DE102004017984A1 - Electrical board manufacture used in power electronics, involves setting conductive strips and heat sinks on conductive layers on both sides of non-conducting base material and fixing heat-dissipating components on conductive strips - Google Patents

Abstract

The method involves setting conductive strips (4) and heat sinks (6) on conductive layers on both sides of a plate-shaped and non-conducting base material (2). A portion of the core, applied on the base material for the heat sinks, is then removed. Heat-dissipating components (5) are conductively fixed on the conductive strips on one side of the base material. The conductive strips and heat-dissipating components are formed on one side of the base material, while the heat sinks are formed on the other side of the base material. An independent claim is also included for the electrical board manufacturing device.

Description

The The invention relates to a method for producing an electrical Assembly, wherein an essentially plate-shaped, electrically non-conductive carrier on at least one side with conductor tracks and at least one producing heat loss Component and on a substantially opposite this component Area of the other side is provided with at least one heat sink, as well a corresponding assembly itself.

By the constantly advancing miniaturization of electrical and electronic Components and assemblies (computer CPUs, laser technology, power electronics, .....) is the heat loss produced to ever smaller spatial Areas concentrated, which is a way of avoiding undue local temperature increases active cooling of the heat loss producing component required. Except for relatively minor ones cooler capacity Providing, mounted convection heatsinks with or without interacting with it Radiator fans on the one hand and relatively complex and expensive Peltier or heat pipe coolers On the other hand, there have been many areas in recent years relatively simple liquid cooling systems enforced, in which a heat sink through which the cooling medium flows preferably direct contact with the component producing heat loss brought and the warmed coolant flows through a remotely located recooler which the heat mostly simply releases into the ambient air. It is problematic always the fact that the most direct possible contact for thermal reasons heat loss producing component with the most loss-free heat transfer possible due to metallic heat sinks (mostly made of copper) is not easily possible because short circuits or even unwanted ones potential transfers excluded are. While individual element coolers still relatively easy, for example by means of electrically non-conductive connecting hoses and non-conductive fasteners must be securely insulated, already provides the liquid cooling medium even mostly a big one A source of danger because, for example, the usual deionized water when refilling or exchanges due to ignorance, carelessness or carelessness can easily be confused with normal water (and always is confused again) which immediately leads to catastrophic damage.

Around the need to use non-conductive cooling media to avoid, arrangements have become known recently in which thermally good to excellent conductive but electrically good to very good insulating technical ceramics, for example Aluminum oxide or aluminum nitride ceramic on one side the heat loss producing component in as possible direct contact and on the other hand, on the one to be cooled Component essentially opposite Area, one side delimited by the ceramic support, through which the cooling medium flows hollow body wear. The electrical component is then together with its conductor tracks contacted connections electrically isolated from the cooling medium and still in for heat dissipation sufficient direct thermal contact with the cooling medium, which eliminates the problems mentioned above.

adversely with these last-described arrangements is particularly the very complicated and expensive production and the susceptibility to errors the manufactured assembly. The ceramic base plate is thereby provided with conductor tracks according to the DBC process (direct bonding copper process), where either a continuous copper foil producing a laminated eutectic connection and then by selective etching a conductor track structure produced or a previously punched out Conductor structure is laminated on - both only possible with great effort the fine structures required today to provide the conductor tracks. Liquid heatsinks are stacked on top of each other Laminating several copper foils made, the individual Films have recesses, which then the cavity and the and derivatives for the coolant result. The stacking the exempted copper foils and their connection must be made with the highest precision, since already minor No shifts or swapping of individual layers or result in a limited usable element. The connections for the and discharge of the cooling medium can only in an elaborate way by soldering or similar Processes are created, which further sources of error and risks results.

at another method known as Z-STRATE becomes a ceramic plate chemically or electrolytically with copper coated, then by selectively etching away part of the coating a conductor track structure is produced. Heat sinks can then be soldered and glued separately or similar Methods on desired Places are attached. This method also shows in essentially the disadvantages mentioned above.

The object of the present invention is to address the disadvantages of the known methods of production and of such electrical methods To avoid assemblies themselves and in particular to improve the method mentioned at the outset and an assembly manufactured thereafter in such a way that direct and simple cooling of the point of the carrier having the component producing the heat loss remains possible in a simple and inexpensive manner without the aforementioned restrictions with regard to the conductor track structure or heat sink production must be accepted.

This Object is according to the present invention solved in a method of the type mentioned in that for the Heatsink for now a lost core on the carrier is applied, after which the conductor tracks and the heat sink through simultaneous coating of both sides of the carrier with conductive material are made, and that the core is then made from the remaining Cavity removed in the heat sink and the components on the carrier be attached conductively. The assembly according to the invention itself is thereby characterized in that the conductor tracks and the heat sink from one at the same time on the carrier and an arranged on it, defining the interior of the heat sink, lost core applied thick film coating.

Cave Heatsink and whose manufacture is by coating a lost core known per se, for example, from WO 02/17377 A1. But while with these and the like known methods always a self-contained, separately usable Made heat sink was made according to the invention now the heat sink on the heat loss producing component facing side directly through the electrical non-conductive support limits which one on the opposite Side this heat loss producing component in as possible has direct thermal contact. It follows an arrangement with the same thermal and electrical properties as with the known ones mentioned at the beginning of the prior art Arrangements, but the method of manufacture is much simpler and is therefore safer and less expensive than this known method was the case. The chemical and / or electrolytic Process for applying coatings to non-conductive carrier and / or hollow body defining cores are well known and simple, safe and inexpensive in the location of relatively wide ranges of layer thicknesses, conductor track thicknesses, hollow body shapes (if necessary including installation parts, connections and the like), material combinations etc. to cover. The method according to the invention thus enables the use of electrical assemblies of the type mentioned in areas where so far mainly for cost reasons had to be waived.

In A preferred embodiment of the invention provides that the lost core of wax or the like electrically non-conductive during the Coating hard and chemical and / or by means of removal warming at least partially liquefiable Substances exist and by injection molding, melting, gluing or the like on the carrier is attached. this makes possible a simple and inexpensive Production of the cores and their easy removal after coating.

As carrier preference is given to those already mentioned technical ceramics, preferably aluminum oxide or aluminum nitride ceramic, or multi-layer technology panels arranged inside Conductor tracks, used, in particular aluminum nitride ceramic excellent properties in terms of electrical insulation and thermal conductivity having. As necessary or at least advantageous further increase thermal conductivity such carrier can in a manner known per se, so-called "thermal via" s "in the areas between heat source and heatsink manufactured be those by the carrier reaching openings (for example bores) with metallic pastes, solders or the like filled out be what a local raise thermal conductivity causes. can in the present case Such thermal bridges are of course not through the whole carrier but go for example in the form of blind holes or through holes be carried out only by a few panels of a multilayer panel the electrical insulation between the two opposite surfaces of the carrier guaranteed remains.

The surface of the carrier can in a further embodiment of the invention prior to attachment the core, or before the base coating with conductive material, by roughening, etching or the like can be pretreated, causing the adherence of the lost Core or also of the conductive material applied by the coating improved.

The carrier or possibly also the carrier together with the core is in advance in a further embodiment of the invention a chemical coating process, preferably with copper, in strength of a few μm coated electrically conductive, whereby this chemically attached, electrically conductive base layer in an electrolytic process too can be galvanically reinforced for stabilization. So that is the for the subsequent selective application of a thick film coating required base layer easily and quickly with known Process steps attached.

That of the further thick film coating areas to be kept free with electrically conductive material on both sides of the precoated carrier or the structural unit consisting of carrier including core and applied, electrically conductive coating are provided in a further preferred embodiment of the invention with an electrically non-conductive mask, preferably by means of known liquid-resistant or solid-resistant Processes in which protection of the carrier plate, for example in the region of break lines, connection points, outer edges or the like, is produced, for example, by lacquer or pastes applied by printing technology. In addition to layers applied by printing technology, layers produced by photolithography or by film laminates can also be used.

In Another embodiment of the invention provides that the thick-film coating with electrical conductive material, preferably copper, by means of a chemical or galvanic coating process is carried out, one any necessary electrical contact via the continuous electrically conductive base layer under the mask or about flag-like connections of the thick-film areas to a continuous, around the entire assembly, later separated conductive Edge. This enables the required stability and current conductivity to be achieved quickly and easily for the Printed conductors and the heat sink be, preferably taking into account the respective requirements also a locally different thickness of the thick-film coating accomplished can be, preferably by selectively attaching curtains in the Coating bath, targeted positioning and shaping of sacrificial anodes or adapted construction of the holding frames. For example different layer thicknesses on front and back, middle and edge or Locally differently stressed areas of the carrier are provided become.

to An improvement in the further workability of the arrangement can additional Coating the thick-film areas, preferably with a thin layer made of nickel, gold or nickel phosphorus.

In Another embodiment of the invention provides that subsequently the thick-film coating (or additional coating) the masking before a differential etching to eliminate the initially applied continuous electrically conductive coating in the areas not provided with the thick-film coating Will get removed. For can remove the masking any suitable method known per se is used chemical or mechanical methods of removal the lacquer layer or the masking film. Instead of the differential etching you can also other suitable methods of removing those initially applied conductive base layer are used, of course, on it it must be ensured that the Thick film coating is not removed unduly so for example in the area of the heat sink Tightness and stability remains guaranteed.

In a particularly preferred further embodiment of the invention is provided that several assemblies simultaneously on a continuous common carrier be prepared for the mechanical separation of fault lines, preferably attached to the carrier by means of diamond scribing or laser grooving are, preferably only after the initially applied, continuous electrically conductive layer. Many can do that same or similar assemblies on a larger and correspondingly easier-to-handle carriers are produced and only then separated. The application of the fracture lines only after the initially applied, continuous electrically conductive layer is therefore preferred since this prevents these fine break lines from being continuous electrically conductive layer can be refilled, which complicates the mechanical separation.

In A further embodiment of the invention provides that the suspension of the Unit for the Thick film coating on the connections or corresponding separate openings of the heat sink itself takes place, which can be easily ensured that a drain of the to detach liquefied Kerns over these openings becomes possible.

In a particularly preferred further embodiment of the invention is provided that the lost core for the heat sink in Range of its connections with at least a part of the connection geometry defining Form is executed. Because the inner contour of the coating is very dimensionally and dimensionally stable the outer contour of the core can thus functional areas for the Line connections, for example in the form of threads or sealing surfaces, clamping surfaces or the like, simple and without additional Machining step are made. Something similar can also be done, for example for other openings or functional areas on Heat sink advantageous exploited can - for example additional openings to remove the lost core or additional connection options for example for other attachments, fasteners or the like created become.

The invention is explained in more detail below on the basis of the schematically illustrated exemplary embodiments. 1 - 9 show schematic side views of an assembly according to the invention in various stages of the manufacturing method according to the invention, 10 shows an alternative to in 4 process step shown, 11 the detail XI from 10 in an enlarged view, 12a and b such as 13a and b show the detail XII and XIII 10 in an enlarged view in two alternatives and different process steps, and 14 to 16 show perspective views of appropriately manufactured modules from above and below.

The electrical assembly shown or produced according to the invention 1 is according to 14 to 16 a total of six times on a continuous common carrier 2 has been produced, with break lines for the final mechanical separation 3 (as in 15 visible), for example by means of diamond carving or laser grooving, on the carrier 2 be attached, after which the six individual assemblies 1 can be separated. Every single assembly 1 then consists of the essentially plate-shaped, electrically non-conductive carrier 2 , preferably made of technical ceramics, such as aluminum oxide or aluminum nitride ceramic, the conductor tracks on at least one side 4 and at least one of the only in 15 Components drawn symbolically at the bottom right, producing heat loss 5 and on this component 5 essentially opposite area of the other side at least one heat sink 6 wearing. The conductor tracks 4 are exaggerated in all figures with regard to their width and thickness - the same applies to the thickness of the heat sink 6 forming coating and the other layers mentioned in the description of the manufacturing process in the 1 to 9 ,

The conductor tracks 4 and the heat sink 6 consist of a simultaneously on the carrier 2 and one arranged thereon, the interior of the heat sink 6 including connections 7 defining, lost core 8th attached thick film coating 9 what the manufacture of assemblies 1 simple, safe and inexpensive.

According to 1 is on the carrier 2 , if necessary after pretreatment by roughening, chemical etching or the like, for each of the assemblies to be produced 1 a core 8th attached to the heat sink to be produced, which also determines the connections in the manner described in more detail below. The cores 8th can consist, for example, of wax, plastic, or similar materials, which can be detached from the hollow body formed at the end of the manufacturing process using a variety of suitable methods of detachment. The attachment of the cores 8th on the optionally pretreated carrier 2 can be done, for example, by injection molding, melting, gluing or the like.

According to 2 then becomes the carrier 2 with the cores already attached 8th in a chemical coating process all around with a continuous electrically conductive base layer 10 provided, which consists for example of copper and can subsequently also be galvanically reinforced for stabilization in an electrolytic process. The starting layer, which was originally chemically applied, is reinforced by known methods by means of nucleation, activation and deposition, for example of a copper layer a few micrometers thick.

According to 3 then an electrically non-conductive mask at certain points 11 applied in order to be able to keep these areas free of further thick-film coating with electrically conductive material. This masking 11 can consist, for example, of lacquer, a paste applied by printing, or the like and enables protection for those areas of the wearer 2 to produce, which must be kept free of the further coating for technical reasons, for example for fracture lines, connection points, outer edges and the like. On the side of the carrier 2 that already have the cores 8th for the heat sink 6 can wear the masking 11 apart from the illustrated keeping of the edges or break lines, also define, for example, further conductor tracks, inscriptions or the like in a manner not shown here.

Using known chemical or galvanic coating methods, according to 4 the unmasked base layer 10 with a thick layer coating 9 provided to the necessary final thickness, with which both the conductor tracks 4 as well as the heat sink 6 be formed at the same time. Any electrical contacting required for this is made either via the continuous base layer 10 or via flag-like connections (not shown here) of the individual webs to a continuous, all-round electrically conductive edge, which is separated in a later working process. The thick film coating 9 can also be made with locally different thicknesses, taking into account the respective requirements, for example by selectively attaching curtains in the coating bath, targeted positioning and shaping of sacrificial anodes or an adapted construction of the holding frames. If necessary, an asymmetrical and / or geometry-dependent application of different layer thicknesses, for example on the front and back, center / edge of the carrier, can thus be carried out 2 or the like.

In A further step can then be carried out on the thick-film coating if necessary, an additional one Coating with certain metal layers, e.g. Nickel, gold or related compounds e.g. Nickel phosphate, for the better Further processability (e.g. solderability, bondable Surfaces, Corrosion protection, etc.). This layer can also be used as an additional etching reserve serve for later operations.

According to 5 the masking is then carried out again down to the base layer using known suitable methods 10 removed, after which 6 a difference etching to remove the base layer applied at the beginning 10 at the no longer masked points, such as between the conductor tracks, along the break lines, etc. Because this base layer 10 was only a few micrometers thick, the material removal affects the thick-film coating areas, for example, in the order of magnitude of 300-500 micrometers 9 the quality of the assembly 1 Not.

According to 7 then break lines 3 (see also 15 ) for the mechanical separation of the individual assemblies 1 on the carrier 2 attached, which can be done for example by means of diamond scribing or laser grooving. According to 8th the individual assemblies are then mechanically separated 1 at the break lines. This can be done, for example, by mechanical action, by breaking or similar processes, by machining with a roller ball, by vibration, flexible vacuum films or suitable automatic devices. In addition, the individual assemblies 1 but can also be separated, for example, by sawing or the like.

According to 9 is then the core by suitable methods such as thermal processes, mechanical or chemical effects or the like 8th from the resulting heat sink 6 away. For this purpose, for example, the suspension of the assemblies for the electroplating process can be designed in such a way that tubular receptacles on the connections 7 immediate drainage of the liquefied core 8th becomes possible.

It is easy to see that, for example, removing the cores 8th even immediately after applying the thick-film coating 9 it is possible. Some of the other process steps mentioned could also take place in a different order if this proves to be more favorable in the production process.

Then to in 9 Process step shown (or even before separating the modules 1 ) can electrical or electronic components (as in 15 indicated with 5) by means of known suitable methods, such as soldering, gluing, welding, bonding and the like, which of course on both sides of the carrier 2 it is possible. Additional mechanical components or the like can also be attached to these assemblies.

At the in 10 respectively. 11 obvious alternative to 4 is due to a relatively narrower masking 11 between the neighboring cores 8th achieved the thick film coating 9 in the area 12 the circumferential contact edge of the resulting heat sink 6 wider at the base layer 10 or the carrier 2 sticks to what the heat sink 6 or the entire assembly 1 gives greater stability if necessary.

According to 12a have the cores 8 in the area of the ultimately formed connections 7 a shape defining at least part of the connection geometry, with which the thick-film coating 9 then the in 12b Obvious connection form generated, which makes it easy, for example, to attach an elastic hose as a connection.

According to 13a defines the lost core 8th in the area of the connections 7 inner functional surfaces 13 with great form and dimensional accuracy, which it according to 13b enable collet-like insert parts 14 or sealing rings 15 to be used immediately without further processing into which only a connecting line (not shown) is then inserted.

According to 16 apart from that in the 1 to 15 shown and discussed training of the heat sink 6 than about connections 7 Hollow bodies through which liquid cooling medium can flow can also be used to produce simple convection heatsinks on corresponding electrical assemblies according to the invention for tasks that are simpler in terms of cooling technology. Only the connections are omitted 7 on the core 8th or these connections are to be replaced by suitable openings in the hollow bodies ultimately created, which are either subsequently drilled after the thick-film coating has been produced or are already formed in the thick-layer coating by appropriate inserts on the cores. The cores 8th are provided in this case with suitable, cooling fin-like surface enlargements or the like and then fulfill without additional Flow through with heat transfer medium, possibly together with a radiator fan, their cooling function. Apart from the above description, the manufacturing process of the assembly remains unchanged.

It could also be an alternative to applying the cores as described above 8th directly on the carrier 2 with subsequent common base coating of the carrier 2 and cores 8th also be provided the plate-shaped carrier 2 to be provided beforehand with a continuous electrically conductive base layer and to apply the masking for the further production of the conductor tracks in advance in a simpler planar process. The steep, then the cores 8th must be applied, of course, remain free of masking. After attaching the cores 8th the entire assembly can then, for example, in a chemical immersion bath with a core 8th covering base layer, which does not adhere to the mask anyway. The further manufacturing process then takes place as described.

in the It would also be in connection with the latter alternative possible, the masking together with the cores in one operation already with the continuous electrically conductive base layer provided carrier to be applied using a two-spindle injection molding machine, what kind of certain cases further facilitates the production process.

The are electrical assemblies manufactured in the manner described simple and inexpensive and point towards usual corresponding assemblies also with regard to the cooling effect size Advantages on. conventional Power modules are, for example, on an insulating ceramic generated and mechanical directly with the heat sink connected by pressing. Because of the available surfaces cost reasons usually not absolutely available and the ceramic plate also a superficial one If there is waviness, a compensation medium is usually required; in the in the simplest case, a thermal paste or a conductive foil with a relatively high thermal resistance. Without such additional activities there are air pockets, which have an even more serious thermal insulation. With the described method according to the invention this disadvantage is avoided in the simplest way, since annoying thermal badly conductive areas or materials are completely eliminated and an optimal coupling for the thermal management of the electronics is given.

Claims (19)

Method of manufacturing an electrical assembly ( 1 ), an essentially plate-shaped, electrically non-conductive support ( 2 ) on at least one side with conductor tracks ( 4 ) and at least one component that produces heat loss ( 5 ) and on this component ( 5 ) essentially opposite area of the other side with at least one heat sink ( 6 ) is provided, characterized in that for the heat sink ( 6 ) initially a lost core ( 8th ) on the carrier ( 2 ) is applied, after which the conductor tracks ( 4 ) and the heat sink ( 6 ) by simultaneous coating ( 10 . 9 ) both sides of the carrier ( 2 ) are made with conductive material and that the core ( 8th ) then from the remaining cavity in the heat sink ( 6 ) removed and the components on the carrier ( 2 ) are attached in a conductive manner. A method according to claim 1, characterized in that the lost core ( 8th ) made of wax or similar electrically non-conductive substances which are hard during the coating and which can be at least partially liquefied chemically and / or by heating and by injection molding, melting, gluing or the like on the carrier ( 2 ) is attached. Method according to Claim 1 or 2, characterized in that the carrier ( 2 ) Ceramic, preferably aluminum oxide or aluminum nitride ceramic, or a multilayer technology plate with conductor tracks arranged inside, is used. Method according to one or more of claims 1 to 3, characterized in that the surface of the carrier ( 2 ) before attaching the core ( 8th ), or before the base coating ( 10 . 9 ) is pretreated with conductive material, by roughening, etching or the like. Method according to one or more of claims 1 to 4, characterized in that the carrier ( 2 ) or, if applicable, the carrier ( 2 ) with core ( 8th ) is first electrically coated in a chemical coating process, preferably with copper, in the thickness of a few μm. A method according to claim 5, characterized in that the chemically attached, electrically conductive base layer ( 10 ) is galvanically reinforced for stabilization in an electrolytic process. A method according to claim 5 or 6, characterized in that the further thick-film coating ( 9 ) areas to be kept free with electrically conductive material on both sides of the precoated carrier ( 2 ) or the carrier ( 2 ) with core ( 8th ) and applied, electrically conductive coating ( 10 ) existing unit with an electrically non-conductive mask ( 11 ) are provided, preferably by means of known liquid-resistant or solid-resistant processes. A method according to claim 7, characterized in that the thick-film coating ( 9 ) is carried out with electrically conductive material, preferably copper, by means of a chemical or galvanic coating process, any electrical contact being made via the masking ( 11 ) continuous, electrically conductive base layer ( 10 ), or via flag-like connections of the thick-film areas to a continuous, around the entire assembly ( 1 ) running, later separated conductive edge. A method according to claim 8, characterized in that the thick-film coating ( 9 ) taking into account the respective requirements with locally different thicknesses, preferably by selectively applying curtains in the coating bath, targeted positioning and shaping of sacrificial anodes or adapted construction of the holding frames. A method according to claim 9, characterized in that to improve the further machinability, an additional coating of the thick-film areas ( 9 ), preferably with a thin layer of nickel, gold or nickel phosphorus. Method according to one or more of claims 7 to 10, characterized in that the masking ( 11 ) before a differential etching to remove the initially applied continuous electrically conductive coating ( 10 ) in the not with the thick-film coating ( 9 ) provided areas is removed. Method according to one or more of claims 1 to 11, characterized in that on a continuous common carrier ( 2 ) several assemblies ( 1 ) are prepared at the same time, for the mechanical separation of fracture lines ( 3 ), preferably by means of diamond scoring or laser grooving, on the carrier ( 2 ) are attached, preferably only after the initially applied, continuous, electrically conductive layer has been removed ( 10 ). Method according to one or more of claims 8 to 12, characterized in that the suspension of the structural unit for the thick-film coating ( 9 ) at the connections ( 7 ) or corresponding separate openings in the heat sink ( 6 ) takes place and thus also a drainage of the core liquefied for removal ( 8th ) is possible through these openings. Method according to one or more of claims 1 to 13, characterized in that the lost core ( 8th ) for the heat sink ( 6 ) in the area of its connections ( 7 ) with a shape defining at least part of the connection geometry. Electrical assembly ( 1 ) with an essentially plate-shaped, electrically non-conductive support ( 2 ) which has conductor tracks on at least one side ( 4 ) and at least one component that produces heat loss ( 5 ) and on this component ( 5 ) essentially opposite area of the other side at least one heat sink ( 6 ), characterized in that the conductor tracks ( 4 ) and the heat sink ( 6 ) from a simultaneously on the carrier ( 2 ) and an interior of the heat sink arranged on it ( 6 ) defining, lost core ( 8th ) applied thick film coating ( 9 ) consist. Assembly according to claim 15, characterized in that on the thick-film coating ( 9 ) an additional coating, preferably a thin layer of nickel, gold or nickel phosphorus, is arranged. Assembly according to claim 15 or 16, characterized in that the carrier ( 2 ) made of technical ceramics, preferably aluminum oxide or aluminum nitride ceramics, or a multi-layer technology plate with conductor tracks arranged inside and the thick-layer coating ( 9 ) is made of copper. Assembly according to one or more of claims 15 to 17, characterized in that the thick-film coating ( 9 ) has locally different thicknesses taking into account the respective requirements. Assembly according to one or more of claims 15 to 18, characterized in that the connections ( 7 ) of the heat sink ( 6 ) directly in one piece with the thick-film coating ( 9 ) executed by the outer contour of the lost core ( 8th ) Functional areas defined in this area ( 13 ) for pipe connections for the heat transfer medium.