JP2012156195A - Electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stress on solder by decreasing the difference of an expansion/contraction degree between a circuit substrate and an electronic component joined to the circuit substrate by soldering, in an electronic device mounted with the electronic component on the circuit substrate by soldering.SOLUTION: A circuit substrate 10 has a linear expansion coefficient larger than that of an electronic component 20. The electronic component 20 is fixed to the circuit substrate 10 at a first electrode 21 and a second electrode 22 through solder 30. A part 13 between fixed portions which is a part positioned between a fixed portion of the first electrode 21 and a fixed portion of the second electrode 22 of the circuit substrate 10 is provided with trough-holes 14 on one surface 11. Therefore, a degree of thermal expansion and thermal contraction of the part 13 between the fixed portions is smaller than that of a part except for the part 13 between the fixed portions of the circuit substrate 10.

Description

  The present invention relates to an electronic device formed by soldering an electronic component on a circuit board such as a printed board.

  In general, this type of electronic device includes a circuit board such as a printed circuit board and an electronic component mounted on the circuit board. The electronic component has a first electrode on one end side and the other end facing the one end side. It is assumed that a second electrode is provided on the side, and electronic components are fixed to the circuit board via solder with the first electrode and the second electrode, respectively (for example, Patent Documents) 1).

  Here, the circuit board and the electronic components mounted on the circuit board are expanded and contracted due to a change in temperature to which they are exposed. When the degree of expansion / contraction is different between the circuit board and the electronic component, the difference is applied as stress (or distortion) to the solder used for fixing / conducting the component.

  In general, the circuit board is made of resin, glass epoxy, or the like, and when the electronic component is made of a ceramic capacitor or the like, the circuit board has a larger linear expansion coefficient than the electronic component. By repeating this temperature change, stress (strain) to the solder is also repeatedly generated, resulting in defects such as poor conduction at the solder fixing portion and part dropping as a crack.

  When the electronic component is enlarged, the distance between the electrodes of the electronic component that is bonded and fixed by the solder also increases, so that the stress (strain) applied to the solder also increases proportionally, and the crack progresses easily. In addition, since expansion / contraction is proportional to temperature, even when the temperature encountered by the device increases, the stress (strain) applied to the solder increases in proportion to the temperature rise, and cracks easily progress. It will be.

  In order to deal with such problems, conventionally, in order to cope with the temperature change to which the device is exposed and the life against it, the electronic parts are divided into functionally equivalent forms for downsizing or a material having a small linear expansion coefficient. By using a technique such as using an electronic component to which the solder is applied, the stress (strain) to the solder is reduced, and the crack does not easily progress.

JP 2002-344092 A

  However, in the conventional method of dividing the electronic component to reduce the size (for example, the resistance having a rated 1 / 2W is reduced to 1 / 4W × 2), the total size of the plurality of electronic components is increased by the division. In addition, since a component interval is required to ensure mountability when mounted on a circuit board, a large component mounting area on the circuit board is required. As a result, the size of the circuit board increases, leading to an increase in cost of the circuit board and an increase in product size. Furthermore, an increase in mounting man-hours due to an increase in the number of components and an increase in component costs are caused.

  In addition, the application of an electronic component made of a material having a small linear expansion coefficient also requires the use of a special material that is not general-purpose, which increases the cost of the electronic component and the circuit board.

  The present invention has been made in view of the above problems, and in an electronic device in which an electronic component is solder-mounted on a circuit board, both expansion and contraction of the circuit board and the electronic component solder-bonded to the circuit board The purpose is to reduce the stress on the solder by reducing the difference in degree.

  In order to achieve the above object, the present inventor has intensively studied. As described above, in this type of electronic device, the degree of thermal expansion and contraction, that is, the linear expansion coefficient, is originally small for electronic components and large for circuit boards. Since the electronic component is fixed to the circuit board by solder bonding at both ends at each electrode, the circuit board having large expansion / contraction causes stress on the solder and damages it.

  In this case, the part of the circuit board located between the two fixed parts fixed to the electronic component, that is, the difference between the degree of expansion / contraction of the part between the fixed parts and the degree of expansion / contraction of the electronic part is It greatly affects the stress. Therefore, attention has been paid to reducing the degree of expansion / contraction of the portion between the fixed portions of the circuit board closer to the electronic component.

  The present invention was created by paying attention to the above points. In the invention according to claim 1, the circuit board (10) and the electronic component (11) mounted on one surface (11) of the circuit board (10) ( 20), and the circuit board (10) has a larger linear expansion coefficient than the electronic component (20). The electronic component (20) has a first electrode (21) on one end side and the one end A second electrode (22) is provided on the other end opposite to the side, and the electronic component (20) includes a circuit board (1) at the first electrode (21) and the second electrode (22), respectively. 10) In the electronic device fixed to the circuit board (10) via the solder (30), the fixed part of the circuit board (10) with the first electrode (21) and the second electrode (22) The part (13) between the fixed parts, which is the part located between the parts, also has holes (14, 15) on one side (11). Ku is characterized in that cuts are provided.

  According to this, the hole (14, 15) or the portion (13) between the fixed parts, which is the part of the circuit board (10) located between the two fixed parts of the electronic component (20) and the circuit board (10), By providing the cut, the degree of expansion / contraction of the part (13) between the fixed parts is made smaller than the part of the other circuit board (10). The difference in the degree of shrinkage can be further reduced, and the stress on the solder (30) can be reduced.

  According to a second aspect of the present invention, in the electronic device according to the first aspect, the hole is a through hole (14) penetrating the circuit board (10) from one surface (11) in the thickness direction. Features.

  According to this, the through hole (14) can be easily formed in the circuit board (10) using a general through hole forming step.

  According to a third aspect of the present invention, in the electronic device according to the first aspect, the hole is a bottomed hole (15) having a bottom while opening on one surface (11) of the circuit board (10). It is characterized by.

  According to this, although there is a possibility that the effect of reducing the degree of expansion / contraction of the portion (13) between the fixed portions may be reduced as compared with the case where the hole is a through hole (14), There is an advantage that it becomes easy to secure a space inside the circuit board (10).

  Further, as in the invention described in claim 4, the hole, that is, the through hole (14) or the bottomed hole (15) in the electronic device according to claim 2 or 3, wherein the conductor is not present on the inner surface, It is preferable that the insulating substrate serving as the base of the circuit board (10) is exposed.

  This is because the conductor is generally a metal, so in order to reduce the degree of expansion / contraction of the circuit board (10) in the hole portion and to approximate the degree of expansion / contraction of the electronic component (20), This is because it is better not to exist inside the hole.

  Furthermore, in the invention according to claim 5, in the electronic device according to claim 4, the circuit board (10) has a glass cloth (10c) inside and is on the one surface (11) side of the glass cloth (10c). An epoxy resin layer (10b) is provided on the bottom, and the bottomed hole (15) penetrates only the epoxy resin layer (10b) from one surface (11) of the circuit board (10). 10c) as a base.

  The present invention is suitable when a glass epoxy board is used as the circuit board (10). According to this, the epoxy resin layer (10b) having a large linear expansion coefficient is formed in the bottomed hole (15). By removing the glass cloth (10c) having a smaller linear expansion coefficient than that of the epoxy resin, the linear expansion coefficient of the portion (13) between the fixed portions can be brought close to the value of the glass cloth (10c). The difference between the degree of expansion and contraction between the device (20) and the circuit board (10) can be easily reduced.

  According to a sixth aspect of the present invention, in the electronic device according to any one of the first to fifth aspects, the hole (14, 15) or the break is the first portion at the portion between the fixing portions (13). It is located in the site | part adjacent to a fixing | fixed part with an electrode (21), and the site | part adjacent to the fixing | fixed part with a 2nd electrode (22), It is characterized by the above-mentioned.

  According to this, in the circuit board (10), the main generation range of the stress applied to the solder (30) by the circuit board (10) can be further limited, so that the stress can be further reduced.

  According to a seventh aspect of the present invention, in the electronic device according to any one of the first to sixth aspects, the holes (14, 15) are formed from the first electrode (21) to the second electrode (22). ) In the shape of a long hole extending in a direction orthogonal to the direction toward the head.

  According to this, the difference in expansion / contraction degree between the electronic component (20) and the circuit board (10) can be further reduced as compared with the case where the holes (14, 15) are simple round holes, and the circuit board (10 ) Can reduce the stress applied to the solder (30).

  According to an eighth aspect of the present invention, in the electronic device according to any one of the first to seventh aspects, the hole (14, 15) or the break is formed between the fixed portions of the circuit board (10). It is characterized in that it is provided in the vicinity of the fixing part with the first electrode (21) and in the vicinity of the fixing part with the second electrode (22) at a part other than the part (13).

  According to this, in the circuit board (10), the main generation range of the stress applied to the solder (30) by the circuit board (10) can be further limited, so that the stress can be further reduced.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a schematic cross-sectional view of an electronic device according to a first embodiment of the present invention. FIG. 2 is a top schematic plan view in FIG. 1. It is sectional drawing of typical through-hole TH. It is a schematic sectional drawing which shows an example of the through hole of the said 1st Embodiment. It is a schematic sectional drawing of the electronic device which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing of the electronic device as another example of the said 2nd Embodiment. It is a schematic sectional drawing of the electronic device as another example of the said 2nd Embodiment. It is a schematic sectional drawing of the electronic device which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing of the electronic device which concerns on 4th Embodiment of this invention. It is a schematic sectional drawing of the electronic device as another example of the said 4th Embodiment. It is a schematic sectional drawing of the electronic device as another example of the said 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is a diagram showing a schematic cross-sectional configuration of an electronic device according to the first embodiment of the present invention, and FIG. 2 is a diagram showing a schematic plan configuration of the electronic device when viewed from above in FIG. is there.

  The electronic device according to the present embodiment is roughly arranged between the circuit board 10, the electronic component 20 mounted on one surface 11 of the circuit board 10, and the circuit board 10 and the electronic component 20. And a solder 30 for fixing. The circuit board 10 has a larger linear expansion coefficient than the electronic component 20.

  Examples of the circuit board 10 include a resin board made of a resin such as an epoxy resin, a glass epoxy board made of glass epoxy obtained by impregnating a glass cloth with an epoxy resin, and the like. The circuit board 10 has one plate surface as one surface 11 as a mounting surface on which the electronic component 20 is mounted, and the other plate surface as another surface 12.

  The circuit board 10 is typically a single-layer or multi-layer printed circuit board, which is configured on the basis of the resin or glass epoxy described above, and has wiring formed by patterning a copper foil on the surface or between the layers. It is. Here, in the case of a multilayer substrate or the like, it is usual that a through hole penetrating each individual layer or the entire substrate is provided.

  The electronic component 20 has a first electrode 21 on one end side and a second electrode 22 on the other end side facing the one end side. Examples of such an electronic component 20 include a ceramic capacitor and a chip resistor.

  And the electronic component 20 is being fixed to the one surface 11 of the circuit board 10 via the solder 30 with the 1st electrode 21 and the 2nd electrode 22, respectively. Examples of the solder 30 include general eutectic solder and lead-free solder, and the electronic component 20 and the circuit board 10 are electrically and mechanically joined via the solder 30.

  Here, in the circuit board 10, a portion of the circuit board 10 located between the fixing part by the solder 30 with the first electrode 21 and the fixing part by the solder 30 with the second electrode 22 is defined as a circuit. A region 13 between the fixed portions of the substrate 10 is used. Specifically, the fixing portion is a portion of the circuit board 10 that contacts the solder 30.

  In the present embodiment, as shown in FIGS. 1 and 2, the degree of thermal expansion / contraction of the inter-fixed portion portion 13 is smaller than the portion other than the inter-fixed portion portion 13 in the circuit board 10. A hole 14 is provided in one surface 11 of the fixed portion portion 13. This hole 14 is a through hole 14 that penetrates the circuit board 10 from one surface 11 to the other surface 12 in the plate thickness direction. Here, a plurality of through holes 14 having a circular opening shape are provided in the portion 13 between the fixed portions. ing.

  In the present embodiment, as shown in FIGS. 1 and 2, the circuit board 10 exerts an influence on the solder 30 as stress (strain) by providing the through hole 14 in the portion 13 between the fixed portions of the circuit board 10. The degree of expansion and contraction can be reduced.

  Compared with the case where the through hole 14 is not provided, the expansion / contraction generated in the inter-fixed part site 13 is divided by the through hole 14 of the inter-fixed part site 13, thereby This is because the degree of expansion / contraction is greatly reduced and approaches the degree of expansion / contraction of the electronic component 20.

  In the case of the present embodiment, as indicated by an arrow Y in FIG. 1, a portion of the circuit board 10 where the difference between the degree of expansion and contraction of the electronic component 20 is large and affects the stress is mainly, This is a part other than the part 13 between the fixed parts where the through hole 14 does not exist. In FIG. 1 and other drawings, the arrow Y indicates the direction of expansion / contraction.

  That is, in the circuit board 10, the main generation range of the stress applied to the solder 30 by the circuit board 10 is reduced. As a result, the difference in the degree of expansion / contraction between the circuit board 10 and the electronic component 20 is reduced. Thus, the stress can be reduced and the progress of cracks in the solder 30 can be suppressed.

  As described above, according to the present embodiment, by providing the hole 14 in the portion 13 between the fixed portions located between the two fixed portions of the electronic component 20 and the circuit board 10, the expansion of the portion 13 between the fixed portions is performed. Since the degree of shrinkage is smaller than that of the other parts of the circuit board 10, the difference between the degree of expansion and contraction of the both 10 and 20 can be made smaller, and the stress on the solder 30 is reduced. It becomes possible.

  In this embodiment, since the hole 14 is a through hole 14 that penetrates the circuit board 10 in the thickness direction from the one surface 11, the through hole 14 is formed in the circuit board 10 by using a general through hole forming process. Can be easily formed.

  Here, FIG. 3 is a diagram showing a cross-sectional configuration of a typical through hole TH formed in the circuit board 10. The through hole TH is formed by making a through hole in the circuit board 10 with a drill or the like and then applying a copper plating M from the copper foil 10a on the surface to the inner surface of the hole. Thereafter, the copper foil 10a on the surface is patterned into a predetermined wiring pattern by etching.

  Here, also in the present embodiment, when the circuit board 10 has the through hole TH, the through hole 14 may be formed simultaneously with the formation of the through hole TH. On the other hand, when the circuit board 10 does not have the through hole TH, the through hole 14 may be formed separately by performing a drilling process using a general through hole forming process.

  Here, the through hole 14 of the present embodiment may be provided with a conductor such as copper plating on the inner surface of the hole as in the case of the through hole TH shown in FIG. As shown, no conductor is present on the inner surface of the through hole 14 and the inner surface of the through hole 14 is a surface on which an insulating material (for example, resin or glass epoxy) serving as a base of the circuit board 10 is exposed. May be.

  When there is a conductor on the inner surface of the through hole 14, since the conductor is generally a metal, in order to reduce the degree of expansion / contraction of the circuit board 10 in the portion of the through hole 14, the degree of expansion / contraction of the electronic component 20 can be approached. It is desirable that such a conductor does not exist inside the through hole 14. This is apparent from the “linear expansion coefficient” which is a coefficient for calculating expansion / contraction.

  Here, the linear expansion coefficient of the main material which comprises the electronic component 20 and the circuit board 10 is shown. Here, the electronic component 20 is made of ceramic, and the circuit board 10 is made of a printed board as a glass epoxy board having a copper foil pattern. In this case, ceramic: 10 ppm / ° C., average of the entire printed circuit board: 15 ppm / ° C., copper: 16 ppm / ° C., glass: 5 ppm / ° C., epoxy resin: 77 ppm / ° C. From this, it is clear that the through hole 14 in which no conductor exists is preferable.

  In the present embodiment, when the through hole 14 in which such a conductor does not exist is formed in the circuit board 10 having the through hole TH, by etching when patterning the copper foil 10a, What is necessary is just to remove the copper plating M inside the through-hole 14 simultaneously.

(Second Embodiment)
FIG. 5 is a diagram showing a schematic cross-sectional configuration of an electronic device according to the second embodiment of the present invention. The present embodiment is different from the first embodiment in that the bottomed hole 15 is used in place of the through hole 14, and here, the difference will be mainly described.

  The hole provided in the first embodiment is a through hole 14 that penetrates the circuit board 10 in the thickness direction. However, when the circuit board 10 is a multilayer board, such a through hole 14 is an inner layer of the board. There is a possibility of hindering the degree of freedom in wiring.

  Therefore, as a means for realizing the improvement in the degree of freedom of wiring, in this embodiment, as shown in FIG. 5, a bottomed hole having a bottom while opening the hole 15 in the non-through hole, that is, one surface 11 of the circuit board 10. 15 is configured.

  In this case, since only the surface layer is processed, the expansion / contraction generated from the circuit board 10 is larger than the case where the through hole 14 is provided, but the effect of reducing the expansion / contraction generated in the vicinity of the fixing portion of the electronic component 20 is achieved. Therefore, the stress reduction effect on the solder 30 can be obtained. In addition, there is an advantage that it is easy to secure a space for forming wiring and the like inside the circuit board 10.

  Here, FIG. 6 is a diagram showing a schematic cross-sectional configuration of an electronic device as another example of the second embodiment. This is an example showing a preferable form when a multilayer glass epoxy substrate is applied to the circuit board 10 of the present embodiment. Here, as a means for enhancing the solder stress reduction effect by the bottomed hole 15, only the epoxy resin of the circuit board 10 is processed as the bottomed hole 15.

  Specifically, the circuit board 10 shown in FIG. 6 has a glass cloth 10c inside and is provided with an epoxy resin layer 10b on the surface 11 side of the glass cloth 10c. Here, it is a multi-layer glass epoxy substrate, and a set of glass cloth 10c and epoxy resin layer 10b is used as a single layer, and a plurality of these layers are laminated, and an inner layer pattern 10d made of Cu or the like is interposed between the layers. .

  The bottomed hole 15 is configured as a hole that penetrates only the epoxy resin layer 10b from one surface 11 of the circuit board 10 and reaches the glass cloth 10c, and has the glass cloth 10c as a bottom.

  According to this, by removing the epoxy resin having a larger linear expansion coefficient than the electronic component 20, leaving the glass cloth 10c having a smaller linear expansion coefficient than the epoxy resin and usually smaller than the electronic component 20, The linear expansion coefficient of the fixed portion 13 in the circuit board 10 is brought close to the value of the glass cloth 10c.

  Therefore, the configuration shown in FIG. 6 reduces the degree of expansion / contraction of the portion 13 between the fixed parts to approach the degree of expansion / contraction of the electronic component 20, and expands / contracts between the electronic device 20 and the circuit board 10. This is a preferable configuration for reducing the degree difference.

Here, the bottomed hole 15 as in the present embodiment is formed by laser drilling, drilling, or the like. However, as shown in FIG. When leaving the cloth 10c, CO ₂ laser processing is desirable as a selective drilling method. Since the glass cloth 10c requires a larger laser output than the epoxy resin, it is possible to process only the epoxy resin by reducing the laser output.

  In the bottomed hole 15 of the present embodiment, metal may be disposed on the inner surface of the hole by plating or the like, but for the same reason as the through hole 14 shown in FIG. Instead, the inner surface of the hole may be a surface on which an insulating material serving as a base of the circuit board 10 is exposed.

  FIG. 7 is a diagram showing a schematic cross-sectional configuration of an electronic device as another example of the second embodiment. In the example shown in FIG. 7, the position of the bottomed hole 15 is made as close as possible to the electrode fixing portion of the electronic device 20 in FIG.

  That is, in this example, the bottomed hole 15 is positioned at a portion adjacent to the fixing portion with the first electrode 21 and a portion adjacent to the fixing portion with the second electrode 22 at the portion 13 between the fixing portions. I am letting. According to this, in the circuit board 10, the main generation range of the stress applied to the solder 30 by the circuit board 10 is reduced by bringing the position of the bottomed hole 15 as close as possible to the fixing part of the electrodes 21 and 22 at the portion 13 between the fixing parts. Since it can be further limited, the stress can be further reduced.

  The example of FIG. 7 can also be applied to the through hole 14. That is, the through hole 14 may be positioned at a portion adjacent to the fixing portion between the electrodes 21 and 22 at the fixing portion portion 13. The effect by this is the same as in the case of the bottomed hole 15.

(Third embodiment)
FIG. 8 is a diagram showing a schematic cross-sectional configuration of an electronic device according to the third embodiment of the present invention. The present embodiment is different from the first embodiment in that the through hole 14 is changed from a circular hole having a circular opening shape to a long hole having an elongated opening shape. We will focus on the differences.

  As shown in FIG. 8, the through hole 14 of the present embodiment has a long hole shape extending in a direction orthogonal to the direction from the first electrode 21 toward the second electrode 22. That is, the long hole has an elongated shape extending in a direction orthogonal to the direction from one fixing part of the circuit board 10 to the electronic component 20 toward the other fixing part.

  When the through hole 14 is a simple round hole (see FIG. 2 above), the expansion / contraction generated from the portion between the hole 14 and the hole 14 tends to remain as stress on the solder 30. In contrast, according to the present embodiment, since the expansion / contraction generated in the portion 13 between the fixed portions can be more reliably divided, the difference in the degree of expansion / contraction between the electronic component 20 and the circuit board 10 is reduced. The effect of reducing the stress applied to the solder 30 by the circuit board 10 can be increased.

  The example of FIG. 8 can also be applied to the bottomed hole 15. That is, the bottomed hole 15 may have a long hole shape extending in a direction orthogonal to the direction from the first electrode 21 toward the second electrode 22. The effect of this is the same as in the case of the through hole 14.

(Fourth embodiment)
FIG. 9 is a diagram showing a schematic cross-sectional configuration of an electronic device according to the fourth embodiment of the present invention. The present embodiment is different from the first embodiment in that the through hole 14 is provided not only in the inter-fixed portion portion 13 of the circuit board 10 but also in a portion other than the inter-fixed portion portion 13. Here, the differences will be mainly described.

  That is, in this embodiment, as shown in FIG. 9, the through-hole 14 is further provided in the vicinity of the fixing portion with the first electrode 21 at a portion other than the fixing portion-to-fixing portion 13 in the circuit board 10. It is provided in the vicinity of the fixing portion with the second electrode 22.

  Accordingly, the expansion / contraction generated in the portion of the circuit board 10 outside the fixed portion portion 13 is divided by the through hole 14. Therefore, as shown by an arrow Y in FIG. 9, the main generation range of stress applied to the solder 30 in the circuit board 10 is further reduced, and the stress reduction effect is further enhanced.

  FIG. 10 is a diagram illustrating a schematic cross-sectional configuration of an electronic device as another example of the fourth embodiment. In the example of FIG. 9, the example of the through hole 14 is shown, but it is obvious that the effect is similarly exhibited even when the bottomed hole 15 is used instead of the through hole 14.

  FIG. 11 is a diagram showing a schematic plan configuration of an electronic device as another example of the fourth embodiment. In the present embodiment, the through hole 14 or the bottomed hole 15 may be used, but the opening shape may be a round hole shape as shown in FIG. 11 (a) or as shown in FIG. 11 (b). Thus, a long hole shape may be sufficient.

(Other embodiments)
In each of the above embodiments, the holes 14 and 15 such as the bottomed hole 15, the so-called dent or the through hole 14 are provided on the one surface 11 of the portion 13 between the fixed portions in the circuit board 10. Instead, what is called a cut may be provided by cutting the surface 11 of the circuit board 10 with a cutting tool or the like. Also in that case, it can be expected that the degree of expansion / contraction of the portion 13 between the fixed portions is reduced.

  The electronic component 20 may be any electronic component having the first electrode 21 on one end and the second electrode 22 on the other end. For example, three or more electrodes such as a ceramic ultrasonic oscillator may be used. You may have. Even in such a case, any two of the three may be configured as the first electrode and the other as the second electrode.

  In addition, a plurality of electronic components 20 may be mounted on one surface 11 of the circuit board 10, and in that case, the configuration in which the holes 14 and 15 of the above embodiments are provided for each electronic component 20. Should be applied.

DESCRIPTION OF SYMBOLS 10 Circuit board 10c Glass cloth 10b Epoxy resin layer 11 One surface of a circuit board 13 Location between fixed parts of a circuit board 14 Through hole 15 Bottomed hole 20 Electronic component 21 First electrode of electronic component 22 Second electrode of electronic component 30 Solder

Claims (8)

A circuit board (10) and an electronic component (20) mounted on one surface (11) of the circuit board (10);
The circuit board (10) has a larger linear expansion coefficient than the electronic component (20),
The electronic component (20) has a first electrode (21) on one end side and a second electrode (22) on the other end side facing the one end side,
The electronic component (20) is an electron fixed to the circuit board (10) via a solder (30) by the first electrode (21) and the second electrode (22), respectively. In the device
A portion (13) between the fixing portions which is a portion located between the fixing portion with the first electrode (21) and the fixing portion with the second electrode (22) in the circuit board (10). In the electronic device, holes (14, 15) or cuts are provided on the one surface (11).   2. The electronic device according to claim 1, wherein the hole is a through hole (14) that penetrates the circuit board (10) in the thickness direction from the one surface (11). 3.   2. The electronic device according to claim 1, wherein the hole is a bottomed hole having a bottom while opening on one surface of the circuit board.   4. The electronic device according to claim 2, wherein the hole has a surface on which an insulating material serving as a base of the circuit board (10) is exposed without a conductor on the inner surface. . The circuit board (10) has a glass cloth (10c) inside and is provided with an epoxy resin layer (10b) on the one surface (11) side than the glass cloth (10c),
The bottomed hole (15) penetrates only the epoxy resin layer (10b) from the one surface (11) of the circuit board (10) and has the glass cloth (10c) as a bottom. The electronic device according to claim 4.   The hole (14, 15) or the cut line is a portion adjacent to the fixing portion with the first electrode (21) at the portion (13) between the fixing portions, and the second electrode (22). The electronic device according to claim 1, wherein the electronic device is located in a portion adjacent to the fixed portion.   The hole (14, 15) has a long hole shape extending in a direction orthogonal to a direction from the first electrode (21) toward the second electrode (22). The electronic device according to any one of 1 to 6.   Further, the hole (14, 15) or the cut is in the vicinity of the fixing portion with the first electrode (21) at a portion other than the fixing portion portion (13) in the circuit board (10). 8. The electronic device according to claim 1, wherein the electronic device is provided in the vicinity of a fixing portion between the second electrode and the second electrode.

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