DE102014118655A1 - Contact element for a printed circuit board - Google Patents

Abstract

A surface-mountable contact element (1) for a printed circuit board (L, P) has a lower-side contact surface (U) for resting on the printed circuit board, and the contact surface (U) has on the outside at least two adjacently arranged recesses (4). A printed circuit board has at least one contact element (1), wherein the printed circuit board (L, P) has at least one line structure (M) to which the at least one contact element (1) is attached. In a system (1, L, P) having at least one printed circuit board (L, P), a current conductor is connected to at least one contact element (1) of the printed circuit board (L, P). For example, the invention is applicable to electrical systems of vehicles, e.g. for use in on-board networks, in particular for connection to at least one busbar.

Description

The invention relates to a contact element for a printed circuit board, wherein the contact element has a lower-side contact surface for resting on the printed circuit board. The invention further relates to a printed circuit board which has at least one such contact element. The invention also relates to a system having at least one such printed circuit board and at least one current conductor connected to such a contact element. For example, the invention is applicable to electrical systems of vehicles, e.g. for use in on-board networks, in particular for connection to at least one busbar.

Contact systems for plugged or screwed high-current connectors in the form of PCB mounting circuit boards are often expensive and usually have poor heat dissipation and high mounting accuracy requirements.

A pure soldering of busbars with a printed circuit board, e.g. By means of a Surface Mounted Technology (SMT), the soldering point (s) and / or the circuit board is often not allowed due to the mechanical stress, so that the busbar is either soldered into a through hole or a dedicated power dissipation is provided. Current through-hole solder joints have poor heat dissipation and / or are expensive to solder. A pure SMD soldering (SMD = Surface Mounted Device) of the busbars requires in addition to the power dissipation due to the assumed necessary large-scale planarity of the contact to the circuit board also high technical accuracy to allow the current carrying capacity. In order to apply a surface-mountable element (hereinafter also referred to as "SMD element") by means of an SMT method on a printed circuit board, it has hitherto been required that an associated contact surface for soldering must lie flat over a large area on the printed circuit board. Because the contact surface is not sufficiently plan, the soldering may not be able to produce sufficient connection to the circuit board more, which also no sufficient current carrying capacity is given.

Furthermore, there are press-fit connections for high current contacts, which are however expensive to procure.

DE 10 2009 029 476 A1 discloses an electronic device for switching currents and a manufacturing method thereof, which is reliable and durable. Such an electronic device comprises a power semiconductor which is controllable for switching between at least two states; a substrate having thermo-mechanical properties compatible with the power semiconductor, on which the power semiconductor is disposed on one side; a bus bar disposed on the other side of the substrate for conducting a current, wherein the substrate and the bus bar are coupled together such that a heat conductive connection is provided so that heat can be dissipated from the power semiconductor to the bus bar.

DE 10 2010 003 515 A1 discloses a bus bar for a power distributor in vehicles, comprising at least one mounting area for fuses, the mounting area being separated from the remainder of the bus bar by at least one slot separating the bus bar such that connection of the mounting area to the remainder of the bus bar is via only one Web occurs whose cross-section is smaller compared to the adjacent mounting portion and the adjacent remaining part of the busbar.

DE 10 2012 214 366 A1 discloses a switching device for a busbar-based vehicle power distributor and a power distributor. The switching device is provided with a printed circuit board and at least one switching element arranged thereon, power semiconductors or relays, and a fuse carrier for receiving a plurality of fuses, wherein the circuit board is on the one hand connected to a busbar of the vehicle power distributor and on the other hand connected to the fuse carrier, and Switching element, power semiconductor or relay is designed for switching, so that an electric current from the busbar to the fuse carrier via the at least one switching element, power semiconductor or relay (also solder relay) flows.

It is the object of the present invention to overcome the disadvantages of the prior art at least partially and in particular to provide a way of contacting printed circuit boards by high-current connectors, in particular busbars, which is particularly inexpensive, easy to produce and process.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a particular surface-mountable element (hereinafter referred to as "contact element" without restriction of generality) for a printed circuit board, wherein the contact element has a lower-side contact surface for resting on the printed circuit board and the contact surface on the outside or on an outer Side edge has at least two adjacent recesses arranged.

The contact element consists in particular of an electrically conductive material or composite material, in particular of metal.

Due to the plurality of recesses is achieved that an outer edge or an outer contour of the contact surface is extended and so increased current carrying capacity is achieved.

In this case, the knowledge found by experiments is exploited that it depends on a reliable soldering at the edge regions of the contact surface for producing a sufficient current carrying capacity, since there the highest current densities occur. By extending the outer edge, the proportion of the current flow transmitted in an edge region of the contact surface can be greatly increased in comparison to a portion of the current flow through a (typically much larger) non-peripheral or inner region of the contact surface. As a result of the enlargement of the length of the outer edge of the contact surface, the edge region of the contact surface which is decisive for a current flow is also increased. In turn, the planarity of the contact surface is no longer so critical to the current carrying capacity. Parts of the inner region of the contact surface below the contact element, which are not wetted by solder (so-called "voids" or blowholes) thus represent virtually no restriction on the current carrying capacity. It can be, if desired, below the inner region of the contact surface even solder at least partially save by providing there only incomplete soldering or incomplete soldering is performed. This has only a small influence on the current carrying capacity due to the low current flow there.

The underside contact surface may thus be a flat surface, but accuracy of planarity is no longer critical. The underside contact surface may also be deliberately shaped or domed in an inner region in a dome-like manner.

The contact element can be used in particular for the mechanically secure attachment of a high-current connector, in particular a busbar, to the printed circuit board.

If the contact element has at least one inner (i.e., laterally or laterally completely surrounded by material of the contact element) edge, it may be smooth or have at least two adjacently arranged recesses.

In order to avoid current losses, the contact element has a lower electrical resistance, in particular in the main extension or plane direction of the contact element, than a line structure of the printed circuit board of a conductor track on which the contact element is mounted, and / or a soldering arranged therebetween. For example, the resistance can be set precisely and easily by selecting the thickness of the contact element. Furthermore, in order to achieve particularly high current densities in the region of the outer edge, the contact element advantageously has the same material as the conductor track (for example copper) or even a material with a lower electrical resistivity.

The contact element may be surface treated, for example, by adjustment of a surface structure (e.g., roughness) and / or by a surface coating. The surface coating may comprise, for example, a surface treatment (e.g., nitration) of the base material and / or a coating of at least one layer (e.g., silver, tin, or zinc).

It is an embodiment that the contact element is plate-shaped and has at its two outer edge at least two adjacent recesses. Such a contact element can be produced particularly easily. In addition, the plate-like basic shape allows a good thermal heat dissipation. Also, such a large contact surface with respect to the conductor track and the external conductor, in particular high current connector, provided.

A plate-like shaped contact element may, in particular, be understood as meaning an element which has at least approximately the same thickness or thickness along its lateral extent. The plate-like contact element need not be completely flat, but may also be at least locally curved.

In particular, such a contact element can be produced simply from a metal sheet such as a copper sheet, etc., for example by singulating and, if necessary, reshaping. The singulation may be done, for example, by cutting, e.g. Laser cutting, can be achieved. Particularly easy and suitable for mass singling can be achieved by punching. The reshaping may include bending, for example. A sheet thickness may be e.g. be between 0.5 mm and 3 mm, in particular about 1 mm. In this case, the starting sheet may be a sheet but is not limited thereto.

It is a development that the contact surface at least on one side at least two having adjacently arranged recesses. As a result, an already significantly increased current density can be generated in the region of this at least one side. In particular, such a high current density can be achieved in the region of these recesses that, if necessary, a flow of current through other edge regions can be dispensed with. This simplifies positioning of the contact element, in particular in the event that not all the edge regions are electrically contacted.

It is still an embodiment that the contact surface has a rectangular basic shape. As a result, several contact elements can be singulated with only a small amount of waste or even no waste from a metal sheet.

It is an embodiment of this that three sides of the contact surface each have at least two adjacently arranged recesses and the fourth side has no recesses (ie in particular is smooth or straight). This provides the advantage that at high current density at the three recessed sides, the fourth, smooth side can be used to position and align the contact element on the circuit board, for example by being aligned with a side edge of the circuit board.

The recesses may all have the same shape. Alternatively, at least two recesses may have a mutually different shape. Recesses of the same shape may have the same size or different sizes.

It is a particularly simple embodiment that at least one recess, in particular all recesses, are circular segment-shaped. So they can be generated by introducing a plurality of rows of holes in a sheet and separating the contact elements by separating the sheet through the rows of holes therethrough. At least one side of the outer contact of the contact surface may then be similar to a perforation of a stamp.

However, the recesses may basically have any shape, e.g. as a rectangle, triangle, oval or freeform. It may also be combined two or more basic forms.

Also, the configuration that on the outside at least two adjacently arranged recesses are present, be satisfied by the fact that the outer edge is formed at least partially undulating. The waveform may be, for example, sinusoidal, rectangular, triangular, sawtooth, or a combination thereof. A return may be e.g. correspond to a section between two locally maximum external points or local maxima. A period of the wavy edge or edge portion may be constant or change. In particular, a period on one side of the outer edge may be the same.

It is a further embodiment that at least two returns directly into each other. Thus, a length of the outer edge can be extended particularly effective.

It is yet another embodiment that at least two recesses are spaced close to each other. The spacing may be achieved by a smooth (e.g., rectilinear) intermediate section. By "near-to-each other" spacing, it may be understood, in particular, that two recesses adjacent the outer edge are spaced apart by no more than two times the width of the widest of the two recesses, in particular not more than the single width of the widest two recesses, in particular not more than half the width of the widest of the two recesses, in particular not more than a quarter of the width of the widest of the two recesses. The spacing can facilitate a precise introduction of the recesses.

It is also an embodiment that the contact element has at least one projection projecting below the underside contact surface. This can be plugged into the circuit board and thereby causes a mechanical relief of the soldering at the contact surface and a power dissipation from the soldering. The at least one projection may also be referred to as a "force contact".

The mechanical relief can be further improved if the at least one projection is fixed or fixable in a through hole of the printed circuit board, eg non-positively, positively and / or cohesively. For example, the projection in the through hole of the printed circuit board may be press-fitted (eg by means of a so-called "press fit" technology) and / or soldered therein, etc. The soldering of the at least one projection may, for example, in the process step for soldering the contact surface (eg surface mount or SMT), in particular by means of a so-called "paste-in-via" technology, "through hole reflow" technology (THR), "pin in paste" technology (PiP) or "pin in Hole Intrusive Reflow Technology (PIHIR). The soldering of the at least one protrusion may alternatively be soldered in an additional soldering process, eg according to a through-hole technology (THT, or "pin-in"). Hole Technology ", PIH.) Soldering after through-hole mounting may, in particular, be carried out separately from an SMT contacting of the contact surface of the (SMD) contact element on the printed circuit board.

The at least one projection or force contact may, for example, be a partial region of the contact element which is in particular vertically downwardly deformed. The reshaped portion is in particular rectangular or tab-shaped. The forming may be e.g. be a bending forming, for example by folding.

It is an advantageous for a particularly viable power dissipation and protection against rotation of the contact element development that the contact element has at least two force contacts. The force contacts can be arranged symmetrically to each other on the contact element to each other (for example, mirror-symmetrical to a body axis of the contact element). To protect against tilting of the contact element, at least two force contacts may be arranged asymmetrically on the contact element.

It is also an embodiment that the contact element has at least one through hole (also referred to as a "mounting hole" or through hole). The mounting hole may be used to secure a conductor (not associated with the circuit board), particularly a high current connector such as a bus bar, etc.

For example, the conductor may be inserted through the bore (and then soldered or screwed, for example).

The contact element may also arise without a hole for attachment of a (not the circuit board associated) conductor. Thus, the contact element itself may be formed as a plug-in part. For this purpose, it may have one or more projections which can be brought into engagement with a plug-in part.

The object is also achieved by a printed circuit board which has at least one contact element as described above. Such a printed circuit board gives the same advantages as the contact element and may be designed analogously.

In particular, the printed circuit board has at least one line structure to which the at least one contact element is attached. The at least one line structure may have at least one printed conductor and / or at least one contact field or "contact pad". The at least one contact element has been attached to the at least one line structure, in particular by means of surface mounting or SMT.

If, for example, the contact element has a fastening bore, the printed circuit board may also have a bore or through hole congruent thereto.

The printed circuit board may have two or more contact elements, between which at least one functional element is electrically interposed, for example, at least one electrical or electronic component, at least one fuse, etc.

The object is further achieved by a system with at least one printed circuit board as described above and with at least one connected to a contact element of the printed circuit board conductor, in particular high-current connector, in particular busbar. Such a system gives the same advantages as the printed circuit board and the contact element and may be analogous.

The above devices are particularly advantageous for use in vehicles, particularly motor vehicles, but e.g. also airplanes. Thus, the devices may be part of a vehicle electrical system of a car, truck or motorcycle.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following schematic description of an embodiment which will be described in detail in conjunction with the drawings.

1 shows in a view obliquely from above a contact element according to the invention;

2 shows the contact element according to the invention in a first side view;

3 shows the contact element according to the invention in a second side view;

4 shows in a view obliquely from above a printed circuit board with two contact elements according to the invention; and

5 shows in plan view the contact element according to the invention together with a possible range of high current density.

1 shows in an oblique view on an upper side O a contact element according to the invention 1 with a plate-like rectangular basic shape. A lower flat side serves as the lower side Contact surface U to rest on a support, for example a printed circuit board L, such as in 5 shown.

The contact element 1 may have been made as a stamped / bent part from a copper sheet having a sheet thickness d of about 1 mm. While the contact element 1 on three sides 2a . 2 B and 2c an outer edge 3 or an outer contour in each case a plurality of adjacently arranged recesses 4 is a fourth page 2d straight and has no recesses. 2 shows the contact element 1 in side view on the first page 3 . 2a , 3 the contact element 1 in side view on the fourth page 3 . 2d ,

The laterally inward recesses 4 are here circular segment-shaped, in particular semicircular, formed. Neighboring recesses 4 one page 2a . 2 B respectively. 2c are mostly from each other by straight, not receding intermediate sections 5 spaced apart. A length of the intermediate sections 5 along the outer edge 3 is less than a width of the recesses 4 , The width of the semicircular recesses 4 corresponds to their diameter. At a transition of the pages 2a and 2 B respectively. 2 B and 2c go the end-side recesses 4 both sides into each other.

At least approximately in the middle of both sides 2a and 2c has the contact element 1 at its outer edge 3 one each usable as a force contact tab-shaped projection 6 on that from the plate plane of the contact element 1 is bent vertically downwards and so under the lower contact surface U protrudes. The projections 6 are here mirror-symmetrically arranged to a center line through the contact element to each other.

In the middle of an inner area 7 has the contact element 1 a circular through hole 8th on.

4 shows in a view obliquely from above a populated printed circuit board L with two contact elements 1 , The assembled printed circuit board L has the board P as such and at least one electrical functional element F arranged on the top side, for example at least one fuse.

On the upper side, the circuit board P has at least one metallization or metallic line structure M, by means of which the at least one electrical functional element F is electrically connected. Exposed areas of the line structure M are at least partially by means of the two contact elements 1 occupied, so that the at least one electrical functional element F here electrically with respect to the contact elements 1 are interposed.

The contact elements 1 lie flat on the board P, with the protrusions 6 protrude through through holes B in the board and can be fixed there, for example, soldered or press fitted. The contact elements 1 are soldered by means of a surface mounting with the board P and thus represent SMD components. This is particularly advantageous in terms of manufacturing technology, although the at least one electrical functional element F is an SMD component. Through the inserted projections 6 a mechanical relief of the solder joint between the respective contact element and the board P is achieved.

The fourth, smooth side 2d the contact elements 1 is flush with a respective side edge of the board P and is aligned there exactly.

Below the through holes 8th the contact elements 1 also has the board P holes (not shown), which are congruent to the through holes 8th are and advantageously the through holes 8th do not cover.

To the contact elements 1 For example, a respective busbar (not shown) can be connected, eg in the through-holes 8th soldered or bolted to it. The busbars are in particular flat on the respective contact elements 1 on.

5 shows a contact element 1 together with a possible area C of high current density at the transition to the soldering or to the printed circuit board L. This area C extends from the outer edge 3 for one compared to the planar extent of the contact element 1 short distance in the contact element 1 in, thus corresponds to an edge region of the contact element 1 ,

If an external conductor, such as a busbar, in the through hole 8th of the contact element 1 Introduced and contacted, this can cause current from the conductor into the contact element 1 flow, in the area of the through-hole 8th , As the electrical resistance in the contact element 1 is significantly lower than an electrical resistance of the soldering and / or the underlying line structure of the circuit board L (for example, due to a higher thickness of the contact element 1 compared to a thickness of the line structure), it flows as long as possible through the contact element 1 , It then occurs particularly strongly in the (edge) region C of the outer edge 3 from the contact element 1 in the soldering and on in the line structure M over. In the inner region complementary to the region C. 7 On the other hand, a comparatively low current flows. The difference in the current density of the contact element 1 outgoing electricity is greater, the longer the outer edge 3 is. The lower electrical resistance of the contact element 1 can be adjusted for example by choosing a sufficiently strong sheet thickness d. On a surface continuous soldering of the inner area 7 it is less important to achieve a planned current carrying capacity.

In 5 the case is shown that the contact element 1 over the entire surface rests on a line structure or metallization of the circuit board L or board P. Is only a part of the outer edge 3 on the line structure, the associated area C has a high (crossing) current density even in this subsection only.

Of course, the present invention is not limited to the embodiment shown.

So may be dispensed with downwardly directed projections. Also, the top may not be flat, but may, for example, have at least one functional area, for example, a mounting area, which is specially designed for attachment of an external conductor.

Also, the circuit board does not need to be populated.

Generally, "on", "an", etc. may be taken to mean a singular or a plurality, in particular in the sense of "at least one" or "one or more" etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc.

Also, a number may include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

LIST OF REFERENCE NUMBERS

1

contact element

2a-d

 Side of the outer edge

3

Outer edge

4

return

5

intermediate section

6

head Start

7

Inner area

8th

Through Hole

C

High current density range

D

Through Hole

d

sheet thickness

F

functional element

L

circuit board

M

management structure

O

top

P

circuit board

U

Lower contact surface

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009029476 A1 [0005]
• DE 102010003515 A1 [0006]
• DE 102012214366 A1 [0007]

Claims (13)

Surface mountable contact element ( 1 ) for a printed circuit board (L, P), wherein the contact element - a lower-side contact surface (U) for resting on the printed circuit board and - the contact surface (U) on the outside at least two adjacently arranged recesses ( 4 ) having. Contact element ( 1 ) according to claim 1, wherein the contact element ( 1 ) is plate-shaped and at its outer edge ( 3 ) at least two adjacently arranged recesses ( 4 ) having. Contact element ( 1 ) according to one of the preceding claims, in which the contact surface (U) has a rectangular basic shape, on three sides ( 2a . 2 B . 2c ) of the contact surface (U) in each case at least two adjacently arranged recesses ( 4 ) and the fourth page ( 2d ) has no recesses. Contact element ( 1 ) according to one of the preceding claims, in which the recesses ( 4 ) are circular segment-shaped. Contact element ( 1 ) according to one of the preceding claims, in which the outer edge ( 3 ) is formed wavy at least in sections. Contact element ( 1 ) according to one of the preceding claims, in which at least two recesses ( 4 ) directly into each other. Contact element ( 1 ) according to one of the preceding claims, in which at least two recesses ( 4 ) are spaced close to each other. Contact element ( 1 ) according to one of the preceding claims, wherein the contact element ( 1 ) at least one under the lower side contact surface (U) projecting projection ( 6 ) having. Contact element ( 1 ) according to one of the preceding claims, wherein the contact element ( 1 ) at least one through hole ( 8th ) having. Contact element ( 1 ) according to one of the preceding claims, wherein the contact element ( 1 ) is designed as a plug-in part. Printed circuit board, comprising at least one contact element ( 1 ) according to one of the preceding claims, wherein the printed circuit board (L, P) has at least one line structure (M) on which the at least one contact element ( 1 ) is attached. Printed circuit board according to claim 11, comprising at least one contact element ( 1 ) according to claim 8, wherein the at least one projection ( 6 ) is inserted in an associated through hole (B) of the printed circuit board (L, P). System ( 1 , L, P) with at least one printed circuit board (L, P) according to one of claims 11 or 12, wherein at least one contact element ( 1 ) according to one of claims 1 to 10 of the circuit board (L, P), a conductor is connected.

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