JP7025845B2 - Wiring boards, electronic devices and electronic modules - Google Patents

Description

The present invention relates to a wiring board, an electronic device, and an electronic module including an insulating substrate in which a plurality of connection pads are arranged on the lower surface.

As a wiring board on which electronic components such as semiconductor elements, sensor elements, and capacitive elements are mounted, a board including an insulating substrate such as a square plate and a plurality of connection pads provided on the lower surface of the insulating substrate is used. .. Electronic components are mounted on the upper surface of an insulating substrate to manufacture an electronic device.

For the manufactured electronic device, a connection pad is connected to a predetermined portion of an external electric circuit such as a circuit board, and the electronic component and the external electric circuit are electrically connected. The connection pad and the external electric circuit are connected by a conductive connecting material such as a low melting point brazing material containing a tin-lead-based or tin-silver-based solder. For example, the connection pad and the external electric circuit city are joined to each other via a low melting point brazing material, and are electrically and mechanically connected to each other.

Japanese Patent Application Laid-Open No. 2003-347457 Japanese Unexamined Patent Publication No. 2004-140102

In such a wiring board, improvement of connection reliability such as electrical connection to an external electric circuit (circuit board) is required. In particular, the amount of heat generated during the operation of the mounted electronic components is increasing, and the connection pad is becoming smaller (that is, the joint area between the connection pad and the external electric circuit is decreasing) due to the miniaturization of the wiring board. , The demand for improving the connection reliability is increasing.

The wiring board of one aspect of the present invention has an upper surface including a mounting portion for electronic components and a lower surface opposite to the upper surface, and has a polygonal insulating substrate in a plan view and a lower surface thereof on the lower surface of the insulating substrate. It is provided with a plurality of connection pads arranged along the outer edge of the surface, and the width of the plurality of connection pads increases in order from the central portion of the outer edge of the lower surface toward the end portion, and the plurality of connection pads are formed. The pitch of the connection pads of the above surface is larger than that of the central portion at the end portion of the outer side of the lower surface, and the adjacent distance between the plurality of connection pads adjacent to each other increases in order as it approaches the end portion.

An electronic device according to one aspect of the present invention includes a wiring board having the above configuration and an electronic component housed in the recess and electrically connected to the plurality of electrode pads.

An electronic module according to one aspect of the present invention includes an electronic device having the above configuration, a plurality of connection pads of the electronic device, and a circuit board having a plurality of terminals connected via a conductive connecting material. .. Further, the volume of the conductive connecting material interposed between the connection pad located at the end portion of the outer side of the lower surface of the insulating substrate and the terminal is located at the central portion of the outer side of the lower surface of the insulating substrate. It is larger than the volume of the conductive connecting material interposed between the connecting pad and the terminal.

According to the wiring board of one aspect of the present invention, the width of the plurality of connection pads increases in order from the central portion of the outer edge of the lower surface toward the end portion, and the pitch of the plurality of connection pads increases on the lower surface thereof. The heat that is larger from the central part to the end part at the outer edge part is larger than the central part, and the adjacent distance between the adjacent ones among the plurality of connection pads increases in order as it approaches the end part. The amount (volume) of the connecting pad and the conductive connecting material can be increased in response to the stress, and the space between the connecting pad at the end portion and other adjacent connecting pads can be further increased. Therefore, even if the amount (volume) of the solder or the like that connects the connection pad at the end and the circuit board is relatively large, the electrical short circuit between the adjacent connection pads due to the solder or the like is effectively suppressed. can do. Further, it is possible to improve the connection reliability between the connection pad at the end portion having a large thermal stress and the circuit board through the solder having a relatively large volume. Therefore, it is possible to provide a wiring board that is effective for improving the connection reliability with the circuit board.

According to the electronic device of one aspect of the present invention, since the wiring board having the above configuration is included, it is possible to provide an electronic device which is advantageous for improving the connection reliability with respect to the terminals of the circuit board.

According to the electronic module of one aspect of the present invention, the volume of the conductive connecting material interposed between the connection pad and the terminal located at the end portion of the outer side of the lower surface including the wiring board having the above configuration is insulated. Since it is larger than the volume of the conductive connecting material interposed between the connection pad located in the center of the outer edge of the lower surface of the board and the terminal, the connection reliability between the connection pad and the terminal at the end portion where the thermal stress is large Can be improved. Therefore, it is possible to provide an electronic module in which the connection reliability between the electronic device and the terminal of the circuit board is effectively improved.

(A) is a bottom view showing the wiring board of the embodiment of the present invention, and (b) is a top view showing an example of the upper surface of the wiring board shown in (a). (A) is a side view showing an electronic device according to an embodiment of the present invention, and (b) is a side view showing an electronic module according to an embodiment of the present invention. (A) and (b) are bottom views showing enlarged main parts in the modified example of the wiring board shown in FIG. 1, respectively. It is a bottom view which shows the other modification of the wiring board shown in FIG. Each of (a) and (b) is a bottom view which shows the main part in the other modification of the wiring board shown in FIG. 1 in an enlarged manner. (A) is a bottom view showing another modification of the wiring board shown in FIG. 1, and (b) and (c) are cross sections showing a part of the cross section of the AA line portion of (a) in an enlarged manner. It is a figure. It is a side view which shows the modification of the electronic module shown in FIG.

A wiring board, an electronic device, and an electronic module according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1A is a bottom view showing a wiring board according to an embodiment of the present invention, and FIG. 1B is a top view showing an example of the upper surface thereof. FIG. 2A is a side view showing an electronic device according to an embodiment of the present invention, and FIG. 2B is a side view showing an electronic module according to an embodiment of the present invention. Although FIGS. 1 and 2 are not cross-sectional views, some parts are hatched for easy identification. Similarly, in each of the following figures, hatching may be applied to a figure that is not a cross-sectional view. It should be noted that the distinction between the upper and lower parts in the following description is for convenience, and does not limit the upper and lower parts when the wiring board, the electronic device, or the like is actually used.

The wiring board 10 is basically composed of an insulating substrate 1 having an upper surface 1b including a mounting portion 1a for electronic components and a plurality of connection pads 2 arranged on the lower surface 1c of the insulating substrate 1. Further, the electronic device 20 is basically composed of the wiring board 10 and the electronic component 11 mounted on the mounting portion 1a thereof. Further, the electronic module 30 is basically composed of the electronic device 20 and the circuit board 31 on which the electronic device 20 is mounted, and the connection pad 2 and the terminal 32 of the circuit board 31 are connected to each other via the conductive connecting material 33. It is connected.

The insulating substrate 1 is a portion that functions as a substrate for mounting and fixing the electronic component 11.
The insulating substrate 1 also functions as an electrically insulating substrate for arranging a plurality of connection pads 2 so as to be electrically insulated from each other.

The insulating substrate 1 has a polygonal shape such as a rectangle in a plan view (top view), and an electronic component mounting portion 1a is provided at the center of the upper surface thereof or the like. The mounted electronic component 11 has a rectangular shape such as a square shape in a plan view. The mounting portion 1a provided in the central portion of the polygonal insulating substrate 1 is set within a range in which the electronic component 11 can be accommodated.

In the example shown in FIG. 1, the insulating substrate 1 has a rectangular flat plate shape, but it may have another shape such as an octagonal plate shape in which each corner portion is cut out in a plane shape. Further, the insulating substrate 1 may have a concave portion (not shown) on the upper surface 1a, and the bottom portion of the concave portion may be used as a mounting portion.

The insulating substrate 1 is formed of, for example, a ceramic sintered body such as an aluminum oxide-based sintered body, a glass-ceramic sintered body, an aluminum nitride-based sintered body, or a mulite-based sintered body. The insulating substrate 1 can be manufactured as follows, for example, when it is made of an aluminum oxide sintered body. First, a raw material powder such as aluminum oxide and silicon oxide is formed into a sheet together with an appropriate organic binder and an organic solvent to prepare a square sheet-shaped ceramic green sheet. After that, the insulating substrate 1 can be manufactured by cutting the ceramic green sheet to an appropriate size, laminating a plurality of molded sheets, and firing the laminated laminate at a temperature of 1300 to 1600 ° C. Each of the plurality of fired sheets becomes an insulating layer (not shown) forming the insulating substrate 1.

The plurality of connection pads 2 are portions for electrically connecting the wiring board 10 to the circuit board 31. The plurality of connection pads 2 are electrically led out to the mounting portion 1a by, for example, a wiring conductor 3 provided from the connection pad 2 to the mounting portion 1a. Although FIG. 2 shows only the wiring conductor 3 located in the mounting portion 1a, the through conductor (so-called via conductor) provided inside the insulating substrate 1 and the internal wiring conductor such as the internal wiring (internal wiring) ( (Not shown) may be included. The wiring conductor 3 provided in the mounting portion and the connection pad 2 are electrically connected to each other by an internal wiring conductor. The through conductor is provided, for example, from the connection pad 2 toward the inside of the insulating substrate 1, and penetrates at least a part of the insulating substrate 1 in the thickness direction. Of the wiring conductors 3, the internal wiring is, for example, provided between the layers of the insulating layers and directly connected to the through conductors, and there is also a land pattern in which the upper and lower through conductors are connected to each other between the upper and lower insulating layers. include.

When the electronic component 11 is electrically connected to the wiring conductor 3, the electronic component 11 is electrically led out to the lower surface side of the insulating substrate 1 by the wiring conductor 3 and the connection pad 2. When these connection pads 2 are electrically connected to the terminal 32 of the circuit board 31 via the conductive connecting material 33, the electronic component 11 and the terminal 32 of the circuit board 31 are electrically connected to each other. This makes it possible to exchange electric signals, electric potentials, and the like between the electronic component 11 and the circuit board 31.

These connection pads 2 are provided on the lower surface of the polygonal insulating substrate 1 and on the outer side of the lower surface in order to facilitate connection with the terminal 32 of the circuit board 31 via the conductive connecting material 33. Arranged along.

Further, in these connection pads 2, the pitch of the plurality of connection pads 2 is larger than that of the central portion at the end portion of the outer side of the lower surface of the insulating substrate 1. The above pitch is the distance between the central portions of the widths of the connecting pads 2 adjacent to each other, and is the length between the virtual lines KK shown by the two-dot chain line in FIG. 1 (a). The width of the connection pad 2 is a dimension of the connection pad 2 in the direction along the outer side of the lower surface of the insulating substrate 1. The pitch of the central portion of the outer side of the lower surface of the insulating substrate 1 is the pitch of the two central connection pads when six connection pads 2 are arranged as in the example shown in FIG. 1 (a). The pitch between 2a and 2a, and the pitch between either of the two central connection pads 2a and the connection pad 2b adjacent to the outside thereof is the pitch of the end portion. Further, the pitch between the connection pad 2b adjacent to the central connection pad 2 and the connection pad 2c further adjacent to the outer side is also the pitch of the end portion. That is, when four or more even-numbered connection pads 2 are arranged, the pitch between the two central connection pads 2 is the pitch of the central portion, and the other pitches are the pitchs of the end portions. Further, as in the example shown in FIG. 4 described later, when five or more odd-numbered connection pads 2 are arranged, the pitch between the central connection pad 2 and the adjacent connection pad 2 is the central portion. The pitch of the other part is the pitch of the end part. The details of the arrangement of such a connection pad 2 will be described later.

Each of the plurality of connection pads 2 is formed of, for example, a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, platinum, nickel or cobalt, or an alloy material containing these metal materials. .. Such a metal material or the like is provided on the lower surface of the insulating substrate 1 as a metal layer such as a metallized layer or a plating layer.

When the connection pad 2 is, for example, a tungsten metallized layer, a metal paste prepared by mixing tungsten powder with an organic solvent and an organic binder is applied to the surface of a sheet to be an insulating substrate 1 by a method such as a screen printing method. It can be formed by printing with, and then simultaneously firing.

Further, the wiring conductor 3 can also be formed by the same method using, for example, the same metal material as the connection pad 2. The portion of the wiring conductor 3 arranged inside the insulating substrate may be formed by printing the metal paste in a predetermined pattern on the main surfaces of a plurality of sheets serving as an insulating layer and then firing the laminate. can. Further, in the part of the through conductor of the internal wiring conductor, a through hole is formed in advance in the sheet to be the insulating layer, and the above metal paste is filled in the through hole of this sheet by a method such as a screen printing method. , Can be formed by simultaneous firing. Through holes of the sheet can be formed by a method such as mechanical drilling or laser machining.

The portion of the wiring conductor 3 exposed to the outer surface of the insulating substrate 1 is a metallized layer on which a plating layer such as nickel and gold is further adhered by a method such as an electrolytic plating method or a electroless plating method. There may be.

The electronic components 11 mounted on the wiring board 10 include semiconductor integrated circuit elements such as ICs and LSIs, optical semiconductor elements such as LEDs (light emitting diodes), PDs (photoconductors), and CCDs (charge coupling elements), and current sensors. Examples thereof include sensor elements such as elements or magnetic sensor elements, and various electronic elements such as micromachines (so-called MEMS elements) in which minute electromechanical mechanisms are formed on the surface of a semiconductor substrate. Further, the electronic component 11 may be a passive component such as a piezoelectric element, a capacitive element or a resistor. Further, a plurality of electronic components 11 may be mounted, or a plurality of types may be included.

The electrical and mechanical connection of the electronic component 11 to the mounting portion 1a is made by, for example, a low melting point brazing material such as solder or a bonding material 12 having electrical conductivity such as a conductive adhesive. A connection portion (not shown) such as an electrode of an electronic component 11 and a wiring conductor 3 of a wiring board 10 are electrically and mechanically connected to each other by a bonding material 12.

For example, if the electronic component 11 is a semiconductor element such as a semiconductor integrated circuit element, various electric signals are exchanged between the electronic component 11 and the electronic circuit (not shown) of the circuit board 31, and the semiconductor element (electron). Various processes such as calculation or storage are performed in the component 11). If the electronic component 11 is a sensor element such as an acceleration sensor element, a physical quantity such as an acceleration detected by the sensor element (electronic component 11) is transmitted to the circuit board 31 as an electric signal. This electric signal is transmitted to the electronic circuit of the circuit board 31 or another electronic device mounted on the circuit board 31 (not shown), and is used for processing such as control of the electronic device on which the circuit board 31 is mounted. Will be done.

Further, in this embodiment, a groove (so-called casting) is provided on the side surface of the insulating substrate 1 from the lower end to the upper end of the side surface. The casting is, for example, a part for arranging an auxiliary conductor layer (not shown).

If a conductor layer (side conductor) (not shown) connected to the connection pad 2 is provided on the surface of these casters, the joint area of the conductive connection material 32 can be effectively increased. Further, a fillet of the conductive connecting material is formed from the connecting pad 2 to the side conductor. Therefore, the strength of the bond between the wiring board 10 and the circuit board 31 via the conductive connecting material 32 can be improved.

Such a side conductor can be formed by the same method using, for example, the same metal material as the connection pad 2. In this case, a region to be a plurality of wiring boards 10 is manufactured in the form of a multi-layered board arranged vertically and horizontally on a mother board (not shown), and the boundary of the above area is punched out in the thickness direction of the mother board to casters. You may try to form a ration. When the mother substrate is divided along the boundary by dicing or the like, the punched portion becomes a groove on the side surface of the individual wiring board 10 (insulated substrate 1).

As described above, the electronic component 11 is mounted on the mounting portion 1a of the wiring board 10, and the electronic device 20 according to the embodiment shown in FIG. 2A is manufactured. The mounting of the electronic component 11 on the wiring board 10 and the manufacture of the electronic device 20 are performed, for example, as follows. First, it is set on the mounting portion 1a on the upper surface of the insulating substrate 1 and aligned so that the connecting portion such as an electrode of the electronic component 11 and the wiring conductor 3 face each other. At this time, a bonding material 12 such as solder is interposed between the connection portion and the wiring conductor 3. Next, these aligned materials are heated in an electric furnace or the like to melt the bonding material 12. After that, if necessary, the electronic component 11 is sealed with a sealing material (not shown) such as a lid or a mold resin, and if necessary, the electronic component 11 and the mounting portion 1a (upper surface of the insulating substrate 1) are joined. A reinforcing material (not shown) such as an underfill is placed between the two. Through the above steps, it is possible to manufacture an electronic device 20 in which the electronic component 11 is mounted on the mounting portion 1a of the wiring board 10 and is electrically and mechanically connected to each other.

The manufactured electronic device 20 is electrically and mechanically connected to the circuit board 31 via the conductive connecting material 33. That is, as described above, for example, the electronic device 20 having the above configuration, the plurality of connection pads 2 of the electronic device 20, and the circuit board 31 having the plurality of terminals 32 connected via the conductive connecting material 33, for example. The electronic module 30 of the embodiment as shown in FIG. 2B is manufactured.

In this electronic module 30, as described above, the pitch of the plurality of connection pads 2 is larger at the end portion of the outer side of the lower surface of the insulating substrate 1 than at the central portion. Further, the volume of the conductive connecting material 33 interposed between the connection pad (hereinafter, also referred to as the connection pad at the end) 2 located at the end portion of the lower surface of the lower surface of the insulating substrate 1 and the terminal 32 is the volume of the insulating substrate. It is larger than the volume of the conductive connecting material 33 interposed between the connection pad (hereinafter, also referred to as the central connection pad) 2 located in the central portion of the outer side of the lower surface of 1 and the terminal 32.

In the electronic module 30 of the embodiment, the volume of the conductive connecting material 33 interposed between the connection pad 2 at the end and the terminal 32 is the conductive connection interposed between the connection pad 2 at the center and the terminal 32. Since it is larger than the volume of the material 33, it is possible to improve the connection reliability between the connection pad 2 at the end where the thermal stress is large and the terminal 32. Therefore, it is possible to provide the electronic module 30 in which the connection reliability between the electronic device 20 and the terminal 32 of the circuit board 31 is effectively improved.

Further, at this time, since the pitch of the connection pad 2 at the end is relatively large, the amount (volume) of the conductive connecting material 33 interposed between the connection pad 2 at the end and the terminal 32 is relatively large. However, the possibility that the adjacent connection pads 2 are electrically short-circuited by the conductive connecting material 33 can be effectively reduced.

Such an effect in the electronic module 30 is obtained by the wiring board 10 and the electronic device 20 having the above-mentioned configuration. That is, according to the wiring board 10 of the embodiment, since the pitch of the plurality of connection pads 2 is larger than the central portion at the end portion of the outer side of the lower surface of the insulating substrate 1, the connection pads 2 at the end portions are adjacent to each other. The space between the connection pads 2 can be made larger. Therefore, even if the amount (volume) of the conductive connecting material 33 such as solder connecting the connection pad 2 at the end and the terminal 32 of the circuit board 31 is relatively large, the connecting pads adjacent to each other due to the solder or the like are used. The electrical short circuit between the two can be effectively suppressed.

Further, the connection reliability between the connection pad 2 at the end having a large thermal stress and the circuit board 31 can be improved through the solder having a relatively large volume. Therefore, it is possible to provide the wiring board 10 which is effective for improving the connection reliability of the circuit board 31 with the terminal 33.

Further, according to the electronic device 20 of the embodiment, since the wiring board 10 having the above configuration is included, the electronic device 30 which is advantageous for improving the connection reliability of the connection pad 2 with respect to the terminal 32 of the circuit board 31 is provided. Can be provided.

3A and 3B are bottom views showing enlarged main parts of the modified example of the wiring board shown in FIG. 1, respectively. The main part in this case is a part between the central part of one side and one corner part of the lower surface 1c of the insulating substrate 1. In FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals.

In the example shown in FIG. 3A, the width of the plurality of connection pads 2 located at the end portion of the outer side of the lower surface 1c of the insulating substrate 1 is larger than the width of the plurality of connection pads 2 located at the central portion of the outer side of the lower surface 1c. Is also big. For example, in the example shown in FIG. 3A, when the width of one connection pad 2a in the central portion of the plurality of connection pads 2 is W, the width of the connection pad 2b at the end portion adjacent to the connection pad 2b is about 1.19 × W. It is larger than the connection pad 2a in the central portion. Further, the width of the connection pad 2c adjacent to the end side of the connection pad 2b adjacent to the connection pad 2a in the central portion is about 1.42 × W, which is also larger than the connection pad 2a in the central portion. When the pitch of the connection pad 2a in the central portion is P1, the pitch of the connection pad 2 at the end portion between the connection pad 2a in the central portion and the connection pad 2b adjacent thereto is about 1.16 × P1. Further, on the outside, the pitch is about 1.40 × P1, and the pitch is relatively large at the connection pad 2 at the end portion as in the above example.

Also in the case of this modification, the pitch of the plurality of connection pads 2 is larger at the end portion of the outer side of the lower surface 1c of the insulating substrate 1 than at the central portion. Therefore, the connection pad 2 at the end portion can have a larger space between the connection pads 2 and the other adjacent connection pads 2, and the connection pad 2 and the terminal 32 can be connected to each other via a larger amount of the conductive connection material 33. Can be connected. This makes it possible to improve the connection reliability with the circuit board 31.

Further, in this example, the width of the connection pad 2 located at the end portion of the outer side of the lower surface 1c of the insulating substrate 1 (hereinafter, also simply referred to as the end portion) is relatively large. That is, in this case, the length of the bond between the connection pad 2 and the conductive connection material 33 is in the direction along the outer side, which is the direction in which the thermal stress generated in the electronic module 30 including the wiring board 10 acts. Relatively large at the edges. The thermal stress is greater at the edges than at the center. Therefore, the dimension in the direction in which the thermal stress acts can be made longer in the portion where the thermal stress is larger, and the connection reliability between the wiring board 10 (electronic device 20) and the circuit board 31 can be effectively improved. Can be done.

Since the pitch of the plurality of connection pads 2 is also relatively large at the end portion of the outer side where the width of the connection pad 2 is relatively large, the conductive connection material 33 electrically between the adjacent connection pads 2. Sufficient space can be secured to suppress such short circuits.

Further, in the example shown in FIG. 3A, the pitch of the connection pad 2 at the end portion increases as it approaches the end. Further, the width of the connection pad 2 also increases as it approaches the end. According to such a configuration, the amount (volume) of the connecting pad 2 and the conductive connecting material 33 can be increased in response to the thermal stress increasing from the central portion to the end portion, so that the reliability can be further improved. Can be done.

In the example shown in FIG. 3B, a plurality of connection pads 2 are arranged along each of two adjacent outer sides of the lower surface 1c of the insulating substrate 1. Further, the connection pads 2 located at the respective ends of the two outer sides and adjacent to each other have a width at the outer end portion larger than the width at the inner end portion. The outer end portion is the end portion on the outer side side of the connection pad 2 extending from the outer side of the lower surface of the insulating substrate 1 toward the center portion, and the inner end portion is the end portion on the center portion side. ..

Also in the case of this modification, the pitch of the plurality of connection pads 2 is larger at the end portion of the outer side of the lower surface 1c of the insulating substrate 1 than at the central portion. Therefore, in the connection pad 2 at the end portion, a larger amount of the conductive connection material 33 can be present between the connection pad 2 and the other adjacent connection pads 2. Therefore, the wiring board 10 can be used to improve the connection reliability with the circuit board 31.

Further, in this example, among the connection pads 2 arranged along each of the two outer sides of the lower surface 1c of the insulating substrate 1 adjacent to each other, the width of the connection pads 2 located at the respective ends of the outer sides and adjacent to each other is , The outer side of the lower surface 1c of the insulating substrate 1 is larger than the central side. Therefore, it is possible to effectively reduce the possibility that the inner end portions of the connection pads 2 extending in the directions adjacent to each other and intersecting with each other are too close to each other on the central portion side of the lower surface of the insulating substrate 1. can.

Therefore, in the case of this example, it is easy to arrange a plurality of connection pads 2 on a plurality of sides of the lower surface of the insulating substrate 1. For example, even if the number of connection pads 2 increases due to higher functionality of the electronic components 11, it is easy to arrange and arrange these connection pads 2 on the lower surface of the insulating substrate 1.

FIG. 4 is a bottom view showing another modification of the wiring board 10 shown in FIG. 1. In FIG. 4, the same parts as those in FIG. 1 are designated by the same reference numerals. In the example shown in FIG. 4, the adjacent spacing between the plurality of connection pads 2 adjacent to each other is the same for the plurality of connection pads 2 arranged on the outer side of the lower surface 1c of the insulating substrate 1.

Further, also in the example shown in FIG. 4, the pitch of the plurality of connection pads 2 is larger in the connection pads 2 at the ends than in the connection pads 2 in the center. Also in the example shown in FIG. 4, the pitch (1.2 × P2) of the connection pad 2 at the end is larger than the pitch (P2) of the connection pad 2 at the center. Therefore, in the connection pad 2 at the end portion, a larger amount of the conductive connection material 33 than the connection pad 2 at the center portion can be interposed between the terminal 32 of the circuit board 31. As a result, the connection reliability between the wiring board 10 and the circuit board 31 can be improved.

Further, in this example, the adjacent spacing between the plurality of connection pads 2 adjacent to each other is d, which is constant. If the adjacent spacing is set to be constant in this way, when the width of the connection pad 2 at the end is relatively large as in the example shown in FIG. 3 (a), the adjacent connection pads are adjacent to each other. It is suppressed that the two are too close to each other.

Therefore, in this example, the electrical insulation between the plurality of connection pads 2 (particularly the connection pads 2 at the ends) can be enhanced. In other words, when the width of the connection pad 2 at the end is relatively large, the adjacent spacing between the adjacent connection pads 2 at the end is about the same as the adjacent spacing of the connection pad 2 at the center. It may be set.

As described above, in the configuration in which the adjacent spacing between the plurality of connection pads 2 adjacent to each other is constant, only one outer side of the plurality of (two in this embodiment) outer side of the lower surface of the insulating substrate 1 is used. However, it may be multiple outer edges. Further, when a plurality of connection pads 2 are arranged along each of three or more outer edges (not shown), a plurality of connection pads arranged along the outer edges of all the outer edges are arranged. The adjacent intervals of the two may be the same as each other. Further, adjacent spacings that are the same on each outer edge may be the same on all outer edges. In other words, a plurality of connection pads 2 having the same adjacent spacing to each other may be arranged on each of the plurality of outer sides.

When the adjacent intervals of the plurality of connection pads 2 are the same on at least one side, the above-mentioned effects such as improvement of connection reliability and suppression of electrical short circuit can be obtained. Further, if the adjacent intervals of the plurality of connection pads 2 are the same on each of all the sides, the above-mentioned effects such as improvement of connection reliability and suppression of electrical short circuit can be enhanced.

5 (a) and 5 (b) are bottom views showing enlarged main parts in other modified examples of the wiring board shown in FIG. 1, respectively. In this case, the main part is the part between the central portion of one side and the one corner portion of the lower surface 1c of the insulating substrate 1, as in FIG. 3A. In FIG. 5, the same parts as those in FIG. 1 are designated by the same reference numerals.

In the example shown in FIG. 5, the length of the plurality of connection pads 2 located at the end portion of the outer side of the lower surface 1c of the insulating substrate 1 is larger than the length of the one located at the central portion of the outer side of the lower surface 1c. .. For example, in the example shown in FIG. 5, when the length of one connection pad 2a in the central portion of the plurality of connection pads 2 is L, the length of the connection pad 2b at the end portion adjacent to this is about 1.20 × L. It is longer than the connection pad 2a in the central part. Further, the length of the connection pad 2c adjacent to the end side of the connection pad 2b adjacent to the connection pad 2a in the central portion is about 1.40 × L, which is also longer than the connection pad 2a in the central portion. In this example as well, as in the above example, the connection pad 2 at the end portion between the connection pad 2a in the central portion and the connection pad 2b adjacent thereto has a pitch of about 1.16 × P1. Further, on the outside, the pitch is about 1.40 × P1, and the pitch is relatively large at the connection pad 2 at the end portion as in the above example. In this example, since the length of the connection pad 2 (connection pad 2 at the end) located at the end of the outer side is long, the connection pads 2b and 2c at the ends have a larger amount of conductivity than the connection pad 2a at the center. The sex connecting material 33 can intervene between the terminal 32 of the circuit board 31 and the terminal 32. As a result, the connection reliability between the wiring board 10 and the circuit board 31 can be improved.

Further, in the example shown in FIG. 5, the pitch of the connection pad 2 increases as it approaches the end. Further, the length of the connection pad 2 also increases as it approaches the end. According to such a configuration, the amount (volume) of the connecting pad 2 and the conductive connecting material 33 can be increased in response to the thermal stress increasing from the central portion to the end portion, so that the reliability can be further improved. Can be done.

Further, in the example shown in FIG. 5A, the widths of the connection pads 2a, 2b, and 2c are all the same W, but in the example shown in FIG. 5B, the width of the connection pad 2a in the central portion is the same. With respect to W, the width of the connection pad 2b at the adjacent end portion is about 1.19 × W, and the width of the connection pad 2c further adjacent to the end side of the connection pad 2b is about 1.42 × W. This is also larger than the connection pad 2a in the central part. As described above, when the connection pads 2b and 2c at the ends are larger than the connection pads 2a at the center in both width and length, the reliability can be further improved.

6 (a) is a bottom view showing another modification of the wiring board 10 shown in FIG. 1, and FIGS. 6 (b) and 6 (c) are one of the cross sections of the AA line portion of FIG. 6 (a). It is sectional drawing which shows the part enlarged. In FIG. 6A, two examples included in this modified example are shown separately in the upper and lower parts. In FIG. 6, the same parts as those in FIG. 1 are designated by the same reference numerals.

In the example shown in FIG. 6, in a plan view, the connection pad 2 has a convex portion (unsigned) having an arc shape or an elliptical arc shape in the end direction of the outer side of the lower surface 1c of the insulating substrate 1. In this case, the conductive connecting material 33 is joined to the convex portion. Therefore, the bonding area between the connection pad 2 and the conductive connecting material can be increased to improve the bonding strength. These convex portions have an arc shape in the lower example of FIG. 6A and an elliptical arc shape in the upper example.

Further, since the convex portion has an arc shape or an elliptical arc shape, it is possible to suppress the concentration of thermal stress on a part of the convex portion. Therefore, the reliability of the connection between the wiring board 10 and the circuit board 31 via the conductive connecting material 33 can be improved. If the convex part of the elliptical arc is extended along the virtual line part indicated by the alternate long and short dash line, it becomes an elliptical shape. In these elliptical virtual portions, their respective major axes are inclined in the direction in which thermal stress acts with respect to the outer side of the insulating substrate 1.

Further, in the configuration having such a convex portion, the through conductor (a part of the wiring conductor 3) connected to the connection pad 2 may be shifted in the direction of the convex portion in a plan view. In this case, for example, as shown in FIGS. 6 (b) and 6 (c), the surface of the connection pad 2 is also provided with irregularities according to the irregularities of the end face portion of the through conductor, and the connection pad of the conductive connecting material 33 is provided. It is also possible to improve the strength and reliability of the connection to 2.

FIG. 7 is a side view showing a modified example of the electronic module 20 shown in FIG. In this example, the plurality of terminals 32 of the circuit board 31 are arranged at a constant pitch and adjacent intervals. The wiring board 10 of the above embodiment is mounted on the circuit board 31. Therefore, the distance between the terminal portion of the plurality of terminals 31 and the connection pad 2 of the wiring board 10 is larger than that at the central portion of the array. In other words, the terminal portion of the plurality of terminals 31 at the end of the array can secure a larger space between the terminal and the connection pad 2 of the wiring board 10.

Therefore, also in the case of this example, the volume of the conductive connecting material interposed between the terminal 32 and the connecting pad 2 at the end is larger than that of the connecting pad 2 at the center, and the electronic device 20 and the circuit board 31 are made larger. The connection reliability with the terminal 32 can be improved. At the same time, in the connection pad 2 at the end portion, it is possible to effectively suppress an electrical short circuit between the adjacent connection pads 2 due to the conductive connecting material 33.

In the example shown in FIG. 7, for example, as in the example shown in FIG. 6, the connection pad 2 may have a convex portion, or the through conductor may be shifted in the direction of the convex portion. In this case, the area of the connection between the connection pad 2 and the conductive connecting material 33 becomes large at the end side of the outer side of the lower surface 1c where the stress tends to be large in the connection pad 2, and the concentration of stress is also suppressed. Will be done. Therefore, the strength and reliability of the connection between the electronic device 20 and the circuit board 31 can be effectively improved.

As described above, the electronic device 20 of the embodiment includes the wiring board 10 of any of the embodiments and the electronic component 11 mounted on the mounting portion 1a thereof. Since the electronic device 20 includes the wiring board 10 having the above configuration, it is advantageous in terms of improving the connection reliability of the circuit board 31 with respect to the terminal 32.

The electronic component 11 is positioned and set on the mounting portion 1a, the electrodes of the electronic component 11 and the wiring conductor 3 of the wiring board 10 are joined by a joining material 12 such as a low melting point brazing material, and the electronic component 11 is joined as necessary. The electronic device 20 can be manufactured by sealing the electronic device 20.

Further, as described above, the electronic device 20 having the above configuration, the plurality of connection pads 2 of the electronic device 20, and the circuit board 31 having the plurality of terminals 32 connected via the conductive connecting material 33 are included. , The electronic module 30 of the embodiment is configured. In this electronic module 30, the volume of the conductive connecting material 33 interposed between the connecting pad 2 at the end and the terminal 32 is located at the center of the outer side of the lower surface of the insulating substrate 1 with the connecting pad 2 and the terminal 32. It is larger than the volume of the conductive connecting material 33 interposed between the and.

Since this configuration is provided, the electronic module 30 of the embodiment can improve the connection reliability between the connection pad 2 and the terminal 32 at the end portion where the thermal stress is large. Therefore, it is possible to obtain the electronic module 30 in which the connection reliability between the electronic device 20 and the terminal 32 of the circuit board 31 is effectively improved.

1 ... Insulation substrate 1a ... Mounting part 1b ... Top surface 1c ... Bottom surface 2 ... Connection pad 3 ... Wiring conductor
10 ・ ・ ・ Wiring board
11 ・ ・ ・ Electronic components
12 ・ ・ ・ Joining material
20 ... Electronic device
30 ・ ・ ・ Electronic module
31 ... Circuit board
32 ・ ・ ・ Terminal
33 ・ ・ ・ Conductive connecting material

Claims (6)

An insulating substrate having an upper surface including a mounting portion for electronic components and a lower surface opposite to the upper surface and having a polygonal shape in a plan view.
The lower surface of the insulating substrate is provided with a plurality of connection pads arranged along the outer edge of the lower surface.
The width of the plurality of connection pads increases in order from the central portion of the outer side of the lower surface toward the end portion, and the width thereof increases.
The pitch of the plurality of connection pads is larger than that of the central portion at the end portion of the outer edge of the lower surface, and the adjacent distance between the plurality of connection pads adjacent to each other increases in order as the distance between the plurality of connection pads approaches the end portion. Wiring board. The plurality of connection pads are arranged along each of the two adjacent outer sides of the lower surface, and the connection pads located at the respective ends of the two outer sides and adjacent to each other are the outer ends. The wiring board according to claim 1, wherein the width at the portion is larger than the width at the inner end portion. The wiring according to claim 1 or 2, wherein the length of the plurality of connection pads located at the end portion of the outer side of the lower surface is larger than the length of the one located at the central portion of the outer side of the lower surface. substrate. The wiring board according to claim 3, wherein the length of the plurality of connection pads increases as the length approaches the end portion. The wiring board according to any one of claims 1 to 4,
An electronic device including electronic components mounted on the mounting portion. The electronic device according to claim 5 and
It comprises a plurality of connection pads of the electronic device and a circuit board having a plurality of terminals connected via a conductive connecting material.
The volume of the conductive connecting material interposed between the connection pad located at the end portion of the outer side of the lower surface of the insulating substrate and the terminal is located at the central portion of the outer side of the lower surface of the insulating substrate. An electronic module larger than the volume of the conductive connecting material interposed between the connection pad and the terminal.

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