JP4381248B2 - Electrode terminal fixing structure and fixing method thereof - Google Patents

Description

  The present invention relates to an electrode terminal fixing structure and a fixing method thereof, and more specifically, to surface mounting in which soldering is performed by a reflow process, such that a sub-board is mounted on a main board and a reflow furnace is passed. The present invention relates to an improvement in electrode terminal mounting support in an assembly including a reheating process.

  Regarding electronic circuit mounting technology, there is a technique in which a part of a circuit is modularized on a sub-board and this sub-board is mounted on a main board. For example, as concrete examples are shown in Patent Documents 1 and 2 and the like, in a computer apparatus, a DC / DC converter of a power supply unit is formed on a sub-board and modularized, and this is used as a main board (main board). Implementation has been done.

  The mounting of the modular sub-board has a configuration in which connection pins and positioning pins are assembled to the sub-board and connected to the main board by these pins, as can be seen in Patent Document 1 and the like. However, such a configuration requires drilling for raising the pins, which is disadvantageous in terms of man-hours, cost, and miniaturization. For this reason, as seen in Patent Document 2 and the like, the electronic component has a configuration in which an electrode terminal, that is, a chip component for connection is interposed between the electronic component and the main substrate so as to be surface-mounted on the substrate.

For assembly and mounting of the board, a method of soldering by a reflow process is often employed. In this method, a solder paste is applied in advance to each pattern on the substrate by printing or the like, and then each electronic component is mounted in a predetermined manner and then soldered by passing it through a reflow furnace.
JP 2004-79776 A JP 2002-76566 A

  However, in the electrode terminal fixing structure by such surface mounting, there is a problem that when the modular sub-board is mounted on the main board, the electrode terminal moves due to heat of the reflow process and is displaced.

  That is, since the electrode terminals are soldered to the pattern surface (terminal pads) of the sub-board and mounted on the main board, the solder is remelted on the side of the sub-board during the second reflow process. Semi-melting occurs, and at this time, the electrode terminal or the sub-substrate and the main substrate develop thermal stress. As a result, the electrode terminal that should have been fixed to the sub-substrate may move and be displaced.

  And since this electrode terminal is a power system connection line, if the position shift occurs, the electrical connection state changes and the connection resistance changes, so the electrical characteristics change, and the performance assumed at the time of design You will not be able to get.

  The present invention solves the above-described problems. The object of the present invention is to prevent the electrode terminals from moving even in a situation where the solder remelts, such as performing a reflow process again in the assembly mounting of the electronic circuit board. It is an object of the present invention to provide an electrode terminal fixing structure and a method for fixing the electrode terminal which can prevent the performance from being deteriorated.

In order to achieve the above-described object, the electrode terminal fixing structure according to the present invention includes a terminal pad for surface mounting the electrode terminal on both the main board and the sub board, and the electrode terminal interposed therebetween. In the electrode terminal fixing structure in which the sub-board is mounted on and electrically connected to the main board, the sub-board is provided with a non-solder portion where solder is not attached to a surface region on which the electrode terminal is mounted. The solder pad is configured to be coated with a thermosetting adhesive, and the terminal pad provided on the sub-board is formed to have an outer shape in which a part of the region overlapping with the electrode terminal is cut out. The pad portion is the non-solder portion .

  In addition, the non-solder parts may be provided in pairs on two opposite sides of the terminal pad, and the area of the non-solder parts may be set to at most ½ or less of the total area where the electrode terminals overlap. it can.

Further, the terminal pad is formed to have a size that is at least larger than the mounting surface of the electrode terminal, and a resist film having a predetermined pattern that covers a part of the region is provided on the terminal pad, and the portion of the resist film is made non-conductive. It may be a solder part .

Also, terminal pads for surface mounting the electrode terminals are formed on both the main board and the sub board, and the sub board is mounted on the main board and electrically connected via the electrode terminals. In the terminal fixing method, the terminal pad provided in the surface region on which the electrode terminal of the sub-board is mounted is formed in an outer shape in which a part of the region overlapping with the electrode terminal is notched, The non-pad part is a non-solder part where solder is not applied, a thermosetting adhesive is applied to the non-solder part, and a solder paste is applied to the terminal pad in advance, and then the electrode terminal The sub-board is passed through a reflow furnace, and after the reflow process is completed, the electrode terminals on the sub-board are mounted toward the terminal pads of the main board and both boards are passed again through the reflow furnace.

  With this configuration, in the present invention, assembly mounting of the sub-board is performed by applying a solder paste to the terminal pad in advance, applying a thermosetting adhesive to the non-solder part, and then applying the electrode terminal and each electronic device. Soldering is performed by mounting the parts in a predetermined manner and passing the parts through a reflow furnace. For mounting on the main board, soldering is performed by mounting the electrode terminals on the sub-board toward the terminal pads of the main board and passing both boards through the reflow furnace again.

  Therefore, by passing through a reflow furnace, the solder paste is melted and the electrode terminals are soldered and electrically connected. Then, the adhesive is cured at the non-solder part, and the corresponding part of the electrode terminal is fixed.

  Furthermore, the assembled and mounted sub-board mounts the electrode terminals on the terminal pads of the main board and passes both boards again through the reflow furnace, so that the solder is remelted by this heating, but the electrode terminals are fixed by an adhesive. Because it does, it does not move.

  In the electrode terminal fixing structure and the fixing method according to the present invention, the assembly mounting of the sub-board is performed by applying a thermosetting adhesive to the non-solder part. At this time, the adhesive is cured at the non-solder part and the corresponding part of the electrode terminal is fixed. And mounting on the main board is because the electrode terminals on the sub-board are mounted facing the terminal pads of the main board and both boards are again passed through the reflow furnace. Since it is fixed by adhesive, it does not move.

  Therefore, it is possible to prevent the electrode terminal from moving even in a situation where the solder is remelted, for example, by performing the reflow process again in the assembly mounting of the electronic circuit board, and it is possible to prevent the performance from being deteriorated due to misalignment.

  FIG. 1 is a plan view of a sub-board showing an embodiment of the present invention. In the present embodiment, the sub-board 1 is formed with a predetermined circuit pattern, and a surface-mounting electronic component constitutes a DC / DC converter and becomes a single functional component.

  The circuit pattern is formed on the front and back of the sub-board 1, and electronic components are mounted on the front and back. 1 is provided with a terminal pad 2 for surface mounting electrode terminals to be described later, and is electrically mounted by surface mounting on the main substrate with the electrode terminals interposed therebetween. It has become. Of course, it is assumed that terminal pads are formed on the main board at positions corresponding to the electrode terminals and mounted on the main board (main board) of the computer device, for example.

  The sub-board 1 is formed to have an outer dimension of 13 × 33 mm using, for example, a laminated board having a thickness of 0.9 mm. The electrode terminal has a rectangular parallelepiped shape as shown in FIG. 4, and is formed into a chip shape having a cross section of 1.5 mm square and a length of 2.5 mm, for example.

  The electrode terminal fixing structure according to the present invention is applied to the sub-board 1, and the sub-board 1 is provided with a non-solder part 4 to which solder is not attached in a surface region on which the electrode terminal is mounted. 4 is applied with a thermosetting adhesive.

  Further, the non-solder parts 4 are provided in pairs on the two opposing sides of the terminal pad 2. The area of the non-solder part 4 is set to 1/2 or less of the entire area where the electrode terminals overlap. That is, the outer shape of the terminal pad 2 has a recessed portion in a substantially semicircular shape on two opposing sides as shown in FIGS. 2 and 3, and the recessed portion becomes the non-solder portion 4.

  2 and 3 are two different examples in which the circuit pattern in the part is different. In the example shown in FIG. 2, the circuit pattern serving as the base of the terminal pad 2 has a rectangular outer shape. As shown in FIG. 2 (a), this is formed at least larger than the mounting surface of the electrode terminal, and as shown in FIG. 2 (b), a part of the region is covered on this rectangular pad. A resist film 6 having a predetermined pattern is provided, and a corresponding portion of the resist film 6 is a non-solder part 4.

  In the example shown in FIG. 3, the circuit pattern itself that becomes the terminal pad 2 is formed in a substantially gourd shape. That is, a part of a region overlapping with the electrode terminal is formed in a cutout outer shape, and a non-pad portion by the cutout outer shape is defined as a non-solder part 4. In any case, the non-solder part 4 is coated with a thermosetting adhesive 5.

  FIG. 4 is a perspective view for explaining the mounting of the electrode terminals on the terminal pads. The assembly mounting of the sub-board 1 employs a method of soldering by a reflow process. That is, a solder paste is applied to each pattern on the sub-substrate 1 in advance by printing or the like, then each electronic component is mounted in a predetermined manner, and soldered by passing it through a reflow furnace. At this time, in the present invention, along with the application of the solder paste, the thermosetting adhesive 5 is applied to the non-solder part 4 and the electrode terminal 3 is mounted on the terminal pad 2. For this reason, by passing it through a reflow furnace, the solder paste is melted, and of the mounting surfaces of the electrode terminals 3, the overlapping surface with the terminal pads 2 is soldered and electrically connected. Then, the adhesive 5 is cured at the non-solder part 4 and the corresponding part of the electrode terminal 3 is fixed. Thus, since the adhesive 5 is applied to the non-solder part 4 and separated from the solder paste application region, both the solder and the adhesive melted during the reflow process are not mixed. Both can function together.

  Next, as shown in FIGS. 5A and 5B, this assembled and mounted sub-board 1 is surface-mounted on the main board 7 with the electrode terminals 3 interposed therebetween, which is also soldered by a reflow process. Take the method of attaching.

  That is, terminal pads 8 are formed on the main substrate 7 at positions corresponding to the electrode terminals 3, and solder paste is applied to these terminal pads 8 in advance by printing or the like. Then, the electrode terminals 3 of the sub-board 1 are mounted on the terminal pads 8 of the main board 7 (a) and passed through a reflow furnace (b). At this time, the solder is remelted by heating in the reflow furnace, but the electrode terminal 3 does not move because it is fixed by the adhesive 5.

  That is, according to the present invention, it is possible to prevent the electrode terminal 3 from moving even in a situation where the solder is remelted, such as performing a reflow process again in the assembly and mounting of the electronic circuit board, and to prevent deterioration in performance due to misalignment. it can.

It is a top view of the sub-board | substrate which shows one embodiment of this invention. It is a top view which expands and shows a terminal pad site | part. It is a top view which expands and shows the other example of a terminal pad site | part. It is a perspective view explaining mounting of the electrode terminal with respect to a terminal pad. It is a side view explaining the assembly | attachment operation | work with respect to a main board | substrate, (a) shows the mounting work of a subboard | substrate, (b) shows the state in a reflow process.

Explanation of symbols

1 Sub-board 2 and 8 Terminal pad 3 Electrode terminal 4 Non-solder part 5 Adhesive 6 Resist film 7 Main board

Claims (5)

Terminal pads for surface-mounting electrode terminals are formed on both the main board and the sub-board, and the sub-board is mounted on the main board and electrically connected via the electrode terminals. In the fixed structure,
The terminal to which the the sub said electrode terminal surface region for mounting a substrate, providing a non-solder sites not attached solder, a thermosetting adhesive constitutes the coating so that the said non-solder site, provided that the sub-substrate The pad is formed in an outer shape in which a part of an area overlapping with the electrode terminal is cut out, and a non-pad portion by the cut-out outer shape is used as the non-solder portion .   2. The electrode terminal fixing structure according to claim 1, wherein the non-solder parts are provided in pairs with respect to two opposing sides of the terminal pad. 3.   3. The electrode terminal fixing structure according to claim 1, wherein the region of the non-solder part is set to at most ½ or less of the entire region where the electrode terminals overlap. 4.   The terminal pad is formed to be at least larger than the mounting surface of the electrode terminal, a resist film having a predetermined pattern covering a part of the region is provided on the terminal pad, and the portion of the resist film is formed as the non-solder portion. The electrode terminal fixing structure according to any one of claims 1 to 3, wherein: Terminal pads for surface-mounting electrode terminals are formed on both the main board and the sub-board, and the sub-board is mounted on the main board and electrically connected via the electrode terminals. Fixing method,
The terminal pad provided in the surface region on which the electrode terminal of the sub-board is mounted is formed to have an outer shape in which a part of the region overlapping with the electrode terminal is cut out, and solder is applied to a non-pad portion due to the cut-out outer shape. A non -solder part, a thermosetting adhesive is applied to the non-solder part, and a solder paste is previously applied to the terminal pad, and then the electrode terminal is mounted in a predetermined manner and the sub-board is mounted. An electrode terminal fixing method comprising: passing an electrode terminal on the sub-board toward a terminal pad of the main board after passing through the reflow furnace and completing the reflow process, and passing both boards through the reflow furnace again.

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