printed circuit board, and the thermal expansion coefficient of the protective component is set in the vicinity of the thermal expansion coefficient of the protected component.   The circuit board according to claim 1, wherein the protected component is mounted on any one surface of the printed circuit board, and the protective component is mounted on any other surface.   The circuit board according to claim 2, wherein the protected component is opposed to the dummy component through the printed board in a thickness direction of the printed board. The printed circuit board is formed with a wiring pattern constituting the electric circuit,
The protected component is connected to a first land formed on the wiring pattern,
4. The circuit board according to claim 1, wherein the protective component is connected to a second land formed independently of the wiring pattern on the printed board. 5. The printed circuit board is formed with a wiring pattern constituting the electric circuit,
4. The circuit board according to claim 1, wherein the protective component includes a plurality of terminal portions, and the plurality of terminal portions are respectively connected to portions having the same potential in the wiring pattern. 5.

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