JP2014107325A - Circuit board packaging electronic components with terminal row or terminal array thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shear crack or fracture in a solder junction between an electronic component terminal and a pad on a circuit board, in the circuit board packaging electronic components with a terminal array thereon.SOLUTION: On a packaging surface to package electronic components thereon, a plurality of pads (106, 116a-106d) are provided to which terminals of the electronic components are joined. With respect to at least one occupant region (108a-108d) of occupant regions (108) on the packaging surface to be occupied by the terminals, respectively, at least one through hole (110a-110d) is provided. The through hole is provided at such a position that a part of the outer circumference thereof is settled within a predetermined distance range from an outer circumferential position of the at least one occupant region, at such a position that a part of the outer circumference is in contact with the outer circumference of the occupant region or at such a position that a part of the through hole is overlapped with the at least one occupant region, thereby reducing shear stress generated from the terminal occupying the at least one occupant region to a junction.

Description

  The present invention relates to a circuit board on which an electronic component having a terminal array or terminal arrangement composed of a plurality of terminals is mounted, and in particular, due to a difference in linear expansion coefficient between the circuit board and the electronic component package. The present invention relates to a circuit board that can reduce the shear stress generated at the joint between the circuit pattern and the circuit pattern on the circuit board and prevent the joint from being cracked or separated.

  With the advancement of functions of semiconductor integrated circuits, electronic components that require a large number of electrode terminals, such as a CPU (Central Processing Unit), use a package having a grid-like terminal array such as a BGA (Ball Grid Array). ing.

  Also, in electronic parts using such high-function integrated circuits, it is necessary to improve the heat dissipation characteristics of the package due to the large amount of heat generated during operation, and ceramic with high thermal conductivity is used as the package material. There are many.

  On the other hand, the circuit board material on which the electronic component is mounted is usually made of glass epoxy from the viewpoint of insulation and flame retardancy, and is different from the ceramic constituting the electronic component package. It has an expansion coefficient.

  For this reason, as the temperature of the electronic component package or the like changes due to changes in the environmental temperature or the operation of the electronic component, the solder joint between the terminal of the electronic component and the pad on the circuit board has a surface of the circuit board. Shear stress is generated along the direction, and the joint may be cracked or broken by the stress.

  In particular, in a vehicle device, since the temperature change range of the vehicle environment is wide, a temperature change in a very wide range occurs in the circuit board and the electronic component in combination with the increase in the internal temperature accompanying the operation of the device. This means that the probability of occurrence of cracks and fractures in the joint due to the shear stress is further increased.

  Conventionally, as a method for avoiding separation of the joint portion, the tensile stress on the joint portion caused by the bending of the circuit board caused by the force applied in the direction perpendicular to the board surface of the circuit board is mainly used. Preventive measures for separation of the joint are disclosed. As a measure for preventing such joint separation due to tensile stress, for example, a configuration in which an L-shaped through hole is provided outside the corner of the electronic component mounting region on the circuit board (see Patent Document 1 and Patent Document 2), A configuration in which a through hole is provided in a substantially central portion of the mounting area, and small through holes are arranged in a rectangular shape in an area inside the mounting area where terminals of electronic components are not provided (Patent Document 3) It has been known.

  However, the circuit boards described in these patent documents are provided with a through hole at a specific position so that the influence of the bending of the circuit board does not reach the joint, and the shear applied to the joint is It does not provide a means for reducing stress. Therefore, even if the above conventional technique is used, the shear stress generated at the joint cannot be effectively reduced.

JP 2007-165469 A JP-A-11-103137 JP 2001-148548 A

  From the above background, in a circuit board on which an electronic component having a terminal arrangement is mounted, a solder joint between an electronic component terminal and a pad on the circuit board due to a difference in linear expansion coefficient between the electronic component package and the circuit board It is a problem to effectively prevent shear cracks and breaks in

The present invention is a circuit board on which an electronic component having a terminal array or a terminal array composed of a plurality of terminals is mounted, and each of the terminals is joined to a mounting surface on which the electronic component is mounted. And at least one through hole is provided for at least one of the occupied areas on the mounting surface occupied by the terminals. The through hole is a position where a part of the outer periphery of the through hole is within a predetermined distance range from the outer peripheral position of the at least one occupied region, or a part of the outer periphery of the through hole is the outer periphery of the occupied region. From the terminal occupying the at least one occupied area in a state where the terminal and the pad are joined to each other, or in a state where a part of the through hole overlaps the at least one occupied area. The resulting shear stress in the mounting surface direction at the joint with the pad is reduced.
According to one aspect of the present invention, one of the pads bonded to the terminal, the part of which is lost due to the through hole, is replaced with another pad in a state where the through hole is provided. When bonding to the terminal is performed using the same amount of solder as the amount of solder used, the solder is formed so as to have an area that does not protrude from the outer periphery of the one pad to the outside. The
According to another aspect of the present invention, the terminal arrangement is a lattice-like terminal arrangement arranged in a rectangular pattern in a rectangular region, and the pads are arranged on the mounting surface so that the terminals are bonded to each other. The at least one occupied area is an occupied area of terminals arranged at corners of the rectangular area.
According to another aspect of the present invention, the at least one through hole includes the at least one occupied area and two occupied areas adjacent to the occupied area along an outer periphery of the rectangular area. The two occupied areas are provided. And this through hole is a position where a part of the outer periphery of the through hole is within a predetermined distance range from the outer peripheral position of the three occupied areas, or a part of the outer periphery of the through hole is the three occupied areas. Each of the through holes is formed at a position in contact with each outer periphery or a position where a part of the through hole overlaps each of the three occupied areas, and occupies the three occupied areas in a state where the terminal and the pad are joined. The shear stress in the mounting surface direction to each joint portion with the pad generated from each terminal is reduced.

  According to the present invention, in a circuit board on which an electronic component having a terminal arrangement is mounted, a solder joint between an electronic component terminal and a pad on the circuit board caused by a difference in linear expansion coefficient between the electronic component package and the circuit board It is possible to effectively prevent shear cracks and breaks in.

It is a figure which shows the structure of the circuit board which concerns on embodiment of this invention. It is an enlarged view of the circuit board shown in FIG. It is a figure which shows the other example of the through-hole provided in the circuit board shown in FIG. It is a figure which shows the further another example of the through-hole provided in the circuit board shown in FIG. It is a figure which shows the further another example of the through-hole provided in the circuit board shown in FIG. It is the elements on larger scale near the through-hole which shows the modification of the circuit board shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a circuit board according to the first embodiment of the present invention, and FIG. 2 is an enlarged view of the circuit board shown in FIG.

  The circuit board 100 is a circuit board that constitutes an electronic control unit (ECU, Electronic Control Unit) that is mounted on a vehicle and controls the engine of the vehicle, for example. The circuit board 100 is mounted with electronic components having a grid-like terminal arrangement. The package mounting area 102 (dotted line rectangle) shown in FIG. 1 represents an area where the electronic component package is mounted. Note that the relative size of the circuit board 100 with respect to the package mounting area 102 illustrated in FIG. 1 is an example, and the circuit board 100 may have an arbitrary size regardless of the size of the package mounting area 102. it can.

  On the circuit board 100, pads 106, 116 a, 116 b, 116 c, and 116 d to be bonded to the terminals of the electronic component are arranged in a rectangular region 104 (illustrated on the circuit board 100) in accordance with the grid-like terminal arrangement of the electronic component. Are arranged in a lattice pattern on a one-dot chain line). In other words, the rectangular area 104 represents the rectangular area where the pads 106, 116 a, 116 b, 116 c, and 116 d are arranged, and corresponds to the rectangular area occupied by the grid-like terminal arrangement of the mounted electronic component on the circuit board 100. doing.

  Pads 116a, 116b, 116c, and 116d are pads arranged at the upper right corner, the lower right corner, the lower left corner, and the upper left corner of the rectangular region 104, respectively. The pad 106 is a pad other than these pads. . The pad 106 has a circular shape, whereas the pads 116a to 116d have a shape different from the pad 106 by forming through holes 110a to 110d (described later) after being formed in a circular shape like the pad 106. ing.

  2 is a partial enlarged view in which the portion of the package mounting area 102 of the circuit board 100 shown in FIG. 1 is enlarged. In FIG. 2, only the vicinity of the four corners of the rectangular area 104 is shown. Omitted.

  In FIG. 1, pads and terminals are arranged in a grid pattern without gaps in the rectangular area 104, but the rectangular area 104 may include an area without terminals and pads therein. For example, an area without terminals and / or pads may be included over the rectangular area at the center of the rectangular area 104. Further, another grid-like terminal arrangement of the same electronic component package and / or an arrangement of pads on the circuit board 100 may exist outside the rectangular region 104.

  In the present embodiment, the package of electronic components mounted on the circuit board 100 is a BGA, and each terminal of the BGA is configured by a pad-shaped electrode and ball-shaped solder formed on the pad-shaped electrode. ing. When the BGA package is mounted on the circuit board 100, the ball solder of each terminal is melted by heating the BGA package, and the ball solder is melted with the pads 106 and 116a to 116d on the circuit board 100 to be cooled. Thus, the terminals and the pads 106 and 116a to 116d are joined and electrically connected, and the BGA package is fixed on the circuit board 100.

  In FIG. 1, the electrode occupation region 108 indicated by a dotted circle on the pad 106 and 116 a to 116 d is each terminal of the BGA package (in this embodiment, when the BGA package is mounted on the circuit board 100). This is an area on the circuit board 100 that the pad electrode) occupies. In FIG. 1, for convenience, reference numeral 108 is attached to the electrode occupation region of one terminal. However, in the following description, “electrode occupation region 108” is defined as the occupation region of each pad-like electrode of the BGA package. When used as a general term and distinguishing and indicating individual electrode occupation regions, the alphabets are attached as shown in the electrode occupation regions 108a and 108b.

  On the circuit board 100, through holes 110a, 110b, 110c, and 110d are provided at four corners of the rectangular region 104 where the pads 116a to 116d are formed. Each of these through holes 110a to 110d is formed such that a part of the outer periphery thereof is in contact with the outer periphery of the electrode occupation regions 108a to 108d located at the four corners of the rectangular region 104 (see FIG. 2). . Here, “formed so as to touch” means “formed” within a position range that is determined by taking manufacturing error and measurement error around a substantially “contacting” position.

  Generally, the shear stress generated at the joint between the terminal of the electronic component and the pad on the circuit board due to the difference in coefficient of linear expansion between the electronic component package and the circuit board is given from the outer peripheral part of each terminal, It becomes maximum at the outer peripheral portion of the electrode occupation region of each terminal. Further, when the mounted electronic component has a grid-like terminal arrangement, the shear stress is maximum at the outer peripheral portion of the electrode occupation area of the terminal located at the four corners of the rectangular area formed by the terminal arrangement. Become.

  The circuit board 100 having the above-described configuration is in contact with the outer periphery of the electrode occupying regions 108a to 108d of the terminals (that is, the terminals giving the maximum shear stress) located at the four corners of the rectangular region 104 occupied by the terminal arrangement. , Rectangular through holes 110a to 110d are respectively provided. Therefore, in the circuit board 100, when an electronic component is mounted and the terminals of the electronic component are joined to the pads 106 and 116a to 116d, the shear applied from the outer peripheral portions of the terminals located at the four corners of the rectangular region 104 is applied. The stress is effectively released and reduced by the through holes 110a to 110d in the immediate vicinity of the outer periphery of the terminal.

  Therefore, the circuit board 100 generates shear stress generated at the joint between the terminal of the electronic component and the pads 116a to 116d due to the difference between the linear expansion coefficient of the electronic component package and the linear expansion coefficient of the circuit board 100. As a result, it is possible to prevent cracks and breaks from occurring in the joint due to the shear stress.

  It should be noted that the shear stress generated at the joints in the electrode occupying regions 108a to 108d at the corners of the rectangular region 104 during thermal expansion is more specifically described in the electrode occupying regions 108a to 108d. Of the two intersections between the respective outer peripheries and the diagonal lines of the rectangular area 104, the intersection is the largest at each intersection in the outward direction of the rectangular area 104. Therefore, in the present embodiment, the through holes 110a to 110d are formed so as to be in contact with the outer circumferences of the electrode occupation regions 108a to 108d at the respective intersections in the outer direction.

  However, at the time of heat shrinkage, when the shear stress becomes a size that cannot be ignored in the inner direction of the rectangular region 104 among the two intersections on the outer circumferences of the electrode occupation regions 108a to 108d, the respective points in the inner direction are The through holes 110a to 110d may be formed so as to be in contact with the outer periphery of the electrode occupation regions 108a to 108d at the intersections.

  In addition, in the case where there is a terminal that is not limited to the terminal located at the corner of the rectangular region 104 but is considered to generate a shear stress that cannot be ignored at the joint with the pad on the circuit board, one such or For a plurality of terminals, similarly to the above, by providing a through hole in the electrode occupation region of the terminal, it is possible to reduce the shear stress generated at the joint between the terminal and the pad. Whether or not “shear stress that cannot be ignored” is generated is confirmed in advance by evaluating whether or not a crack occurs in the joint using a circuit board that does not have through holes. can do.

  In addition, the electronic component mounted on the circuit board is not limited to having a grid-like terminal arrangement, and the electronic component package and the circuit board are different even if the electronic component has a single-row terminal array. In the case of having a linear expansion coefficient, a shear stress is generated at the joint between the terminal of the package and the pad on the circuit board due to the difference between these linear expansion coefficients. Therefore, even in the case of electronic components having terminal rows arranged in a row, for terminals that are considered to generate a non-negligible shear stress, by providing a through hole in the same manner as described above, the shear stress is reduced, It is possible to prevent cracks and breaks from occurring in the joint portion.

  Further, in the present embodiment, the through holes 110a to 110d are formed so that part of the outer periphery thereof is in contact with the electrode occupation regions 108a to 108d, but the positions of the through holes 110a to 110d are not limited thereto. That is, as long as a part of the outer periphery of each of the through holes 110a to 110d is disposed within a distance range where the shear stress generated in the outer periphery of the electrode occupation regions 108a to 108d reaches, the shear stress is effectively reduced. can do. Naturally, the through holes 110a to 110d have a greater effect of reducing the shear stress as the formation position of a part of the outer periphery thereof is closer to the electrode occupation regions 108a to 108d.

  Therefore, the through holes 110a to 110d can be formed such that a part of the outer periphery thereof is disposed within a predetermined distance range from the outer peripheral portions of the electrode occupation regions 108a to 108d. It can be made into the range which the shear stress to the junction part of the said terminal and pads 116a-116d which arises from the terminal which occupies electrode occupation area | region 108a-108d reaches. Note that the degree of the predetermined distance range is determined according to the target reduction amount of the shear stress (for example, from the outer peripheral position of the electrode occupation regions 108a to 108d to the through holes 110a to 110d). The circuit board 100 having various distances is made as a prototype, and a confirmation experiment is performed to determine whether or not a crack occurs in the solder joint under a predetermined temperature condition.

  Further, the through holes 110a to 110d may be formed so as to overlap with part of the electrode occupation regions 108a to 108d, respectively. In this case, the shear stress at the joints in the electrode occupation regions 108a to 108d can be effectively reduced by the portions of the through holes 110a to 110d formed in the electrode occupation regions 108a to 108d.

  Moreover, in this embodiment, although the shape of the through-holes 110a to 110d is rectangular, the shape of the through-hole is not limited to this, and can be any shape.

  FIG. 3 is a diagram showing another example of the through hole that can be provided in the circuit board 100 shown in FIG. In FIG. 3, for easy understanding, only the through hole in the upper right corner of the rectangular region 104 (FIG. 1) and its surrounding components are shown.

  In the example of FIG. 3A, the through hole 310 has a circular shape, and a part of the outer periphery thereof is formed so as to be disposed within the predetermined distance range from the outer periphery of the electrode occupation region 108a. Since the circular through hole has a simple shape, the machining process for forming the through hole can be simplified to reduce the machining cost. Note that the pad at the corner of the circular region 104 remains circular without losing its area due to the through-hole, so that the pad 106 has the same shape and size as the other pads.

  In the example of FIG. 3B, the through hole 312 has an oval shape, and a part of the outer periphery thereof is formed so as to be disposed within the predetermined distance range from the outer periphery of the electrode occupation region 108a. In the example of FIG. 3C, the same oval through hole 314 as in FIG. 3B is formed so as to overlap a part of the electrode occupation region 108a. These oval through-holes 312 and 314 can be provided, for example, by a simple straight sweep of an end mill, so that the machining process for forming the through-hole can be simplified and the machining cost can be reduced. Note that the pad 316 in FIG. 3C has a shape in which a part thereof is scraped relatively large by the through hole 314.

  FIG. 4 is a view showing still another example of the through hole that can be provided in the circuit board 100 shown in FIG. In FIG. 4, as in FIG. 3, only the through hole in the upper right corner of the rectangular region 104 (FIG. 1) and its surrounding components are shown.

  In the example of FIG. 4A, a substantially L-shaped through hole 410 is formed so as to contact two points on the outer periphery of the electrode occupation region 108a. In FIG. 4B, substantially L-shaped through holes 414 are formed so as to be in contact with three points on the outer periphery of the electrode occupation region 108a. These substantially L-shaped through holes 410 and 414 are in contact with the outer periphery of the electrode occupying region 108a as compared with the circular, oval, or rectangular through holes 110a to 110d, 310, 312, and 314 described above. Therefore, the shear stress generated at the solder joint between the pads 412 and 416 and the electronic component terminal can be more effectively released and reduced.

  FIG. 5 is a view showing still another example of the through hole that can be provided in the circuit board 100 shown in FIG. In FIG. 5, as in FIG. 3, only the through hole in the upper right corner of the rectangular region 104 (FIG. 1) and its surrounding components are shown.

  A part of the outer periphery of the through-hole 510 shown in FIG. 5A is processed into an arc shape, and the arc-shaped part is arranged so as to be in contact with a part of the outer periphery of the electrode occupation region 108a. Since the through hole 510 is in contact with the outer periphery of the electrode occupying region 108a at a larger portion than the through hole 414 shown in FIG. 4B, the shear stress generated at the solder joint on the pad 512 is further effectively reduced. can do.

  The through-hole 514 shown in FIG. 5B is in contact with the outer periphery of the electrode occupation region 108a at the corner of the rectangular region 104, and the two electrode occupation regions 108e and 108f adjacent to the electrode occupation region 108a along the outer periphery of the rectangular region 104. It is formed so as to be in contact with the outer periphery. In this example, the shear stress generated at the solder joint between the terminal of the electronic component and the three pads 516a, 516b, and 516c can be reduced by one through hole 514, and a through hole is provided for each electrode occupation region. Compared with the structure to provide, the process process of a circuit board can be simplified and the manufacturing cost of a circuit board can be reduced.

Next, a modified example of the circuit board 100 according to the present embodiment will be described.
In this modification, in the state where the pad at the corner of the rectangular region 104 is provided with a through hole, an electronic component terminal is used by using an amount of solder that is substantially the same as the amount of solder used for other pads. Is formed so that the solder does not protrude from the outer periphery of the corner pad to the outside.

  In the example shown in FIGS. 1 and 2, the pads 116 a to 116 d provided at the corners of the rectangular region 104 are provided with through holes 110 a to 110 d, respectively, so that the area thereof is smaller than the other pads 106. ing. For this reason, depending on the amount of the ball-shaped solder provided in the electronic component terminal, when the electronic component is mounted on the circuit board 100, a part of the solder protrudes outside the pads 116a to 116d, and the adjacent circuit Problems such as forming a bridge between the pattern and the like may occur. Such a bridge causes a part of the electric circuit on the circuit board 100 to be short-circuited, resulting in an abnormal circuit operation.

  In this modification, the corner pad of the rectangular region 104 is formed in an area that does not protrude from the outer periphery even when the same amount of solder as that of other pads is used in a state where the through holes are provided. Therefore, the problem of bridge formation as described above does not occur.

  FIG. 6 is a diagram illustrating a specific example of pads at the corners of the rectangular region 104 in this modification. In FIG. 6, for easy understanding, only the through hole in the upper right corner of the rectangular region 104 (FIG. 1) and its surrounding components are shown.

  In the two examples shown in FIG. 6, the corner pads of the rectangular region 104 are formed to have the same area as the other pads 106 in the state where the through holes 110 a are provided.

  The pad 610 shown in FIG. 6A has a shape in which a square pad is cut out by the through hole 110a. The pad 610 forms a square pad having an area obtained by adding the area of another pad 106 and the area to be cut out by forming the through hole 110a on the circuit board 100 before the through hole 110a is formed. It is formed by providing the through hole 110a after that. Such a square, for example, can be made the same size as the circumscribed square of the pad 106 by adjusting the area to be cut out by the shape and dimensions of the through hole 110a. In addition, when the area cut out by the formation of the through hole 110a cannot be adjusted, the square pad is formed as a square having a size different from the circumscribed square in a range not contacting the adjacent pad 106. You can also.

  The pad 612 shown in FIG. 6B has a shape in which a circle and the circumscribed rectangle of the circle are combined, and the circular lower left quarter fan portion replaces the lower left quarter portion of the circle circumscribed rectangle, A part of the circular portion that is not replaced is cut out by the through hole 110a. The pad 612 has a larger area than when the replacement is not performed because a part of the circle is replaced with a part of the circumscribed rectangle. Therefore, the area to be cut by the through hole 110a can be compensated by the increase in the area by the replacement, and the area of the pad 612 can be made equal to the area of the pad 106 as a whole.

  In the example shown in FIG. 6, the corner pad of the rectangular region 104 is formed in a shape other than a circle before forming the through-hole 110a. It can be prepared. For example, a circular pad having a larger area than the pad 106 is formed before the through hole 110a is formed, and the pad has the same area as the other pads 106 in a state where the through hole 110a is formed. It can also be configured.

  In this modification, the pad arranged at the corner of the rectangular region 104 is adjusted to an area satisfying a predetermined condition. However, the pad to be adjusted is the pad at the corner. However, the present invention can be applied to any pad whose part is to be cut off by the through hole provided in order to reduce the shear stress described above.

  As described above, the circuit board according to the present embodiment is a circuit board on which an electronic component having a grid-like terminal arrangement is mounted, and has a pad that is bonded to a pad-like electrode constituting the terminal, At least one through hole is provided for at least one occupied region on the circuit board occupied by each pad-like electrode. The through hole has a part of the outer periphery of the through hole located within a predetermined distance range from the outer peripheral position of the at least one occupied region, or a part of the outer periphery of the through hole is occupied. It is formed so as to be in contact with the outer periphery of the region, or a part of the through hole is formed so as to overlap the at least one occupied region. Here, the predetermined distance range is a state in which the shear stress in the mounting surface direction to the joint between the terminal and the pad generated from the terminal occupying the at least one occupied area in a state where the terminal and the pad are joined. Defined as the distance

  As a result, in the circuit board, the electronic component terminal and the pad on the circuit board are joined to each other due to the difference between the linear expansion coefficient of the package of the electronic component and the linear expansion coefficient of the circuit board. It is possible to effectively reduce the shear stress in the surface direction generated at the joint between the component terminal and the pad on the circuit board, thereby preventing the joint from being cracked or broken by the shear stress.

  DESCRIPTION OF SYMBOLS 100 ... Circuit board, 102 ... Package mounting area, 106, 116a-d, 316, 412, 416, 512, 516a-c, 610, 612 ... Pad, 108, 108a-d ... Electrode Occupied area, 110a-d, 310, 312, 314, 410, 414, 510, 514...

Claims (4)

A circuit board on which an electronic component having a terminal array or terminal arrangement composed of a plurality of terminals is mounted,
On the mounting surface on which the electronic component is mounted, a plurality of pads to which each of the terminals is bonded,
At least one through-hole is provided for at least one of the occupied areas on the mounting surface occupied by each terminal,
The through hole has a position where a part of the outer periphery of the through hole is within a predetermined distance range from the outer peripheral position of the at least one occupied area, or a part of the outer periphery of the through hole is in contact with the outer periphery of the occupied area. Formed in a position or a position where a part of the through hole overlaps the at least one occupied area, and the terminal occupies the at least one occupied area when the terminal and the pad are joined. Reduce the shear stress in the mounting surface direction to the joint with the pad,
Circuit board. Of the pads bonded to the terminals, one of the pads whose area is lost by the through hole is substantially equal to the amount of solder used for other pads in the state where the through hole is provided. When bonding with the terminal using the same amount of solder, it is formed to have an area in a range where solder does not protrude from the outer periphery of the one pad to the outside.
The circuit board according to claim 1. The terminal array is a grid-like terminal array arranged in a grid pattern in a rectangular area,
The pads are arranged in a grid pattern on the mounting surface so that the terminals are bonded to each other.
The at least one occupied area is an occupied area of a terminal arranged at a corner of the rectangular area;
The circuit board according to claim 1. The at least one through hole is provided for three occupied areas including the at least one occupied area and the two occupied areas adjacent to the occupied area along the outer periphery of the rectangular area. And
The through hole is a position where a part of the outer periphery of the through hole is within a predetermined distance range from the outer peripheral position of the three occupied areas, or a part of the outer periphery of the through hole is a position of each of the three occupied areas. Each position occupying the three occupied areas is formed in a position in contact with the outer periphery, or a position where a part of the through hole overlaps each of the three occupied areas, and the terminal and the pad are joined. Reduce the shear stress in the mounting surface direction to each joint with the pad resulting from the terminal,
The circuit board according to claim 3.

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