JP2743936B2 - Backboard and method of assembling the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backboard for mounting, for example, a plug-in board, and more particularly to a backboard characterized by a connection structure for connecting a plurality of printed boards and a through-mount connector.

[0002]

2. Description of the Related Art Some conventional backboards include a printed circuit board and a connector fixed on the printed circuit board and connected to the printed circuit board. In the conventional backboard, the printed circuit board is generally constituted by one sheet. The connection between the printed circuit board and the pins of the connector may be press-fitted or soldered. Further, in any case, it is possible to connect the wiring to the pins protruding on the back side of the printed circuit board.

In the case of press-fit connection, on the back side,
A female connector is connected or the wiring is directly wrapped. On the other hand, in the case of soldering, the wiring is directly wrapped.

In some cases, the backboard is composed of two or more printed boards. In most cases, a dedicated connector or wiring for connecting the two or more printed boards to each other is provided. In need of.

[0005]

As described above, in the conventional backboard, it is common that the printed board is constituted by one sheet. For this reason, when the wiring density of the printed circuit board increases, it is necessary to increase the number of layers of the printed circuit board in one printed circuit board in proportion thereto.

Generally, as the number of layers of a printed circuit board increases, its price rises in a quadratic curve. This is because, in addition to the primary factor that the number of processes increases and the material price rises in proportion to the number of layers, the need for higher processing accuracy due to the increase in the number of layers causes price increases, In addition, secondary factors such as deterioration in fractionation are multiplied.

[0007] Therefore, there is a disadvantage that the price of the printed circuit board rapidly rises as the function of the device becomes higher and the wiring density of the printed circuit board increases.

Further, when the backboard is formed of one printed circuit board, the required number of layers is determined at a location where the wiring density is maximized. As a result, all other areas on the printed circuit board will have the same number of layers as where the wiring density is greatest, whether or not required. For this reason, when the wiring density is different in each area on the printed circuit board, there is a disadvantage that an unreasonable price rise occurs more than in the case described above.

On the other hand, as a measure for lowering the price of such a printed circuit board even a little, there is a method of dividing the printed circuit board into portions having different wiring densities. However, the conventional method generally used requires a dedicated connector or wiring for connecting two or more divided printed circuit boards to each other.

Although this is effective to some extent in reducing the area per printed circuit board, it has little effect on reducing the number of layers per printed circuit board. This is because, when the division is performed so as to reduce the number of layers, the number of wirings connecting the divided printed circuit boards becomes enormous.

As a solution to such a problem, several methods have been invented in which two or more printed circuit boards are used in an overlapping manner. When two printed circuit boards are stacked, the number of layers per printed circuit board is reduced by half compared to the case of one printed circuit board.
Moreover, it can be handled in the same manner as a single printed circuit board having the total number of layers apparently. Since the price of the printed circuit board increases in a quadratic curve with respect to the number of layers, the total price of the two divided printed circuit boards can be significantly reduced as compared with the case where one printed circuit board is used. Various connections of a connector to a printed circuit board in which two sheets are stacked are disclosed. For example, the actual opening 61-14
As disclosed in Japanese Patent Application Laid-Open No. 0562, there is an apparatus in which two printed circuit boards are overlapped with no gap so that the pins of a connector penetrate. The through holes of the two printed circuit boards are arranged such that their centers are aligned. When viewed from the pin insertion direction, the through hole of the upper printed board is larger than the through hole of the lower printed board. This is because the pins have two large and small press-fit portions corresponding to the two large and small through holes described above, and these are connected to the corresponding printed circuit boards.

However, this configuration has not been put to practical use. The reason is that the relative positional tolerance of the through holes on the two printed boards and the positional deviation due to the thermal expansion cannot be tolerated, and the two printed boards are pressed with a force of 2 to 3 tons when performing press-fit assembly. Directly intense and insulation between patterns cannot be guaranteed.

In view of this, when two or more printed circuit boards are connected in an overlapping manner, it is indispensable to have a certain space between the printed circuit boards.

Next, as a connection structure satisfying this condition,
For example, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 3-263677. FIG. 4 (a) shows the first invention described in Japanese Patent Application Laid-Open No. 3-263771. In this invention, press-fit portions 51e and 51f are formed on both sides of a pin 51. These two press-fit parts 51e, 5
1f is connected to the main printed board 2 and the sub printed board 3, respectively. Also, FIG.
The second invention described in US Pat.
According to the present invention, the press-fit portions 51f and 51g are formed in two stages, large and small, and each of the sub-printed substrates 3-f.
1. It is connected to the sub print board 3-2. FIG.
(C) shows a third invention described in Japanese Patent Application Laid-Open No. 3-263771. In this invention, the pins 51 are press-fitted to the main printed circuit board 2 and the opposite ends are connected to the sub-printed circuit board 3. Soldered.

However, at present, none of these have been put to practical use. The reason is that the assembling work is impossible or extremely difficult. Generally, in order to press-fit a pin on a printed circuit board, it is necessary to apply a vertical force of 10 to 20 kg per pin to push the pin. 100-20 for molded connectors
A press force of 1 to 4 t is required to press-fit zero pins simultaneously. To reliably and vertically transmit the pushing force to the pin, it is essential to use a dedicated mold for pushing. However, the aforementioned FIGS. 4 (a), (b), (c)
In the method shown in the above, two problems arise. First
The problem is that, after assembling the printed board and the pins to be press-fit connected in advance, the tips of the assembled pins must be inserted into through holes of another printed board. This is an indispensable procedure for preventing the other printed circuit board from structurally interfering when the stamping die is set on the printed circuit board and pins to be assembled first. However, when the number of assembled pins increases, the alignment tends to be incomplete. When the total number of pins is 400 or more, insertion into another printed circuit board is empirically impossible. On the other hand, the number of pins of a connector mounted on this type of printed circuit board generally reaches several thousands to tens of thousands of pins, and therefore, generally speaking, FIGS.
Assembly of what is shown in (c) is very difficult in practice. As a second problem, in the case shown in FIGS. 4A and 4B, it is necessary to press-fit after inserting the previously assembled pins into another printed circuit board. At this time, it is structurally difficult to set the pressing die so as not to interfere with the printed circuit board previously assembled.

[0016] Even if a stamp having a special structure is set, since the pins are integrated with the printed circuit board previously assembled, it is necessary to push in the thousands to tens of thousands of pins at the same time. Causes technical problems.

As described above, due to the first and second problems, FIG. 4A and FIG.
The connection structures (b) and (c) are actually difficult to assemble. On the other hand, Japanese Unexamined Patent Application Publication No. Hei 3-3-2 shown in FIG.
In the case of the fourth invention described in Japanese Patent No. 63771, a spacer 6 is placed between the sub printed board 3-1 and the sub printed board 3-2. By using the spacer 6, two sub-printed substrates 3 can be press-fit connected at the same time. However, the main printed circuit board 1
No solution has been obtained as to how to insert and push the pin assembled in the device. That is, the work of inserting pins into the two sub-printed circuit boards and the spacer
As the total number of pins increases, it becomes more difficult.
Is actually applicable only to a very limited range (about 300 pins or less in total number of pins).

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a backboard and a method of assembling the same, in which a plurality of printed boards are superimposed, and the plurality of printed boards can be connected to a large number of pins penetrating therethrough. It is in.

[0019]

According to the first aspect of the present invention, there is provided a printed circuit board having a through hole, and a connector having a pin inserted through the through hole and mounted on the printed circuit board. On the backboard,
A plurality of the printed circuit boards are stacked with a spacer interposed therebetween, and each of the stacked printed circuit boards is
Having an engaging portion, the spacer has an insertion hole through which the pin is inserted, and an engaging portion which engages with the engaging portion of the printed circuit board to perform positioning between the printed circuit board, Each through-hole of the stacked plurality of printed circuit boards is arranged so as to be substantially continuous in the thickness direction of the printed circuit board, and the insertion hole of the spacer is arranged to face the through-hole of the printed circuit board. A backboard characterized by the fact that

According to the second aspect of the present invention, the pin has at least one press-fit portion that is press-fit into the through-hole, and the pin includes a plurality of printed circuit boards stacked by the press-fit portion. The backboard according to claim 1, wherein the backboard is connected to at least one of the following.

According to the third aspect of the present invention, the pin is connected to at least one of the stacked printed circuit boards by soldering. Is obtained.

According to the fourth aspect of the present invention, the engaging portion of the printed circuit board is a positioning hole, and the engaging portion of the spacer is a boss. A backboard is obtained.

According to a fifth aspect of the present invention, there is provided the backboard assembling method according to any one of the first to fourth aspects, wherein the pins of the connector are attached to a housing of the connector in advance, and Wherein the printed circuit boards are stacked in advance with the spacer interposed therebetween, and the pins of the pre-assembled connectors are inserted into through holes of the plurality of printed boards stacked in advance. A method is obtained.

[0024]

1 shows a first embodiment of a backboard according to the present invention. FIG. 1 (a) is an exploded perspective view of a main part, FIG. 1 (b) is a sectional view of the main part, and FIG. It is a perspective view which shows the use condition of the shown backboard.

Referring to FIG. 1 and FIG. 2, the back board 1 of the present embodiment has a main printed board 2, a sub printed board 3, a connector 5, and a spacer 6.

The main printed circuit board 2 has a through hole 2
It has 0. The sub printed board 3 also has a through hole 30. These through holes 20 and 30
In a state where the sub printed circuit board 3 is positioned with respect to the main printed circuit board 2, the sub printed circuit boards 3 are arranged so as to be continuous in the thickness direction of the main printed circuit board 2. Also,
The main printed circuit board 2 has a positioning hole 21 which is an engagement portion with the spacer 6. Similarly, the sub printed circuit board 3 has a positioning hole 31 which is an engagement portion with the spacer 6.

The connector 5 has a housing 50 and a number of pins 51 provided on the housing 50. The connector 5 is used for connection with the plug-in board 9 and is fixed on the main printed circuit board 2. Each pin 51 of the connector 5 is inserted into the through hole 20 and the through hole 30. Each pin 51
A press-fit portion 51a is formed at a central portion of the main printed circuit board 2, and the press-fit portion 51a is press-fitted into the through hole 20 of the main printed circuit board 2. Therefore,
Each pin 51 is connected to the main printed circuit board 2 through the press-fit portion 51a and the through hole 20. On the other hand, the lower end 51b of each pin 51 is inserted into the through-hole 30 of the sub-printed circuit board 3 and connected to each of these through-holes 30 by soldering. Therefore, each pin 51 is also connected to the sub printed board 3 through the lower end 51b and the through hole 30.

The spacer 6 is interposed between the main printed circuit board 2 and the sub printed circuit board 3 so as to keep a constant distance therebetween. The planar shape of the spacer 6 is substantially the same as the planar shape of the connector 5. Spacer 6
Bosses 60 are formed at both ends of the upper surface of the main body 2 as engagement portions with the main printed circuit board 2. On the other hand, bosses 61 as engagement portions with the sub-printed circuit board 3 are formed at both ends of the lower surface of the spacer 6. When the spacer 6 is interposed between the main printed board 2 and the sub printed board 3, the boss 60 is positioned in the positioning hole 21 of the main printed board 2.
By inserting the bosses 61 into the positioning holes 31 of the sub-printed circuit board 3, the sub-printed circuit board 3 is positioned with respect to the main printed circuit board 2. The spacer 6 has a pin 51 of the connector 5.
Is formed. Insertion hole 62
Has a series of hole arrangements corresponding to the pin arrangement of the integrated connector 5, and the spacer 6 is connected to the main printed circuit board 2.
Are formed so as to face the through holes 20 and the through holes 30 when interposed therebetween. If the connector is not of a unitary construction, a series of holes are provided in the spacer 6 corresponding to one set of pins arranged to form the connector.

Next, an embodiment of the above-described method of assembling the backboard will be described.

First, the sub-printed circuit board 3 is placed on a receiving table (not shown). Next, the spacer 6 is placed on the sub printed board 3.

Next, the spacer 6 is positioned on the sub-printed board 3 by inserting the boss 61 of the spacer 6 into the positioning hole 31 of the sub-printed board 3. Spacer 6
Are arranged in all necessary positions on the sub-printed board 3 without fail.

Next, the main printed board 2 is overlaid on the sub printed board 3 on which the spacers 6 are arranged. At this time, the boss 60 of the spacer 6 is fitted into the positioning hole 21 of the main printed circuit board 2. Thereby, positioning between the main printed board 2 and the sub printed board 3 is performed. The bosses 60 and 61 and the positioning holes 21 and 31 have appropriate fitting tolerances. For example, the fitting on the sub-printed circuit board 3 side is set to a slightly tight fit, and the fitting on the main printed circuit board 2 side is performed. A loose fit allows easier assembly.

Next, the sub printed board 3, the spacer 6,
The main printed circuit board 2 is overlaid and the bosses 60, 6
The pins 51 of the pre-assembled connector 5 are inserted into the through holes 20 and 30 and the insertion holes 62 in a state where their relative positions are fixed by the 1 and the positioning holes 21 and 31. At this time, by providing a suitable entrance into the insertion hole 62 of the spacer 6, for example, if the diameter of the hole on the entrance side is slightly larger and the diameter of the hole on the exit side is slightly smaller when viewed from the pin insertion direction, assembly is possible. Will be easier. Since the pin 51 is fixed to the housing 50 of the connector 5 with a certain degree of freedom, the pin 51 is guided by the tapered portion 51c formed at the tip of the pin 51, and the main printed circuit board 2,
It penetrates through the spacer 6 and the sub printed board 3 without difficulty.
Since the insertion of the pins 51 is performed in units of the connector 5, the number of pins to be inserted at one time is at most about 200. That is, the insertion of the pins 51 can be performed without any difficulty as compared with the case of the normal structure in which one printed circuit board is formed.

Finally, the pins 51 of the connector 5 are pushed down vertically, and the press-fit portions 51 a of the pins 51 are press-fit connected to the through holes 20 of the main printed circuit board 2. At this time, a pressing die (not shown) can be used in exactly the same manner as in the case of a normal structure including one printed circuit board. Further, since the pressing force received by the main printed circuit board 2 is transmitted to the sub-printed circuit board 3 and the receiving stand (not shown) via the spacer 6, the stress on the printed circuit board is equal to that of the conventional structure. . Further, the connector 5 is exactly the same as the conventional ordinary structure in that the press-fit can be performed one by one in order.

As described above, in the structure of the backboard according to the present embodiment, the two printed boards 2 and 3 and the spacer 6 located therebetween are overlapped in advance and positioned with respect to each other, so that the printed board is The assembling work can be performed easily as in the case of the conventional ordinary structure composed of one piece.

Next, the connection structure of the pins 51 corresponding to the main printed board 2 and the sub printed board 3 in this embodiment will be described in detail.

As shown in FIG. 1 (b), the pins 51 of the connector 5 have the shape of a very common press-fit pin. Therefore, in the present embodiment, there is an advantage that the connector 5 can be selected with compatibility with the case of the normal structure including one printed circuit board.

In this embodiment, in the assembling method described above, the pins 51 are connected only to the main printed circuit board 2 at the time when the work of pushing in the connector 5 (press fit) is completed. The connection between the lower end 51b of the pin 51 and the sub-printed circuit board 3 is performed after the above-described press-fitting by dipping in a molten solder layer and soldering. actually,
The printed circuit boards 2 and 3 and the set of connectors 5 that are being assembled may be passed directly to an automatic soldering apparatus (not shown). At this time, the automatic soldering apparatus may be an ordinary one, and the carrier or the board clamp clamps the sub-printed board 3 side.

When there is a possibility that the main printed circuit board 2 and the connector 5 may interfere with the automatic soldering apparatus, the outer mold of the sub printed circuit board 3 may be devised, or a clamp may be provided as a split board.

Also, it is pointed out in Japanese Patent Application Laid-Open No. 3-263771 that in this soldering step, the heat of soldering is transmitted to the press-fit portion 51a through the pins 51, which may reduce the reliability of the press-fit connection. Have been. However, actually, by devising the thickness of the spacer 6, the soldering time, and the like, it is possible to prevent the reliability of the press-fit connection from lowering.

Next, a second embodiment of the backboard of the present invention will be described. FIG. 3 is a sectional view of a main part of a second embodiment of the backboard according to the present invention. Referring to FIG. 3, the backboard of the present embodiment has substantially the same configuration as the backboard shown in FIG. 1, and the same components as those of the backboard in FIG. Omitted.

In the case of the back board 1 of this embodiment, the pins 51 of the connector 5 are also press-fitted to the sub-printed board 3. For this reason, the pin 51 of the connector 5 has two press-fit portions 51a and 51d. The two press-fit portions 51a and 51d are different in size, and the press-fit portion 51a connected to the main printed circuit board 2 is larger than the press-fit portion 51d connected to the sub printed circuit board 3. Also, corresponding to this, the through holes 20 of the main printed circuit board 2 are provided.
Are made larger than the through holes 30 in the sub-printed board 3. For this reason, in the above-mentioned assembling process, the connector 5 is attached to the main printed board 2 and the sub-printed board 3 which are overlapped with the spacer 6 therebetween.
When the pin 51 is inserted, the press-fit portion 51 d at the bottom easily passes through the through hole 20 of the main printed circuit board 2, and passes through the through hole 30 of the sub printed circuit board 3.
It is inserted until just before. At the same time, the press-fit portion 51a is inserted just before the through hole 20 of the main printed circuit board 2. When the pushing operation in the above-described assembling process is performed in this state, the two press-fit portions 51a and 51d are simultaneously connected to the main printed board 2 and the sub printed board 3, respectively.

At this time, the vertical load applied to the sub-printed circuit board 3 is directly transmitted to a receiving table (not shown).
The vertical load applied to the main printed circuit board 2 is
Through the sub-printed circuit board 3 and further transmitted to a receiving table (not shown). For this reason, the aforementioned pushing work
What is necessary is just to carry out exactly the same as the case of the conventional normal structure which consists of one printed circuit board, and the same thing can be used for the receiving stand and the press type as that of the conventional normal structure.

The positions of the through holes 20, 30 in the printed boards 2, 3 have respective tolerances. For this reason, the through holes 20 and 30 of the superimposed main printed board 2 and sub printed board 3 cannot be strictly and completely coaxial. However, this misalignment is at most ± 5/10 by analogy with the accuracy of a general printed circuit board.
It is about 0 mm. Therefore, if the thickness of the spacer 6 and the thickness of the pin 51 are devised, it is possible to sufficiently absorb the elasticity of the pin 51. That is, a certain level of connection reliability can be guaranteed.

[0045]

As described above, the backboard of the present invention is obtained by superposing a plurality of printed boards with spacers interposed therebetween and connecting the plurality of printed boards to pins penetrating through the through holes. Has the same effect as a single printed circuit board having a plurality of layers, and has an effect that the cost can be significantly reduced as compared with a case where a back board is constituted by a single printed circuit board having a plurality of layers. is there.

The backboard of the present invention is superior to the prior art in that it can be easily realized, can be easily assembled, and can secure a certain connection reliability.

Similarly, the method for assembling the backboard of the present invention can be easily realized, and the backboard can be easily assembled.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a backboard of the present invention,
(A) is an exploded perspective view of a main part, and (b) is a cross-sectional view of the main part.

FIG. 2 is a perspective view showing a use state of the backboard shown in FIG. 1;

FIG. 3 is a sectional view of a main part of a second embodiment of the backboard of the present invention.

4A and 4B show a conventional backboard, wherein FIG. 4A is a cross-sectional view of a main part of a first conventional example, FIG. 4B is a cross-sectional view of a main part of a second conventional example, and FIG. FIG. 10D is a cross-sectional view of a main part of a conventional example, and FIG.

[Description of Signs] 1 Back board 2 Main printed board 3 Sub printed board 5 Connector 6 Spacer 20 Through hole 21 Positioning hole 30 Through hole 31 Positioning hole 51 Pin 51a Press fit part 51d Press fit part 60 Boss 61 Boss

Claims (5)

(57) [Claims] A printed circuit board having a through hole;
A back board including a pin inserted into the through hole and a connector mounted on the printed board, wherein a plurality of the printed boards are stacked with a spacer interposed therebetween, and each of the stacked printed boards is Has an engaging portion, the spacer has an insertion hole through which the pin is inserted, and an engaging portion that engages with the engaging portion of the printed circuit board to position the printed circuit board. The through holes of the stacked printed circuit boards are arranged so as to be substantially continuous in the thickness direction of the printed circuit board, and the through holes of the spacer are arranged to face the through holes of the printed circuit board. A backboard characterized by being made. 2. The pin has at least one press-fit portion press-fit into the through hole, and is connected to at least one of the stacked printed circuit boards by the press-fit portion. The backboard according to claim 1, wherein: 3. The backboard according to claim 1, wherein the pins are connected to at least one of the stacked printed circuit boards by soldering. 4. The backboard according to claim 1, wherein the engaging portion of the printed board is a positioning hole, and the engaging portion of the spacer is a boss. 5. The method of assembling a backboard according to claim 1, wherein the pins of the connector are attached to a housing of the connector in advance, and the plurality of printed circuit boards are attached to the spacer in advance. A method of assembling a backboard, wherein the pins of the pre-assembled connector are inserted into through holes of the plurality of pre-stacked printed circuit boards.