DE102009027530A1 - circuit board - Google Patents

Abstract

The invention relates to a printed circuit board (100), comprising a recess (150) adjoining an upper side of the printed circuit board (100) for receiving an integrated circuit (160). The printed circuit board (100) is characterized by an intermediate layer (130) arranged inside the printed circuit board (100) for dissipating heat, wherein the recess (150) adjoins the intermediate layer (130). The invention further relates to a chip module with such a printed circuit board (100) and an integrated circuit (160).

Description

The The present invention relates to a circuit board having a recess for receiving an integrated circuit and a chip module with such a printed circuit board and an integrated circuit.

State of the art

PCBs be considered as a carrier for integrated circuits or semiconductor chips used. The integrated circuits are common installed in housings with connection elements, which are soldered are connected to contact points of the circuit boards. usual Printed circuit boards have a carrier layer made of an electrical insulating material (base material) on which a layer of an electrically conductive material (interconnect layer) is arranged. Also known are double-sided printed circuit boards, where on both sides of a base layer is a conductive Coating is provided. Furthermore come multilayer printed circuit boards used, also referred to as "multilayer printed circuit boards", in which several such coated base layers with each other are connected to a high packing density for integrated To allow components.

Developments such as increasing power compression and increasingly compact dimensions of electronic components mean that temperature requirements must increasingly be taken into consideration when designing printed circuit boards. Different concepts are used for the effective dissipation of heat. One possibility is, for example, to laminate the circuit board to a metal support, which serves as a heat sink for receiving and transporting away an excess amount of heat. Furthermore, inserts of a thermally conductive material, so-called "inlays" are formed in recesses on the circuit boards. On the deposits components can be arranged to dissipate their heat. Another embodiment for heat dissipation is in the DD 277 165 A1 described. Here, the circuit board on an upper side serving as a heat sink plate made of a metallic material on which electronic components are arranged. The metallic plate is provided with recesses, through which pins of the components can be guided to interconnect layers below the plate.

In addition to providing an effective heat dissipation, there is a further tendency to arrange components as space as possible on a circuit board. The DE 10 2007 010 731 A1 provides for this purpose to form a recess on an upper side of a printed circuit board, in which an integrated circuit can be arranged. However, measures are not described to efficiently dissipate an amount of heat generated during operation of the circuit.

Disclosure of the invention

The Object of the present invention is an improved Printed circuit board and an improved chip module with a printed circuit board and an integrated circuit.

These Task is a printed circuit board according to claim 1 and solved by a chip module according to claim 10. Further advantageous embodiments of the invention are specified in the dependent claims.

According to the invention a printed circuit board is proposed, which is connected to an upper side of the Circuit board adjacent recess for receiving an integrated Circuit has. The circuit board is characterized by a disposed within the circuit board intermediate layer for heat dissipation from, wherein the recess adjacent to the intermediate layer.

The PCB allows a space-saving arrangement of a integrated circuit within the recess. In this way Further, protection of the integrated circuit can be achieved. This makes it possible, instead of a housed an unhoused integrated circuit with relatively small Dimensions to use, whereby also the recess of the circuit board can be formed with correspondingly small dimensions. By the intermediate layer, to which the recess adjoins, can above it In addition, occurring during operation of the integrated circuit Amount of heat can be dissipated effectively, reducing the circuit board even demanding temperature requirements. This is especially the case with high frequency applications.

In a preferred embodiment, the circuit board Continue a contact surface on top in one area next to the recess, which for a contact is formed by wire bonding. An arranged in the recess integrated circuit may have another such contact surface have on the upper side, so that the two contact surfaces over a bonding wire can be connected together. The order the integrated circuit within the recess provides this the ability to perform the bond relatively short. By this configuration, high-frequency applications continue favored.

In Another preferred embodiment has the intermediate layer a metallic material such as in particular copper. Such Material is characterized by a relatively high thermal conductivity which allows effective heat dissipation becomes. Such an effect is further promoted by that the intermediate layer in a further preferred embodiment has a thickness of several hundred micrometers.

In In another preferred embodiment, the recess is adjacent not only to the intermediate layer, but the intermediate layer (also) penetrated by a part of the recess. This configuration leaves Produce in a relatively simple manner, for example by Drilling or milling of previously composed of individual layers and layers PCB.

In Another preferred embodiment, the circuit board further comprising a layer arrangement adjoining the upper side of the printed circuit board two layers of an electrically conductive material, which are separated by an insulating layer. The Layer arrangement is in this case penetrated by the recess. When Material for the insulating layer is preferably polytetrafluoroethylene into consideration. In this way, the layer arrangement for High frequency applications suitable.

In Another preferred embodiment, the circuit board further a the printed circuit board at least to a part vertically penetrating connecting element for producing an electrical and / or thermal connection on. With regard to thermal purposes, such a connection element also penetrate the interlayer (at least in part), so that, for example, provided in the circuit board layers an electrically conductive material to the intermediate layer can be coupled.

According to the invention further proposed a chip module, which is a circuit board and includes an integrated circuit. The circuit board has a on a top of the circuit board adjacent recess, in which the integrated circuit is arranged. The chip module draws characterized in that the circuit board one within the circuit board arranged intermediate layer for heat dissipation has, wherein the recess of the circuit board adjacent to the intermediate layer. Such a chip module allows a space-efficient Arrangement of the integrated circuit and an effective discharge an amount of heat occurring during operation.

The Invention will be described below with reference to the accompanying figure explained in more detail.

1 shows a schematic side view of a chip module with a printed circuit board and an integrated circuit.

Based on the following 1 is a possible embodiment of a chip module with a multilayer printed circuit board 100 and an integrated circuit 160 described. The chip module is suitable for high frequency applications, such as radar applications. Considered, for example, the use in a radar sensor of a motor vehicle, for example in connection with a distance keeping system such as ACC (Adaptive Cruise Control).

The circuit board 100 has an asymmetric layer structure with a number of different layers and layers. At an upper side of the circuit board 100 is a layer arrangement with two electrically conductive layers 110 . 112 provided, which by an insulating layer 111 are separated from each other. The upper of the two layers 110 . 112 acts as a conductor track situation 110 , in which conductor track structures are formed, and the lower as a corresponding ground position 112 , As material for the two conductive layers 110 . 112 For example, copper is considered. The insulation layer 111 has a suitable for high frequency applications material such as in particular polytetrafluoroethylene (PTFE).

This layer arrangement is via a connection layer 120 with an intermediate layer 130 connected, which for cooling the circuit board 100 is used. The intermediate layer 130 Therefore, it has a material with a relatively high thermal conductivity, such as copper. Also owns the intermediate layer 130 a relatively large thickness ("thick copper layer"), which is for example several hundred microns or even more. Furthermore, the lateral dimensions of the intermediate layer are correct 130 with those of the circuit board 100 match, leaving the interlayer 130 (in a plan view) comprises a relatively large area. For the connection layer 120 comes into consideration in the printed circuit board area used prepreg material (Preimpregnated Fibers) into consideration.

Towards a bottom, the circuit board points 100 adjacent to the intermediate layer 130 a further layer arrangement with connecting layers 120 , several electrically conductive layers 140 (Conductor layers) and insulating base layers 141 on. Here are the base layers 141 on both sides with the conductive layers 140 coated, and these layer structures of the coated base layers 141 are with each other and with the intermediate layer 130 over the connecting layers 120 connected. In this case, the connecting layers 120 again a prepreg mate rial, and the conductive layers 140 Have copper. For the base layers 141 For example, a base material used in the printed circuit board area, such as, for example, FR4 (epoxy resin and glass fiber fabric), may be considered.

Using the superimposed conductive layers 140 Power connections can be distributed to different levels or separated from each other. In this way, the circuit board offers 100 a large area for unbundling, making on the circuit board 100 arranged components such as high-frequency circuits, analog and digital circuits can be effectively separated or decoupled from each other.

The circuit board 100 furthermore has a cavern or recess in the area of the upper side 150 for receiving an integrated circuit 160 on. The recess 150 has a floor 151 and opposite side walls 152 or sections of a (in the supervision) circumferential side wall 152 on. The recess 150 intersperses the layers 110 . 111 . 112 . 120 and an upper portion of the intermediate layer 130 , The one in the recess 150 arranged integrated circuit 160 is over an adhesive layer 170 on the ground 151 attached and thus with the intermediate layer 130 (thermally) connected.

Due to the recess 150 can the integrated circuit 160 space-saving on the circuit board 100 to be ordered. Also is the circuit 160 inside the recess 150 protected. At the circuit 160 Therefore, it may be an unhoused chip, which (compared to a packaged device) has relatively small dimensions. In this respect, the recess can also 150 the circuit board 100 include relatively small dimensions.

Because of the integrated circuit 160 only through the adhesive layer 170 from the intermediate layer 130 is disconnected, may further in the operation of the integrated circuit 160 occurring heat output with a high efficiency on the intermediate layer 130 be transmitted. This can also be favored by the fact that for the adhesive layer 170 an adhesive with a high thermal conductivity (thermal adhesive) is used. The amount of heat can continue through the intermediate layer 130 or their relatively large "area" are distributed, whereby an effective heat dissipation is made possible. This will be the circuit board 100 especially temperature requirements, as they can occur in high-frequency applications.

By the arrangement of the integrated circuit 160 inside the recess 150 There is also the possibility of an electrical connection between the integrated circuit 160 and the (top) interconnect layer 110 run as short as possible. The electrical connection is here via bonding wires 180 produced, which contact surfaces (bondpads) 115 the conductor track situation 110 and contact surfaces (bondpads) 165 on a top of the circuit 160 to contact. For example, gold-bearing bonding wires may be considered 180 , In such a case, the contact surfaces 115 . 165 Copper have, which is galvanically gold plated. Contrary to the schematic representation of 1 can be the top of the integrated circuit 160 also in the same plane as the top or top edge of the circuit board 100 , which causes the electrical connection via the bonding wires 180 very short.

In addition to the integrated circuit 160 can on the circuit board 100 additional circuits or (active and passive) components may be provided (not shown). Such components can be arranged on the top and / or the bottom, and to the interconnect layers 110 . 140 or associated contact points, for example, be connected via solder joints. Due to the space-saving arrangement of the integrated circuit 160 in the recess 150 There is also the possibility of a (further) device over the circuit 160 provided.

As indicated above, the chip module may be an electronic device designed for radar applications. In such a case, the integrated circuit 160 preferably a so-called MMIC chip (Monolithic Microwave Integrated Circuit), which is designed for operating frequencies in the microwave range, ie, for example, up to 80 GHz. In order to be able to radiate and / or receive electromagnetic radiation (radar or microwave), the conductor layer has position 110 in this case additionally an antenna or antenna surface (not shown), which via interconnects of the interconnect layer 110 and bonding wires 180 with the integrated circuit 160 connected is.

The circuit board 100 also has the circuit board 100 vertically penetrating connecting elements, which can be used for producing a thermal and / or electrical connection. This includes a in 1 exemplified and the circuit board 100 completely penetrating via 190 , which as a through hole or as a bore with a metallic side wall 195 (Metallization) may be formed. The metallization 195 is formed, for example, by copper. About the via 190 can all conductive layers 110 . 112 . 140 thermally to the intermediate layer 130 angebun be, which increases the heat dissipation capacity of the circuit board 100 can be further improved.

In addition, the circuit board 100 further vertical connections or via (Vertical Interconnect Access) 191 . 192 . 193 at the top or the bottom, which only by a part of the circuit board 100 extend and therefore only a part or only two of the conductive layers 110 . 112 . 140 connect electrically and / or thermally. The connections 191 . 192 . 193 can in this case according to the via 190 be formed as holes with metallized side walls. It is also a (thermal) contact with the intermediate layer 130 possible, as based on the connection 192 is indicated. Also possible are buried (electrical and / or thermal) connections, which are provided only inside the circuit board (not shown).

Furthermore, the circuit board 100 further the circuit board 100 have penetrating holes (possibly threaded) in which fasteners such as screws can be performed to the circuit board 100 For example, to attach to a mounting housing. In this way, in particular the intermediate layer 130 be thermally coupled to such a housing, whereby an effective heat dissipation is further promoted.

For the production of the printed circuit board 100 In the printed circuit board area, usual manufacturing processes can be carried out. A possible manufacturing process consists, for example, of initially base layers 141 and the insulating layer functioning as a (high-frequency) base layer 111 provide, and the base layers 111 . 141 on both sides with the electrically conductive layers 110 . 112 . 141 to provide. Forming the layers 110 . 112 . 141 can by large-scale application of a conductive or metallic layer on the base layers 111 . 141 and subsequent structuring to form structural elements such as printed conductors, contact surfaces, antenna surfaces, etc. The following are the coated base layers 111 . 140 and the intermediate layer 130 pasted over a prepreg material. Following this, the via can 190 and the connections 191 . 192 . 193 are produced, wherein the composite layer stack is subjected to drilling or milling, and subsequently side walls of the holes are metallized. Also the cavity or recess 150 can by drilling or milling at the top of the layer stack to the intermediate layer 130 be generated.

To complete the chip substrate, the manufactured circuit board 100 be stocked with conventional standard manufacturing processes such as gluing, soldering and bonding. In particular, the integrated circuit 160 into the recess 150 used and over the adhesive layer 170 on the ground 151 the recess 150 or on the intermediate layer 130 attached. Subsequently, the contacting of the circuit takes place 160 with the conductor track situation 110 wherein a wire bonding process is performed.

In addition, optional (housed) integrated circuits and components on the circuit board 100 be arranged (not shown). Such devices can on the top, the bottom or on both sides of the circuit board 100 attached and to the interconnect layers 110 . 140 be connected, adhesive and / or soldering can be used. These components may also be components with an operating frequency in the low frequency range (for example less than 1 GHz). Here, the electrically conductive layers 140 as described above for effective unbundling.

The basis of 1 described embodiment of a printed circuit board 100 or a chip module represents a preferred or exemplary embodiment of the invention. Instead of the described embodiment, further embodiments are conceivable, which may comprise further modifications or combinations. In particular, the specified materials for the individual layers and layers of a printed circuit board are merely exemplary, so that other materials can be used.

In addition, printed circuit boards can be realized with an intermediate layer for heat dissipation and a recess adjacent to the intermediate layer, which has a different layer construction than that of FIG 1 exhibit. In this context, for example, given the opportunity to form a (multi-layer) printed circuit board, in which only base materials with the material designation "FR" (flame retardant) such as FR4 and no base materials for special or high frequency applications such as PTFE are used , so unlike the circuit board 100 from 1 no "mixed substrate" is present.

An embodiment of a printed circuit board is conceivable in which a recess adjoins an intermediate layer for heat dissipation only with the bottom, so that the intermediate layer is not penetrated by the recess in an upper partial region. Furthermore, embodiments are possible in which a circuit board more Recesses for receiving integrated circuits, wherein the plurality of recesses adjacent to an intermediate layer for heat dissipation. The plurality of recesses may in this case also be provided on both sides, ie on an upper side and a lower side of a printed circuit board. Further, a recess is not limited to the inclusion of a single integrated circuit or chip, but may also be designed to receive a plurality of (juxtaposed) circuits.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DD 277165 A1 [0003]
• DE 102007010731 A1 [0004]

Claims (12)

Printed circuit board, having one on an upper side of the printed circuit board ( 100 ) adjacent recess ( 150 ) for receiving an integrated circuit ( 160 ), characterized by a within the circuit board ( 100 ) arranged intermediate layer ( 130 ) for heat dissipation, wherein the recess ( 150 ) to the intermediate layer ( 130 ) adjoins. Printed circuit board according to claim 1, further comprising a contact surface ( 115 ) on top of the printed circuit board ( 100 ) in an area adjacent to the recess ( 150 ), where the contact surface ( 115 ) is designed for contacting by wire bonding. Printed circuit board according to one of the preceding claims, wherein the intermediate layer ( 130 ) comprises a metallic material, in particular copper. Printed circuit board according to one of the preceding claims, wherein the intermediate layer ( 130 ) has a thickness of several hundred micrometers. Printed circuit board according to one of the preceding claims, wherein the intermediate layer ( 130 ) of a part of the recess ( 150 ) is interspersed. Printed circuit board according to one of the preceding claims, further comprising one at the top of the printed circuit board ( 100 ) adjacent layer arrangement with two layers ( 110 . 112 ) made of an electrically conductive material, which by an insulating layer ( 111 ) are separated from each other, wherein the layer arrangement of the recess ( 150 ) is interspersed. Printed circuit board according to claim 6, wherein the insulating layer ( 111 ) of the layer arrangement comprises polytetrafluoroethylene. Printed circuit board according to one of the preceding claims, further comprising an underside of the printed circuit board ( 100 ) adjacent further layer arrangement with separate layers ( 140 ) made of an electrically conductive material. Printed circuit board according to one of the preceding claims, further comprising a printed circuit board ( 100 ) at least to a part vertically penetrating connecting element ( 190 . 191 . 192 . 193 ) for producing an electrical and / or thermal connection. Chip module comprising a printed circuit board ( 100 ) and an integrated circuit ( 160 ), the printed circuit board ( 100 ) one to an upper side of the printed circuit board ( 100 ) adjacent recess ( 150 ), in which the integrated circuit ( 160 ), characterized in that the printed circuit board ( 100 ) one within the printed circuit board ( 100 ) arranged intermediate layer ( 130 ) for heat dissipation, wherein the recess ( 150 ) of the printed circuit board ( 100 ) to the intermediate layer ( 130 ) adjoins. Chip module according to claim 10, wherein the printed circuit board ( 100 ) on the upper side in an area next to the recess ( 150 ) a contact surface ( 115 ), wherein the integrated circuit ( 160 ) another contact surface ( 165 ), and wherein the contact surfaces ( 115 . 165 ) of the printed circuit board ( 100 ) and the integrated circuit ( 160 ) via a bonding wire ( 180 ) are connected. Chip module according to one of claims 10 or 11, further comprising an adhesive layer ( 170 ), via which the integrated circuit ( 160 ) in the recess ( 150 ) of the printed circuit board ( 100 ) with the intermediate layer ( 130 ) connected is.

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