DE20008346U1 - Electrical arrangement with several electrical components - Google Patents

Description

Stuttgart, May 5, 2000 P7530Gm Rk/pa

Applicant;

Sidler GmbH & Co. Bismarckstrasse 72 D-72072 Tübingen

Representative:

Kohler Schmid + Partner Patent Attorneys GbR Ruppmannstrasse 27 D-70565 Stuttgart

Electrical arrangement with several electrical components

The invention relates to an electrical arrangement with at least two contact plates held at a distance from one another and with a plurality of electrical components, in particular LEDs, electrically connected to the contact plates.

In a known electrical arrangement, light-emitting diodes (LEDs) are pressed onto a lead frame, thereby keeping the individual contact plates of the lead frame spaced apart from one another. Fig. 5a shows such a known electrical arrangement 50 with two LEDs 51 (so-called HP SNAP LED), whose wide contacts 52 (Fig. 5b) are each clinched (pressed) onto the contact plates 53, 54. However, SNAP LED technology has the disadvantage that these LEDs are very expensive and must be purchased in large quantities.

Circuit boards with soldered LEDs (wired or SMD) are particularly common in signal lights. The costs for such circuit boards with populated LEDs are very high due to the relatively expensive LEDs and the soldering process.

Finally, electrical lighting arrangements are also known in which several LED chips are applied directly to a circuit board (PCB). This process is known as "Chip On Board (COB)". Such electrical lighting arrangements are used primarily for backlighting symbols or switches and large-area displays. Due to the wide beam angle, these LEDs are not used in signal lights. Fig. 6a and 6b show a known electrical lighting arrangement 60 with a COB LED chip 61 that is attached to a circuit board 62. The LED chip 61 is attached with a lower contact surface in an electrically conductive manner by means of silver conductive adhesive 63 to a thin gold contact surface (anode) 64 of the circuit board 62. On the top of the LED chip 61 there is an upper contact surface that is electrically connected to another gold contact surface (cathode) 66 of the circuit board 62 by means of a bonded gold wire 65. The two gold contact surfaces 64, 66 are electrically

insulated. The LED chip 61 and the two contact surfaces 64, 66 are covered with a protective layer 67. However, due to the very thin copper layer on the circuit board 62, the heat dissipation from the LED chip 61 to the environment is very low. As a result, the LED current must be reduced and more or more expensive LEDs are required.

It is therefore the object of the invention to improve an electrical arrangement of the type mentioned at the outset in such a way that the highest possible heat dissipation from the electrical component can be achieved at low manufacturing costs.

This object is achieved in the electrical arrangement mentioned at the beginning in that the contact plates are kept spaced apart from one another by an electrically insulating carrier.

The advantage achieved with the invention is that the heat dissipation from the electrical component to the environment is significantly improved due to the large thickness and cross-section of the contact plates (approx. 0.2 to approx. 1 mm) compared to the copper layer of a conventional circuit board. This allows a significant increase in the maximum permissible LED current and a reduction in the number of LEDs required, thus saving costs. On the other hand, with low current, the reliability at high temperatures can be improved. The smaller number of components and the elimination of the soldering process and mounting holes allow a small tolerance in the placement of the electrical component and thus a more uniform appearance. The elimination of circuit board production (exposure, etching, varnishing with solder mask, ...) also places less strain on the environment. With this

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This process also makes it possible to have step-shaped offsets in the contact plates. If the electrical arrangement is designed as an electrical lighting arrangement with LEDs, it can then be used in the rear lights of a motor vehicle, for example, whereby the step-shaped offsets allow the position of the LEDs to be better adapted to the outer contour of the rear light.

The contact plates, which are preferably strip-shaped, can be punched, cut out or etched out of a metal sheet. Alternatively, two individual contact plates can be used, which are fixed at a distance from each other by the electrically insulating carrier.

The carrier can be provided on the top and/or bottom of the contact plates. The two contact plates can be glued to the common carrier or attached in any other way.

The carrier is particularly preferably manufactured by overmolding the contact plates with plastic. This measure has the advantage that the plastic coating makes the entire electrical arrangement less sensitive during transport and assembly. At the same time, means can be injected that make it easier to fix the electrical arrangement in a housing. The carrier can also be designed directly as a housing for the electrical arrangement or as a housing for connection contacts of the contact plates. These connection contacts of the electrical arrangement (e.g. contact receptacles) are preferably integrated into the contact plates, e.g. punched out, and then overmolded. Such a plastic coating can thus simultaneously form a plug housing for the contact receptacles, which reduces the costs for this additional

parts are eliminated. This reduces the number of components and, since there are no tolerances between the contact plates and the housing, also the assembly tolerances, i.e. the quality is improved and the costs are reduced.

Each electrical component can be at least partially covered by the carrier, in particular overmolded, so that the electrical component (e.g. a resistor) is protected by the plastic casing. In the case of a light source (LED) as an electrical component, the cover must be transparent to the light from the light source.

Each electrical component can be electrically connected to one contact plate and electrically connected to the other contact plate by means of a bonded wire. This electrical connection is particularly suitable for COB components (e.g. for an LED chip), which are electrically connected to one contact plate with their lower contact surface. On the top of the COB component there is an upper contact surface, which is then electrically connected to the other contact plate by means of a wire. The COB technology eliminates the costs of manufacturing and assembling the other LED components (lead frame, housing, etc.), which means that the costs per LED are very low. It is therefore possible to compensate for the light loss caused by the wide light emission of the COB LED chip by using additional COB LED chips. The entire electrical lighting arrangement is still significantly more cost-effective than a conventional electrical lighting arrangement with SNAP LEDs or with soldered LEDs. In addition, the LED spacing can be reduced, which enables a more homogeneous appearance of the electrical lighting arrangement.

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One electrical component can be a light source (e.g. an LED or an LED chip). Since LED chips have a very wide beam angle (up to 180°), the use of Fresnel optics is not very effective. Most of the emitted light goes into the housing and is not captured by the optics. A reflector optics would be an alternative, but the low height makes it very difficult to place the LED at the focal point of the reflector and the reflector is not very effective. In addition, the reflector surface must be vapor-deposited, which is very expensive. It is therefore particularly advantageous if the carrier forms a reflector section for the light sources around each carrier-free receiving area. The reflector section can be a polished (e.g. white) funnel that reflects the light emitted from the side by the LED forwards. This can further increase the optical efficiency of the light source and a smaller number of LEDs are required. The beam characteristics of the LED can thus be influenced and adapted to requirements. The plastic coating of the contact plates and the recessed LEDs within the reflector section make the entire electrical lighting arrangement less susceptible to damage.

The electrical arrangement is even better protected if the electrical components in the carrier-free receiving area are each covered by a separate protective layer. This protective layer can be, for example, a resin layer or silicone layer that is transparent to the light from the LED.

Further advantages of the invention emerge from the description and the drawing. Likewise, the above-mentioned and further listed features can be invented

According to the invention, each of the embodiments can be used individually or in groups in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather are exemplary in nature for the description of the invention.

It shows:

Fig. 1 shows schematically an embodiment of an electrical arrangement according to the invention;

Fig. 2 shows the individual steps of a first method for producing the electrical arrangement shown in Fig. 1;

Fig. 3 shows the individual steps of a second method for producing the electrical arrangement shown in Fig. 1;

Fig. 4 shows the individual steps of a third method for producing the electrical arrangement shown in Fig. 1;

Fig. 5 shows an electrical arrangement (Fig. 5a) according to the prior art, in which two conductor tracks are each held together by LEDs (Fig. 5b); and

Fig. 6 shows the structure of a COB-LED luminaire arrangement on a conventional circuit board in side view (Fig. 6a) and in top view (Fig. 6b).

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Fig. 1 shows an electrical arrangement 1 with an electrical component, which in the illustrated embodiment is an LED chip 2 with two chip contacts. The electrical arrangement 1 forms a lamp overall.

The LED chip 2 is attached to a first contact plate 3, wherein the chip contact located on the underside of the LED chip 2 is electrically connected to the contact plate 3. The other chip contact, which is located on the top of the LED chip 2, is electrically connected to a second contact plate 5 via a (bonding) wire 4. The two contact plates 3, 5, which can be punched out of a copper sheet, for example, are kept spaced apart from one another (gap 7) by a carrier 6. The gap 7 should be as small as possible, e.g. approx. 0.5 mm. The carrier 6 consists of electrically insulating material (e.g. plastic) and encases the two contact plates 3, 5 with an upper and a lower carrier layer 6a and 6b, respectively, wherein the upper side of the contact plates 3, 5 in the receiving area 8 around the LED 2 is carrier-free. The end faces of the carrier 6 adjacent to this carrier-free receiving area 8 run at an angle to the optical axis 9 of the LED and thus form reflector sections 10 which reflect light rays emitted laterally by the LED forwards. In order to protect the LED chip 2 from damage, the carrier-free receiving area 8 is covered with a protective layer 11 which is transparent to the light from the LED. The LED chip 2 and its contact can correspond, for example, to the COB LED chip 61 in Fig. 6.

Fig. 2 shows the individual process steps for producing the electrical arrangement 1 shown in Fig. 1. From a sheet 20 (Fig. 2a) made of electrically conductive material (eg

A grid 21 with the two contact plates 3, 5 is punched, cut out or etched out of a metal sheet (e.g. copper) (Fig. 2b), which are spaced apart from one another by a wide separating gap 22 and are initially connected to one another via several web-shaped connections 23. On one contact plate 3, two projections 24 protrude into the separating gap 22, as a result of which the separating gap 22 in this area is narrowed to the width of the narrower gap 7, e.g. to approx. 0.5 mm. In contrast to the wide separating gap 22, which can be manufactured with a large tolerance, the narrower gap 7 has only a small tolerance and can either be punched or manufactured using a laser. The grid 21 is encased in the carrier 6 made of plastic by placing the entire grid 21 in an injection molding tool and overmolding it with plastic (Fig. 2c). On the top of the contact plates 3, 5, circular receiving areas 8 around the projections 24 and circular areas 25 around the connections 23 are left free of plastic or carrier by covering these areas 8, 25 during the injection molding process, e.g. using a stamp. The projections 24 are each arranged centrally in the carrier-free receiving areas 8. In order to be able to electrically contact the contact plates 3, 5, the contact ends 3a, 5a of the contact plates 3, 5 also remain free of carrier. The connections 23 are then severed either in the injection molding tool or subsequently in a further operation, so that the two contact plates 3, 5 are completely separated from one another (Fig. 2d). Two LED chips 2 are each attached in the carrier-free receiving areas 8 with their lower chip contact in an electrically conductive manner to the projections 24 of the first contact plate 3 and are electrically connected (bonded) with their upper chip contact via the wire 4 to the second contact plate 5 (Fig. 2e).

Finally, each LED chip 2 is covered with the transparent protective layer.

Fig. 3 shows another variant for producing the electrical arrangement 1 shown in Fig. 1. A grid 32 with the two contact plates 3, 5 is produced from a sheet 30 (Fig. 3a) made of electrically conductive material (e.g. copper) by punching, cutting out or etching out the separating gap 31 (Fig. 3b), which are initially connected to one another at the ends via a connection 33. Projections 34 of the contact plate 3 protrude into the separating gap 31, as a result of which the separating gap 31 is narrowed in these areas to the width of the narrower gap 7, e.g. to approx. 0.5 mm. An LED chip 2 is applied in an electrically conductive manner to each projection 34 with its lower chip contact and is electrically conductively connected (bonded) with its upper chip contact to the second contact plate via the wire 4 (Fig. 3c). The grid 32 is then placed in an injection molding tool and overmolded with the carrier 6 (Fig. 3d), whereby the contact plates 3, 5 are left free of carriers in the area of the connections 33 and the circular receiving areas 8 around the LED chips 2. The connections 33 are then severed either in the injection molding tool or subsequently in a further operation (Fig. 3e). The contact ends 3a, 5a of the contact plates 3, 5 are formed by their ends protruding over the carrier 6. Finally, each LED chip 2 is coated with the transparent protective layer.

In Fig. 4, a further variant for producing the electrical arrangement 1 shown in Fig. 1 is shown. On a sheet 40 (Fig. 4a) made of electrically conductive material (eg copper), several LED chips 2 are placed with their lower

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Chip contacts are each applied in an electrically conductive manner (Fig. 4b). By punching out, cutting out or etching out the separation gap 41 near the LED chips 2, a grid 42 is produced with the two contact plates 3, 5, which are initially connected to one another at the end via a connection 43. Projections 44 of the contact plate 3, to which the LED chips 2 are attached, protrude into the separation gap 41. The projections 44 narrow the separation gap 41 in these areas to the width of the narrower gap 7, e.g. to approx. 0.5 mm. The upper chip contacts of the LED chips 2 are each connected (bonded) to the other contact plate 5 in an electrically conductive manner via the wire 4 (Fig. 4c). The grid 42 is then placed in an injection mold and overmolded with the carrier 6 (Fig. 4d), whereby the contact plates 3, 5 in the area of the connections 43 and the circular receiving areas 8 around the LED chips 2 are each left free of carriers. The connections 43 are then severed either in the injection mold or subsequently in a further operation (Fig. 4e). The contact ends 3a, 5a of the contact plates 3, 5 are formed by their ends protruding over the carrier 6. Finally, each LED chip 2 is coated with the transparent protective layer.

Claims (11)

1. Electrical arrangement ( 1 ) with at least two contact plates ( 3 , 5 ) held at a distance from one another and with a plurality of electrical components, in particular LEDs, electrically conductively connected to the contact plates ( 3 , 5 ), characterized in that the contact plates ( 3 , 5 ) are held at a distance from one another by an electrically insulating carrier ( 6 ). 2. Electrical arrangement according to claim 1, characterized in that the carrier ( 6 ) is provided on the upper and/or lower side of the contact plates ( 3 , 5 ). 3. Electrical arrangement according to claim 1 or 2, characterized in that the carrier ( 6 ) is produced by encapsulating the contact plates ( 3 , 5 ) with plastic. 4. Electrical arrangement according to one of the preceding claims, characterized in that the carrier ( 6 ) forms a housing part of the electrical arrangement ( 1 ) and/or a housing for connection contacts of the contact plates ( 3 , 5 ). 5. Electrical arrangement according to one of the preceding claims, characterized in that the electrical components are each attached to only one of the contact plates ( 3 ). 6. Electrical arrangement according to one of the preceding claims, characterized in that the electrical components are at least partially covered by the carrier ( 6 ). 7. Electrical arrangement according to one of claims 1 to 5, characterized in that carrier-free receiving areas ( 8 ) for the electrical components are provided on the contact plates ( 3 , 5 ). 8. Electrical arrangement according to claim 7, characterized in that each electrical component is electrically conductively attached to one contact plate ( 3 ) and is electrically conductively connected to the other contact plate ( 5 ) by means of a wire ( 4 ). 9. Electrical arrangement according to claim 7 or 8, characterized in that the electrical components are each an LED chip ( 2 ). 10. Electrical arrangement according to one of claims 7 to 9, characterized in that the carrier ( 6 ) forms a reflector section ( 10 ) for the electrical components designed as a light source around each carrier-free receiving area ( 8 ). 11. Electrical arrangement according to one of claims 7 to 10, characterized in that the electrical components in the carrier-free receiving area ( 8 ) are each covered by a separate protective layer ( 11 ).