CN1245629A - Ceramic composite wiring structure of semiconductor device and manufacturing method thereof - Google Patents

Abstract

A composite wiring structure (10) for use on at least one semiconductor device (16). The composite wiring structure has a first conductive member (12) to which a semiconductor device can be mounted for electrical connection. A dielectric element (20) formed of a ceramic or organic-ceramic composite material is bonded to the first conductive element (12) and has a conductive network (24) and a thermal distribution network (26) embedded therein. A second conductive element (32) may be combined with the composite wiring structure with a capacitor (64) electrically connected between the conductive network (24) and the second conductive element (32). The bond between the dielectric element and the conductive element may be formed as a direct covalent bond at a temperature insufficient to adversely affect the structural integrity of the conductive network and the thermal distribution network.

Description

Ceramic composite wiring structure of semiconductor device and manufacturing method thereof

This application claims priority to the inventor's earlier provisional application S.N. 60/033983, filed December 30, 1996, entitled "Ceramic Composite Wiring Structure for Semiconductor Devices and Method of Manufacturing the Same."

FIELD OF THE INVENTION This invention relates generally to circuit wiring boards, and more particularly to ceramic composite wiring boards and/or multi-chip modules and methods of making the same.

Semiconductor integrated circuits ("SICs") or semiconductor chips are evolving to operate at ever higher speeds and process ever greater amounts of data. This trend has led to a dramatic increase in the density of electrical interconnections required between semiconductor chips and larger electronic systems. Conversely, this very large-scale integration limits the physical size of the SIC. In order to achieve more advanced SICs, far more electrical interconnections need to be packed into smaller physical dimensions, which constitutes a technical bottleneck, where the performance of SICs is increasingly limited by connecting the chip to a larger electronic system. limitations of the board/package.

It is industry practice to employ a lead frame to electrically interconnect the SIC to a printed circuit board ("PCB") and to enclose the chip and lead frame in a ceramic stack package. The packaged SIC is inserted into the PCB, electrically connecting the SIC to the larger electronic system. Modern more sophisticated SICs generate significantly more heat than their predecessors. This heat, if not dissipated from the SIC, degrades circuit performance. A robust lead frame can double as an electrical connection and heat sink, but as the density of lead frames per unit area increases, the physical size of the individual leads must shrink. The smaller lead size significantly limits its heat sink function. This forces system manufacturers to dissipate thermal loads through unmanageably large heat sinks affixed to the SIC, hindering the move to smaller, transportable platforms.

Also, the operating speed of more sophisticated SICs is increasingly limited by the printed circuit board. Conventional PCBs have electrical signals communicated between the system and the SIC through a network of electrodes patterned on the surface of the PCB on which the semiconductor chips are mounted. In order for SICs to operate at higher speeds, the interconnection between the semiconductor chip and the electronic system must be low-resistance. By shortening the length of the electrodes and reducing the resistivity of the electrodes, a lower resistance electrical contact can be obtained. Shorter electrode lengths can be made by embedding the electrical interconnection network in the circuit board rather than patterning it on the surface. The prior art discloses methods of making multilayer ceramic composite printed circuit boards having an electrical interconnection network embedded in the circuit board. However, the performance of these methods is limited because the embedded electrode network is composed of thin metal films, conductive pastes, or both that have a much higher resistance than wiring formed from the same conductive metal. Low resistance at higher signal frequencies can also be improved by making the wiring board out of low dielectric constant material. Therefore, embedding an electrode network consisting of conductive metal wiring in a low dielectric constant ceramic such as silicon dioxide or alumina and simultaneously containing a heat sink embedded in the ceramic to dissipate the heat generated by the SIC Circuit layout boards and multi-chip module designs may be highly desirable.

Related prior art includes the following patents. US Patent No. 5,396,034 to Fujita et al. discloses a method of making a thin film ceramic multilayer wiring hybrid board. U.S. Patent No. 5,396,032 to Bonham et al. discloses the construction of a multi-chip module ("MCM") with two sets of leadframes, one set supplying input/output bond pads and a separate set supplying test pins. The electrical connections can be used to isolate and check the performance of one or more devices mounted on the substrate in the MCM cavity, where the devices are wire bonded to the pads. The material comprising the MCM package can be ceramic, plastic, laminate or metal, but the substrate on which the device is mounted does not contain internal electrical interconnects and/or heat sinks. US Patent No. 5,375,039 to Wiesa discloses the fabrication of a printed circuit board with internal heat dissipation means for channeling heat from a power unit mounted on the board to a heat sink, wherein the core of the printed circuit board comprises glass cloth. U.S. Patent No. 5,363,280 to Chobot et al. discloses a method of making a multilayer ceramic circuit board in which certain metal film layers serve as an electrode network and are separated from other metal film layers that serve as heat sinks. U.S. Patent No. 5,300,163 to Ohtaki et al. discloses a process for manufacturing a multilayer ceramic circuit board comprising a ceramic substrate, multiple layers of green tape with conductive adhesive patterns therein, and layers for assembly Vias with conductive adhesive for electrical interconnection. US Patent No. 5,256,469 to Cherukuri et al. discloses a multilayer co-fired ceramic-on-metal circuit board prepared from ceramic green tape and a low temperature high expansion glass ceramic system. U.S. Patent No. 5,113,315 to Capp et al. discloses the construction of a ceramic circuit board structure in which the heat dissipating attachment Embedded in a ceramic element. US Patent No. 4,679,321 to Plonski discloses a method of manufacturing an interconnection board having coaxial wiring interconnects on the outer major surface of the board substrate opposite the major surface on which integrated circuits are mounted. U.S. Patent No. 4,598,167 to Ushifusa et al. discloses the construction of a multilayer ceramic circuit board comprising a plurality of integrally bonded ceramic layers, each layer having a patterned layer of conductive adhesive and a conductor filled circuit board for connection. The conductive layer on each ceramic layer is patterned to form via holes for predetermined wiring circuits. U.S. Patent No. 4,551,357 to Takeuchi discloses a process for manufacturing a ceramic circuit board comprising firing a circuit pattern formed of an organic-impregnated conductive paste on the surface of a green ceramic with an organic binder.

Accordingly, it is an object of the present invention to provide a composite wiring structure that enhances the performance of a SIC.

Another object of the present invention is to provide a complex circuit wiring structure which improves the allowable operating speed of the SIC.

Yet another object of the present invention is to reduce compressive and shear stresses in composite structures.

Yet another object of the present invention is to provide a composite circuit wiring board structure wherein the dielectric elements of the structure are ceramic or organic-ceramic composites.

Another object of the present invention is to provide a high-efficiency ceramic composite wiring structure for SIC and its manufacturing method.

The above objects as well as further objects and advantages of the invention are achieved by the preferred embodiments of the invention described herein.

Preferred embodiments include having one or more electrodes on one major surface of the dielectric element, and wherein a semiconductor integrated circuit ("SIC") is in electrical contact with the electrodes through an electrical interconnection network in the dielectric ceramic element Composite circuit wiring structure for direct electrical contact to external input/output signal drivers.

The preferred embodiment also provides a composite circuit layout in which the dielectric elements also contain embedded heat distribution networks.

The preferred embodiment also provides a composite circuit wiring having one or more electrodes on one major surface of the dielectric element, and wherein at least one SIC is located on the mounting area and is electrically contacted to at least one electrode by conductive wiring means structure.

The preferred embodiment also reduces thermally induced compressive or shear stresses between the dielectric elements of the circuit wiring board and either the embedded electrical interconnection network or the embedded heat distribution network by employing the network with curved connections.

The present invention also reduces the contact between the dielectric components of the circuit wiring board and the embedded electrical interconnection network or embedded network by applying an organic resin with a high thermal decomposition temperature to the network before embedding the network into the ceramic component. Thermally generated compressive stress or shear stress between the heat distribution network.

The present invention also allows for a DC blocking capacitor comprising a dielectric element having a composite wiring structure.

The present invention also provides the above-mentioned embodiments constituted by using ceramic or organic-ceramic materials as the dielectric elements of the composite wiring structure.

More specifically, the preferred embodiments of the present invention relate to a dielectric having one or more electrodes on one major surface of a ceramic component and wherein a semiconductor integrated circuit ("SIC") is in direct electrical contact with the electrodes. Electrical (ceramic or organic-ceramic) composite circuit wiring boards. The SIC is in electrical contact with other SICs in electrical contact with other electrodes on the main surface of the circuit wiring board and/or with the ceramic circuit wiring board through an electrical interconnection network made of conductive wiring, preferably copper wiring external input/output signal driver. This is achieved by another electrode on the main surface of the circuit wiring board, or by a conductive wiring segment connected to an electrical interconnection network protruding through the subsurface of the dielectric element of the circuit wiring board. The dielectric element also contains an embedded heat distribution network of heat sinks made of elongated strips of thermally conductive material such as metal or empty tubes through which an absorbing fluid circulates. The embedded heat distribution network is located near the electrodes, but not directly in contact with the electrodes, making direct electrical contact with the SIC, while the terminals of the embedded heat sinks protrude through the subsurface of the ceramic components to communicate with other components outside the circuit wiring board. A heat sink or heat container forms the thermal contact.

As an example, the dielectric element comprises an aluminate or silicate ceramic phase. The silica ceramic phase is particularly beneficial at lower signal attenuation levels through dielectric loss mechanisms at higher signal frequencies. On the main surface of the ceramic component of the circuit wiring board opposite to the main surface on which the SIC is in contact with the electrodes, another metal component is bonded. The present invention also includes various methods of fabricating circuit wiring board structures by cryogenic processing methods.

The use of solution precursors enables ceramics to form in the network by filling the area surrounded by the injection molding material, mounting supports and base metal components with liquid precursors, and inducing chemical reactions to transform the liquid precursors into corresponding solid ceramics around the assembly. A combination of metal organic precursors is preferred in the present invention whereby the ceramic oxide metal precursor is first reacted with a carboxylic acid such as 2-ethylhexanoic acid to form a carboxylate solution in an organic acid solution. However, other solution processing techniques, such as sol-gel techniques, may also work effectively and are considered to be within the spirit and scope of the present invention.

After the conversion chemistry is complete, the area that was filled with the liquid precursor is now filled with the ceramic. As described below, the conversion chemistry bonds the ceramic to the network assembly, metal elements, and surrounding injection molding material and/or walls of the mounting support. The liquid nature of the solution allows the precursor material to uniformly wrap the network assembly. When metal organic precursors are used, pyrolysis decomposes the carboxylates to their corresponding metal oxides. As a result of pyrolysis, unstable metal oxide radicals are formed that rapidly bond to stable organic and inorganic surfaces that are part of network assemblies, base metal elements, and injection molding materials and/or mounting supports. The unstable metal oxide radicals also bond with other decomposed metal oxide radicals to form a connected ceramic network.

As the decomposition (or unwanted reaction) products are scavenged, the volume fraction of the solid ceramic is less than that of the bulk solution precursor. Thus, it is useful to use precursor solutions with a high solids content, which are often very viscous, or to pyrolyze the precursor in situ as it is applied, as is the case when the precursor is sprayed and pyrolyzed onto an already heated assembly. Pros.

The action of spray pyrolysis allows unwanted reaction by-products such as precursor solvents and decomposition products to be physically removed at a much higher rate than coating a ceramic precursor while simultaneously forming the ceramic. Spray pyrolysis then enables a larger volume ratio of solid ceramic to occupy the area it is coated on.

The present invention also allows for the formation of organoceramic dielectrics (if such dielectric elements are desired) by incomplete decomposition of dissolved metal organic ceramic precursors. The present invention forms metal organic precursors by reacting the metal precursors directly or indirectly with a carboxylic acid solvent to produce a carboxylate solution dissolved in the carboxylic acid. 2-Ethylhexanoic acid is an optimal solvent with a fire point of 210°C. Depending on the chemistry of the metal of the salt, the 2-ethylhexanoic acid precursor salt typically begins to decompose above the temperature range of 225-375°C. Thermal decomposition is usually accomplished at temperatures above 400-475°C. A circuit by means of spray pyrolysis of a solution heated above the temperature at which the dissolved carboxylate begins to decompose (225-375°C), but still below the temperature at which the organic ligands of the salt decompose completely (400-475°C) On wiring board assemblies, composite organic-ceramic dielectrics can be fabricated. During spray pyrolysis, the carboxylic acid evaporates and the decomposed waxy carboxylate is deposited in situ. When the circuit wiring board assembly is heated to the proper temperature, the resulting dielectric material is a matrix consisting of a fully deflagrated oxide ceramic with incompletely decomposed organic material, resulting in an organo-ceramic dielectric element.

Another embodiment of the present invention relates to a dielectric (eg, "pure" ceramic or organic-ceramic) composite circuit wiring board comprising one or more electrodes on one major surface of a ceramic element. and one or more metal elements of the installation area. At least one SIC is positioned on the mounting area and is electrically contacted to the at least one electrode through the conductive wiring means. Through an electrical interconnection network, the SIC is further electrically contacted to other SICs that are in electrical contact with other electrodes on the main surface of the dielectric circuit wiring board, or to another electrode on the main surface of the circuit wiring board or by connecting to a slave circuit Conductive traces, preferably sections of copper traces, of the electrical interconnection network extending from the subsurface of the dielectric component of the wiring board are in electrical contact with external input/output signal drivers of the dielectric circuit wiring board. The dielectric element also contains an embedded heat distribution network comprising heat sinks consisting of elongated thermally conductive material such as metal or empty tubes through which an absorbing fluid circulates. This heat distribution network may or may not be in thermal contact with the SIC through the mounting area, and the ends of the embedded heat sinks protrude through the subsurface of the dielectric element to make thermal contact with the thermal capacitor outside the circuit wiring board . Dielectric elements may consist of aluminate or silicate ceramic phases. Another metal element is bonded to the major surface of the circuit wiring board dielectric element opposite the major surface on which the SIC contacts the mounting pads and electrodes.

In the present invention, two approaches are used to reduce the detrimental effects of stress on the dielectric elements and embedded network structures. The first is the placement of curves at high stress points induced by sharp edge structures in the design of embedded network structures. When the network structure is designed with curved rather than sharp L-joints and T-joints, the stresses are more evenly distributed on the circular arcs, whereas strong compressive stresses occur at sharp points in the network. Second, compressive stress is also reduced by coating the (copper) metal wiring forming the electrical interconnection network and the heat pipes forming the heat dissipation network with an organic resin.

For a better understanding of the present invention together with other and further objects, reference is made to the following description taken in conjunction with the accompanying drawings, the scope of which is set forth in the appended claims.

Fig. 1A shows the top view of the preferred embodiment of the dielectric composite wiring structure of the present invention;

Figure 1 B shows a front view and a partial sectional view of the preferred embodiment of the present invention shown in Figure 1A;

FIG. 2A shows a top view of another preferred embodiment of the dielectric composite wiring structure of the present invention;

Figure 2B shows a front view and a partial sectional view of the preferred embodiment of the present invention shown in Figure 2A;

3A (stereoscopic view), 3B and 3C show the details of the assembly method used to form the dielectric composite wiring structure of the present invention;

3D (perspective view), 3e and 3F show further details of the assembly method used to form the dielectric composite wiring structure of the present invention;

FIG. 4A shows a top view of another embodiment of the dielectric composite wiring structure of the present invention;

Figure 4B shows a side sectional view of an embodiment of the invention along line IV-IV in Figure 4A; and

Figures 5A and 5B schematically show a curved network element portion embedded in a dielectric using a dielectric composite wiring structure of the present invention.

Referring now to FIGS. 1A, 1B, 2A and 2B, these figures show the preferred embodiment of the composite structure of the present invention also known as composite wiring structures 10 and 10', while FIGS. Sequential steps in the composite structure of the network, interconnection and heat sink inside the composite dielectric element. In order to facilitate understanding of the present invention, throughout the following description, the same elements described in all the embodiments are denoted by the same reference numerals.

Although not limited thereto, the composite circuit wiring structure 10 is mainly used as a circuit wiring board, or alternatively, as a multi-chip module. In the preferred embodiment of the invention shown in Figures 1A and 1B, composite structure 10 has a top conductive metal element 12 preferably having an outer major surface 14 on which at least one SIC 16 will ultimately be mounted. Any suitable series of conductive elements 18 make up the electrical contact between top metal element 12 and the integrated circuit of SIC 16 . For the preferred embodiment of the invention shown in Figures 1A and 1B, the top metal element 12 serves as the electrode contact. The composite structure 10 of the present invention also includes a ceramic or organic-ceramic dielectric element 20 and an electrical interconnection network 24 bonded to the inner major surface 22 of the top metal element electrode 12, preferably by covalent bonding. The electrical interconnection network 24 consists of at least one conductive trace, preferably of metal such as copper, embedded in a ceramic or organo-ceramic element 20 (also referred to as a dielectric element 20). One end of the copper wiring is bonded to inner major surface 22 of top metal element electrode 12 at least at one location where the top metal element makes electrical contact with SIC 16 . The at least one wiring forming the electrical interconnection network 24 may also optionally have wiring terminals 24A protruding through the outer subsurface of the dielectric element 20 to form at least one input/output connection between the top metal element electrode 12 and the outside of the circuit wiring board. The electrical contact between the signal drivers 25 is through the electrical interconnection network 24 . Another embodiment of the present invention illustrating the use of mounting supports employed by the interconnection network 24 is described in detail with reference to FIGS. 4A and 4B. Electrical contact between SIC 16 and external signal input/output drivers may also be formed between two top metal element electrodes connected by metal (preferably copper) wiring of electrical interconnection network 24 .

The composite wiring structure 10 of the present invention further includes a heat distribution network 26 embedded in the dielectric element 20 and electrically insulated, ie isolated, from the electrical interconnection network 24 . The heat distribution network 26 includes at least one heat sink located adjacent to but not in contact with the inner major surface 22 of the top metal element 12 where the top metal element 12 makes electrical contact with the SIC. The heat sinks 28 forming the heat distribution network 26 may consist of an elongated thermally conductive material such as a highly thermally conductive metal such as copper, or alternatively the heat sinks may also consist of empty tubes through which an absorbing fluid circulates. Heat sinks 28 forming the heat distribution network 26 protrude through at least one outer secondary surface of the ceramic or organo-ceramic dielectric element 20 and are in thermal contact with the thermal capacitor 30 .

The thermal capacitor 30 may be used simultaneously or connected to a mechanical fixing means for fixing the circuit wiring board to ground potential or both. Embodiments of both the composite wiring structures 10 and 10 ′ of the present invention also include a bottom metal element 32 bonded to the opposite major surface of the dielectric element 20 . Dielectric element 20 may be composed of aluminate (Al ₂ O ₃ ) or silicate (SiO ₂ ) based ceramics or organic-ceramic composites. The composite wiring structure 10 of the present invention may be configured to electrically connect a single SIC to one or more external signal input/output drivers, or to interconnect multiple SICs mounted on the top metal element to each other and to one or more Multiple external input/output signal drivers.

2A and 2B illustrate another preferred embodiment of the present invention, wherein a composite wiring structure 10' has a top metal element 12 divided into an electrode area 34 and at least one mounting area 36. In this embodiment of the invention, the electrical interconnection network 24 is embedded in the dielectric element 20 and connects the electrode region 34 of the top metal element 12 to the External signal input/output driver. The SIC 16 bonded to the mounting area 36 of the top metal element 12 is electrically connected to at least one electrode area 34 using a wiring conductor 38 . The electrical interconnection network 24 may electrically connect the SIC 16 to external signal input/output through at least one metal trace protruding through the subsurface of the dielectric element 20, or through another free electrode area 34 that is part of the top metal element 12 driver. Furthermore, in this embodiment of the invention, the at least one heat sink 28 of the heat distribution network 26 may optionally connect the mounting area of the top metal element 12 directly to 36 is connected to the thermal capacitor 30 (shown at 40) outside the circuit wiring board. Bottom metal element 32 is bonded to the outer major surface of dielectric element 20 opposite the major surface bonded to top metal element 12 .

A method of making the above-mentioned ceramic composite wiring structures 10 and 10' practical will now be explained in detail with reference to Figs. 3A-F. As shown in FIG. 3A, the top metal element 12, preferably a copper sheet with a thickness of 0.5-3 mm, is initially used as the substrate on which the electrical interconnection network 24, heat distribution network 26 and dielectric element 20 are fabricated. . Opposing areas on both outer major surface 14 and inner major surface 22 are designated as electrode regions 34 and, if the design shown in the embodiment of FIGS. 2A and 2A is to be produced, as mounting regions 36 . The remaining area 42 of the top metal element 12, which is not the designated area 44, may be selectively scratched, etched or pressed to a thickness less than the top of what will become the outer major surface 14 prior to using the copper sheet or metal element 12 as a substrate. A designated area on the major surface of the metal element 12. During construction, it is preferable to face the outer major surface 14 downward (i.e., Figures 3A-F are actually viewed upside down) and place the mounting support 46, which is movable on the inner major surface, on a surface not used as a circuit wiring board. Part of those areas of the remaining area 42 .

Mounting support 46 (preferably removable) can be made of solid material with holes of appropriate diameter to secure the ends of those sections of heat sink 28 used to form heat distribution network 26, or even at Fixed electrical network wiring 24 in some cases. The removable mounting support 54 shown in FIGS. 4A and 4B may be utilized with the metal traces used to form the electrical interconnection network 24 extending from the subsurface of the dielectric element 20 . The actual details of the mounting support 54 are described in detail with reference to Figures 4A and 4B.

Alternatively, removable mounting support 46 may be solid or semi-solid after sections of heat sink 28 and/or metal wiring (preferably made of copper or other thermally conductive material) are embedded therein. In the form of a solid injected plastic material, or may be in the form of a combination of solid material and plastic material. Provided the selected material does not form a permanent bond to the copper substrate, maintains its solid or semi-solid injection molded form over the process temperature range of 225-475°C, and can preferably be used without corrosion of the dielectric 20, metal 12 And 32 and the soluble method of network element 24 and 26 are easy to remove, then various plastic, glass, ceramic or metal materials can be used as removable mounting support 46. Recommended purgeable injection molding materials include plastic compounds containing polyvinyl formal or polyvinyl butyral loaded with empty silica and high-temperature organic binders. Suitable high temperature adhesives include, but are not limited to, aromatic heterocyclic polymers such as benzimidazole polymers, or ethynyl-terminated polyimides with small amounts of hydroquinone added to retard the thermal reaction of the ethynyl groups. amines, or commercially available arylene ethers under the trade names Polymer 360 or Astrel 360. Removable injection molding materials are usually made in the temperature range of 350-470°C at pressures of 50-2000psi, and should be made to withstand ceramic processing temperatures (225-475°C), resistant to removal of metal components12 and The etchant in the remaining region 42 of 32 is also susceptible to dispersion in a solvent that is inert to dielectric elements 20 , metal elements 12 and 32 , and the materials comprising electrical interconnection network 24 and heat dissipation network 26 .

It is critical to the circuit wiring board that the electrical interconnection network 24 and the heat distribution network 26 be electrically isolated, or isolated, from each other in the finished product. Therefore, no part of the electrical interconnection network 24 must physically touch any part of the heat dissipation network 26 before and after the use of the dielectric film 20, and vice versa. It is also essential to weave the electrical interconnection network 24 and the heat dissipation network 26 so that they are separated by a distance sufficient to ensure isolation from the applied voltage after the dielectric element 20 is interposed therebetween. Ideally, the heat dissipation network 26 should be electrically grounded.

If some of the mounting supports 46 also include portions of removable material 48 that do not constitute the final circuit board assembly and the heat distribution network 26 passes through the heat sink 28 embedded in the dielectric element 20 protruding from the subsurface of the dielectric element 20 A thermal capacitor connected thereto can improve manufacturing efficiency. The heat sink/mounting support can only be located in the remaining area 42 adjacent to the subsurface of the dielectric element 20 through which only the heat sink 28 connected to the heat distribution network protrudes.

Once the circuit wiring board is completed, those copper wiring sections 50 used to make the electrical interconnection network 24 and those sections of the heat sink 28 protruding from the dielectric element 20 used to make the heat distribution network 26 are buried. Set in the mounting support 46. When the thermal capacitor 30 is assembled as a part of the mounting support 46, those heat sink sections that are to protrude from the subsurface of the dielectric element 20 are secured to the thermal capacitor 30 by the material 48 of the mounting support. Then, as shown in FIG. 3B , mounting supports 46 with copper wiring buried sections and heat sinks are placed on the inner surface 22 of top metal element 12 on the remaining areas 42 that are not used as part of the composite wiring board.

Then, as shown in FIG. 3B, the terminations of the metal wiring forming the electrical interconnection network 24 are bonded to the inner surface 22 of the metal sheet at those regions of the substrate designated as electrode regions 34 as described in FIG. 2A. The metal wiring can be bonded to the metal sheet using various brazing materials well known to those skilled in the art, electric welding, arc welding or ultrasonic bonding. Selection of a bonding technique appropriate to the desired electrical performance of the finished circuit board is recommended. The preferred method of the present invention utilizes a bonding technique such as arc welding to form the metallic bond between the electrical interconnection network 24 and the defined electrode regions 34 of the copper metal sheet, although other conventional techniques may be used.

The electrical interconnection network 24 is made by bending and electrically contacting a bonded metal wire to another metal wire or a plurality of such metal wires, so as to be compatible with the circuit wiring pattern characteristic of the SIC and external input/output signal drivers. constituted in a consistent manner. While arc welding is the preferred method of making electrical interconnections between such formed metal (preferably copper) traces, other conventional methods may be used. By choosing not to bond the copper wiring thus formed to any other copper wiring and terminating the closed via metal wiring in another electrode area, or by terminating the closed via metal wiring in a removable mounting support, The invention can be used to make closed vias. A prefabricated wiring network for making the electrical interconnection network 24 can also be made that is press-fit at its ends into the inserts 52 drilled into the electrode regions 34 of the copper sheet substrate, for example by vacuum casting methods. For convenience, this method of making an electrical interconnection network is shown in Figure 3B. According to the preferred embodiment described in FIGS. 2A and b, when a circuit wiring board including an electrode area and a mounting area is to be produced, the above-mentioned method for making the terminals of the electrical interconnection network 24 contact the electrode area 34 can be used to The contact areas of the heat sink 28 comprising the heat distribution network 26 are bonded to the mounting area 36 .

As mentioned above, the mounting support 46 may optionally be removed after the circuit wiring board "CWB" is fully assembled. It is also possible to keep the mounting support in the finished CWB as an element, as a permanent attachment. As shown in FIGS. 4A and 4B , mounting supports 54 electrically connect conductive traces 50 forming electrical interconnection network 24 to input/output signal drivers (not shown) outside the CWB. Figures 4A and 4B show the complete form of this embodiment including the electrical connection permanent mounting support.

Once the electrical interconnection network 24 and thermal distribution network 26 are affixed to the metal substrate as shown in FIG. In a solution process, the dielectric material 20A forming the dielectric element 20 is applied to the metal substrate and network structure as shown in FIG. 3C. The ceramic precursors can be dissolved in solution using techniques such as sol-gel and/or metal organic decomposition ("MOD"). The sol-gel technique described above utilizes metal alkoxide precursors to polymerize inorganic ceramic networks through alcohol concentration reactions. Relatively viscous precursor solutions can be applied to metal substrates and networks by pouring, spraying, spray-pyrolysis or screen printing precursor formulations into wells defined by removable mounting supports 46 structure. Then, by means of heating the metal-organic precursor to a temperature above its decomposition point (i.e., preferably 225-475 °C), or, in the case of MOD-prepared ceramics, by means of heating to accelerate the polymerization and the removal of the alcohol from the sol - Evaporation in the gel-forming ceramic, allowing the precursor to react or decompose in an oxidizing atmosphere to form the desired ceramic phase.

Alumina with a relative permittivity of 10 and silica with a relative permittivity of 3.8 enable electrical signals to operate at up to 1.2-1.5GHz due to the ability to limit dielectric losses in the case of pure silica ceramic components The frequencies are propagated through the electrical interconnection network 24 to optimal ceramic phases.

The ceramic precursor can be recoated with a solution formulation of decreasing viscosity and the reaction/decomposition repeated to fill voids in the dielectric (ceramic) 20A that may exist after initial fabrication of the ceramic component. Such voids may also be filled by infiltrating or impregnating the ceramic element with a low dielectric or stress relieving organic compound, such as polyvinyl formal, to form an organic-ceramic composite dielectric. The dielectric constant of polyvinyl formal is 3, the dissipation factor is 0.02, and the dielectric strength (1/8 thickness) is equal to 300V/mm. Polyvinyl butyral, which has a dielectric constant of 2.6 and a dissipation factor of 0.027, is another suitable penetrant. The use of carboxylate precursors and the MOD process is a preferred embodiment of the present invention. For alumina ceramic components, aluminum 2-ethylhexanoate is the best metal-organic precursor, while for silica ceramic components, silicon 2-ethylhexanoate is the best metal-organic precursor. quality.

It can also be used to spray the solution and pyrolyze the circuit wiring board heated to a temperature higher than the initial decomposition temperature of the dissolved carboxylate (225-375°C) and lower than the complete decomposition temperature (400-475°C) of the organic ligand of the salt assembly method to fabricate organic-ceramic composite dielectric materials. During the spray-pyrolysis process, the carboxylic acid evaporates, depositing a waxy carboxylate that decomposes in situ. When the circuit wiring board assembly is heated to the proper temperature, the resulting dielectric material is a fully deflagrated oxide ceramic matrix with incompletely decomposed organic material, resulting in an organo-ceramic dielectric element. This organo-ceramic composite can be maintained if the deposited dielectric and circuit wiring assembly are not exposed to temperatures above 400°C which could drastically decompose the organic components. By adding a low volatility resin such as polyvinyl butyral, and/or a high temperature binder consistent with polyvinyl butyral, to the carboxylate ("MOD") solution, improved Organic content in these sprayed-pyrolyzed organic-ceramic composite dielectrics. Polyvinyl butyral typically decomposes at temperatures above 450°C and adheres to the partially decomposed carboxylate matrix deposited by deposition at temperatures of 225-375°C.

Once the dielectric material 20A is formed to completely encase the electrical interconnection network 24 and the heat distribution network 26 embedded therein, its surface is rough ground to produce a microscopically rough surface, ie, an average surface roughness greater than 35 microns. As shown in FIG. 3D , the major surface of the ceramic face of a similarly prepared metal-ceramic composite, which may not require any electrical interconnection and thermal distribution network inside, comprising the bottom metal element 32 and the dielectric element 20B, is bonded. to the dielectric element 20A. Through low melting point oxide glass 66 (such as silica-borate, silica-phosphate, or alumina-silica-phosphate or alumina-silica-borate phases) or polymer adhesive, to achieve this. At a temperature above the softening point of the glass phase, a low melting point bonding agent is applied to dielectric elements 20A and/or 20B, the two composites are pressed together, dielectric side to dielectric side, and the The compact cools below the softening point of the glass. It is also possible to bond the two dielectric members 20A and 20B to each other by using a suitable polymer instead of the low-melting glass. If an organic adhesive is used to bond the composite, it must be resistant to the solvents used to crush the removable material 48 of the removable portion of the mounting support 46 . Therefore, the use of cross-linked ethynyl-terminated poly(arylene ethers) that exhibit excellent adhesion at elevated temperatures and are resistant to solvents is recommended.

Once the entire composite is fabricated as shown in FIG. 3E, the remaining areas 42 which do not form part of the finished wiring board are removed by etching those thinned portions of the top metal element 12 and bottom metal element 32. The partially completed composite must be designed and constructed to expose the removable material 48 of the mounting support 46 once the remaining areas of the top metal element 12 and bottom metal element 32, respectively, have been comminuted. The removable material portion 48 of the mounting support 46 is then shredded to obtain the finished composite circuit wiring board with internal copper wiring electrical interconnections and a thermal distribution network as shown in FIG. 3E.

In yet another embodiment of the present invention, at least one internal DC blocking capacitor, preferably a solid state or ceramic capacitor (designated individually as capacitors 60A and 60B), connects at least one conductive trace 50 in electrical interconnection network 24 to ground. potential. The capacitance of the internal DC blocking capacitors 60A and B is chosen to reduce any unwanted spurious electrical signals (noise) and improve the electrical interconnection network 24 between the SIC and any input/output signal drivers (not shown) outside the CWB The signal-to-noise ratio of the traveling electrical signal. FIG. 4B shows the connection of the internal DC blocking capacitor, wherein the metal element 32 on which the SIC is placed, which is opposite to the metal element 12, is configured to act as a ground potential.

Internal blocking capacitor 60A can be embedded in dielectric element 20 by affixing internal blocking capacitor 60A to metal element 32 prior to coating the portion of dielectric element 20 that encloses internal blocking capacitor 60A. By means of making a via 62 in the dielectric element 20 above the internal DC blocking capacitor 60A, and filling the via 62 with a conductive substance 64 such as solder or metal glue that is also in electrical contact with the at least one conductive wiring 50, it is possible to Capacitor 60A is electrically connected to at least one conductive wire 50 in electrical interconnection network 24 .

Utilizing the present invention, it is possible to house the internal DC blocking capacitor 60B in the mounting support 54 remaining as a permanent attachment to the CWB. Like the capacitor 60A, the via 62 having the conductive substance 64 is also in electrical contact with the at least one conductive wiring 50 . Capacitor 60B is used to electrically connect the SIC through electrical interconnection network 24 to the input/output signal drivers outside the CWB. This preferred embodiment of the invention is also shown in Figure 4B. Examples of DC blocking capacitors that can be used in the present invention may be, but are not limited to, ceramic capacitors, preferably multilayer ceramic capacitors.

Fundamental problems in combining metal wiring or piping networks in dielectric components involve large mismatches in thermal expansion coefficients between the metal and ceramic dielectric components and internal stresses, cracks, or deformations that occur when the composite is thermally cycled. This problem is particularly serious when copper with a thermal expansion coefficient of 16.5×10 ^-6 /°C is embedded in pure silicon dioxide with a thermal expansion coefficient of 0.5×10 ^-6 /°C. The mismatch between alumina ceramics with a coefficient of thermal expansion of 8.8×10 ^-6 /°C and copper is not as serious and the problem is less. The heat generated by the SIC16 is dissipated into the circuit wiring board. As the heat distribution network 26 transfers this heat to heat sinks on the outside of the circuit wiring board, it causes the dielectric elements to heat, expand and compress.

Two approaches are used in the present invention to mitigate the detrimental effects of stress on the ceramic elements and embedded network structures. The first is to place the curves in the design of the embedded network structure at points of high stress induced by the sharp edge structure. When the network structure is designed as curved lines instead of the sharp-angled L-joints and T-joints shown in Figures 5A and 5B, the stress is more evenly distributed on the circular arcs without building up strong stress at the sharp points of the network. The optimal radii of curvature of the network connections, and even the specific cross-sectional shape of the copper traces or heat sinks used to form these networks, depend on the thermal load imposed by the SIC and can be determined by anyone skilled in the art by computer simulation methods such as the finite element method. personnel derived. Second, as shown in FIG. 3A, the (copper) forming the electrical interconnection network 24 is coated with an organic resin 56 that partially contains a high-temperature adhesive, such as polyvinyl formal whose decomposition temperature is higher than 430° C. Metal wiring and heat pipes 28 forming a heat dissipation network 26 also reduce compressive stress. The resin can be applied by immersing the prefabricated network in a resin bath before it is secured to the top metal element 12 and/or mounting support 46 . In the present invention, the organic resin is preferably applied by a "pultrusion" method so that when assembled into the electrical interconnection network 24 on the surface of the sheet metal substrate, the metal wiring elements are pulled through the application of the applied resin mold. The high decomposition temperature of the resin enables the resin to occupy the immediate space of the network elements. Ceramic components are fabricated and hardened to the surface of the organic resin at temperatures below the temperature at which the resin decomposes. The "soft" organic resin can be left as a buffer layer to accommodate uneven lateral displacement between the metal network elements and the ceramic elements.

The applied resin compound must be resistant to the solvents used to pulverize the removable material 48 in the mounting support 46 if it is to remain an integral part of the composite. Alternatively, the resin can also be removed by heating the compound above its thermal decomposition temperature in an oxidizing atmosphere, or by dissolving it in a suitable dispersant. Once the resin is removed, a void space is created between the hardened ceramic component and the metal wiring and/or heat sink. This void space allows the network element to slip relative to the surrounding dielectric elements when the metal network element expands or contracts more than the surrounding dielectric elements. The depth of the void space, and thus the thickness of the organic resin coating, depends on the degree of relative interaction that may be required between the metal network elements and the surrounding dielectric during the highest duty cycle for a given SIC.

While the invention has been described with respect to various embodiments, it will be understood that the invention is also capable of various further and other embodiments within the spirit and scope of the appended claims.

Claims (48)

1. A composite structure for handling conduction of electricity and heat from at least one semiconductor device, comprising: Composite having at least one electrical conductor forming part of an electrical network and at least one thermal conductor forming part of a thermal network, said electrical conductor being bonded to an electrically insulating dielectric element which surrounds both the electrical and thermal network ; Said electrical and thermal conductors and electrical and thermal networks thus formed are arranged in said dielectric element, electrically isolated from each other; and The entire structure is constructed and arranged to transfer heat from the electrical network and semiconductor devices to and through the thermal network. 2. The composite structure of claim 1 , by means of in situ fabrication of said electrical network and said thermal network surrounding said electrical network and said thermal network at temperatures insufficient to adversely affect the structural integrity of said electrical network and said thermal network. made of dielectric. 3. The composite structure of claim 2, wherein the dielectric element is bonded to the at least one electrical conductor by a covalent bond formed below 475°C. 4. The composite structure of claim 2, wherein the ceramic element is bonded to the at least one electrical and thermal conductor and the network so formed by covalent bonding formed below 475°C. 5. The composite structure of claim 3, wherein the electrical and thermal networks consist of elements coated with an organic resin that decomposes above 475°C. 6. The composite structure of claim 1, wherein said electrical network is formed of a plurality of interconnected conductive wiring segments, some of which protrude through the major surface of said dielectric element for electrical connection to at least one semiconductor device. 7. The composite structure of claim 1, further comprising means external to said dielectric element connectable to said thermal network for providing a thermal capacitor for said heat distribution network. 8. The composite structure of claim 1, further comprising additional conductive elements for electrically connecting the electrical network to at least one semiconductor device. 9. The composite structure of claim 1, further comprising at least one capacitor embedded in said dielectric element and electrically connected between said electrical network and another electrical conductor. 10. The composite structure of claim 1, wherein the electrical and thermal networks are comprised of curvilinear elements. 11. The composite structure of claim 1, further comprising a support structure, and the electrical and thermal networks are secured to the support structure. 12. The composite structure of claim 11, wherein the support structure includes a thermal capacitor for the thermal network. 13. The composite structure of claim 1, wherein said thermal network is comprised of at least one heat sink, a portion of said heat sink being connectable to said at least one electrical conductor. 14. The composite structure of claim 1, wherein at least one semiconductor device is combined with the at least one electrical conductor. 15. The composite structure of claim 1, wherein at least one semiconductor device is combined with the at least one electrical and thermal conductor. 16. The composite structure of claim 1, wherein the dielectric element is a ceramic. 17. The composite structure of claim 1, wherein the dielectric element is an organo-ceramic. 18. A composite structure for at least one semiconductor device comprising: means for providing electrical conduction, the electrical conduction means having an outer major surface and an inner major surface; said outer main surface of said electrically conducting means can have at least one semiconductor device mounted thereon electrically connected thereto, means for providing electrical isolation, said electrical isolation means having a major surface bonded to said inner major surface of said conductive means; a conductive network consisting of at least one conductive wiring segment embedded in said electrically insulating means, said at least one wiring segment being electrically connected to said electrically conducting means; and means for providing heat distribution embedded within said electrically insulating means and electrically isolated from said conducting means and said conducting network, said heat distributing means being capable of being effectively dissipated in at least one Heat generated during the operation of semiconductor devices. 19. The composite wiring structure of claim 18, wherein said conductive network is formed of a plurality of interconnected conductive wiring segments, a portion of said wiring segments protruding through said major surface of said electrical isolating means so as to communicate with At least one semiconductor device is electrically connected. 20. The composite structure of claim 19, further comprising at least one capacitor embedded in said electrically insulating means and electrically connected between said conductive network and a conductive element. 21. The composite structure of claim 19, wherein the electrically insulating means is ceramic and is bonded to the electrically conductive means. 22. The composite structure of claim 19, wherein the electrically insulating means is an organo-ceramic and is bonded to the electrically conductive means. 23. The composite structure of claim 19, further comprising means external to said electrical insulation means connectable to said heat distribution means for providing a thermal capacitor for said heat distribution means. 24. The composite structure of claim 19, wherein the conductive network and heat distribution means are comprised of curvilinear elements. 25. A composite structure as claimed in claim 24, wherein the conductive network and heat distribution means consist of elements coated with an organic resin which decomposes above 475°C. 26. The composite structure of claim 25, further comprising a support structure, and the heat distribution device is secured to the support structure. 27. The composite structure of claim 26, wherein the support structure comprises a thermal capacitor of the heat distribution device. 28. The composite structure of claim 18, wherein the electrically insulating means is ceramic and is bonded to the electrically conductive means by a covalent bond formed below 475°C. 29. The composite structure of claim 20, wherein the electrically insulating means is an organo-ceramic, and is bonded to the electrically conducting means by a covalent bond formed below 475°C. 30. The composite structure of claim 29, wherein said heat distribution means is constituted by at least one heat sink, a portion of said heat sink being connectable to at least one semiconductor device. 31. The composite structure of claim 18, wherein at least one semiconductor device is combined with said conductive means. 32. The composite structure of claim 16, wherein at least one semiconductor device is combined with said conductive means and said heat distribution means. 33. A method of constructing a composite structure for at least one semiconductor device, comprising the steps of: providing at least one electrical conductor to form part of the electrical network; providing at least one thermal conductor to form part of the thermal network; and applying a dielectric material to the electrical conductor by forming a direct covalent bond between the electrical conductor and the dielectric material, the thermal network and the electrical network being surrounded by the dielectric material . 34. The method of construction of a composite structure as claimed in claim 33, further comprising the step of providing at least one capacitor in said dielectric material prior to the step of applying said dielectric material, said at least one capacitor being electrically connected at between the electrical network and the conductive element. 35. The method of construction of a composite structure as recited in claim 33, further comprising the step of providing at least one electrically conductive wiring segment and electrically isolating said electrical network from said thermal network. 36. A method of constructing a composite structure as recited in claim 33, further comprising the step of securing said thermal network to a mounting support prior to applying said dielectric material. 37. The method of constructing a composite structure as recited in claim 33, further comprising the step of selectively clearing a portion of a major surface of said electrical conductor to define at least one electrode region for mounting a semiconductor device thereon. 38. The method of construction of a composite structure of claim 33, wherein the dielectric material comprises an aluminum based ceramic. 39. The method of construction of a composite structure of claim 33, wherein the dielectric material comprises an organo-ceramic. 40. The method of constructing a composite structure of claim 33, further comprising the step of fabricating the composite structure by spray pyrolysis of a solution containing carboxylic acid precursors containing polyvinyl butyral. 41. The method of construction of a composite structure of claim 33, wherein the dielectric material comprises a silica-based ceramic. 42. A method of constructing a composite structure as claimed in claim 33, further comprising the step of electrically connecting at least one semiconductor device to said electrical conductor. 43. The method of construction of a composite structure of claim 33, further comprising connecting at least one semiconductor device to the electrical conductor and the thermal conductor. 44. The composite structure of claim 1, wherein the dielectric element comprises an aluminum-based ceramic material. 45. The composite wiring structure of claim 1, wherein the dielectric element comprises a silica-based ceramic material. 46. A composite structure for use on at least one semiconductor device, comprising: a first conductive element having at least one semiconductor device mounted on its surface for electrical connection thereto, a dielectric element having a major surface bonded to the first conductive element; a conductive network consisting of at least one conductive wiring segment embedded in said ceramic element, said at least one wiring segment being electrically connected to said first conductive element; a heat distribution network embedded in the ceramic element and electrically isolated from the conductive network, the heat distribution network is capable of effectively dissipating heat generated during operation of the semiconductor device; and A second conductive element bonded to the dielectric element on a side thereof opposite the first conductive element. 47. The composite structure of claim 46, wherein the dielectric element is ceramic. 48. The composite structure of claim 46, wherein the dielectric element is an organo-ceramic.

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