JP2016163020A - Board connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for facilitating the visual inspection at a joint, when mounting a board mounted with a component on a mounted member.SOLUTION: A board connection structure (1) has such a structure that a module board (7) mounted with an electronic component (15) and a mother board (3) are superposed via a spacer board (5) and connected electrically. When viewing from the direction of superposition, the spacer board (5) has a shape spreading outward from the outer periphery of the module board (7). A third wiring pattern (35) on the outer side of the module board (7) and a second wiring pattern (37) on the surface of the spacer board (5) are joined by a first fillet (23). The second wiring pattern (37) on the side of the spacer board (5) and a first wiring pattern (57) on the surface of the mother board (3) are joined by a second fillet (27).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for mounting a substrate (for example, a module substrate) on which a component is mounted on a mounted member (for example, a mother substrate).

  Conventionally, as a method for connecting (mounting) a module substrate on which components such as electronic components are mounted on both sides to a mother substrate which is a mounted member, for example, as disclosed in Patent Document 1, for example, the same resin material as the module substrate A technique is disclosed in which a spacer substrate such as a strip-shaped substrate or a square-shaped substrate is sandwiched between a module substrate and a mother substrate.

  In this technique, for example, the wiring pattern on the surface (lower surface) of the module substrate and the wiring pattern on the side surface of the spacer substrate are joined by solder (solder), and the wiring pattern on the side surface of the spacer substrate and the surface (upper surface) of the mother substrate are used. These wiring patterns are similarly joined by solder (see FIG. 11A).

JP 2001-156222 A

  However, in this prior art, a substrate having a smaller outer shape in plan view than the module substrate is used as the spacer substrate. Therefore, after mounting the module substrate on the mother substrate, the solder joints on the outer peripheral side between the substrates are mounted. (Fillet) is hidden behind the top module board.

For this reason, after the module substrate is mounted on the mother substrate, the solder bonding state cannot be observed well, and there is a problem that the appearance inspection of the solder cannot be performed.
As a countermeasure, it is conceivable to match the side surfaces (peripheral shapes) of the module substrate and the spacer substrate (see FIG. 11B). In this method, the fillet formed between the spacer substrate and the mother substrate can be observed, but the fillet between the module substrate and the spacer substrate cannot be observed (cannot be observed because the fillet is not formed). Another problem arises that the bonding state with the substrate cannot be reliably recognized.

  The present invention has been made to solve the above-described problems, and provides a technique capable of easily performing an appearance inspection of a joint portion when a substrate on which a component is mounted is mounted on a mounted member. is there.

  In the substrate connection structure of the present invention, a substrate (for example, a module substrate) on which a component is mounted and a mounted member (for example, a mother substrate) on which the substrate is mounted are overlapped via a spacer (for example, a spacer substrate). And the mounted member are electrically connected. Further, the substrate and the spacer, and the spacer and the mounted member are joined by a fillet obtained by melting and solidifying a conductive metal material (for example, solder).

  Furthermore, when the substrate connection structure is viewed from the overlapping direction, the spacer has a shape that extends outward from the outer periphery of the substrate. The conductive portion on the outer side surface of the substrate and the conductive portion on the outer surface of the spacer are joined by a first fillet having conductivity, and the conductive portion on the outer side surface of the spacer and the mounted member The conductive portion on the surface outside the spacer is joined by a second fillet having conductivity.

  Thus, in the substrate connection structure of the present invention, the spacer has a shape that spreads outward from the outer periphery of the substrate. Therefore, when viewed from the overlapping direction, the upper surface of the spacer ( That is, the conductive portion on the surface when viewed from the overlapping direction is located. Therefore, the first fillet that joins the conductive part on the outer side surface of the substrate and the conductive part on the upper surface of the spacer can be observed from the superimposed direction.

  Similarly, when viewed from the overlapping direction, the conductive portion on the upper surface of the mounted member is positioned around the spacer. Therefore, the second fillet joining the conductive portion on the outer side surface of the spacer and the conductive portion on the top surface of the mounted member can be observed from the superimposed direction.

  That is, since the first and second fillets can be observed from the overlapping direction (specifically, from the substrate side), it is possible to easily and reliably perform the appearance inspection of the joint portion by the fillet.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is sectional drawing (II sectional drawing of FIG. 2) which fractures | ruptures and shows along the direction which overlaps the board | substrate connection structure of 1st Embodiment. It is a top view which shows the board | substrate connection structure of 1st Embodiment. It is a disassembled perspective view which decomposes | disassembles and shows the principal part of the board | substrate connection structure of 1st Embodiment. It is sectional drawing which expands and shows the principal part of the board | substrate connection structure of 1st Embodiment (sectional drawing which expands and shows a part of II cross section of FIG. 2). It is a perspective view which shows the spacer board | substrate of 1st Embodiment. It is explanatory drawing which shows the manufacture procedure of the board | substrate connection structure of 1st Embodiment. It is explanatory drawing which shows the board | substrate connection structure of 2nd Embodiment, and its manufacturing procedure. It is a perspective view which shows the spacer board | substrate of 2nd Embodiment. It is a perspective view which shows a part of spacer substrate of 3rd Embodiment. It is sectional drawing fractured | ruptured and shown along the direction which overlaps the board | substrate connection structure of other embodiment. It is explanatory drawing of a prior art.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[1. First Embodiment]
[1.1. Constitution]
As shown in FIGS. 1 to 3, the substrate connection structure 1 according to the first embodiment physically and electrically connects (mounts) a module substrate 7 to one surface of a mother substrate 3 via a spacer substrate 5. : Installed). That is, the mother board 3, the spacer board 5, and the module board 7 are stacked so as to be arranged in this order, and are joined and integrated by soldering.

  Among these, the mother substrate 3 is a printed wiring board having a rectangular shape as viewed from the vertical direction (overlapping direction) in FIG. 1, for example, an insulating substrate made of a resin-based substrate material (for example, epoxy resin). A wiring pattern or the like is formed on both sides or one side. The mother board 3 may or may not have electronic components mounted thereon.

  The module substrate 7 is obtained by mounting the electronic component 15 on a rectangular printed wiring board, for example, in a plan view. The printed wiring board is an insulating substrate made of, for example, a resin-based substrate material (for example, epoxy resin). A wiring pattern or the like is formed on both sides.

  That is, on one surface (upper surface: first main surface in FIG. 1) 11 and the other surface (lower surface: second main surface in FIG. 1) 13 of the module substrate 7, for example, an electronic component such as an IC, a resistor, or a capacitor 15 is implemented.

The spacer substrate 5 is a member having a rectangular frame shape in plan view, for example, and is obtained by forming a wiring pattern on an insulating substrate made of, for example, a resin material (for example, epoxy resin).
In the substrate connection structure 1 described above, the relationship between the outer shape (outer periphery size) of the mother substrate 3, the outer shape (outer periphery size) of the spacer substrate 5 and the outer shape (outer periphery size) of the module substrate 7 in plan view is as follows. The mother substrate 3 is the largest, the spacer substrate 5 is the next largest, and the module substrate 7 is the smallest.

  Therefore, in the plan view, the substrate connection structure 1 has the outer peripheral edge portion 17a of the upper surface 17 of the spacer substrate 5 protruding and exposed in a square frame shape so as to surround the outer peripheral side of the module substrate 7, and the spacer substrate 5, the outer peripheral edge 19 a of the upper surface 19 of the mother substrate 3 protrudes in a square frame shape and is exposed.

  A plurality of first fillets 23 that join a part of the side surface 21 of the module substrate 7 and a part of the outer peripheral edge portion 17a of the upper surface 17 of the spacer substrate 5 along the outer periphery of the module substrate 7 are provided. It is provided in the place. Similarly, the second fillet 27 that joins a part of the outer side surface 25 of the spacer substrate 5 and a part of the outer peripheral edge portion 19 a of the upper surface 19 of the mother substrate 3 along the outer periphery of the spacer substrate 5. Are provided at a plurality of locations.

  Further, as shown in FIG. 1, the inner side surface 29 of the spacer substrate 5 is located on the inner peripheral portion of the upper portion of the inner side surface 29 of the spacer substrate 5 and the lower surface 13 of the module substrate 7 from the portion where the spacer substrate 5 abuts. 3rd fillet 31 which joins a part of and a part of lower surface 13 of module board 7 is formed. Similarly, a part of the side surface 29 on the inner side of the spacer substrate 5 and a mother substrate on the inner peripheral portion of the lower surface of the inner side surface 29 of the spacer substrate 5 and the upper surface 19 of the mother substrate 3 from the portion where the spacer substrate 5 abuts. A fourth fillet 33 is formed to join a part of the upper surface 19 of the third.

  The first to fourth fillets 23, 27, 31, and 33 are solder joints formed by solidifying after solder (solder) is melted by heating. As the solder, for example, Sn-Pb solder or lead-free solder containing no Pb can be used.

[1.2. Main part of the configuration]
Next, the main part of the substrate connection structure 1 will be described in more detail.
As shown in FIG. 4, a plurality of first wiring patterns 35 are formed on a part of the upper surface 19 of the mother substrate 3 where the spacer substrate 5 is placed. The plurality of first wiring patterns 35 are annularly arranged along the entire circumference of the spacer substrate 5 in plan view.

  In addition, a plurality of second wiring patterns are formed on a part of the spacer substrate 5 so as to cover the frame portion, for example, around the frame portion, that is, so as to circle the pillars constituting the frame portion (see FIG. 5). 37 is formed. There are some places that do not go around. The plurality of second wiring patterns 37 are annularly arranged at predetermined intervals along the entire circumference of the spacer substrate 5 in plan view.

  The second wiring pattern 37 (one round) includes a second lower surface pattern 41 on the lower surface 39 side of the spacer substrate 5, a second upper surface pattern 45 on the upper surface 43 side, and an outer side surface 25 side (outer periphery side). The second outer pattern 47 and the second inner pattern 49 on the inner side surface 29 side (inner peripheral side).

  Further, a plurality of third wiring patterns 51 are formed on the module substrate 7, and the plurality of third wiring patterns 51 are arranged along the entire circumference of the spacer substrate 5 in the plan view (therefore, the module substrate 7). Along the outer circumference).

The third wiring pattern 51 includes a third lower surface pattern 53 on the lower surface 13 side that contacts the spacer substrate 5 and a third side surface pattern 55 on the side surface 21 side.
Among these, each 1st wiring pattern 35 of the mother board | substrate 3 is arrange | positioned so that each 2nd wiring pattern to which the spacer board | substrate 5 respond | corresponds, respectively. The first wiring pattern 35 is set to have a larger dimension (width) in the left-right direction (X direction) in FIG. 4 than the second lower surface pattern 41 of the spacer substrate 5.

  That is, in a plan view (when viewed from above in the Z direction), the outer side of the first wiring pattern 35 (the left side in FIG. 4) protrudes from the second lower surface pattern 41 over the entire circumference, and the first wiring pattern 35 The inner side (right side in FIG. 4) also protrudes beyond the second lower surface pattern 41.

  Then, a second fillet 27 having a shape that widens outward toward the lower portion is formed so as to join the projecting portion 35 a on the outer side of the first wiring pattern 35 and the second outer pattern 47. Accordingly, the external appearance of the second fillet 27 can be observed in a plan view (when viewed from above in the Z direction).

The fourth fillet 33 is formed so as to join the overhanging portion 35 b inside the first wiring pattern 35 and the second inner pattern 49.
Further, the second upper surface pattern 45 of the spacer substrate 5 protrudes outward (left side in FIG. 4) from the third lower surface pattern 53 of the module substrate 7. Further, the third lower surface pattern 53 of the module substrate 7 protrudes to the inner side (right side in FIG. 4) than the second upper surface pattern 45 of the spacer substrate 5.

  And the 1st fillet 23 of the shape which spread | expanded greatly outward was formed so that the overhanging part 45a of the outer side of the 2nd upper surface pattern 45 and the 3rd side surface pattern 55 might be joined. Therefore, the external appearance of the first fillet 23 can be observed in a plan view (when viewed from above in the Z direction).

The third fillet 31 is formed so as to join the overhanging portion 53 a inside the third lower surface pattern 53 and the second inner pattern 49.
Separately, a lower surface pad 61 is formed on the inner peripheral side of the lower surface 13 of the module substrate 7 (that is, the lower surface of the portion surrounded by the spacer substrate 5), and the electronic component 15 is formed on the lower surface pad 61. Are joined (mounted) by the lower face fillet 63.

Similarly, an upper surface pad 65 is formed on the upper surface 11 of the module substrate 7, and the electronic component 15 is joined (mounted) to the upper surface pad 65 by an upper surface fillet 67.
[1.3. Production method]
Next, the manufacturing method of the board | substrate connection structure of 1st Embodiment is demonstrated easily.

  As shown in the upper diagram of FIG. 6, an upper surface pad 65, a lower surface pad 61, and a third wiring pattern 51 are formed on the surface of the insulating substrate by a well-known pattern forming method to produce a printed wiring board. In addition, as this pattern formation method, for example, a method of forming a pattern or the like by plating (additive method), a method of forming a pattern or the like by etching (subtractive method), or a method of forming a pattern by printing a conductive paste Etc. can be adopted.

Next, the electronic component 15 is mounted on the upper surface pad 65 and the lower surface pad 61 of the printed wiring board by a known surface mounting technique, and the module substrate 7 is manufactured.
Similarly, the second wiring pattern 37 is formed on the surface of the insulating substrate by the pattern forming method, and the spacer substrate 5 is manufactured.

Similarly, the first wiring pattern 35 is formed on the surface of the insulating substrate by the pattern forming method, and the mother substrate 3 is manufactured.
Next, in the surface of the first, second, and third wiring patterns 35, 37, and 51, solder having a composition of, for example, Sn63-Pb37 is formed at a position where the first to fourth fillets 23, 27, 31, and 33 are formed. A solder paste (cream solder) containing (eutectic solder) is applied.

  As the solder to be used, one having a melting point of solder in the solder paste lower than that of the upper face fillet 67 and the lower face fillet 63 can be used, but is not limited thereto. For example, the melting points of the first to fourth fillets 23, 27, 31, 33 may be the same as the melting points of the upper surface fillet 67 and the lower surface fillet 63.

  Next, the module substrate 7, the spacer substrate 5 and the mother substrate 3 coated with the solder paste are combined as shown in the lower diagram of FIG. First to fourth fillets 23, 27, 31, 33 are formed.

  Thereby, the module substrate 7, the spacer substrate 5, and the mother substrate 3 are joined together. That is, the substrate connection structure 1 is completed by mounting the module substrate 7 on the mother substrate 3 via the spacer substrate 5. In addition, the manufacturing method of the board | substrate connection structure 1 is not limited to the manufacturing method mentioned above.

[1.4. effect]
In the first embodiment, the spacer substrate 5 has a shape that extends outward from the outer periphery of the module substrate 7 when viewed from the direction in which the substrate connection structures 1 are overlapped. The third side surface pattern 21 of the module substrate 7 and the protruding portion 45a of the second upper surface pattern 45 of the spacer substrate 5 are joined by the first fillet 23, and the second outer pattern 47 of the spacer substrate 5 and the mother substrate are joined. 3, the protruding portion 35 a of the first wiring pattern 35 is joined by a second fillet 27.

  Accordingly, the first fillet 23 and the second fillet 27 can be observed from the overlapping direction (specifically, from the module substrate 7 side). Therefore, the appearance inspection of the joint portion by the first fillet 23 and the second fillet 27 can be easily and reliably performed by an operator or an inspection device.

[2. Second Embodiment]
Since the basic configuration of the second embodiment is the same as that of the first embodiment, the description of the common configuration will be omitted, and the description will focus on the differences. In addition, the same structure as 1st Embodiment is demonstrated using the same number.

As shown in FIG. 7, the substrate connection structure 71 of the second embodiment is obtained by mounting a module substrate 77 on a mother substrate 73 via a spacer substrate 75, as in the first embodiment.
Among these, the second wiring pattern 79 of the spacer substrate 75 does not go around the frame portion of the insulating substrate but is formed in a U-shape (see FIG. 8).

  Therefore, the third wiring pattern 81 is formed on the module substrate 77 so as to correspond to the shape of the second wiring pattern 79. Specifically, the third lower surface pattern 83 of the third wiring pattern 81 is formed up to the formation position of the second upper surface pattern 85 of the spacer substrate 75 (the position on the right side in FIG. 7).

  Similarly, a first wiring pattern 87 is formed on the mother substrate 73 so as to correspond to the shape of the second wiring pattern 79. Specifically, the first wiring pattern 87 is formed up to the position of the second lower surface pattern 89 of the spacer substrate 75 (the position on the right side in FIG. 7).

  7, the third side surface pattern 21 of the module substrate 77 and the protruding portion 85a of the second upper surface pattern 85 of the spacer substrate 75 are formed by the first fillet 23 as in the first embodiment. It is joined. Further, the second outer pattern 47 of the spacer substrate 75 and the protruding portion 87 a of the first wiring pattern 87 of the mother substrate 73 are joined by the second fillet 27.

Therefore, also in the second embodiment, the same effects as in the first embodiment can be obtained.
[3. Third Embodiment]
Since the basic configuration of the third embodiment is the same as that of the first embodiment, the description of the common configuration will be omitted, and the description will focus on the differences. In addition, the same structure as 1st Embodiment is demonstrated using the same number.

  As shown in FIG. 9, a second wiring pattern 93 is formed on the spacer substrate 91 used in the substrate connection structure of the third embodiment. Specifically, a substantially rectangular second upper surface pattern 97 is formed on the upper surface 95 of the frame portion of the spacer substrate 91. A similar second lower surface pattern (not shown) is also formed on the lower surface 99.

  A semi-cylindrical through hole 101 is formed outside and inside the frame portion so as to electrically connect the second upper surface pattern 97 on the upper surface 95 and the second lower surface pattern on the lower surface 99. The through-hole 101 is a normal cylindrical through-hole that is broken along the axial direction, and an inner peripheral pattern 103 made of the same material as the second upper surface pattern 97 is formed on the inner peripheral surface thereof. .

  In this substrate connection structure, the first fillet 23 bonded to the module substrate 7 is formed on the second upper surface pattern 97 of the spacer substrate 91, and the first fillet 23 bonded to the mother substrate 3 is bonded to the inner peripheral surface of the through hole 101. Two fillets 27 are formed.

Therefore, the third embodiment also has the same effect as the first embodiment.
[4. Fourth to seventh embodiments]
Since the basic configuration of the fourth to seventh embodiments is the same as that of the first embodiment, the description of the common configuration will be omitted, and the description will focus on the differences. In addition, the same structure as 1st Embodiment is demonstrated using the same number.

  As shown in FIG. 10A, the substrate connection structure 111 of the fourth embodiment is obtained by mounting the module substrate 7 on the mother substrate 3 via the spacer substrate 5 as in the first embodiment. In the fourth embodiment, the electronic component 15 is mounted only on the lower surface side of the module substrate 7.

The fourth embodiment also has the same effect as the first embodiment.
As shown in FIG. 10B, the board connection structure 121 of the fifth embodiment is such that the module board 7 is mounted on the mother board 3 via the spacer board 5 as in the first embodiment. In the fifth embodiment, the electronic component 15 is also mounted on the mother board 3. That is, the electronic component 15 mounted on the mother board 3 is disposed in the central space of the spacer board 5.

The fifth embodiment also has the same effect as the first embodiment.
As shown in FIG. 10C, the board connection structure 131 of the sixth embodiment is such that the module board 7 is mounted on the mother board 3 via the spacer board 5 as in the first embodiment. In the sixth embodiment, as in the fifth embodiment, the electronic component 15 is mounted on the mother board 3, but in the module substrate 7, the electronic component 15 is mounted only on the upper surface side.

The sixth embodiment also has the same effect as the first embodiment.
As shown in FIG. 10D, the board connection structure 141 of the seventh embodiment is such that the module board 7 is mounted on the mother board 3 via the spacer board 5 as in the first embodiment. In the seventh embodiment, as in the fifth embodiment, the electronic component 15 is mounted on the mother board 3, but in the module substrate 7, the electronic component 15 is mounted only on the lower surface side.

Also in the seventh embodiment, the same effects as in the first embodiment are obtained.
As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment.

  (1) For example, as a metal material for forming a fillet, Sn-Pb solder or lead-free solder can be used, for example. Metals or their alloys can also be used.

  (2) In addition, as the shape of the spacer, various shapes satisfying the conditions of the present invention such as a combination of a plurality of members having a square shape, a U shape, and a strip shape in a plan view. Can be adopted.

  (3) As a method for forming the fillet, a known method such as a known reflow method (reflow method) or a method of attaching a molten metal material such as solder (flow method) can be employed.

  (4) The functions of one component in the above embodiment may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claim are embodiment of this invention.

[Correspondence]
An electronic component corresponds to a component. The module substrate corresponds to the substrate. The mother board corresponds to the mounted member. The spacer corresponds to the spacer substrate. The first and second fillets correspond to fillets. The first to third wiring patterns correspond to the conductive portions.

DESCRIPTION OF SYMBOLS 1, 71, 111, 121, 131, 141 ... Board connection structure 3, 73 ... Mother board 5, 75, 91 ... Spacer board 7, 77 ... Module board 15 ... Electronic component 23 ... First fillet 27 ... Second fillet 35 , 87 ... 1st wiring pattern 37, 79, 93 ... 2nd wiring pattern 51, 81 ... 3rd wiring pattern

Claims (4)

A substrate (7) on which a component (15) is mounted and a mounted member (3) on which the substrate (7) is mounted are overlapped via a spacer (5), and the substrate (7) and the substrate to be mounted are overlapped. The mounting member (3) is electrically connected to the substrate (7) and the spacer (5), and the spacer (5) and the mounted member (3) are electrically conductive. In the substrate connection structure (1) joined by the fillet (23, 27) in which the metal material having melted and solidified,
When viewed from the superimposed direction,
The spacer (5) has a shape extending outward from the outer periphery of the substrate (7),
A first fillet (23) for joining the conductive portion (35) on the outer side surface of the substrate (7) and the conductive portion (37) on the outer surface of the spacer (5) from the substrate (7);
A second fillet (27) for joining the conductive portion (37) on the outer side surface of the spacer (5) and the conductive portion (57) on the outer surface of the mounted member (3) from the spacer (5); ,
A board connection structure comprising:   The substrate connection structure according to claim 1, wherein the metal material is solder.   The board connection structure according to claim 1 or 2, wherein the component (15) is mounted on at least one of the first main surface and the second main surface of the substrate (7).   The board connection structure according to any one of claims 1 to 3, wherein the component (15) is mounted on a surface of the mounted member (3) on the board (7) side.