JP2008300734A - Printed board, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed board wherein a sub-substrate is mounted on a main substrate without soldering, and to provide a manufacturing method thereof. <P>SOLUTION: In the printed board, a sheet transformer is configured by the main substrate 1 and the sub-substrate 2 which have a coil pattern built-in and on which a through hole-like electrical connecting land 3 is formed, a ferrite core 8 surrounding a coil pattern part of the overlaid main substrate 1 and the sub-substrate 2, a conductive washer 4 which is sandwiched between the electrical connecting lands 3 of the main substrate 1 and the sub-substrate 2 and to which gold plating is applied, a screw 6 whose screw axis is passed through a through hole of the electrical connecting land 3 and the conductive washer 4, and a nut 7 which is engaged with an end part of the axis of the screw 6 to sandwich the main substrate 1, the conductive washer 4 and the sub-substrate 2 with the head of the screw 6 to fasten. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printed board having a structure in which a plurality of boards on which a coil pattern is formed and a manufacturing method thereof.

  In a conventional switching power supply or the like, it has been difficult to reduce the size and thickness due to the restriction of the height of the component that is a component of the transformer. In recent years, a sheet transformer that forms a transformer by forming a coil pattern on a printed circuit board, soldering the sub circuit board on which the coil pattern is formed on the printed circuit board, and combining with a ferrite core has been developed as a technology for thinning the transformer. (For example, Patent Document 1).

JP 2000-91138 A

  In such a printed circuit board, when trying to configure a sheet transformer capable of handling a large current with high efficiency, the current density increases only with the coil pattern built in the printed circuit board (main board), and the loss due to heat generation also increases. Therefore, it is necessary to connect in parallel the sub-boards incorporating the same coil pattern. In addition, as in Patent Document 1, a sheet transformer may be configured using a sub-board for the purpose of separating the primary side and secondary side coils. As for the electrical connection method between the main board and the sub board, conventionally, connection by soldering using lead wires or connection pins has been mainstream.

  However, when soldering connection between the sub board and the main board with connecting pins, the soldering part is placed directly under the sub board, so it is difficult to visually check the soldering state, and quality and reliability There was a problem in terms of. Further, when lead wires are extended from the sub-board so that the solder connection points are not arranged directly under the sub-board, the solder can be visually inspected, but the mounting area increases and the result is contrary to the aim of downsizing. In particular, when two or more sub-boards are to be connected, it is difficult to achieve both miniaturization and high-quality electrical connection by the method using soldering as described above.

  The present invention has been made to solve the above-described problems, and provides a printed circuit board and a method for manufacturing the printed circuit board that can mount a sub circuit board on a main circuit board without a soldering operation. It is intended to provide.

  A printed circuit board according to the present invention includes a first board and a second board, in which a coil pattern is embedded and a through-hole-shaped electrical connection land is formed, the first board and the second board overlaid. A ferrite core that surrounds the coil pattern portion of the substrate, a conductive washer sandwiched between the electrical connection lands of the first substrate and the second substrate, a through hole of the electrical connection land, and the conductivity A screw that is passed through a screw shaft through a washer, a nut that is fitted into the tip of the screw shaft, and that clamps the first substrate, the conductive washer, and the second substrate between the screw heads Thus, a sheet transformer is configured.

  The printed circuit board according to the present invention has a built-in coil pattern, a first board on which a through hole-shaped electrical connection land is formed, a coil pattern connected in series to the coil pattern of the first board, A second substrate on which through-hole-shaped electrical connection lands are formed; the first substrate superimposed; and the ferrite core surrounding the coil pattern portion of the second substrate; the first substrate and the first substrate; A conductive washer sandwiched between the electrical connection lands of the second board, a through hole of the electrical connection land, a screw passed through a screw shaft through the gold plating washer, and a shaft end of the screw. The choke coil is constituted by a nut that clamps the first substrate, the conductive washer, and the second substrate between the screw heads. .

  In the printed circuit board manufacturing method according to the present invention, a conductive washer is sandwiched between a first board and a second board on which a coil pattern is incorporated and a through-hole-shaped electrical connection land is formed. Pass through the shaft portion of the screw in order of the through hole of the electrical connection land of the first or second substrate, the conductive washer, the through hole of the electrical connection land of the second or first substrate, This includes a step of fitting and fixing the first and second substrates by fitting a nut to the shaft tip.

  According to the printed circuit board of the present invention, the first and second substrates are fastened and fixed by the conductive washers, screws, and nuts, so that mechanical and electrical connection between the substrates can be performed at the same time. There is an effect that a printed circuit board that can be reduced in size and can be easily reworked can be obtained.

  According to the printed circuit board of the present invention, the first and second substrates are fastened and fixed by the conductive washers, screws, and nuts, so that mechanical and electrical connection between the substrates can be performed simultaneously. There is an effect that a printed circuit board that can be reduced in size and can be easily reworked can be obtained.

  According to the printed circuit board manufacturing method of the present invention, the first and second substrates are fastened and fixed by the conductive washers, screws, and nuts, so that the mechanical and electrical connection between the substrates can be performed simultaneously. is there.

Embodiment 1 FIG.
FIG. 1 is an exploded perspective view of a printed circuit board according to Embodiment 1 of the present invention. This printed board includes a main board 1 (which becomes a base of the printed board; a first board) and a sub board 2 (second board) in which a coil pattern is incorporated and a through-hole-shaped electrical connection land 3 is formed. ), A ferrite core 8 surrounding the coil pattern 9 portion of the superposed main board 1 and sub-board 2, and a gold-plated conductive washer sandwiched between lands 3 for electrical connection between the main board 1 and the sub-board 2. 4. Electrical connection land 3 through hole, screw 6 threaded through conductive washer 4, screw shaft 6 is fitted into the tip of screw 6, and main board 1 is electrically conductive between screw 6 head. The example which comprised the sheet | seat transformer with the nut 7 fastened on both sides of the washer 4 and the sub-board | substrate 2 is shown. Here, in addition to the main substrate 1, the printed circuit board includes a structure that is stacked on the main substrate 1 and built.

  Here, as described above, the conductive washer 4 is a metal plate that has been subjected to gold plating and has a gold plating layer formed on the surface, and the main substrate 1 and the sub-board 2 are connected to each other via the conductive washer 4. The electrical connection is planned. Further, a washer 5 is disposed between the head of the screw 6 and the sub board 2, and similarly, the washer 5 is disposed between the shaft tip of the screw 6 and the main board 1. The washer 5 is not used for electrical connection between the substrates, but mechanically fixes the substrates by a combination of screws 6 and nuts 7. Therefore, it is necessary to use a gold-plated one. Absent.

  Next, as shown in FIG. 1, the structure of this printed circuit board will be described in detail. The main board 1 and the sub board 2 are provided with a total of four through-hole-shaped electrical connection lands 3 including two terminals of the primary side coil and two places of the secondary side coil, respectively. The main board 1 has a larger board area than the sub-board 2 and can be mounted with other components. In order to arrange the ferrite core 8, an opening is provided in the central part and outside of the coil pattern. Yes.

  FIG. 2 is a cross-sectional view of the terminal portion of the sub-board 2. Thus, the electrical connection land 3 is connected to the coil pattern 9 at the through hole portion. FIG. 3 is a schematic diagram of the coil pattern 9 illustrating the plane of the coil pattern forming layer in FIG. The electrical connection land 3 is exposed on the surface of the sub-substrate 2, but the coil pattern 9 is disposed so as to overlap in the layer with an interlayer film interposed therebetween. In addition, via holes 10 penetrating the substrate are formed in the sub-substrate 2, and the coil patterns 9 of different layers in the substrate are electrically connected by the via holes 10.

  The sub-substrate 2 in FIG. 2 is formed as follows. The sub-substrate 2 has a structure in which, for example, a plurality of sheet substrates made of modified polyimide are laminated, and a total of two layers of coil patterns 9 are formed with copper foil, one layer on each side of one sheet substrate, and then drilled. The interstitial via hole 11 is formed by copper plating and an interlayer connection portion is obtained. A prepreg is arranged between and on the surface of four sheet substrates formed in the same manner, and a sheet substrate (which constitutes the upper surface and the lower surface of the sub-substrate 2) having the electrical connection lands 3 formed on both surfaces of the laminate. Stack and press to make a single laminate. Thereafter, a through hole penetrating the substrate made of the laminate is formed, and surface plating (here, gold plating) is performed to obtain the land 3 for electrical connection, whereby the sub-substrate 2 can be obtained.

The sub-board 2 is connected to coil patterns 9 formed on each layer of the multi-layer board (sub-board 2) by interstitial via holes 11 and via holes 10 for interlayer connection, and the coil pattern 9 is connected to the primary side and the secondary side. These can be used separately as side coils, and a transformer with an arbitrary turn ratio can be formed.
A coil pattern is also formed on the main substrate 1 in the same manner as the sub-substrate 2.

  Next, a method for manufacturing a printed circuit board according to the present invention, particularly a mounting method for connecting the sub board 2 to the main board 1 will be described. First, a conductive washer 4 having a flat surface is formed by etching the copper plate, and the conductive washer 4 having a gold plating layer on the surface is formed by performing gold plating on the conductive washer 4. deep. Next, a conductive washer 4 plated with gold is sandwiched between the main board 1 and the sub board 2, and the through hole of the electric connection land 3 of the main board 1 or the sub board 2, the conductive washer 4, the sub board 2 or the through hole of the electrical connection land 3 of the main board 1 is passed through the shaft part of the screw 6, the nut 7 is fitted to the shaft tip part of the screw 6, and the main board 1 and the sub board 2 are fastened and fixed. Note that the screw 6 and the nut 7 are fastened by sandwiching the washer 5 between the head of the screw 6 and the sub board 2 or the main board 1, and the washer 5 between the nut 7 and the main board 1 or the sub board 2. The power can be further improved. Thereafter, the ferrite core 8 is combined to form a sheet transformer on the printed board.

The sub-board 2 is mounted on the main board 1 by the mounting method as described above, and a printed board having a configuration including a sheet transformer is manufactured, whereby the electric power on the board is obtained by the fastening force of the washer 5, the screw 6 and the nut 7. The connection land 3 and the conductive washer 4 subjected to gold plating are pressed against each other, and electrical conduction can be obtained.
As described above, the conductive washer 4 is improved in electrical connectivity with the electrical connection land 3 by processing both surfaces flat and then performing gold plating. This is highly effective in preventing oxidation and corrosion of the connection surface and obtaining a good electrical connection.
Further, by performing the gold plating on the electrical connection land 3, an even better electrical connection can be obtained. This screw fastening also serves to fix the sub-board 2 and has an advantage that a structure resistant to vibration and impact can be obtained at the same time.

In the above-described example, the case where one sub-board 2 is arranged for one main board 1 is shown, but it is needless to say that a plurality of sub-boards 2 can be arranged. FIG. 4 shows an exploded perspective view of the printed circuit board when there are a plurality of sub-boards 2. In mounting the sub-board 2 with the screws 6 and the nuts 7, even if the number of boards to be mounted increases, the mounting on the main board 1 can be performed by fastening and fixing the conductive washer 4 with gold plating between the boards. Is possible.
FIG. 4 shows an example in which one sub-substrate 2 is superimposed on the upper surface and the lower surface of the main substrate 1, but two (plural) sub-substrates 2 are disposed on the upper surface or the lower surface side. It is also possible.

In addition, as an effect of connecting a plurality of sub-substrates 2 in parallel, the current density flowing in the coil pattern 9 can be reduced, loss due to heat generation can be reduced, and a large-current high-efficiency transformer can be achieved.
Even during assembly, the number of screw fastening processes does not increase even when the number of sub-boards 2 increases, and the connection by screw fastening is easier than solder connection, and the soldering iron is heated to the board. There is no damage. In addition, as with assembly, it is easy to remove and has the advantage of good workability when a leak occurs.

In addition, since this printed circuit board connects the main board 1 and the sub board 2 with screws 6 and nuts 7, a stronger mechanical structure can be obtained than in the case of connection with solder, and vibration and impact are less likely to occur. There is an effect that the present invention can be applied to a large environment (for example, for mounting on an artificial satellite or for an automobile device).
Furthermore, since the conductive washer 4 has a uniform thickness and a good surface flatness, when the main board 1 and the sub board 2 are fixed by screw fastening, the dimension of the gap between the boards is conductive. The gap between the substrates can be easily set to a uniform value, and the arrangement characteristics of the substrates can be improved.

Embodiment 2. FIG.
FIG. 5A is a cross-sectional view showing a cross-sectional structure of the printed circuit board according to the second embodiment of the present invention, and FIG. 5B is an enlarged cross-sectional view in the vicinity of the screw 6. In the second embodiment, an example is shown in which two sub-boards 2 are mounted on the upper surface and one lower surface of the main board 1.
The structure of the screw fastening is the same as that of the first embodiment, but the space between the substrates other than the screw fastening connection portion is filled (laminated) with a heat conductive material layer 13 made of a heat conductive adhesive or a heat conductive sheet. Thus, the heat generated in the sub-board 2 can be released to the main board 1. By efficiently exhausting the heat generated by the sub-board 2, there is an effect that it is possible to obtain a transformer capable of handling a larger current.

Here, as described above, since the dimension between the substrates is determined by the gold-plated conductive washer 4 by screw fastening, the gap for arranging the heat conductive material layer 13 and the heat conductive material layer are arranged. The thickness of 13 can be a uniform value, and the thermal conductivity can be made uniform.
In addition, as the heat conductive material layer 13, a heat conductive sheet made of a sticky and elastic sheet can be used for a silicon-based adhesive or a consumer device.

Embodiment 3 FIG.
FIG. 6 is a cross-sectional view showing a printed circuit board according to Embodiment 3 of the present invention. The screw fastening structure is the same as in the first and second embodiments, but the number of sub-boards 2 is adjusted to match the height of the other electronic components 14 mounted on the main board 1. An example of disposing is shown. In FIG. 6, two sheets are arranged on the C surface side (upper surface side in the drawing) of the main substrate 1, and one sub substrate 2 is arranged on the S surface side (lower surface side in the drawing). The height of the transformer can be made equal to the height of the electronic component 14, the space efficiency can be increased, the sub-board 2 can be mounted on the main board 1, and the power supply module as a whole can be reduced in size. Can be planned.

Embodiment 4 FIG.
FIG. 7 is a cross-sectional view showing a printed circuit board according to Embodiment 4 of the present invention. When a tertiary winding is required for the transformer, a third substrate for the third winding 15 (a third substrate different from the sub-substrate 2 incorporating the coil pattern 9 shown in the first to third embodiments described above) is used. Board)) and can be electrically and mechanically connected to the main board 1 by screw fastening in the same manner as other sub-boards.
For example, a reset winding is formed as a tertiary winding on the sub-board 15 serving as the third board. This reset winding is a reset circuit for extracting the core magnetization and is used in a forward converter or the like. This tertiary winding sub-board 15 has an area larger than that of the above-described sub-board 2, and a through hole is used as a screw fastening portion for connection with the sub-board 2 and the main board 1. The shape is the same as that of the substrate.

  In addition, in the case of the sub-board 15 for the tertiary winding, two screw fastening terminals can be added for the tertiary winding and screw fastening can be performed at a total of six places. In many cases, the connection with screw fastening may be wasteful due to an increase in fastening parts. Therefore, as shown in FIG. 6, the wire 17 is connected between the tertiary winding connection pads 16 provided on the main substrate 1 and the tertiary winding sub-substrate 15. In this way, the electrical connection between the tertiary winding sub-board 15 and the tertiary winding connection pad 16 on the main board 1 is performed by soldering the wire 17 to prevent the weight of the fastening component from being increased. It is also possible to deal with transformers with the next winding or higher windings.

Embodiment 5. FIG.
In the first to fourth embodiments described above, the case where the sheet transformer is formed on the printed board has been described. However, the structure in the board is the same as that of the transformer shown in FIGS. By making the winding pattern only the primary side (connecting the winding patterns of all layers in series), a sheet coil having a choke coil function can be made on the printed circuit board.

  The printed circuit board according to the fifth embodiment has a built-in coil pattern, a main board on which through-hole-shaped electrical connection lands are formed, a built-in coil pattern connected in series to the coil pattern on the main board, and a through-hole shape. A sub-board on which the electrical connection lands are formed, a ferrite core surrounding the coil pattern portion of the superimposed main board and sub-board, a conductive washer sandwiched between the electric connection lands on the main board and the sub-board, and electricity Fasten the main board, the conductive washer, and the sub board between the through hole of the connection land, the screw passed through the screw shaft through the conductive washer, the screw shaft, and the screw head. The nut constitutes a choke coil.

  When the choke coil is formed on the printed circuit board, the secondary winding pattern necessary for forming the transformer and the screw fastening portion connected to the secondary winding are not required, but the two screw fastening portions on the secondary winding side are dummy. It is possible to obtain a stable structure similar to that of the transformer by leaving the connection lands as 4 and fastening the screws at four locations.

In this way, the rectifying choke coil that is absolutely necessary for the switching power supply can be built on the printed circuit board with the same configuration as the sheet transformer, and therefore, the effect of downsizing the power supply module is great.
In addition, as in the case of sheet transformers, the electrical and mechanical connections between substrates using conductive washers, screws, and nuts have the same effect and are resistant to vibrations and shocks. It can also be applied to automobiles.

It is a disassembled perspective view of the printed circuit board by Embodiment 1 of this invention. It is sectional drawing of the sub-board | substrate by Embodiment 1 of this invention. It is a coil pattern schematic diagram of the sub-board | substrate by Embodiment 1 of this invention. It is a disassembled perspective view of the printed circuit board by Embodiment 1 of this invention. It is sectional drawing of the printed circuit board by Embodiment 2 of this invention. It is sectional drawing of the printed circuit board by Embodiment 3 of this invention. It is sectional drawing of the printed circuit board by Embodiment 4 of this invention.

Explanation of symbols

1 main board, 2 sub board,
3 Land for electrical connection, 4 Conductive washer,
5 washers, 6 screws,
7 Nut, 8 Ferrite core,
9 coil pattern, 10 via hole,
11 interstitial via hole, 13 thermally conductive material layer,
14 electronic components, 15 sub-board for tertiary winding,
16 Tertiary winding connection pad, 17 wires.

Claims (9)

  A first substrate and a second substrate having a coil pattern embedded therein and having through-hole-shaped electrical connection lands formed, and surrounding the coil pattern portion of the superimposed first and second substrates. A ferrite core, a conductive washer sandwiched between the electric connection lands of the first substrate and the second substrate, a through hole of the electric connection land, and a screw shaft passed through the conductive washer A sheet transformer is configured by a screw and a nut that is fitted to the tip of the shaft of the screw and is fastened with the first substrate, the conductive washer, and the second substrate sandwiched between the screw head and the screw. Printed circuit board characterized by   A first substrate having a coil pattern and a through-hole shaped electrical connection land, and a coil pattern connected in series to the coil pattern of the first substrate and having a through-hole shaped electrical connection land A ferrite core surrounding the coil pattern portion of the first substrate and the second substrate overlaid, and for the electrical connection of the first substrate and the second substrate A conductive washer sandwiched between lands, a through hole in the land for electrical connection, a screw passed through a screw shaft through the conductive washer, and a screw tip fitted between the screw shaft and the head of the screw. A printed circuit board, wherein a choke coil is constituted by a nut that is fastened to the first board, the conductive washer, and the second board.   The printed circuit board according to claim 1, wherein the conductive washer is gold-plated.   The printed circuit board according to claim 1, wherein the land for electrical connection is gold-plated.   The printed circuit board according to claim 1, further comprising a thermally conductive material layer filled between the first substrate and the second substrate sandwiched between the conductive washers.   The printed circuit board according to claim 1 or 2, wherein one or a plurality of the second substrates are superposed on the upper surface side or the lower surface side of the first substrate.   The printed circuit board according to claim 1, further comprising a third substrate that is fastened and fixed to the first substrate side via the conductive washer and that has a different pattern from the second substrate.   A conductive washer is sandwiched between the first substrate and the second substrate on which a coil pattern is embedded and a through-hole-shaped electrical connection land is formed, for the electrical connection of the first or second substrate. Pass through the shaft part of the screw in the order of the through hole of the land, the conductive washer, the through hole of the land for electrical connection of the second or first board, and fit the nut to the shaft tip part of the screw, A method of manufacturing a printed circuit board comprising the step of fastening and fixing the first and second substrates.   9. The method of manufacturing a printed circuit board according to claim 8, further comprising a step of performing a gold plating process on the conductive washer before the fastening with the screw and the nut.

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