DE102017209083B4 - Circuit board assembly with microprocessor component, electronic control unit and method for producing a printed circuit board assembly - Google Patents

Abstract

Printed circuit board arrangement (10) for an electronic control unit (1) with a printed circuit board (110) having a top side equipped with components (112) and a bottom side (114) equipped with components, and with a metallic heat sink (130) for heat dissipation from the components in that one of the components arranged on the upper side (112) is a microprocessor component (116) with a solder grid base (120), the heat sink (130) has a mounting side (132) facing the lower side (114) of the printed circuit board (110), in that the heat sink (130) has a pedestal (136) overlapping with the solder grid base (120), facing the microprocessor component (116) a capacitor (118) as a component on the underside (114) such that the Condenser (118) in plan view of the bottom (114) with a first portion (122) of the Lotraster base (120) overlaps and another portion (124) of the Lotraster base (120) laterally from the K ondenator (118) is arranged, and wherein the pedestal (136) has a recess (138) for receiving the capacitor (118).

Description

The present disclosure relates to a printed circuit board assembly for an electronic control device having a microprocessor device, an electronic control device having the printed circuit board assembly, and a method of manufacturing the printed circuit board assembly.

In printed circuit board assemblies having microprocessor devices with Lotraster base, for example, from US 2003/0224546 A1 and the DE 10 2007 032 092 A1 known. In this case, the microprocessor components are often cooled at the side facing away from the Lotraster top. The solder grid of the base area is relatively poorly cooled.

From the US 2008/0080142 A1 It is known to arrange a heat generating component on a substrate over a portion of a metallic housing formed as a pedestal and to de-heat the component through the substrate. A similar arrangement is also from the US 2011/0292624 A1 known.

It is therefore an object of the present disclosure to provide a particularly efficiently Entwärmbare circuit board assembly and an electronic control unit with such a circuit board assembly and a method for producing a particularly efficient Entwärmbaren circuit board assembly.

This object is achieved by a printed circuit board assembly, an electronic control unit and a method according to the independent claims. Advantageous embodiments and further developments of the printed circuit board assembly, the control device and the method will become apparent from the respective dependent claims, the following description and the drawings.

In accordance with one aspect of the present disclosure, a printed circuit board assembly for an electronic control device is provided. In accordance with another aspect of the present disclosure, an electronic controller is provided with the circuit board assembly.

The printed circuit board assembly has a printed circuit board. The circuit board has a top equipped with components and a bottom, which is preferably also equipped with components. The top side and the bottom side face each other, in particular with respect to a main extension plane of the printed circuit board. One of the devices arranged on the upper side is a microprocessor component, preferably a microprocessor component with a solder grid base. One of the components arranged on the underside is a capacitor, in particular a blocking capacitor.

A microprocessor component is understood in particular to be an electronic component having an integrated circuit, wherein the integrated circuit contains a microprocessor. The microprocessor component preferably contains, in addition to the integrated circuit, a housing in which the integrated circuit is arranged. The microprocessor component may be, for example, a central processing unit (CPU) or a microcontroller. Under the fact that the microprocessor component has a Lotraster base is particularly understood that the device has at its base solder balls, which are preferably arranged in a grid - sometimes called grid. The grid is in particular a regular grid. Such a Lotraster is also referred to by the English technical term "ball grid array" (BGA). In particular, the device having a Lotraster base is a surface mountable device (SMD) that has no leads or pins extending from the base or side surface of the device to the external electrical connection extend the component to the outside.

The capacitor is in one embodiment, a so-called noise suppression or decoupling capacitor, also called EMC (Electromagnetic Compatibility) capacitor.

The capacitor is opposite the microprocessor component on the underside of the circuit board in such a way that the capacitor overlaps in plan view of the bottom with a first portion of the Lotraster base and another portion of the Lotraster base is arranged laterally of the capacitor. In this way, particularly short line paths between the capacitor and the microprocessor component can be achieved, so that a particularly good suppression of the microprocessor can be achieved. The unbundling of the conductor tracks of the circuit board is so easy.

The circuit board assembly further includes a metallic heat sink for dissipating heat from the devices. The heat sink has a mounting side facing the underside of the printed circuit board. On the mounting side, the heat sink has a pedestal. The pedestal overlaps with the Lotraster base.

Advantageously, the heat dissipation by means of the pedestal of the Lotraster base of the Microprocessor device via the circuit board to the heat sink done. In this way, a particularly efficient cooling is possible. A cooling with a heat sink on the side facing away from the Lotraster base surface side of the microprocessor device is advantageously not required. Rather, with the present circuit board arrangement, a particularly good thermal connection of the microprocessor component to the heat sink can be achieved.

The pedestal has a recess for receiving the condenser. By means of the recess for the capacitor on the one hand, the capacitor can be arranged overlapping with the microprocessor component in order to achieve short cable routes - and so a particularly efficient electromagnetic compatibility (EMC) -. Nevertheless, a particularly small distance between the further, not overlapping with the capacitor, portion of the Lotraster base and the heat sink can be achieved. Thus, at the same time advantageous electrical properties of the printed circuit board arrangement and efficient cooling of the solder balls of the solder grid can be achieved.

Preferably, the heat conducted into the circuit board by the microprocessor device via the solder grid base is thereby spread in the circuit board, i. in particular distributed by means of metallic Wärmeleitstrukturen the circuit board on a surface which is larger than the Lotraster base surface. From the circuit board, the heat is transferred via the pedestal to the heat sink and from there to the environment.

In one embodiment, a heat conducting layer is arranged gap filling between the circuit board and the pedestal. In a further development, the heat-conducting layer surrounds the capacitor laterally at least in places. In a further development, the heat-conducting layer surrounds the capacitor all around. In other words, the heat conduction layer, in particular, laterally surrounds the capacitor laterally or laterally completely around the capacitor, wherein it contacts the capacitor. Preferably, it is also arranged between the side facing away from the circuit board of the capacitor and the pedestal. In addition, the heat-conducting layer covers in an expedient development in plan view of the underside of the circuit board, the further portion.

In a development, the heat-conducting layer has a liquid-applied-in the finished state of the printed circuit board arrangement, in particular hardened-electrically insulating material or consists thereof. The material is, for example, a reaction-curing multicomponent material. Such thermal conductivity materials (TIM - thermal interface material) are known in the art in principle and are therefore not explained in detail here.

It is also conceivable that the heat conducting layer is formed in sections of different materials. For example, a first heat-conducting material is arranged in the recess of the pedestal and next to the recess, the pedestal is covered by a second heat-conducting material, which is different from the first heat-conducting material.

By means of a Wärmeleitschicht, which is formed from a liquid coatable material, a particularly good thermal contact between the pedestal and the circuit board can be achieved, both in the region of the capacitor and at the other part of the Lotraster base covered areas of the pedestal.

In one embodiment, the pedestal is formed stepped to form the depression. In other words, the pedestal has a step, so that the pedestal in particular has two parallel to the circuit board extending platforms whose distance from the circuit board is different. Between the platform further away from the printed circuit board and the printed conductor, in particular, the capacitor is arranged. The recess is formed in this case, in particular by the circuit board further away platform and the circuit board perpendicular or inclined surface extending the step. The recess in this case laterally open and in particular on the side opposite to the inclined or perpendicular to the circuit board extending surface of the stage. In this way, the arrangement is particularly insensitive to mounting tolerances. In addition, the pedestal is particularly easy to produce in this way.

For example, in this embodiment, the heat-conducting layer may be flush with the pedestal at a side of the condenser facing away from the step of the pedestal. Alternatively, it may also protrude laterally beyond the pedestal, for example by a part of the material of the heat-conducting layer being squeezed out of the recess during the production of the printed circuit board arrangement. In this way, the requirements for the accuracy in the dimension of the amount of material for the heat conducting layer, which is filled in the manufacture of the assembly in the recess, particularly low.

In one embodiment, the distance between the underside of the circuit board and the pedestal below the first portion of the Lotraster base, which overlaps with the capacitor, at least as large as under the other portion overlapping the side of the capacitor with the microprocessor device. For example the first portion and the platform of the protest further away from the circuit board are arranged congruently or at least overlapping in plan view of the top. In addition, for example, the further subregion and the platform of the protest arranged closer to the printed circuit board are arranged congruently or at least overlapping in plan view of the upper side. In this way, a particularly good heat dissipation from the circuit board and the capacitor can be equally guaranteed.

In one embodiment, the circuit board has a side mounted from the pedestal, equipped with components area which is spaced from the mounting side of the heat sink. Preferably, this area is separated from the heat sink by an air gap. This means, in particular, that no material of the heat conducting layer is arranged in the air gap. In particular, the air gap is gas-filled, for example air-filled. In the region of the printed circuit board which is separated from the heat sink by the air gap, it is expedient to be able to arrange components which have only a low power loss and thus lower heat dissipation requirements than the microprocessor component and the capacitor.

In one embodiment, the electronic control unit has a housing having at least two housing components. The housing components enclose an interior in which the circuit board is arranged. The heat sink is formed in a development of one of the housing components. Appropriately, the pedestal protrudes into the interior. In this way, the electronic control unit can be heated particularly efficiently with low production costs.

In one embodiment, an outer side of the housing component facing away from the interior, which has the heat sink, has an indentation in the area of the pedestal, so that the contour of the outer side in the region of the pedestal follows the contour of the mounting side. In a further refinement, the housing component forming the heat sink is a metallic die-cast component. With these embodiments, individually or in combination, the pedestal is particularly easy to shape during the manufacture of the housing component.

According to a third aspect of the present disclosure, a method of manufacturing the circuit board assembly is provided.

In one step of the method, a circuit board is provided. The printed circuit board is in particular a printed circuit board according to at least one of the embodiments or developments described above. In particular, it has a top equipped with components and a - preferably also equipped with components - bottom, wherein one of the arranged on top of the components is a microprocessor component with Lotraster base. In one embodiment of the method, a printed circuit board is provided in which the microprocessor component is opposed to a capacitor as a component on the underside such that the capacitor overlaps a first subarea of the solder grid base surface in plan view of the underside and a further subarea of the solder grid Base surface is arranged laterally of the capacitor.

In a further step of the method, a metallic heat sink for heat dissipation is provided by the devices. The heat sink is in particular a heat sink according to one of the embodiments and developments described above. In particular, she has a mounting side, where she has a pedestal. In a further development of the method, a heat sink is provided, in which the pedestal has a recess for receiving the capacitor.

In a further step of the method, the printed circuit board and the heat sink are arranged such that the underside of the printed circuit board faces the mounting side of the heat sink and overlaps the pedestal with the Lotraster base.

In a further step of the method, a heat conducting layer of a liquid, electrically insulating, hardenable material is applied between the circuit board and the pedestal. In particular, the heat conducting layer is applied gap filling between the bottom of the circuit board and the pedestal. In one embodiment, the heat-conducting layer is applied in such a way that the heat-conducting layer laterally encloses the capacitor at least in places.

For applying the heat-conducting layer, in particular gap-filling, the material of the heat-conducting layer is applied to the printed circuit board and / or the heat sink, for example, prior to arranging the printed circuit board and the heat sink. In this case, the amount of material is selected such that it partially or - preferably - completely fills the gap when arranging the circuit board and the heat sink. In a further development, a part of the material is squeezed when arranging the printed circuit board and the heat sink from the recess.

In one embodiment, the material of the thermal conduction layer is prepared prior to application of at least two components by mixing the components. In particular, it is therefore a multi-component heat conducting material. For example, this is the multi-component Thermally conductive reaction-hardening, so that it has a low viscosity during application and in the arrangement of the printed circuit board and the heat sink and in the finished printed circuit board assembly - ie in the cured state - has a high viscosity. The heat conduction material is elastically and / or plastically deformable in this or other embodiments in the finished state of the printed circuit board assembly. In particular, an elastic and / or plastic deformability of the heat-conducting layer is greater than that of the printed circuit board or the pedestal. In this way, the thermal conduction layer may protect the microprocessor device from mechanical stress, such as vibration or impact when the control device is accidentally dropped. The risk of cracks in the Lotraster base by mechanical stress during the life of the controller is therefore particularly low.

Further advantages and advantageous embodiments and further developments of the printed circuit board assembly, the control device and the method will become apparent from the following, illustrated in connection with the figure embodiment. The figure and the proportions of the elements shown in the figure with each other are not to be considered to scale. Rather, individual elements may be exaggerated in size for better representability and / or better intelligibility.

1 shows a schematic sectional view of a section of an electronic control unit 1 , The electronic control unit 1 has a circuit board assembly 10 on. In addition, the controller has 1 a housing 20 , The housing 20 has two housing components 210 . 220 , In addition, the controller has 10 expediently a connector (not shown in the figure). The housing components 210 . 220 enclose an interior together with the connector 230 of the control unit 1 ,

In the interior 230 is a circuit board 110 arranged. In the present case, it is a multilayer printed circuit board; whose four circuit levels are in 1 through broken horizontal stripes inside the circuit board 110 indicated.

The circuit board 110 is equipped on both sides. In other words, she has a top 112 , which is equipped with components, and one of the top 112 opposite bottom 114 , which is also equipped with components. Of these components, with which the top 112 and the bottom 114 are in 1 only a microprocessor component 116 and a suppression capacitor 118 shown. The microprocessor component 116 is on the top 112 the circuit board 110 arranged. The suppression capacitor 118 is on the bottom 114 the circuit board 110 arranged.

The microprocessor component 116 has a lotraster base 120 , This meant in particular that the footprint of the microprocessor device 116 is provided with metallic pads, which are arranged at a regular distance from each other and on which solder balls are mounted. By means of the solder balls is the microprocessor component 116 with the top 112 the circuit board 110 soldered.

The suppression capacitor 118 lies the microprocessor component 116 opposite to the bottom, so that the two components in plan view on top 112 or the bottom 114 overlap with each other. In particular, the suppression capacitor 118 in top view on the bottom 114 within the outer contour of the microprocessor device 116 arranged.

More precisely, the suppression capacitor is located 118 the microprocessor component 116 so opposite, that the capacitor 118 in top view on the bottom 114 with a first subarea 122 the Lotraster base 120 overlaps and another subarea 124 the Lotraster base 120 laterally from the condenser 118 is arranged.

The circuit board assembly further includes a heat sink 130 on, for heat dissipation from the components 116 . 118 is trained. This is in the present case of a housing component 220 educated. In which the heat sink 130 forming housing component 220 this is an aluminum die-cast component. The housing component 220 may also comprise or consist of another metal or alloy. That the heat sink 130 forming housing component 220 has one of the circuit board 110 facing and the interior 230 limiting mounting side 132 and one from the interior 230 away and the housing 20 outward final outside 134 ,

The housing component 220 has on its outside 134 a dent 225 by means of the one in the interior 230 protruding pedestal 136 is formed. In other words, the mounting side has 132 one in the interior 230 protruding projection, which is the pedestal 136 forms, and the contour of the outside 134 of the housing component 220 follows in the area of the pedestal 136 the contour of the mounting side 132 under formation of the indentation 225 ,

The pedestal 136 has a level 139 so that two parallel to a main plane of extension of the circuit board 110 extending platforms are formed, which have a different distance from the PCB 110 to have. In top view on the top 112 the circuit board 110 overlaps the microprocessor device 116 completely or at least partially with the pedestal 136 , with both platforms. The capacitor 118 overlaps in top view on the top 112 only with the platform further from the circuit board 110 is spaced and thus a recess 138 of the pedestal 136 represents, in which the capacitor 118 is arranged. In this way is the distance between the bottom 114 the circuit board 110 and the pedestal 136 under the first subarea 122 the Lotraster base 120 greater than under the further subarea 124 the Lotraster base 120 ,

The platforms of the podium 136 are of a heat conducting layer 140 covered the gap between the circuit board 110 and the pedestal 130 fills and around the condenser 118 runs. At the of the stage 139 opposite side of the depression 138 is the heat-conducting layer with the outer contour of the pedestal 136 flush. For the production of the printed circuit board assembly 10 becomes the material of the heat conduction layer 140 liquid on the pedestal one 36 applied and the assembled circuit board 110 on the pedestal 136 put on, leaving the assembled circuit board 110 with the material of the heat conducting layer 140 comes in contact and displaces this at least in places. Subsequently, the material becomes formation of the heat conduction layer 140 hardened. In particular, it is an electrically insulating, thermally highly conductive, reaction-hardening multicomponent material, as is known in principle to a person skilled in the art.

One with in the 1 not shown components equipped subregion 115 the circuit board 110 juts sideways over the pedestal 136 out. For example, the circuit board protrudes 110 on all sides laterally over the pedestal 136 out. In the side over the pedestal 136 protruding portion 115 is the circuit board 110 from the Wärmeleitschicht 140 uncovered and with an air gap 150 from the heat sink 130 - And thus of the heat sink 130 forming housing component 220 - spaced.

That of the microprocessor component 116 generated heat is in 1 Shown schematically with block arrows, that of the housing in the microprocessor component 116 Arranged IC go out and into the PCB 110 into it. By means of the Lotraster base 120 the heat is especially good from the microprocessor component 116 derivable. The metallic structures of the multilayer printed circuit board 110 distribute the heat in a lateral direction, which is also called heat spreading. So the heat can be distributed very well into the heat sink 130 be coupled. In addition, by means of the stepped pedestal is a particularly small distance between the other part 124 and the circuit board 110 achieved, so that the heat transfer into the heat sink there is particularly efficient. At the same time is also in the field of deepening 138 through the the capacitor 118 enclosing heat conducting layer 140 a good heat transfer achievable.

Claims (12)

Printed circuit board arrangement (10) for an electronic control unit (1) with a printed circuit board (110) having a top side equipped with components (112) and a bottom side (114) equipped with components, and with a metallic heat sink (130) for heat dissipation from the components , in which one of the components arranged on the upper side (112) is a microprocessor component (116) with a solder grid base (120), the heat sink (130) has a mounting side (132) facing the underside (114) of the printed circuit board (110), where the heat sink (130) has a pedestal (136) overlapping the solder grid base (120), the microprocessor component (116) is opposite a capacitor (118) as a component on the underside (114) such that the capacitor (118) in plan view of the bottom (114) with a first portion (122) of the Lotraster base (120 ) is overlapped and a further subregion (124) of the solder grid base (120) is arranged laterally from the capacitor (118), and wherein the pedestal (136) has a recess (138) for receiving the capacitor (118). Printed circuit board assembly (10) according to the preceding claim, wherein a heat conducting layer (140) of a liquid applied, in particular cured electrically insulating material gap-filling between the circuit board (110) and the pedestal (136) is arranged. Printed circuit board assembly (10) according to Claim 2 , wherein the heat conducting layer (140) surrounds the capacitor (118) at least in places laterally and covers the further subregion (124) in a plan view of the underside (114) of the printed circuit board (110). Printed circuit board assembly (10) according to one of Claims 1 to 3 wherein the pedestal (136) for forming the recess (138) is formed with a step (139). Printed circuit board assembly (10) according to the Claims 3 and 4 in which the heat-conducting layer (140) is flush with the pedestal (136) on a side of the condenser (118) facing away from the step (139) of the pedestal (136) or protrudes laterally beyond the pedestal (136). Printed circuit board assembly (10) according to one of Claims 1 to 5 , wherein the distance between the underside (114) of the printed circuit board (110) and the pedestal (136) below the first portion (112) of the Lotraster base (120) is at least as large as under the other portion (124). A printed circuit board assembly (10) according to any one of the preceding claims, wherein the circuit board (110) has a component-mounted area (115) laterally spaced from the pedestal (136) and spaced from the heat sink mounting side (132), and in particular through a gas-filled air gap (150) is disconnected. Electronic control unit (1) with a printed circuit board arrangement (10) according to one of Claims 1 to 7 , Electronic control unit (1) according to the preceding claim with a housing (20) which has at least two housing components (210, 220) enclosing an interior space (230) in which the printed circuit board (110) is arranged, wherein the heat sink (130) of one of the housing components (220) is formed and the pedestal (136) in the interior (230) protrudes into it. Electronic control unit (1) according to the preceding claim, wherein an outer side (134) facing away from the inner space (230) of the housing component (220) having the heat sink (130) has a recess (225) in the area of the pedestal (136), such that the Contour of the outer side (136) in the region of the pedestal (136) follows the contour of the mounting side (132). Method for producing a printed circuit board arrangement (10) according to one of the Claims 1 to 7 comprising the steps of: - providing a printed circuit board (110) having a top side (112) equipped with components and a bottom side (114) equipped with components, one of the components arranged on the top side (112) having a microprocessor component (116) with solder grid base (120), - providing a metallic heat sink (130) for heat dissipation from the components having a mounting side (132) at which the heat sink (130) has a pedestal (136), - arranging the circuit board (110) and the heat sink (130) such that the bottom (114) of the circuit board (110) faces the mounting side (132) of the heat sink (130) and the pedestal (136) overlaps the solder grid base (120), gap filling a heat conducting layer (140) of a liquid, electrically insulating, hardenable material between the circuit board (110) and the pedestal (136). A method according to the preceding claim, wherein - A printed circuit board (110) is provided, in which the microprocessor component (116), a capacitor (118) as a component on the bottom (114) opposite such that the capacitor (118) in plan view of the bottom (118) a first portion (122) of the Lotraster base (120) overlaps and a further portion (124) of the Lotraster base (120) is arranged laterally of the capacitor (118), - A heat sink (130) is provided, the pedestal (136) has a recess (138) for receiving the capacitor (118), and - The application of the Wärmeleitschicht (140) takes place such that the Wärmeleitschicht (140) the capacitor (118) laterally encloses at least in places and in plan view of the underside (114) of the printed circuit board (110) covers the other portion (124).

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