Interconnection structure for circuit boards and terminal members

An interconnection structure for circuit board and terminal members improves a configuration of a terminal member to be soldered to conductors on boards, and relaxes a stress applied to soldered portions, thereby preventing the soldered portions from a problem, such as cracking. An interconnection structure for circuit boards and terminal members includes two boards positioned away from each other. A terminal support base may be disposed on at least one of the boards and provided with a plurality of juxtaposed terminal guiding-holes, and a plurality of terminal members may be soldered to conductors on the two boards, may penetrate the terminal guiding-holes in the terminal support base, and may be provided with bent portions for stress relaxation at a position where the bent portions do not contact with the terminal support base.

BACKGROUND

This invention relates to an interconnection structure for circuit boards and terminal members, and more particularly relates to an interconnection structure for a plurality of printed circuit boards and terminal members contained in an electrical junction box to be mounted on a motor vehicle.

A motor vehicle is provided with an electrical junction box mounted thereon. A plurality of printed circuit boards constituting an inner circuit are contained in the electrical junction box. In the case where conductors on the printed boards are connected to each other, opposite ends of the terminal members are soldered to the conductors on the printed boards.

Such a kind of the interconnection structure for the boards and terminal members is disclosed in JP-A-7-297562. As shown inFIG. 12in the present application, opposite ends of each linear terminal member3are soldered to conductors (not shown) on two printed circuit boards1and2to connect them to each other.

However, in the interconnection structure disclosed in JP-A-7-297562, because the linear terminal members3are soldered to the conductors on the printed circuit boards1and2, when the two printed circuit boards are shifted from each other by a load applied to one of the printed circuit boards, a great stress will be applied to the soldered portions of the terminal members and printed circuit boards1and2. This will cause cracks in the soldered portions, thereby lowering reliability of the electrical junction box.

SUMMARY

In view of the above problems, an object of the present invention is to provide an interconnection structure for circuit boards and terminal members that improves a configuration of a terminal member to be soldered to conductors on circuit boards and can relax a stress applied to soldered portions and prevent the soldered portions from problems, such as cracking.

In order to achieve the above object, an interconnection structure for circuit boards and terminal members in accordance with the present disclosure includes: two circuit boards positioned away from each other, a terminal support base disposed on at least one of the circuit boards and provided with a plurality of juxtaposed terminal guiding-holes, and a plurality of terminal members soldered to conductors on the two circuit boards, penetrating the terminal guiding-holes in the terminal support base, and provided with bent portions for stress relaxation at a position where the bent portions do not contact with the terminal support base.

According to the interconnection structure for the circuit boards and terminal members constructed above, because the bent portion for stress relaxation is provided on each terminal member that is soldered to the conductors on the two circuit boards, even if one circuit board is shifted from the other circuit board, the stress applied to the terminal member can be relaxed by deflection of the bent portion. Thus, a great stress is not applied to the soldered portions that interconnect the terminal members and the conductors on the circuit boards, thereby preventing the soldered portions from problems, such as cracking, and enhancing reliability of the electrical junction box.

Because the bent portion of each terminal member do not contact with the terminal support base mounted on the circuit board, the bent portion can deflect flexibly without contacting with the terminal support base when a stress is applied to the terminal member, thereby sufficiently relaxing the stress applied to the terminal member.

Preferably, the bent portion for stress relaxation provided on each terminal member is inclined by an angle of about 65 degrees to about 80 degrees relative to the opposite connecting ends to be soldered to the conductors on the circuit boards.

As described above, because the bent portion for stress relaxation is inclined with respect to the soldered portions at the opposite connecting ends of the terminal member, it is possible to easily align heights of the opposite connecting ends of the plural terminal members and to surely connect the all terminal members to the conductors on the boards, thereby enhancing reliability of the electrical junction box.

The slant bent portion for stress relaxation can be easily formed in comparison with rectangular bent portion relative to the opposite end soldered portions. Even if the terminal member has a great width or thickness, it is possible to easily form the bent portion for stress relaxation.

Furthermore, by inclining the bent portion for stress relaxation relative to the opposite end connecting portions, it is possible to deflect the bent portion and to prevent the soldered portions from a problem, such as cracking, even if a load is applied to the terminal member in any direction.

Preferably, the terminal guiding-holes juxtaposed in the terminal support base are arranged in a different pattern at opposite longitudinal end portions of the terminal support base.

According to the above construction, even if the terminal support base is put on the circuit board in the position turned by an angle of about 180 degrees in a horizontal plane contrary to the regular position, the terminal members fixed on the terminal support base are shifted from the terminal holes in the circuit board, so that the terminal members cannot be inserted into the terminal holes in the circuit board. Thus, it is possible to prevent the terminal members in the erroneous arrangement from being connected to the conductors on the circuit boards.

In more detail, in the case where the distances between the terminal guiding-holes are different at the longitudinal end portions of the terminal support base, or in the case where there are wider and narrower terminal members, the terminal guiding-holes for penetrating the wider terminal members may be provided on the opposite longitudinal end portions of the terminal support base, or the number of the terminal guiding-holes for the wider terminal members may be different at the opposite longitudinal end portions of the terminal support base.

Preferably, in the case where the terminal support base is disposed on each of the opposite lateral end portions of the circuit boards, the same terminal support bases are opposed to each other at the opposite lateral end portions of the boards, and one of the terminal support bases may be turned by an angle of about 180 degrees relative to the other terminal support base.

According to the above construction, the terminal support bases opposed to each other at the both sides of the circuit boards are the same ones, thereby reducing a count of components and lowering a cost.

As described above, according to the present invention, because the bent portion for stress relaxation is provided on each terminal member that is soldered to the conductors on the two circuit boards and is arranged at the position where the bent portion does not contact with the terminal support base, even if one circuit board is shifted from the other circuit board, the stress applied to the terminal member can be relaxed by deflection of the bent portion. Thus, a great stress is not applied to the soldered portions that interconnect the terminal members and the conductors on the boards, thereby preventing the soldered portions from cracking and enhancing reliability of the electrical junction box.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring now to the drawings, embodiments of an interconnection structure for circuit boards and terminal members in accordance with the present disclosure will be described below.

FIGS. 1 to 8show the first embodiment of the interconnection structure for the circuit boards and terminal members in accordance with the present disclosure.

A circuit board unit15may include an interconnection structure for circuit boards and terminal members100. The circuit board unit15may include a first printed circuit board13, a second printed circuit board14, and a spacer interposed between the first and second printed boards13and14. Conductors (not shown) on the first and second printed circuit boards13and14may be connected through terminal members20to each other. The spacer12is omitted inFIG. 12.

The circuit board unit15may be used as an inner circuit of the electrical junction box to be mounted on the motor vehicle. As shown inFIGS. 5 and 6, the electrical junction box may include a casing assembly having an upper casing10and a lower casing11. A bus bar laminated unit18, in which bus bars16and insulation plates17are alternately laminated, and the board unit15may be contained in the casing assembly so that they are arranged from the upper casing10to the lower casing11.

Shorter size fixing bars10xmay be integrated with an inner surface of a top wall10aof the upper casing10and may extend downward from the inner surface. The shorter size fixing bars10xmay penetrate the bus bar laminated unit18, first printed circuit board13, and spacer12to fix them on the upper casing10by first screws N1. Longer size fixing bars10ymay penetrate the bus bar laminated unit18, first printed circuit board13, spacer12, second printed circuit board14, and lower casing11to fix them on the lower casing11by second screws N2.

As shown inFIG. 3, each of the terminal members20that connect the conductors on the first and second printed circuit boards13and14to each other may be provided on the opposite longitudinal ends with connecting portions20aand20bto be soldered to the conductors on the first and second printed circuit boards13and14and on an intermediate part with a bent portion20cfor stress relaxation that is bent along a longitudinal direction of the terminal member20.

As shown inFIG. 3B, the bent portion20cof the terminal member20may be bent by an inclined angle α of about 65 degrees to about 80 degrees (about 75 degrees in the first embodiment) relative to the opposite end connecting portions20aand20bof the terminal members20. Consequently, the terminal member20can deflect even if a stress is applied to the terminal member20in any direction, thereby absorbing and relaxing a stress applied to the terminal member20by the bent portion20c. Engaging projections20dmay be provided on the opposite lateral end side surfaces of the terminal member20between the bent portion20cand the connecting portion20a. A reinforcing portion20emay be provided on the terminal member20below the engaging projections20dat the side of the connecting portion20a. A width of the reinforcing portion20emay be greater than those of the connecting portions20aand20b.

In the first embodiment, two kinds of terminal members including a wider terminal member20A and a narrower terminal member20B (seeFIGS. 2A,2B) are used. InFIGS. 1 to 3, the terminal members20are turned in the upside down position contrary to the position where the terminal members20are contained in an electrical junction box.

As shown inFIG. 4, a terminal support base19for fixing a plurality of terminal members20may include a housing19athat may be a resin-molding product. The terminal support base19may be provided with a plurality of juxtaposed terminal guiding-holes19bextending vertically. The terminal guiding-holes19bmay include wider terminal guiding-holes19b-1for permitting the wider terminal members20A to pass and narrower terminal guiding-holes19b-2for permitting the narrower terminal members20B to pass. The terminal support base19may be provided in the opposite longitudinal end portions with the wider terminal guiding-holes19b-1and in the intermediate portion with the narrower terminal guiding-holes19b-2. In the first embodiment, six wider terminal guiding-holes19b-1are provided in each of the opposite longitudinal end portions of the terminal support base19.

Also, the terminal support base19may be provided on a side end surface opposed to the first printed circuit board13with a plurality of support legs19cto be mounted on the first printed board13.

InFIG. 4, the terminal support base19is turned in an upside down position contrary to the position where the terminal support base19is contained in the electrical junction box.

When the connecting portion20bof each terminal member20is inserted into each terminal-guiding hole19bin the terminal support base19, the engaging portions20dof each terminal member20engages an interior of the terminal-guiding hole19b, and thus a plurality of terminal members20are fixed on the terminal support base19. At this time, as shown inFIG. 2, the bent portion20cof each terminal member20is disposed on the position where the bent portion20cdoes not contact with the terminal support base19. When a load is applied to the terminal member20, the bent portion20cis deflected to relax a stress.

The terminal members20A and20B may be inserted into and secured to the terminal guiding-holes19bin the terminal support base19in accordance with sizes of the terminal guiding-holes19b. In the first embodiment, a plurality of narrower terminal members20B are secured to and aligned on the longitudinal intermediate portion of the terminal support base19, while six wider terminal members20A are secured to and aligned on each of the opposite longitudinal end portions of the terminal support base19.

The first and second printed circuit boards13and14may also be provided with terminal holes13aand14ain accordance with sizes of the terminal members20A and20B, respectively. When the terminal support base19is disposed on a regular position on one side of the first printed circuit board13, a connecting portion20aat one longitudinal end side of each of the terminal members20A and20B fixed on the terminal support base19may be inserted into the terminal holes13ain the first printed circuit board13. The connecting portions20aof the terminal members20inserted in the terminal holes13ain the first printed circuit board13may be soldered to the conductors on the first printed circuit board13. Furthermore, a connecting portion20bat the other longitudinal end side of the terminal members20may be inserted into the terminal holes14ain the second printed circuit board14and the connecting portions20bof the terminal members20are soldered to the conductors on the second circuit board14.

As shown inFIG. 5andFIG. 6B, the first printed circuit board13may be provided with through-holes13band13cthat permit the shorter size fixing bars10xand longer size fixing bars10yto penetrate while the second printed circuit board14is provided with through-holes14bthat permit the longer size fixing bars10yto penetrate. As shown inFIG. 1A, the second printed circuit board14may be provided with through-holes14cand recesses14dat positions corresponding to the shorter size fixing bars10x.

The first printed circuit board13may be provided with a conductor (conductor pattern) having a great thickness enough to constitute a printed circuit board for a high current circuit.

The second printed circuit board14may be provided with a conductor having a smaller thickness than that of the first printed circuit board13enough to constitute a printed circuit board for a middle or low current circuit.

As shown inFIG. 5, the first printed circuit board13may be provided on the top surface with a board relay22disposed along a part of the peripheral edge of the top surface and may be provided on the top surface with a number of terminal members23soldered to the conductors.

The second printed circuit board14may be provided with electronic/electrical elements on the top surface that is opposed to and spaced away from the base portion12aof the spacer12and on the bottom surface that is opposed to the bottom surface of the lower casing11. The electronic/electrical elements may be connected to the conductors on the printed circuit board14. Terminal members24may be soldered to the conductors on the opposite sides of the second printed circuit board14to project toward a connector-containing section11bin the lower casing11, as shown inFIG. 8.

The spacer12may be disposed between the first printed board13and the second printed board14and may be a product made of an insulation resin material and having a configuration shown inFIG. 7. The spacer12may include a substantially rectangular base portion12aand an outer peripheral frame12dthat projects in a vertical direction from an outer peripheral edge of the base portion12a. The base portion12amay be provided substantially on a whole top surface with substantially grid-like ribs12cfor reinforcement and prevention against deformation. As shown inFIG. 6B, the first printed circuit board13may be disposed on top surfaces of the ribs12c. The base portion12amay not be provided on a bottom surface with the ribs12c. The second printed board14may be disposed on a bottom surface of the outer peripheral frame12d.

As shown inFIG. 7A, the base portion12aof the spacer12may be provided with through-holes12ein positions corresponding to the projecting positions of the shorter size fixing bars10x. As shown inFIG. 7B, each of the through-holes12emay be provided on an interior with an annular flange portion12f. A top surface of the flange portion12fmay receive a lower end surface of the shorter size fixing bar10xwhile a bottom surface of the flange portion12fmay receive a head portion N1aof the first screw N1inserted upward into the through-hole12e. Furthermore, the spacer12may be provided with through-holes12gat the positions corresponding to the projecting positions of the longer size fixing bars10y.

In addition, engaging pawls12h(FIG. 3c) may extend from a lower end surface on a downward projecting portion of the outer peripheral frame12dof the spacer12. The second printed circuit board14may contact with a lower end surface of the outer peripheral frame12d. The engaging pawls12hmay lock the peripheral edge of the second printed circuit board14.

Two cylindrical longer size fixing bars10ymay extend from an inner surface on the top wall of the upper casing10substantially at the opposite sides of a center of the top wall in a diagonal direction. Four shorter size fixing bars10xmay extend at the corners of the top wall. A length of each longer size fixing bar10ymay be set to reach a bottom wall11aof the lower casing11, while a length of each shorter size fixing bar10xmay be set to reach a base portion12aof the spacer12. The longer size and shorter size fixing bars10yand10xmay be provided with threaded holes10y1and10x1at their lower end openings.

The upper casing10may be provided on the top wall10awith a fuse-containing section10d, a connector-containing section10e, and a relay-containing section10fto dispose terminals16aprojecting from the bus bars16, and the terminal members23projecting from the first printed circuit board13in the respective sections.

The upper casing10may be provided on an exterior of a peripheral wall10gwith a locking portion10hto be locked on the lower casing11.

The lower casing11may be provided substantially on a whole top surface of the bottom wall11awith grid-like ribs11cfor reinforcement and on an outer peripheral portion of the bottom wall11awith longer size ribs11kextending upward. Upper end surfaces of the longer size ribs11kmay contact with the bottom surface of the second printed circuit board14to perform positioning and holding functions. Recesses11dmay be provided in the bottom wall11aof the lower casing11at the positions opposed to the projecting positions of the longer size fixing bars10y. Each of the recesses11dmay be provided on a bottom wall with a fixing-hole11eto pass the second screw N2. Lower surfaces of the longer size fixing bars10ymay be put on upper surfaces of the recesses11d. The lower surface of each recess11dmay serve as an engaging surface with a head portion N2aof the second screw N2to be inserted into the fixing hole11efrom the lower side.

As shown inFIG. 5andFIG. 6C, a peripheral wall11iof the lower casing11may have a height that reaches a top surface of the electrical junction box and thus the lower casing11may be formed into a deep box-like configuration. When the peripheral wall11iof the lower casing11is fitted on the exterior of the peripheral wall10gof the upper casing10, the locking portions10hon the exterior of the peripheral wall10gmay engage with a locking groove11jprovided on the peripheral wall11i.

Next, procedures for assembling the electrical junction box will be described below.

First, the upper casing10may be turned in an upside down position so that the shorter size fixing bars10xand longer size fixing bars10yproject upward, the bus bar laminated unit18including the bus bars17and insulation plates16may be inserted into the upper casing10, the longer size fixing bars10yand shorter size fixing bars10xmay be inserted into the through-holes18ain the bus bar laminated unit18from the upper side, and the bus bar laminated unit18may be contained in the upper casing10.

Second, the first printed board13may be inserted into the upper casing10from the upper side. The shorter size and longer size fixing bars10xand10yprojecting from the bus bar laminated unit18may be inserted into the through-holes13band13cin the first printed circuit board13from the upper side. The first printed board13may be disposed on the insulation plate17on the lowermost layer (uppermost layer in the assembling steps) of the bus bar laminated unit18. An end of each terminal member20supported by the terminal support base19may then be soldered to the conductors on the first printed board13. At this time, the terminal support base19may be disposed above the first printed circuit board13.

Then, the spacer12may be inserted into the upper casing10from the upper side. The longer size fixing bars10ymay be inserted into the through-holes12gin the spacer12. The shorter size fixing bars10xmay be inserted into the fixing holes12ein the spacer12. The lower end surfaces (upper end surfaces in the assembling steps) of the shorter size fixing bars may contact with the flanges12fin the fixing holes12e. Under this condition, the first screws N1may be inserted into the fixing holes12eand screwed into the threaded holes10x1in the shorter size fixing bars10x.

Thus, the bus bar laminated unit18may be contained in the upper casing10to project from the casing10, and the first printed circuit board13and spacer12stacked on and secured to the bus bar laminated unit18.

Then, the second printed circuit board14may be inserted into the upper casing10from the upper side. The longer size fixing bars10ymay be inserted into the through-holes14ain the second printed circuit board14. The second printed circuit board14may be put on the distal end of the outer peripheral frame12dof the spacer12. The engaging pawls12hprojecting from the outer peripheral frame12dmay lock the second printed circuit board14. Under this condition, the connecting portion20bof the other end of each terminal member20may be soldered to the conductors on the second printed board14.

Finally, the lower casing11may be mounted on the upper casing10from the upper side. The peripheral wall10gof the upper casing10may be fitted on the interior of the peripheral wall11iof the lower casing11. The lower end surfaces of the longer size fixing bars10ymay contact with the upper surfaces of the recesses11daround the fixing holes11ein the lower casing11. Under this condition, the second screws N2may be inserted into the fixing holes11ein the lower casing11from the upper side and screwed into the threaded holes10y1in the longer size fixing bars10y. The peripheral wall10gof the upper casing10may be fitted on the interior of the peripheral wall11iof the lower casing11, and the locking portions10hmay couple the locking grooves11jto each other.

In the above assembling procedures, in the case where, for example, a step of stacking the first printed circuit board13on the second printed circuit board14may be carried out at a remote factory. The bus bar laminated unit18, first printed board13, and spacer12can be firmly secured to the upper casing10by means of fastening the first screws N1into the shorter size fixing bars. Accordingly, it is possible to prevent the respective components from being detached or shifted from one another when the assembled unit is transmitted to another remote factory.

According to the above construction, because the bent portion20cfor stress relaxation may be provided on the intermediate part of the terminal member20, in which the opposite ends are soldered to the conductors on the first and second printed circuit boards13and14, even if a load is applied to the terminal member20or the first and second printed circuit boards13and14are shifted from each other upon assembling the first and second printed circuit boards13and14, the stress applied to the terminal member20can be relaxed by deflection of the bent portion20c. Thus, a great load is not applied to the soldered portions that interconnect the terminal members20and the conductors on the first and second printed circuit boards13and14, thereby preventing the soldered portions from a problem, such as cracking, and enhancing reliability of the electrical junction box.

Because the bent portions20cof the terminal members20do not contact with the terminal support base19so that the bent portions20ccan deflect flexibly, it is possible to sufficiently relax the stress applied to the terminal members20.

FIG. 9shows a second embodiment of the interconnection structure for the boards and terminal members.

In the second embodiment, the terminal support base19may be provided on one end (right end of the figure) in the longitudinal direction with five terminal guiding-holes19b-1and on the other end (left end of the figure) in the longitudinal direction with six terminal guiding-holes19b-1. The terminal guiding-holes19b-1may be arranged in the terminal support base19so that the number of them may be different on the opposite end sides.

According to the above construction, the terminal support base19permits the plural terminal members20to penetrate and to be secured. The number of the terminal guiding-holes19b-1, in which the wider terminal members20A provided on the opposite longitudinal ends of the terminal support base19are inserted and secured, may be different at the opposite longitudinal ends of the terminal support base19. Consequently, even if the terminal support base19is put on the first printed circuit board13in the position turned by an angle of about 180 degrees contrary to the regular position, the wider terminal members20A fixed on the terminal support base19do not accord with the terminal holes13ain the first printed circuit board13, so that the wider terminal members20cannot be inserted into the terminal holes13ain the first printed circuit board13. Thus, it is possible to prevent the terminal members20in the erroneous arrangement from being connected to the conductors on the first printed circuit board13.

Because the other construction and operational effects in the second embodiment may be the same as those in the first embodiment, explanations of them are omitted by giving the same signs to the same components.

FIG. 10shows a third embodiment of the interconnection structure for the boards and terminal members.

In the third embodiment, the narrower terminal members20B may be disposed on an intermediate portion of the terminal support base19in the longitudinal direction, while the wider terminal members20A are disposed on opposite end portions of the base19in the longitudinal direction. The number of the terminal guiding-holes19b-1for receiving and fixing the wider terminal members20A may be the same on the opposite end portions of the terminal support base19, such as six holes in the third embodiment. However, distances between the terminal guiding-holes19b-1on one end portion of the terminal support base19may be set to be L1, while distances between the terminal guiding-holes19b-1on the other end portion of the terminal support base19may be set to be L2(L1<L2). Thus, the distances on the opposite end portions of the terminal support base19may be different.

According to the above construction, the distances between the terminal guiding-holes19b-1may be different at the opposite end portions of the terminal support base19and thus the distances between the terminal members20A are different. Consequently, even if the terminal support base19is put on the first printed circuit board13in the position turned by an angle of about 180 degrees contrary to the regular position, the wider terminal members20A fixed on the terminal support base19do not depend on the terminal holes13ain the first printed circuit board13, so that the wider terminal members20A cannot be inserted into the terminal holes13ain the first printed circuit board13. Thus, it is possible to prevent the terminal member20in the erroneous arrangement from being connected to the conductors on the first printed circuit board13.

Because the other construction and operational effects in the third embodiment may be the same as those in the first embodiment, explanations of them are omitted by giving the same signs to the same components.

FIG. 11shows a fourth embodiment of the interconnection structure for the boards and terminal members.

In the fourth embodiment, the same terminal support base19as that in the first embodiment may be opposed to each of lateral side end portions of the first printed circuit board13. One terminal support base19A may be disposed at a position turned by an angle of about 180 degrees relative to the other terminal support base19B in a horizontal plane. Consequently, bending directions of the bent portions20cof the terminal members20disposed on the opposite ends of the terminal support bases19A and19B may be symmetrical with respect to the center of the first printed circuit board13.

According to the above construction, as in the case with first embodiment, it is possible to prevent the soldered portions interconnecting the terminal members20and the conductors on the first and second printed boards13and14from a problem, such as cracking. It is also possible to reduce a count of components and lower a cost by changing the terminal support bases19disposed on the opposite lateral end side portions of the first and second printed circuit boards13and14to the same terminal support base.

The same terminal support base as that in the second or third embodiment may be disposed on both sides of the printed boards.

Because the other construction and operational effects in the fourth embodiment are the same as those in the first embodiment, explanations of them are omitted by giving the same signs to the same components.