WO2008055708A2

WO2008055708A2 - Microelectronic subassembly, and method for the production thereof

Info

Publication number: WO2008055708A2
Application number: PCT/EP2007/009854
Authority: WO
Inventors: Dmitry David Polityko; Stephan Wenzel; Erik Jung; Jan Hefer; Michael Niedermayer; Stephan Guttowski
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2006-11-09
Filing date: 2007-11-09
Publication date: 2008-05-15
Also published as: WO2008055708A3; DE102006053461A1; TW200845836A

Abstract

The invention relates to a microelectronic subassembly comprising at least two circuit support layers (1, 2, 3) which are disposed parallel on top of one another, are formed by different sections of a folded substrate that is flexible in at least some areas, are equipped with electronic components, and are mechanically interconnected by means of at least one surface-mounted component (4, 4') that is part of a circuit on at least one of the circuit support layers (1, 2, 3). The invention further relates to a method for producing such a microelectronic subassembly.

Description

Microelectronic assembly and method of making a microelectronic assembly

The present invention relates to a microelectronic assembly comprising at least two parallel arranged circuit carrier layers, according to the preamble of the main claim, and a method for producing a corresponding microelectronic assembly according to the preamble of claim 11th

Such microelectronic assemblies in which the various circuit carrier layers are equipped with electronic components are being developed in order to meet a demand which has been observed for quite some time for ever smaller dimensions of ever more complex electronic systems, for example for portable or mobile applications. From the prior art it is known, for example, to mount a plurality of printed circuit boards in the form of plug-in cards parallel to each other. Another known possibility is stacking based on a respective printed circuit board modules using solder or plug connections. The hitherto known technical solutions bring with it various disadvantages. Thus, in arrangements of several printed circuit boards, which are contacted only laterally as in the case of plug-in cards, only circuits of very limited complexity can be realized. In a connection of printed circuit boards arranged by vertically oriented to these circuit boards connectors results on the one hand, a relatively large height and on the other hand, not sufficiently secure and low-resistance contacting for many applications. Even if soldered connections are used between printed circuit boards arranged one above another, there are disadvantages which result from the fact that such soldered connections can not be loaded during their production, that is to say during the assembly of corresponding components.

It is also known to realize compact microelectronic assemblies by folding a flexible circuit carrier. With such microelectronic assemblies of the prior art, however, disadvantageously only circuit topologies of very limited complexity can be implemented. In addition, these assemblies are mechanically unstable due to the flexibility of the circuit substrate used and therefore very sensitive.

The present invention is based on the object to provide a comparable microelectronic assembly, with the described Disadvantages are avoided and allows for extremely small dimensions complex circuit topology, the microelectronic assembly should also be mechanically as robust as possible. A further object of the invention is to propose a method for producing a corresponding microelectronic assembly.

This object is achieved by a microelectronic assembly with the characterizing features of claim 1 in conjunction with the features of the preamble of claim 1 and by a method having the features of claim 11. Advantageous embodiments and further developments of the invention will become apparent with the features of the dependent claims ,

Because the circuit carriers in a microelectronic assembly according to the invention are mechanically interconnected by at least one surface-mounted component that is part of a circuit on at least one of the circuit carrier layers, a secure connection of the circuit carrier layers can be realized in a very small space because the circuit carrier layers On the one hand in a minimum distance for the electronic components used can be arranged one above the other, and on the other hand used to connect the circuit carrier layers components, which thus fulfill a dual function as part of the circuit. On other components that serve only a mechanical connection of the circuit carrier layers can therefore be largely or even completely omitted. The corresponding advantageous method for producing a microelectronic assembly with at least two The carrier carrier layers accordingly provides for mounting the circuit carrier layers formed by different sections of an at least partially flexible substrate with surface-mounted components and arranging them in parallel by folding the substrate, wherein the circuit carrier layers are each a component of a circuit on at least one of the circuit carrier layers through the surface-mounted components , be mechanically connected to each other.

Typical embodiments of the invention provide that two circuit carrier layers arranged next to one another are mechanically connected to one another by a multiplicity of surface-mounted components, which are preferably each part of a circuit on at least one of the circuit carrier layers, whereby these surface-mounted components are thus connected via the circuit carrier layers. Shares are that they are fixed with respect to all degrees of freedom against each other.

In the present specification, the term "substrate" denotes the entirety of all layers of a circuit carrier which, in addition to a carrier, also comprises at least one conductive layer, for example of copper, preferably at least on each surface. The substrate is executed at least partially flexible.

The invention provides that all or some of the circuit carrier layers are realized by a single substrate which is folded so that in each case two sections of the substrate connected to one another by a convolution lie one above the other and thus each form one of the circuit carrier layers. The term "shellfish" In the present specification, the "carrier layer" thus refers not only to a single complete substrate but also to a section of several sections of a foldable or folded flexible or rigidly flexible (partially flexible) substrate which lie one above the other in the finished module thus be completely flexible or only where it is folded between the individual sections that form the circuit carrier layers, while the substrate itself is rigid in the region of these sections.

Particularly in the case of a completely flexible substrate, the invention brings with it the advantage of a significant increase in stability due to the connection of the layers by means of the surface-mounted components. Unlike comparable assemblies of the prior art, which are very soft due to the flexible substrates and require external support, are stiffened with the present invention, despite the flexible and therefore advantageous thin and lightweight substrates in itself and stiffened by the surface mounted components Assemblies realized, which are accordingly insensitive.

Embodiments of the invention are also conceivable in which the circuit carrier layers and / or all or some of the electronic components mounted on the circuit carrier layers are partly or completely surrounded by an insulating material.

In a preferred embodiment of the invention, at least one of the surface-mounted components to which the adjacent circuit carrier layers are connected forms part of one of the two through this surface-mounted device interconnected circuit carrier layers comprehensive circuit, wherein the surface-mounted device forms a connecting these two circuit carrier layers path of the circuit. As a result, very complex circuits can be realized in a particularly simple manner and in the smallest space, because the surface-mounted components are not only used as components of an electronic circuit and for mechanically connecting the circuit carrier layers, but also for electrically bridging a gap remaining between the circuit carrier layers so for the realization of a three-dimensional circuit topology.

So that the surface-mounted components can serve both as components of a circuit and for mechanically connecting the circuit carrier layers, they should both at least partially conductively connected to the circuit carrier layers as well as be fixed so that there is also a tensile and shear loads enduring mechanical connection. For this purpose, the at least one surface-mounted component can each be electrically conductively connected to at least one connection

Conductor surface (Päd) or conductor track of the two interconnected by this surface-mounted component circuit carrier layers to be attached. In this case, however, a connection of the surface-mounted component can also be fastened on a round insulated conductor surface of one of the circuit carrier layers, if only one mechanical connection and no electrical connection is desired there. In the case of the connections of the surface-mounted components, with which these are fastened to the circuit carrier layers, it can be the case with conventional designs surface-mounted components act around terminal caps, which can be contacted in an advantageous manner in particular in all directions perpendicular to a longitudinal axis of the corresponding surface-mounted component. The at least one surface-mounted component (also referred to as SMD or surface mounted device) may in particular be a passive component because passive components are available in corresponding designs that are suitable for uncomplicated connection of circuit carrier layers in the manner described , Of course, it is also possible to use other surface-mounted and preferably opposing sides made of contactable electronic components in the manner described for connecting the circuit carrier layers, for example simple active components or even more complex electronic components such as integrated circuits.

So that a connection of the at least one surface-mounted component to the circuit carrier layers is achieved in the desired manner, this can be connected to the circuit carrier layers by a joining means, in particular soldered to the circuit carrier layers or adhesively bonded by means of a conductive adhesive. The use of a conductive living substance as a joining agent brings with it the decisive advantage of a particularly simple production of the assembly, since heating of contact points becomes superfluous. In turn, temperature-induced damage to the circuit carrier layers or the electronic components can be avoided. Surprisingly, on the other hand, with conductive adhesive, sufficiently good electrical properties can be achieved. see contacts in assemblies of the type described safely realized. At locations where the connection of the surface-mounted component with the respective circuit carrier layer does not necessarily have to be conductive, it is of course also possible to use another joining means, for example an insulating adhesive. Finally, the at least one surface-mounted component can also be welded to the circuit carrier layers, preferably by welded connections between terminals of the surface-mounted component and conductor surfaces or conductor tracks of the circuit carrier layers.

In a production of such a microelectronic assembly, the surface-mounted components can therefore be electrically conductively connected in particular to conductor surfaces and / or conductor tracks of two adjacent circuit carrier layers in each case, that connections of the surface-mounted

Components are provided and / or the conductor surfaces or conductor tracks with a joining means and the circuit carrier layers are then pressed together with the arranged on the conductor surfaces or conductor tracks surface-mounted components. Accordingly, the joining means, which can be applied, for example, by mask or stencil printing, can be, in particular, a conductive adhesive or solder, for example in the form of solder paste, wherein when solder is used while the circuit carrier layers are pressed against one another Surface mounted components should also be a heating to trigger a Lotprozesses. The bonding of the surface-mounted components with the circuit carrier layers can be effected in particular by reflow soldering. Alternatively, the surface-mounted components can also be connected to the circuit carrier layers by other methods known per se for assembly production, such as, for example, welding and in particular by pressure welding or by diffusion bonding. In this case, the application of a joining agent can be dispensed with.

The surface-mounted components used for connecting the circuit carrier layers then bridge a gap remaining between the circuit carrier layers, in which they also serve as spacers. Since surface mounted components are available in different standardized sizes, depending on the intended placement of the circuit carrier layers such surface mounted components can be easily selected that allow a mutually parallel arrangement of the adjacent circuit carrier layers in a desired, typically smallest possible distance. Before connecting the circuit carrier layers with the surface-mounted components connecting them, the circuit carrier layers are typically populated with other electronic components. However, such devices can also be connected to the circuit carrier layers simultaneously or in the case of external circuit carrier layers involved in the case of external surfaces.

In the case of preferred embodiments of the invention, the at least one surface-mounted component used for mechanically connecting two adjacent circuit carrier layers may also be oriented with a longitudinal axis lying in a plane parallel to the circuit carrier layers. That allows a special simple assembly of this surface-mounted component, wherein in the case of around contactable connection caps of the surface-mounted component as needed, a connection to any of the two adjacent circuit carrier layers is possible. However, it can also be provided that a longitudinal axis of the surface-mounted component connecting two circuit carrier layers is oriented perpendicular to the circuit carrier layers. This makes it possible to realize a vertical contacting of the circuit carrier layers in a particularly small space.

Finally, further conductive connections can be provided between the two circuit carrier layers connected by the at least one surface-mounted component, which can be realized, for example, by solder balls or by metal balls soldered on in each case one conductor surface of the two circuit carrier layers. To produce such a vertical contacting, conductive material, for example solder or additionally a metal ball or a metal pin, can be deposited on at least one conductor surface of at least one of the circuit carrier layers before connecting the circuit carrier layers, which then makes contact between the circuit carrier layers when connecting the circuit carrier layers manufactures.

An even greater mechanical stability of the microelectronic assembly at the same time optimal space utilization can be achieved if in addition to the circuit carrier layers mechanically connecting surface-mounted components at least one further electronic component is provided, mounted on one of the circuit carrier layers and rests with a side facing away from this circuit carrier layer at a nearest other circuit carrier layer. This may again be a passive or active surface-mounted component or even a more complex component such as a packaged or unhoused integrated circuit, for example a multi-chip module or a flip-chip technique or a chip-on -Board technology (using wire bridges) mounted and contacted chip. Even if such an electronic component only bears against one of the circuit carrier layers, it acts as a spacer, thereby increasing the stability of the microelectronic assembly. Eventually, such an electronic component, which belongs to the assembly of only one of the circuit carrier layers, at the nearest circuit carrier layer on which it is applied, also adhered or otherwise secured, thereby mechanically acting in the circuit carrier layers connecting manner and the microelectronic assembly gives even greater stability.

Of course, if additional support of the assembly is not required and there is a sufficiently large gap between the circuit carrier layers, additional components of the type described in the preceding paragraph can also be mounted on one of the circuit carrier layers such that between these components and the next circuit carrier layer a gap remains.

In a typical embodiment of the invention, the circuit carrier layers arranged adjacent to one another will have a distance of between 0.05 mm and 5 mm, preferably between 0.2 mm and 1.5 mm, perpendicular to the circuit carrier layers for example, easy to comply with a use of standardized surface-mounted components. Thus, for example, when using surface-mounted components of the type 0402 and with an orientation of these surface-mounted components with their longitudinal axis parallel to the circuit carrier layers typically results in a distance between the circuit carrier layers of about 0.6 mm.

Preferred embodiments of the invention provide that the microelectronic assembly comprises a multiplicity of circuit carrier layers arranged parallel one above the other, for example at least three circuit carrier layers, wherein the closest circuit carrier layers are in each case also mechanically interconnected in the manner described by surface-mounted components. This makes it possible to realize extremely compact and robust microelectronic assemblies with a very high integration density.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 described. It shows

1 shows a cross section through a microelectronic assembly according to the invention,

2 is a cross-sectional view of a detail of the microelectronic assembly of FIG. 1,

Fig. 3 in a schematic cross-sectional view vertical Kontaktaktierungen between two adjacent circuit carrier layers same microelectronic assembly and

4 shows in perspective and partially transparent representation a further detail of this microelectronic assembly.

1 shows a microelectronic assembly which is constructed on the basis of a flexible printed circuit board serving as substrate, which is folded to form a first circuit carrier layer 1, a second circuit carrier layer 2 arranged parallel above it and one in the same orientation over the second circuit carrier layer 2 The substrate with the circuit carrier layers 1, 2 and 3, each having a conductor structure made of copper on an upper side and an underside, can be constructed, for example, on the basis of a polyimide carrier and is equipped with various electronic components. Among these electronic components are some surface-mounted components 4 and 4 ', which are not only part of a circuit on at least one of the circuit carrier layers 1, 2 or 3, but are also mechanically interconnected by these circuit carrier layers 1, 2 and 3. At least some of the surface-mounted components 4 and 4 ', which in the present exemplary embodiment are passive components such as resistors, coils or capacitors, also each form a path connecting the circuit carrier layers 1 and 2 or 2 and 3 to all three circuit carrier layers 1 , 2 and 3 comprehensive electronic circuit. Fig. 2 shows the example of one of the surface mounted components 4 in detail, as the surface mounted components 4 with the respective adjacent circuit carrier layers 2 and 3 - the same applies elsewhere for the circuit carrier layers 1 and 2 - are connected. The surface-mounted component 4 shown there, which is oriented lying with a longitudinal axis in a plane parallel to the circuit carrier layers 2 and 3, has terminals 5 at two ends, in each case as connections around contactable connection caps. Each of these connections 5 is fixed in an electrically conductive manner to a respective conductor surface 6, also referred to as a connection pad, of both the circuit carrier layer 2 underlying the surface-mounted component 4 and the circuit carrier layer 3 located above the surface-mounted component 4. At least one of the conductor surfaces 6 of the circuit carrier layer 3 shown in FIG. 2 and also at least one of the conductor surfaces 6 of FIG

Circuit carrier layer 2 are connected to a conductor track structure of the respective circuit carrier layer 2 or 3 so that the surface-mounted component 4 forms a circuit carrier layers 2 and 3 connecting path of the already mentioned electronic circuit. Under certain circumstances, the remaining conductor surfaces 6 can also be insulated around in the respective circuit carrier layer 1, 2 or 3 and thus serve only for mechanical connection to the surface-mounted component 4. Others of the surface-mounted components 4 may also be connected so that they are mounted on one of the circuit carrier layers 1, 2 or 3 exclusively on around insulated conductor surfaces 6, so that a path formed by these surface-mounted devices 4 while path in a circuit on one of Integrated circuit carrier layers 1, 2 or 3, but no interconnection between the two adjacent circuit carrier layers 1 and 2 or 2 and 3 forms.

The surface-mounted component 4, which is shown in FIG. 2, is fixed on the respective conductor surface 6 in the exemplary embodiment shown here with the aid of a joining means 7, which is a conductive adhesive or solder Train and shear loadable connection of the circuit carrier layers 2 and 3 is given on the surface-mounted device 4. However, the surface-mounted component can just as well be welded to the conductor surfaces 6. Instead of an adhesive or soldering process, accordingly, the surface-mounted components 4 and 4 can be ^fixed by pressure welding or diffusion bonding during manufacture of the electronic assembly.

The surface-mounted component 4 shown in FIG. 2 is a passive component of the type 0402, so that between the conductor surfaces 6 of the circuit carrier layer 2 and the conductor surfaces 6 of the circuit carrier layer 3 a gap bridged by the surface-mounted component 4 is vertical Expansion of about 0.6 mm remains. Characterized in that between the circuit carrier layers 1 and 2 and between the circuit carrier layers 2 and 3 each have a plurality on the circuit carrier layers

1, 2 and 3 distributed surface-mounted components 4 are arranged and fixed in the manner described, the circuit carrier layers 1, 2 and 3 are joined to a very stable composite, without further measures would be required for a ne ne connection of the circuit carrier layers 1, 2 and 3 , That's it In the case of microelectronic assemblies of the type shown in FIG. 1, however, it is also conceivable to partially or completely inject the circuit carrier layers 1, 2 and 3 and / or all or some of the electronic components mounted thereon with an insulating material. The three circuit carrier layers 1, 2 and 3 are given here by three different sections of a single correspondingly folded, typically completely flexible substrate. In one application of rigidly flexible printed circuit board technology, these individual sections can in turn also be rigid and be connected to one another only by flexible regions of the same substrate.

The surface-mounted component 4 'arranged between the circuit carrier layers 2 and 3 is, unlike the surface-mounted components 4, oriented with a longitudinal axis perpendicular to the circuit carrier layers 1, 2 and 3. This surface-mounted component 4 'is likewise fastened in a corresponding manner to a respective conductor surface 6 of each of the circuit carrier layers 2 and 3 and likewise serves both for the mechanical connection of the circuit carrier layers 2 and 3 and for the formation of a path connecting the two circuit carrier layers 2 and 3 the circuit of the microelectronic assembly shown.

Also shown in FIG. 1 are two integrated circuits 8 each mounted in flip-chip technology on the third circuit carrier layer 3 and on the lower surface of the second circuit carrier layer 2, respectively. The integrated circuit 8 mounted on the circuit carrier layer 2 is dimensioned and arranged such that it is connected to one of the

Circuit carrier layer 2 on the side facing away from lying below lying first circuit carrier layer 1 and the microelectronic assembly thereby gives as a spacer between the circuit carrier layers 1 and 2 additional stability. In the case of another dimensioning of the microelectronic assembly, a gap could, of course, also remain between the integrated circuit 8 mounted on the second circuit carrier layer 2 and the first circuit carrier layer 1. In a corresponding manner, other electronic components such as active or passive SMDs, multi-chip modules or other packaged or unhoused chips can be mounted on one of the circuit carrier layers 1, 2 or 3 and at the same time serve as a spacer causing increased mechanical stability of the composite.

Finally, it would also be conceivable, for example, to additionally adhere the integrated circuit 8 arranged between the circuit carrier layers 1 and 2 to the first circuit carrier layer 1.

Finally, between the circuit carrier layers 1 and 2 and between the circuit carrier layers 2 and 3, further electrically conductive connections are provided, which are realized by solder balls 9, which each connect two opposing conductor surfaces 6 of the circuit carrier layers 1 and 2 or 2 and 3. Two such connections formed by solder balls 9 (also referred to as bumps) between the circuit carrier layers 2 and 3 are shown in more detail in FIG. To bridge larger distances between the adjacent circuit carrier layers 1 and 2 or 2 and 3 and metal balls or metal pins on two opposite conductor surfaces 6, which are integrated into corresponding conductor structures, soldered or glued with a conductive adhesive be. Finally, it is conceivable to use for bridging larger distances between the circuit carrier layers 1 and 2 or 2 and 3 plug connectors and / or connectors from the flexible printed circuit board technology.

Instead of the passive components, which are used in the present case the circuit carrier layers 1, 2 and 3 and mechanically connecting surface mount components 4 and 4 ^■, finally, of course, other surface-mount devices, including active components, adjacent in the manner described with two can plies be connected to the module.

In the manufacture of the microelectronic assembly shown in Fig. 1, the substrate which forms the circuit carrier layers 1, 2 and 3, initially in a conventional manner with the integrated circuits 8 and other electronic components equipped, after which it folded and the circuit carrier layers 1, 2 and 3 forming portions of the substrate by the surface-mounted components 4 and 4 'are mechanically interconnected by these surface-mounted components 4 and 4' with the conductor surfaces 6 or conductor tracks of two adjacent circuit carrier layers 1 and 2 or 2 and 3 be electrically connected. For this purpose, the conductor surfaces 6 or the conductor tracks are provided with a joining means, whereafter the circuit carrier layers 1, 2 and 3 are pressed against one another with the surface-mounted components 4 and 4 'arranged on the conductor surfaces 6 or on the conductor tracks. As a joining agent while a solder paste can be used, wherein the pressing together of the circuit carrier layers 1, 2 and 3 by heating a reflow soldering process is performed, which fixes the surface mounted components 4 and 4 ¹ on the circuit carrier layers 1, 2 and 3. Instead of the solder paste, a conductive adhesive may also be used, whereby heating for connecting the circuit carrier layers 1, 2 and 3 to the surface-mounted components 4 and 4 'may be unnecessary. The solder paste or the conductive adhesive can be applied in each case by mask or stencil printing. Alternatively or additionally, the joining means can of course also be applied to the terminals 5 of the surface-mounted components 4 and 4 'before they are connected to the conductor surfaces 6 of the circuit carrier layers 1, 2 and 3. After carrying out the described method steps form the surface-mounted components 4 and 4 'components of the circuit carrier layers 1, 2 and 3 comprehensive circuit, wherein at least some of the surface mounted components 4 and 4 ¹ see an interconnection between the respective adjacent circuit carrier layers 1 and 2 or 2 and 3 effect. In order to produce the vertical contact connections between the circuit carrier layers 1, 2 and 3, which are realized by the solder balls 9, one or two plumbs are deposited on a conductor surface 6 of the circuit carrier layer 1, 2 before soldering of the circuit carrier layers 1, 2 and 3. which then produces a contact between the circuit carrier layers 1 and 2 or 2 and 3 when connecting the circuit carrier layers 1, 2 and 3, wherein a good conductive and the microelectronic

Assembly also mechanically further stabilizing connection to the conductor surfaces 6 respectively of both adjacent circuit carrier layers 1 and 2 or 2 and 3 by melting the solder on heating comes about. The surface-mounted components 4 and 4 'are used in the finished microelectronic assembly both as a spacer (spacer) between the circuit carrier layers 1, 2 and 3 as well as their fixation in a train and shear forces also enduring manner. Achieved by the described invention, a vertical system integration with a three-dimensional circuit structure, wherein in a particularly simple manner not only by stacking different circuits a compact design, but in addition also a due to the combination of using a flexible printed circuit board with Vertikalkontaktun- gene described type very high circuit - Complexity is made possible. Of course, the present invention can be combined with other features that have not been described in detail here, for example, with embedded in the circuit carrier layers 1, 2 and 3 components, additional mechanical management, Verschraubungs- and other fasteners and housing techniques.

The technique described here thus makes it possible to stack circuit carrier layers with conventional technologies and thus to design a three-dimensional system, for which in particular the following features are used:

• Spacers used in the circuit are surface mounted devices and SMD devices or SMD devices.

• In addition to their direct function as circuit elements and their mechanical function as spacers, electrical connections between planes can be realized via the SMD components or their connection surfaces. Further vertical kale connections from level to level can be realized as solder or conductive adhesive connections (solder balls 9, bumps, balls). However, the nature of further vertical connections and the joining technology used are secondary. There are not any

Connectors, wires or cables to realize interconnections between the layers or levels necessary.

• Economical production of multi-level systems with a very high integration density is possible through:

^■ simultaneous assembly of several subassemblies or group feeders (so-called benefits) one above the other,

■ Use of processes and machinery established in the electronics manufacturing industry (soldering, conductive bonding).

For implementation, during the circuit design phase, conductor surfaces (pads) are defined on the top side of the one level (circuit carrier layer) and correspondingly on the bottom side of the level above it. Size and spacing depend on the distance between the layers.

After a standard SMD assembly with joint average pressure (eg solder paste) and component placement, the layers are stacked on top of each other and finally fixed by an assembly step (eg reflow soldering). For a corresponding adjustment, for example, a guide or bolt device can be provided. The types of passive SMD components that are common in common circuits are standardized. Due to the defined At the same height, components from the same series (eg 0402) serve as spacers and are placed in such a way that a secure hold is provided. By using such standardized SMD components and their joining surfaces, it is possible to electrically connect a large number of modules vertically and mechanically stable to integrate.

The vertical line connections from level to level arise in the exemplary embodiment

• connection caps of the component, which can be electrically and horizontally contacted in all spatial directions,

• Depots of conductive joining material (solder, conductive adhesive) on the modules (circuit carrier layers 1, 2 and 3).

Furthermore, it is conceivable to use vertically arranged components.

The depots for the vertical contacts can e.g. If necessary, it is also possible to introduce copper spheres, generally metal or conductive plastic spheres for particularly large distances, via mask or stencil printing or ballplacer in one step at the same time as the SMD coating pressure. However, the focus of the invention is on the hitherto non-existent use of the passive components for the production of vertical electrical signal lines (paths).

The technique described here leads to an improvement over the prior art, because the already existing electronic components without additional Components improve mechanical stability while increasing vertical connection density.

All lines from one level to the next are achieved in the embodiment by a Simultanmontage- step at the same time. Another advantage, in addition to higher integration and easy installation, are the shorter cable lengths, which means higher system speeds and a reduction of parasitic effects. In particular, the technique described here is suitable for the vertical integration of usually very flat micro and compact assemblies that use unhoused semiconductors - in particular MCMs (multi-chip modules) or SiPs (system-in-packages).

The use of the devices in the manner described here avoids known problems of vertical integration (such as the almost exclusively peripheral contact in connector systems, low mass carrying capacity of the vertical solder joints in BGA-like structures) and opens up new degrees of freedom in the design of a Assembly: from a design point of view, it is possible to have a

Use a device as a quadrupole, which has its pole pairs on physically different levels or modules. Such a constellation is shown for example in FIG. 4.

4 shows again the second circuit carrier layer 2 and the third circuit carrier layer 3, the latter being shown transparently, and a surface-mounted component 4 connecting these two circuit carrier layers 2 and 3, with its connections 5 in the previously described manner is fixed to two equally recognizable conductor surfaces 6 of each of the circuit carrier layers 2 and 3. This surface-mounted component 4 is a capacitor which is connected as an interference suppression capacitor between two lines of a voltage supply of a chip mounted on the second circuit carrier layer 2 and not shown here. The voltage is supplied via two conductor tracks, which lead away from the two printed on the upper circuit carrier layer 3 conductor surfaces 6 and connect the capacitor to a voltage source. Under these two strip conductors run in the same direction and on the second circuit carrier layer 2, two conductor tracks, which lie of the two under the capacitor

Lead surfaces go out and one of which is visible in Figure 4 and the other is covered by the capacitor. These two interconnects run to voltage supply terminals of said chip, which is thus arranged under the interconnects of the voltage source coming interconnects. This results in a construction which is particularly favorable not only with regard to a compact construction, but also for a good suppression, with exceptionally short connection lines. In particular, the voltage source can be arranged in a simple manner on a different level than the chip to be supplied with the voltage. Instead of the chip, which is mentioned here only as an example, it is also possible to arrange any other electronic component to which a capacitor or another component, for example a choke, is to be connected in series. Finally, in circuits of the type described with reference to FIG. 4, it is conceivable to provide a desired capacitance-for example 100 μF-to a plurality of parallel and correspondingly arranged small capacitors. These capacitors can be divided into four capacitors of 25 μF, for example, which means that a smaller overall height can be achieved by using smaller SMD components as well as a more stable connection of the circuit carriers due to the associated larger number of support points.

By the technique proposed here it is possible with simple means (with conventional flexible circuit boards, SMD components, usual assembly processes), a multi-layer system with embedded components and thus (quasi-) multidimensional or vertically integrated electronic systems with a particularly high density which are particularly advantageous wherever there are strong restrictions in terms of volume and mass (eg for portable, mobile, miniaturized products, electronics for aerospace, automotive electronics, mobile sensor and measuring systems).

Claims

claims

1. microelectronic assembly comprising at least two parallel arranged one above the other circuit carrier layers (1, 2, 3), which are formed by different sections of an at least partially flexible folded substrate and equipped with electronic components, characterized in that the circuit carrier layers (1, 2, 3) by at least one surface-mounted component

(4, 4 '), which is part of a circuit on at least one of the circuit carrier layers (1, 2, 3) are mechanically connected to each other.

2. Microelectronic assembly according to claim 1, characterized in that the at least one surface-mounted component (4, 4 ') Bestanteil one of the two by this surface-mounted device (4, 4') connected circuit carrier layers (1, 2, 3) comprising circuit wherein the surface mounted device

(4, 4 ¹ ) forms one of these two circuit carrier layers (1, 2, 3) connecting path of the circuit.

3. Microelectronic assembly according to any one of arrival claims 1 or 2, characterized in that the at least one surface-mounted component (4, 4 ¹ ) each with at least one connection (5) on a conductor surface (6) or conductor track of each of the two through the surface mounted component (4, 4 ¹ ) interconnected circuit carrier layers (1, 2, 3) is fixed.

4. Microelectronic assembly according to one of claims 1 to 3, characterized in that the at least one surface-mounted component (4, 4 ') to the circuit carrier layers (1, 2, 3) is soldered or welded or glued.

5. Microelectronic assembly according to one of claims 1 to 4, characterized in that the at least one surface-mounted component (4, 4 ') is a passive component.

6. Microelectronic assembly according to one of claims 1 to 5, characterized in that a longitudinal axis of the surface-mounted component (4, 4 ') lying in a circuit carrier layers (1, 2, 3) parallel plane or perpendicular to the circuit carrier layers ( 1, 2, 3) is oriented.

7. Microelectronic assembly according to one of claims 1 to 6, characterized in that between the two by the at least one surface mounted device (4, 4 ') connected to the circuit carrier layers (1, 2, 3) further conductive connections are provided.

8. Microelectronic assembly according to one of claims 1 to 7, characterized in that at least one further electronic component that on one of the circuit carrier layers

(1, 2. 3) is mounted, with one of these circuit carrier layer (1, 2, 3) facing away from an adjacent to this other circuit carrier layer (1, 2, 3) is applied.

9. Microelectronic assembly according to one of claims 1 to 8, characterized in that the mutually adjacent circuit carrier layers (1, 2, 3) have a distance of between 0.05 mm and 5 mm.

10. Microelectronic assembly according to one of claims 1 to 9, characterized in that it comprises a plurality of parallel superimposed circuit carrier layers (1, 2, 3), wherein each other closest circuit carrier layers (1, 2, 3) respectively surface-mounted components (4, 4 ') are mechanically connected to one another.

11. A method for producing a microelectronic assembly having at least two circuit support layers (1, 2, 3) formed by different sections of an at least partially flexible substrate, which are equipped with surface mounted components (4, 4 ¹ ) and parallel by folding the substrate be arranged one above the other, characterized in that the circuit support gerlagen (1, 2, 3) by the surface mounted components (4, 4 ¹ ) are mechanically interconnected, wherein the surface mounted components (4, 4 ') each part of a circuit on at least one of the circuit carrier layers (1, 2, 3).

12. The method according to claim 11, characterized in that the surface-mounted components (4, 4 ') with conductor surfaces (6) and / or conductor webs of two adjacent circuit carrier layers (1, 2, 3) are electrically conductively connected by terminals (5) of the surface-mounted components (4, 4 ¹ ) and / or the conductor surfaces (6) or conductor tracks with a

Joining means (7) are provided and the circuit carrier layers (1, 2, 3) are then pressed against each other with the arranged on the conductor surfaces (6) or conductor tracks surface-mounted components (4, 4 ').

13. The method according to claim 12, characterized in that as a joining means (7) solder or a conductive adhesive is used.

14. The method according to claim 11, marked thereby, that the surface-mounted components

(4, 4 ¹⁾ with conductor pads (6) and / or conductors of two adjacent circuit carrier layers (1, 2, 3) are electrically connected by said circuit carrier layers (1, 2, 3) with the (on the conductor surfaces 6 ) or

Conductor tracks arranged surface-mounted components (4, 4 ¹ ) are pressed together, wherein terminals (5) of the surface-mounted components (4, 4 ') by means of welding or diffusion-bonding on the conductor surfaces (6) or printed conductors are attached.

15. The method according to any one of claims 11 to 14, characterized in that prior to the connection of the circuit carrier layers (1, 2, 3) conductive material on at least one conductor surface (6) of at least one of the circuit carrier layers (1, 2, 3) is deposited when contacting the circuit carrier layers (1, 2, 3) a contact tion between the circuit carrier layers (1, I ₁ 3) manufactures.

16. The method according to any one of claims 11 to 15 for producing a microelectronic assembly according to one of claims 1 to 10.