JPS61225048A - Manufacture of multilayer circuit complex - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Although the invention can be used in a wide range of applications, it is particularly suitable for, and will be described with particular reference to, hybrid circuits and multilayer circuits. More specifically, the present invention provides oxygen-free or dedusted (aeoxi,dize4)
The present invention relates to bonding copper alloy foils to ceramic substrates with relatively low temperature bonding glasses. - In a specific example, a copper alloy foil is etched to form all the ridges and then resistive metal strips are bonded to those ridges to form precise resistance paths. In another embodiment, a plurality of foil bonded substrates may be bonded together;
Form a multilayer circuit.

[Prior Art] Centralized circuits, known as chips,
, 11 circuits. Despite advances in design and capabilities, hybrid circuit technology remains virtually static.

An example of a hybrid circuit design is U.S. Patent No. 3.200,2
No. 98, No. 3,723.176, No. 4,299,87
No. 3 and No. 4,313,026. The 7% IPR substrate is typically Al
Ceramic materials such as 2O3 are mixed with organic materials and formed into green sheets or thin, relatively small pieces into a substrate.

Size is typically limited to approximately 41n2 squares. A conductive circuit on a hybrid substrate may be formed as follows. First, a paste of gold, glass and binder,
Silk screen printing on the surface of the raw ceramic substrate in any desired pattern. The resulting composite is fired at about 850° C. to remove the binder from the paste, and then the glass and gold are sintered. The fired glass-gold conductor has only about 60% of the electrical conductivity of the primary gold. The resistor is applied in a similar manner, namely by screen printing of resistor paste and using resistive materials such as nichrome and carbon. Because of their non-uniform geometry and local variations in their composition, the resistors must be individually measured and laser reduced to an acceptable resistance range. , becoming the most expensive and time-consuming procedure. Both resistor and conductor techniques using thick film pasters also have the disadvantage that the paste itself varies from preparation to preparation. The cost associated with this thick film method has inhibited its application when viable alternatives are available. However, the desire to increase the density of IO devices has led to their increased use despite many of the drawbacks listed above.

Alternative methods include thin film methods in which the resistors and conductors are vacuum deposited or sputtered onto a 99% alumina substrate. It is even more expensive because the deposition rate of resistors and conductors is very slow and the 99% alumina substrate material is very expensive.

In order to solve the problem of the need for high-cost gold conductors,
Attempts are being made to replace it with gold paste gold copper foil. One advantage of this alternative would be that precise JB 11 circuits could be formed using dry photoresist films and conventional printed circuit board etching techniques. The use of dry photoresist films and conventional printed circuit etching is an excellent method for forming accurate, reproducible, relatively fine linear circuits in copper layers bonded to ceramic substrates. For example, 6 mil wide lines with 6 mil spacing are relatively easy to form using the above method. In contrast, the silk screen gold paste process typically results in lines that are 10 mils wide and spaced more than 10 mils apart. Even in comparison, it is far more advantageous to form the circuit on a copper layer.

To date, attempts to bond copper foil to alumina with glass under reducing conditions have inevitably resulted in expensive bubble formation of the foil. This is due in part to the common use of 0DA11000 foils that contain cuprous oxide as another phase. When fired in a reducing atmosphere, the alloy ODA 11
Cuprous oxide in 000 is reduced and bubbles are generated by water vapor.

It is also possible that bubble formation is caused in part by air that has become trapped in the glass due to the lack of significant escape routes during the firing process. Air bubbles are particularly harmful to multilayer/hybrid circuits.

This is because it creates a weak bond between the rx ceramic and the copper foil leading to delamination. Additionally, during the etching process, the etching solution may seep into the air bubbles at the glass/foil interface, etching unwanted areas of the foil.

In an attempt to eliminate carbon during bubble formation, bonding under oxidizing conditions was proposed in a paper by Burgegs et al. entitled ``Direct bonding of fluorophores to ceramics by the gas-metal co-method.'' Journal Electrochemical Society (J,) lC1electrochemiaa18
ociety) : From National Science and Technology CSQL 18TATE 5OI
ICNOICAND 'I'l0)INOLOGY)
, I, 1975]. This method attempts to take advantage of the high temperature cuprous oxide formed in the seedling soil. Although this method produces good bonding without bubbles, it forms a high temperature cuprous oxide film on the outer surface of the foil, which is extremely difficult to remove.

The present invention also uses a bin grid array (pin grid array).
rray) or side brazed packages are typical examples. Bin grid arrays are typically small multilayer 99% alumina plates with conductive circuits between the layers. The bin grid array minimizes the thickness required for large integrated circuits and allows for the use of larger pin counts than is possible with conventional quad packs. Side-brazed packages are similar in construction to bin grid arrays, except that the electrical contacts to the electrical circuitry are brazed to the sides of the package along with the bins. Both of these package designs provide a rugged, reliable, hermetic package and are preferred for the 0ERD process. This is because they do not rely on the glass enclosure of the conductor.

Conventional bin grid arrays typically include at least three layers of alumina made by tape casting.

The inner layer circuitry is made by silk screen printing tungsten or moly-manganese powder onto raw alumina 7' (96% Al2O3).

Interconnections between the inner layer circuits are provided through approximately 5-10 mil holes drilled in the raw alumina tape. Interconnects or through-hole conductors are also formed using tungsten or silicate manganese powder. The multilayer alumina tape and conductor tracks are simultaneously fired in the range of about 1550-1600°C. This expels the polymeric binder from the alumina tape and sinters the 96-Al2O3, resulting in partial sintering of the areas that conduct the current. The exposed conductor may then be coated with nickel using an electroless process. Thereafter, the gold-plated wire bin is brazed to the through-hole conductor.

There are technical problems in manufacturing pin-grid arrays using this technology that result in high labor costs. The most important technical problem is that when alumina tape is fired at high temperatures, there is a very large volumetric shrinkage. Volume shrinkage can be as high as 40%, resulting in linear shrinkage of just 20 inches. This also poses severe problems in the location of the through-hole relative to the bottle and in maintaining electrical contact of the through-hole. If this happens, the shrinkage will be so great that the conductive cross-circuit will completely fall out of the bin. Traditional methods of silk-screening inner layer circuits onto alumina tape result in relatively dense and well-sintered circuits. However, through-hole contacts that may be mechanically inserted can be very loose and can only provide low single frequency, small fractional contact.

In the past, glass-ceramic structures with embedded circuit patterns have been developed by Spinelli et al. in U.S. Pat.
, 385,202; U.S. Patent No. 4 to Kumar et al.
, 301,324; U.S. Patent No. 4 by Yamada et al.
No. 313,026; British Patent No. 1.232,621 and British Patent No. 1.349,671. Each of these patents is unique in that it does not teach or suggest bonding deoxidized or oxygen-free copper or copper alloy foils to ceramic substrates using relatively low temperature hermetic glass. It is different from invention.

A multilayer alumina circuit board having multiple layers formed using the method of the present invention was developed by Jerry L.
"Packaging" by yman)
A sentence entitled ng month [11jleCtronics.

54, A26, Dec. 29 (1981) are particularly useful, such as bin grid arrays of the general type described in Ko. High temperature stable hybrid or Forming a multilayer circuit board is the problem underlying the present invention. Manufacturing accurate, easy-to-manufacture resistors on hybrid circuits is an additional problem.

It is an advantage of the present invention to provide improved hybrid or multilayer circuit composites and methods of forming them that obviate one or more of the limitations and disadvantages of the prior art methods and apparatus discussed above.

It is an object of the present invention to provide improved hybrid or multilayer composites having one or more ceramic substrates in which a deoxidized or oxygen-free copper alloy foil is bonded by a glass, and methods for forming the same. Yet another advantage of the invention.

It is a further aspect of the present invention to provide an improved bibrid or multilayer composite having an electrical circuit and a resistor formed from a metal foil coupled to the circuit in accordance with the present invention, and methods of forming such bibrid or multilayer composites. Another advantage.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved side braze package and method of manufacturing a side braze package having circuitry formed on an oxygen-free or deoxidized copper foil bonded to a substrate with glass. This is yet another advantage.

Accordingly, improved hybrid or multilayer circuits and methods of forming multilayer or hybrid circuit composites are provided. The complex is deoxidized or contains oxygen! ! A non-copper alloy foil has at least one ceramic substrate bonded by a cold-sealing glass. The copper alloy foil may be etched and a resistive metal alloy tape bonded thereon to provide a path of precise resistance. Additionally, multiple foils are glass bonded to the substrate and stacked to form a multilayer circuit. A side brazed package and method of manufacturing the package are described. The package includes a deoxidized or oxygen-free copper circuit foil bonded to a substrate with glass.

The invention and further developments thereof will be explained in detail below with reference to preferred embodiments of the drawings.

Hybrid or multilayer integrated circuit scheme according to the invention l1iI
Describe with reference to F'Jjr.

FIG. 1 illustrates a layered composite 10 having a substrate 12 formed from a ceramic material and a cladding layer 14 of copper foil. The substrate and cladding layers are bonded together by glass 16. To manufacture composite 10, a coating of glass may be applied to at least one surface of substrate 12. A cladding layer 14 is then disposed over the coated surface and the composite is fired under reducing conditions such that the glass coating melts into a substantially continuous overlay that bonds the cladding layer to the all-ceramic substrate. do. Finally, the circuitry may be etched into the cladding layer. The circuit may be modified to form a hybrid circuit as shown in FIG. Alternatively, the layered composite may be combined with one or more additional layers similar to composite 10 to form a multilayer composite as illustrated in FIG. 6E.

The substrate 12 is a green ceramic plate that may be made from materials including silica, silicon carbide, arsina silicate, zirconia, zircon, pellium, alumina having a purity of about 90 to about 99%, and mixtures thereof. 13. Shape the raw board). Ceramic materials typically have a Vc
Preferred is commercially available 96% alumina containing 4.5% aluminum and balance silica, manganese, calcium and magnesium.

It is also within the scope of the present invention to use combinations of the above-mentioned ceramic materials or other ceramic materials, if desired.

The cladding layer 14 has a thickness of about 60% and is larger than AO8.
Preferably, it is a copper alloy with high electrical conductivity. This high conductivity steel alloy has an alloying additive 271 which accounts for less than about 10% of the alloy, with the remainder being copper. Examples of copper alloys considered suitable for practicing the invention include 0DA15100, 0DA12200.0DAI
0200, and ODA 19400. The copper alloy crat material selected is preferably a foil, such as 1 oz. foil, which has been deoxidized. By using a deoxidized copper alloy foil, there are
This is particularly important in preventing the formation of air bubbles, as discussed further below.

It is also within the scope of this invention to select from oxygen-free steels that are typically produced electrolytically and substantially free of cuprous oxide and without residual metal deoxidizers or Metalloy V deoxidizers. to go into. Generally, the composition of oxygen-free rust is at least 99.95% copper, considering tin as copper. Examples of oxygen-free copper include ODA 10100 and ODA 1020.
0, CDA 10400°, 0DA 10500 and CDA 10700.

Bonding material 16 is preferably a sealing and/or bonding glass that forms a flowable body at temperatures below about 1000°C. The glass is further selected to adhere to both the ceramic substrate and the copper alloy cladding. The glass may be selected from the group consisting of silicate, borosilicate, phosphate and zinc borosilicate glasses. The general composition of glass is MO-B2(32)-3iO2 (in the formula MO=A14(
32), BaO, GaO, ZrO2.

Borosilicate salt glasses of Na2O, SrO, K2O or mixtures thereof are preferred. The expansivity of glass can be adjusted by adjusting the components or by adjusting the expandability of the glass.
e).

beta-eucryptite
) or by adding suitable fillers such as zirconium silicate. Glass is approximately 50X1
0-full about i ooxlo-7i n/i n/'
Preferably, the material is adjusted to have a desired coefficient of thermal expansion (OTK) within the range of Q. In particular, the OTK of the glass will be slightly smaller than the substrate so that the bonded glass is in compression. For example, in the case of an alumina substrate, the glass G process is about 66 x 10-1 to about 70 x 10-te 1rx/in.
It would be preferable to have 0Tlt of /'Q.

glass at about 1500°C to about 1000°C, most preferably 6″
X, selected to form a flowable body within a temperature range of about 600 to about 950°C.

To apply the glass to a substrate, it is desirable to form a slurry of glass particles suspended in a medium convenient for the specified application method. For example, glass is manufactured by Elbaside (xxvaalte), a product of DuPont Corporation.
) and vehicles such as terpeneols. The result is a paste or slurry of suitable viscosity that can be applied to a substrate by any conventional method such as screen printing. Alternatively, a suspending agent such as vitrified eventonite may be mixed with water as a vehicle to form a sludge of a viscosity suitable for spraying or dipping.

In forming the composite 10 of FIG. 1, a slurry of glass is coated onto the surface 18 of the substrate 12. The substrate and glass coating are then dried and heated to a temperature of about 500 DEG to about 1000 DEG C. to sinter the glass coating onto the substrate. Next, copper alloy foil 14
is placed with its surface 20 facing the sintered glass coating 16. The entire composite is then reheated in a reducing or inert atmosphere to a temperature of about 500 DEG to about 1000 DEG C. so that the copper alloy foil 14 bonds to the substrate 12.

The substrate may also be bonded to the copper foil using a thin, essentially porous glass preform. The preform may be bonded to a foil or substrate. The foil is then placed against the substrate and heated so that the glass bonds the foil to the substrate.

Alternatively, the glass preform may be placed between the foil and the substrate. The composite is then heated and, if desired, placed under pressure to cause the substrate to bond to the foil layer. Solid glass preforms are essentially porous and can be advantageously used in the present invention. The etching agents used to dissolve the foil layers and form the circuits do not tend to attack or dissolve the non-porous glass.

Therefore, the circuit formed in the seedling soil using the glass preformed body is
It will have a more accurate shape as desired.

Preferably, the glass is selected to be free of lead oxide. This is because lead oxide is partially reduced when heated by DO in a reducing atmosphere. Lead in the glass completely destroys the insulation of the ceramic by creating a short circuit in the etched path. It is also desirable that the glass be essentially free of bismuth oxide. This is because bismuth oxide is also partially reduced and reduces or destroys the insulation value of the ceramic by creating a short circuit in a manner similar to that of lead as described above.

There are two important process steps that are preferred to prevent bubble formation in the foil. The first is that the foil is preferably oxygen-free or deoxidized copper or copper alloy.

Second, the binding preferably occurs under reducing or inert conditions. For example, the composite is calcined in an atmosphere of an inert or reducing gas such as nitrogen, nitrogen 4% hydrogen or alden. The use of deoxidized or oxygen-free copper foil prevents bubble formation therein when the foils are bonded under reducing conditions.

Another important key to eliminating the bubbling problem is to allow trapped air to escape before the copper foil is actually bonded to the substrate. This condition can be handled by coating the glass on the substrate and reflowing it before applying the copper foil. The copper foil is then placed on the glass coating and heated to bonding temperature while pressing the foil against the glass coating preferably under a pressure of about 50 to about 300 psi. If air escape between the foil and the coated substrate is insufficient, the coated substrate can be exposed to a moderate vacuum to aggressively drive out any residual air or binder. The desired circuit can then be formed in the bubble-free bonded foil by conventional methods, as described below.

3A-30, there is illustrated the process of processing a structure incorporating an embodiment such as that illustrated in FIG. 1 to form the desired electrically conductive circuitry. Assembly 1
0 outer surface 38fr, first, a positive photoresist (photo-r
eslst) f coat. A patterned mask of a material opaque to the exposure light is then placed in contact with the photoresist. Upon exposure to light, only the unmasked portions of the photoresist layer are exposed. The mask is then removed and the resist developed. The exposed portions of the resist are removed and copper circuitry is formed in a subsequent etching step.

Etching may be accomplished using conventional solutions such as Pθ013/HOI copper etchant. The composite may thus be coated with photoresist several times and etched to produce the desired patterns and structures.

In FIG. 3A, the copper layer or foil has been photoetched, leaving two ridges 40 and 42. Their outermost surfaces 38 extend over the etched top foil surfaces 44 and 46.

The residual ridged foil is particularly advantageous for bonding to electrical components such as the resistors described herein. Details of typical ridge formation can be found in the book "Tab Technolo High Density Interconnections" by Diakaon.
gy Tackles High Density Engineering
A paper entitled Terconnecttona Input (ICl
eatronia Packaging and Pro
duction published December 11984) pages 34-3
It is described on page 9. Although specific means for forming the ridges have been described above, it is within the scope of the present invention to use any other desired manufacturing method, such as a machine, to form the ridges.

A barrier layer 50 is then preferably applied to the surface of the ridge, as illustrated in FIG. 3B. If desired, one barrier layer may cover all or part of the remaining surfaces 44 and 46 of the foil. Note that the barrier layer is illustrated as extending down over portions 52 and 54 of the ridge. A barrier layer is provided to prevent diffusion between the copper layer and the noble metal coated on the surface of the barrier layer as described herein. Additionally, the barrier layer facilitates the bonding of the noble metal to the selected copper layer surface. The material selected for the barrier layer may be selected from the group including nickel, titanium, boron nitride and alloys thereof. It is within the scope of the present invention to use any other barrier material suitable to prevent interdiffusion of the selected metal grains.

The barrier layer may be coated on the surface of each ridge by any desired method, such as electrodeposition, and may be coated on the remainder of the copper layer if desired.

As illustrated in FIG. 30, the barrier layer is then preferably coated with a noble metal layer 56 of a material such as gold, platinum, silver, palladium, and alloys thereof.

The precious metal is coated onto the barrier using any desired method such as electrodeposition.

After forming the conductive circuit components, significant cost is incurred in the application of electrical resistors. As previously mentioned, they typically require electrical inspection and laser ablation when formed by thick film paste application. The present invention discloses a unique method of making a resistor that is relatively inexpensive and easily reproducible. In particular, the die cut paper foil antibodies are attached to the raised portions of the circuit components by any bonding method, such as conventional thermocompression bonding. The resistor foil is preferably made by conventional metal rolling methods, and the thickness can be controlled to very fine tolerances. Additionally, the width of the foil can be precisely controlled by M-tight molding. Resistors made from foil provide highly reproducible and precise electrical resistance values because they are amenable to extremely precise geometrical design, as well as precise compositional control. It is also within the scope of the present invention to form the resistor by photolithography as described herein.

Referring to FIG. 4, there is illustrated an electrically conductive circuit composite 60 having a strip 62 of resistive foil attached thereto. The circuit is essentially the same as illustrated in FIG.
It is connected by 2. It is also within the scope of the present invention to form circuit composites using adhesives of the type described with respect to the embodiment illustrated in FIG. Ridges 40 and 42
is coated with a barrier layer 50 and a noble metal layer 56.

The resistor foil 62 may be formed from a high electrical resistance alloy that is preferably malleable and has reasonably high strength. The resistance value of the material is circular mil (circular mil).
preferably from about 100 to about 10,000 per m1l)-ft. Examples of suitable materials consist essentially of iron-based alloys, nickel-based alloys and copper-based alloys. A particularly useful alloy is the one manufactured by Driver-Harr.
is Oo, )'s product Nichrome OA (Nichrome
It is a nickel-chromium-iron alloy such as e). The foil may be rolled to very thin values, generally greater than about 1 mil thick. It is within the scope of the present invention to use conductor wires that may have diameters as large as about 1 mil. Preferably, the material is malleable in order to roll the foil to the desired thickness. It is important that it be strong enough to be easily handled after it is formed.

5, a top view of circuit arrangement 60 illustrating possible geometries suitable for resistive configuration 62 is illustrated therein. The resistive end 64 coupled to the gold coating on the ridges 40 and 42 is preferably coated with the same precious metal material as the coating 56. The resistive foil strip is bonded to the noble metal layer on the ridges by any desired technique, such as thermocompression bonding, which is typically used in automated tape bonding methods.

The ends of the resistive tape that are bonded to the ridges are bonded to provide a good bond while controlling the final electrical resistance of the foil.
It may be wider than the rest of the tape.

With regard to FIGS. 6A to 6E, the examples shown in FIG.
The steps in forming a multilayer circuit using the basic ceramic-glass-copper foil laminate structure described herein are illustrated. A reference number marked with a ““” is essentially the same as the part described herein with the unmarked reference number.

Referring to FIG. 6A, the first ceramic substrate 12'' is first coated or applied as a top coat with bonding material 16# on both outer surfaces 70 and T2 to form a top coated substrate 74. The medicated substrate is processed to form an arbitrary number of through holes 76 in desired positions or patterns as shown in Fig. 6B.The through holes may be formed by any desired method such as laser drilling. Then, as shown in Figure 6C, the through holes may be plated with conventional conductive paste, solid conductive wire, or by methods such as electroless plating and/or electrodeposition, and then soldered. Conductor 78 by filling with a conductor such as
You can fill it with A first layer 14' of deoxidized or oxygen-free copper foil is placed over top layer 16#.

The resulting composite 80 is then heated to the bonding temperature while pressing the foil layer against the glass substrate N16' at a pressure of about 50 to about 300 psi.

It is also within the scope of the invention to replace the overcoat with a thin, essentially porous glass preform of the same composition. The glass preform may be bonded to either the foil or the substrate, or alternatively may be placed between the foil and the substrate. The stacked layers are then bonded together by applying heat and pressure. The through holes may be formed after forming the bonded layers.

If necessary, the use of deoxidized or oxygen-free copper alloy foil in conjunction with a moderate vacuum will prevent bubble formation in the foil on the sealing glass as described herein.

The desired circuit portions may then be formed into the foil 14'' using conventional techniques such as photo-etching.

The resulting structure 82, as illustrated in FIG. 6D, may be stacked with any number of similarly formed structures. For example, the structure 84 includes a second ceramic substrate 75, a glass 16' and a second layer of copper foil 77, preferably a first foil 1
Consists of a second layer of copper foil made of the same material selected as #4. The structure 84 overlaps the structure 82 and the glass 16
’ may be used to join. If desired, additional glass layers, such as preforms of the desired glass composition, may be placed between the structures to form a suitable bond and at the same time electrically insulate the metal layers from each other. The thickness of the glass may be given. Structures 82 and 84 can then be pressed together and subjected to glass sealing temperatures in excess of about 500°C to form multilayer circuit portion 85 as shown in Figure 6E. If desired, conductive material may extend from the through hole and contact intermediate circuit components as desired. Additionally, several additional structures similar to structures 82 and 84 may be stacked in a multilayer circuit section to form any desired number of layers. The pins may also be brazed to exposed circuit portions for interconnection with other electronic devices.

7A-7D, which illustrate equipment for alternative methods similar to the steps illustrated in FIGS. 6A-6D for forming the multilayer circuit structure 109 of FIG. 7D. ing. FIG. 7A shows a structure 86 formed from a ceramic substrate 88 essentially the same as substrate 12 and a glass layer 90.
is exemplified. A glass coating or preform 90 of essentially the same composition as glass 16 is applied to both outer surfaces 92 and 94 of substrate 880. As explained above, the glass may be a solid, poreless preform bonded to or disposed adjacent to the substrate. The resulting structure 86t may then be further processed with at least two spears.

7B, any desired number of through holes 96 are formed through the glass and ceramic substrate using any method such as laser drilling. The holes are filled with a conductive material 91 such as glass steel paste or solid metal or alloy NO as described herein.

Next, the eyebrows 100 and 102 of deoxidized or oxygen-free copper or copper alloy foil selected from the same material as the foil 14 are applied to the glass layer 90.
join to. The glass layer may be an essentially porous preform bonded to the foil layers prior to placing the foil layers on the substrate. The copper foil layer is then etched using conventional techniques to form circuit components of the desired shape, as illustrated by the example structure 104 of FIG. 7B.

Structure 86 of FIG. 7A may alternatively be fabricated to form structure 106 as shown in FIG. 70. In this embodiment, the through holes 107 are first formed by any desired manufacturing method, such as laser drilling or stamping. The through-holes 107 are then filled with a conductor 108, such as a conductive paste, a solid wire or plate, or, if desired, an electrical conductor, such as a solder as described herein.

The structures 104 and 106 may be stacked one on top of the other such that one structure 104 is between two structures 106. The layered structure is then heated and pressed together to give 3g
7. A porous composite 109 as shown in Figure 7D is formed. If desired, additional glass preforms can be added to structures 104 and 1.
It may be placed between 06 and 06. An advantage of forming different structures 104 and 106 is that the separate structure, 106, does not require a copper layer application or etching step. Although the three structures tm are stacked to form a multilayer circuit complex 109, any desired number of alternating layers may be used to form a complex having any desired number of circuit layers. 1
Stacking 04 and 106 is also within the scope of this invention.

8A-8D, there is illustrated an alternative method for making a multilayer circuit composite of the type illustrated in FIG. 7D. In FIG. 8A, structure 118 includes a ceramic substrate B2O. of substantially the same material as substrate 12. and a bonding glass 122 having substantially the same composition and structural characteristics as glass 16. Glass 16 is applied as a coating or preform to both surfaces of the substrate. This basic structure can now be processed in at least two different ways.

The first is to heat the structure by applying deoxidized or oxygen-free copper foil layers 124 and 126, as shown in FIG. 8B, and pressing the foil layers against a bonding glass as described herein. bonding to the glass layer 122. It is also within the scope of the invention to provide glass preforms bonded to their foil layers.

With reference to FIG. 80, copper foil layers 124 and 126 may be etched by any conventional technique to form circuit portions 128 and 130 of any desired shape. A through hole 132 may then be formed through the foil-glass-substrate structure 134 by any conventional technique. The through hole 132 is filled with a conductive material 133 such as conductive paste or solid wire.
It may be filled or plated and filled with a conductive material such as copper if desired. Through hole 136 may be filled with a conductive material 137 that is the same as or similar to conductor 133 .

In a preferred embodiment, two structures 118 are structure 1
340 are stacked on both sides and combined. The stack is pressurized and heated to a bonding temperature, thereby forming a multilayer composite of the type shown in Figure 7D. It is also within the scope of the present invention to stack any number of structures 134 and 118 in an alternating manner to form a multilayer composite having any number of circuit layers.

9A-91F, there is illustrated a series of steps for bonding multiple glass substrates, circuit layers to assemble a multilayer circuit, and a unique method for bonding all circuit foil layers together. FIG. 9A illustrates a first ceramic substrate 170 having a bonding glass 176 coating or overlay on opposite sides 172 and 174. Glass pre-molded body 1
Replacing the lid at 76 also falls within the scope of the present invention. The next glass coated substrate 178 has a number of through holes 180 formed therethrough by any desired technique, such as stamping or laser drilling. The resulting structure 181 is illustrated in FIG. 9B.

As shown in Figure 90, deoxidized or oxygen-containing! ! There is no layer of copper foil 182 on the glass inscription on the underside of the base.
It is preferable that the

A metal wire 184 having a length substantially equal to the length of through holes 180 is placed into the holes. This step may be accomplished by inserting a metal wire into the through hole and cutting m essentially over the top of the substrate after the wire is in electrical contact with the foil layer 182. In order to ensure that the wire is inserted into the through-hole during the manufacturing process, it is preferred that the wire has a diameter that is substantially smaller than the diameter of the through-hole. For example, if the diameter of the through hole is about 5 mils, the diameter of the metal wire should be about 3 to
About 4 mils is sufficient. These sizes are just examples;
Foil layers 182 and 18 whose lines are located at each end of the through hole
It may have any diameter compared to the diameter of the through hole as long as it is connected in contact with 6'.

As illustrated in FIG. 9D, the next step is to place a foil layer 186 on top of the glass coated substrate. foil 18
Layers 2 and 186 may be permanently attached to the coated substrate by heating composite 188 to a temperature in the range of about 600 to about 1000C. Composite 188 may be subjected to a lamination pressure of less than about 300 psi to promote adhesion of the substrate to the foil.

The metal wire 184 is preferably selected from a high expansion alloy, preferably having an engineering AO8 of about 60%, which is about 600% as required to bond the glass to the foil layer and the substrate.
It becomes a semi-solid state at processing temperatures in the range of ~1000<0>C. The material of the metal wire is further selected to have from about 2 to about 40 volumes of liquid in the semi-solid state, preferably from 5 to about 25 volumes of liquid. The liquid phase of the metal wire connects the wire to the foil layer 18.
2 and 186. It is important that the metal wire does not sag in the through-hole to the extent that it no longer makes contact with one or both of the foil layers.

``Metal parts joining method'' by Pryor et al.
A Method of, Toining Meta
This unique means of interconnecting two foil layers separated by a coated substrate utilizes the higher coefficient of thermal expansion ( OTK), approximately 160X10
- 0 of the ceramic substrate compared to fin/in/'Q
TIC is substantially lower, approximately 50 X I F' in
/in/°C. The a'rmO difference between the ceramic and the metal wire results in even larger linear expansion of the metal wire compared to the through hole 0@expansion. The metal wire is thus pressed against the foil layer as long as the rate of sagging is kept within limits determined by the particular material system being processed. Metal I! Braze the two foil layers,
After cooling the composite, the bonded wires are under tension. The material for the metal wire is therefore selected to have sufficient malleability after exposure to the required bonding temperature range for the particular material system.

Process metal wire: about 2 to about 13% Sn, about 0.2 to about 4% P1, about 5 to about 15% SB, about 3 to about 6% Si, about 4 to about 12% As , and mixtures thereof; up to about 4% iron; and a balance copper.

An example of an alloy that can form metal lines suitable for the environments described herein is 8% Sn, about 0.025% P1, about 2% F.
It is a copper alloy containing e and the remaining copper.

Other examples are Ou and about 2% P, Ou and about 12% sb.

These are combinations of O and about 5% Si, O and about 9% As, and ternary or quaternary combinations of these alloys. It is within the scope of the present invention to use any other alloy threads that have the desired high electrical conductivity in conjunction with the described semi-solid state at the processing temperature.

91st! Referring to Figure i, composite 188 has foil layers 182 and 184 on which are formed circuit portions having any desired shape formed using a desired technique such as photolithography.

Two or more of the obtained structures 190 may be stacked with a structure 181 placed between them as illustrated in FIG. 9B. The result is a multilayer composite 19 as shown in Figure 9F.
It becomes 2.

The complex includes one complex 1 above one complex 190.
By placing 81, you can reassemble it, but it's gold [! 18
A metal wire 194e, which may be selected from the same material as in No. 4, is inserted into the through hole 180. As described herein, the metal wire is cut to have the same length as the through hole 180. A second composite 190 is then stacked on top of composite 181 and the stacked composite is heated to a bonding temperature to form multilayer composite 192. Although the composite has been described as having a lower and upper arrangement, it is within the scope of this invention to arrange the members in any position during their assembly.

2, there is illustrated a ceramic side braze package 150 incorporating a deoxidized or oxygen-free copper or copper alloy circuit foil 152 of the type described herein. Ceramic layer 15 is formed by a bonding or sealing glass 155 of the same composition as the glass 16 described above.
4 and 156 is preferable. The glass can be applied as a slurry to the sealing surface of the ceramic substrate by dipping or spraying. Additionally, the sealing glass may be a solid, pore-free preform placed between the foil and the ceramic layer. Ceramic substrate 157 is preferably formed from a ceramic layer 158 bonded to intermediate ceramic layer 156 by any conventional technique, such as heating to a bonding temperature. The ceramic layer 156 has a hollow center portion 16 to form a cavity 163.
1. A shaped metallization layer 159 is coated on the surface of layer 158 within the confined interior of cavity 163 .

The metallization layer can be formed by any method such as applying tungsten or silicate manganese powder and heating it to sintering temperatures. Sealing ring 160 is ceramic layer 15
4 is located on the outer surface 162 of 4. Preferably, the sealing ring is a deoxidized or oxygen-free copper or copper alloy foil, which is sealed to the ceramic 154 by a glass 155 with a glass seal associated with the circuit foil layer 152. Conductive wires 164 and 166 are soldered to the outwardly extending portions of foil layer 152. A lid 169 of any desired material, such as a metal or alloy, may be sealed to the seal ring 160 using any desired technique, such as soldering.

The ceramic layer 154 is made with a hollow center portion 165 on which an electronic or semiconductor device 167 is disposed and leads from the device 167 to the circuit foil 15.
This allows it to be combined into 2.

A method of making side braze package 150 may include first creating ceramic substrate 157 by bonding ceramic layers 156 and 158 together in a high temperature environment of approximately 1500°C. At the same time, the molded metallization layer 1
59 is sintered within the cavity 161. A circuit 152 is then placed between the substrate 157 and the ceramic layer 154. also,#
! The sealing ring 160t may be fixed to the ceramic layer 154 by sealing glass using the same bonding method as for the foil 152. Electronic components 167 are attached to metallization layer 159 and conductive wires are bonded to device 167 and the ends of circuit foil 152. Finally, the lid 169 is sealed to the sealing ring 160.

It is clear that the present invention provides a hybrid and multilayer circuit which fully satisfies the objects, means and advantages set forth above. Although the invention has been described in conjunction with specific embodiments thereof, it is obvious that many changes and modifications will become apparent to those skilled in the art in light of the foregoing description. Accordingly, all such changes and modifications are intended to fall within the scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view illustrating a copper alloy layer bonded to a ceramic substrate with a bonding glass. FIG. 2 is a schematic cross-sectional view illustrating a side braze package according to the invention. 3A-30 are schematic cross-sectional views illustrating a series of steps for etching ridges in a copper alloy layer and coating those ridges with a noble metal coating. FIG. 4 is a schematic cross-sectional view of a resistive tape bonded between two coated ridges. FIG. 5 is a top view of the apparatus of FIG. 4. 6A to 6E are schematic cross-sectional views illustrating a series of steps for forming a multilayer circuit. FIGS. 7A to 7D are schematic cross-sectional views illustrating another series of steps for forming a multilayer circuit. FIGS. 8A to 8D are schematic cross-sectional views illustrating yet another series of steps for forming a multilayer circuit. FIGS. 9A to 9P are schematic cross-sectional views illustrating yet another series of steps for forming a multilayer circuit. DESCRIPTION OF SYMBOLS 12... Base body, 14... Clad layer, 16... Glass coating, 62... Resistor band, 40.42... Protrusion part, 50... Barrier layer, 56... Precious metal layer .

Claims (1)

Claims: (1) providing a ceramic substrate (12) and providing a layer (14) of a copper alloy foil selected from the group consisting of deoxidized copper alloys and oxygen-free copper alloys;
providing a bonding glass (16) forming a flowable object at a lower temperature, a layer of bonding glass (16) being disposed between said substrate (12) and a layer of foil (14); and Approximately 100% of the composite consisting of the foil layer, glass layer and substrate was
A method for manufacturing a circuit composite (10), characterized in that it consists of the steps of firing under reducing conditions at a temperature below 0° C., thereby bonding the foil layer to the substrate by the glass layer. . 2. A method according to claim 1, characterized by the step of: (2) selecting the bonding glass (16) from the group consisting of silicate, borosilicate, phosphate and zinc borosilicate glasses. (3) The method according to item 2, further comprising the step of forming a circuit on the layer of copper alloy foil. (4) The step of disposing the layer of bonding glass includes the step of providing a substantially porous bonding glass preform and disposing the preform between the substrate and the foil layer. The method according to item 2 above. (5) disposing a layer of bonding glass comprises mixing particles of bonding glass with a binder and a vehicle to form a glass paste and applying said glass paste to at least one surface of said ceramic substrate (12); (18) The method according to item 2, further comprising the step of coating and sintering a bonding glass onto the surface of the substrate. (6) providing a ceramic substrate (12), bonding a copper alloy foil layer (14) to said substrate, etching away selected portions of the foil layer and forming at least two ridges (40), (42); an electrically conductive circuit characterized by the steps of forming a strip of resistive metal alloy foil (62), and bonding an end of the resistive foil strip to the ridge to provide an electrical connection. How to combine resistance to. (7) The method according to item 6, characterized by the step of selecting a resistant metal alloy from the group consisting of nickel-based alloys, iron-based alloys, and copper-based alloys. (8) providing a barrier material from the group consisting of nickel, titanium, boron nitride and alloys thereof; and plating a layer of said barrier material on at least a portion of each of the ridges. The method described in section. 9. The method of claim 8, further comprising plating the layer of barrier material with a noble metal selected from the group consisting of gold, palladium, silver, platinum and alloys thereof. (10) The method according to item 9, characterized by the step of selecting the copper alloy foil from the group consisting of deoxidized copper alloys and oxygen-free copper alloys. (11) bonding the layer of copper foil to the ceramic substrate,
providing a bonding glass that forms a flowable object at temperatures below about 1000°C, and comprising steps of bonding said layer of copper alloy foil to said substrate by said layer of bonding glass. The method according to item 10 above. (12) The method according to item 11, characterized by the step of selecting the bonding glass from the group consisting of silicate, borosilicate, phosphate, and borosilicate glasses. (13) a ceramic substrate (12), a layer of copper alloy foil (14) selected from the group consisting of oxygen-free deoxidized copper alloys;
), and a bonding glass layer (16) forming a flowable body at temperatures below about 1000° C. and bonding the ceramic substrate to the alloy foil layer (1).
0). 14. The circuit composite according to claim 13, wherein the bonding glass is selected from the group consisting of silicate, borosilicate, phosphate and zinc borosilicate glasses. (15) The ceramic substrate is selected from the group consisting of alumina, silica, silicon carbide, zirconia, beryllia, alumina silicate, zircon, and mixtures thereof with a purity greater than about 90%. 15. The circuit complex according to item 14. (16) The circuit composite according to item 15, wherein the copper alloy foil has a circuit pattern thereon. (17) a ceramic substrate (12), a copper foil layer (14), the substrate with the foil layer, at least two raised portions (40);
(42) and further characterized by means for bonding to a foil layer having a conductive circuit formed thereon, and a strip of resistive metal alloy foil (62) having an end bonded to said ridge. circuit complex. (18) The circuit composite according to item 17, wherein the resistive metal alloy is selected from the group consisting of nickel-based alloys, iron-based alloys, and copper-based alloys. (19) further comprising a layer of barrier material plated on at least a portion of each of the ridges, wherein the barrier material is selected from the group consisting of nickel, titanium, boron nitride, and alloys thereof. 19. The circuit complex according to item 18 above. (20) The method further comprising a layer of a noble metal coated on the layer of barrier material, wherein the noble metal is selected from the group consisting of gold, platinum, silver, palladium and alloys thereof. 20. The circuit complex according to item 19. (21) The circuit composite according to item 20, wherein the copper alloy foil is selected from the group consisting of deoxidized copper alloys and oxygen-free copper alloys. (22) The circuit composite according to item 21, wherein the bonding means is a glass selected from the group consisting of silicate, borosilicate, phosphate and zinc borosilicate glasses. (23) a first ceramic substrate (12″), a first layer of copper alloy foil (14″), and a bonding glass (16″) forming a body flowable at temperatures below about 1000°C; first and second layers of glass for bonding the first layer of copper alloy foil to the first surface of the first substrate, respectively. ), (72) a bonding glass (16″) disposed on at least one second ceramic substrate (75) having at least one third layer of said bonding glass on its first surface. a second ceramic substrate (75), the second ceramic substrate (75)
5) at least one second layer of copper alloy foil bonded to (
77), characterized in that the first and second layers of copper alloy foil are selected from the group consisting of oxygen-free copper alloy and deoxidized copper alloy, and the copper foil is bonded thereon. The first and second ceramic substrates are stacked and bonded to each other with a second layer of bonding glass such that a second layer of copper alloy foil is bonded to a second surface of the first substrate. A multilayer circuit complex (85), characterized in that the multilayer circuit complex (85) is disposed adjacent to. (24) further comprising at least one through hole (76) extending through the first and second substrates and the layer of bonding material, the conductor (78) being disposed within the at least one through hole; 24. The multilayer circuit composite according to item 23, wherein the multilayer circuit composite is arranged to electrically connect the first layer and the second layer. (25) The general composition of the bonding glass is MO-B_2O_3-
SiO_2 (in the formula MO=Al_2O_3, BaO, Ca
O, ZrO_2, ZnO, Na_2O, SrO, K_2
25. The multilayer circuit composite according to claim 24, characterized in that the multilayer circuit composite is a borosilicate glass of O and mixtures thereof. (26) At least the first and second ceramic substrates (1
2″), (75) and at least the first and second layers (14) of copper alloy foil selected from the group consisting of deoxidized copper alloys and oxygen-free copper alloys
″), (77) and providing a bonding glass (16″) forming an object flowable at temperatures below about 1000° C., and combining the first and second layers of the bonding glass with the first ceramic. a third layer of bonding glass is disposed on at least one surface of the ceramic substrate (75) and a third layer of bonding glass is disposed on the first surface of the first substrate; disposing at least the first layer of foil on the first layer of bonding glass; disposing the second layer of foil on the third layer of bonding glass disposed on the surface of the second substrate; forming a circuit in the first and second layers of the foil, overlaying the first substrate on the second substrate, and disposing the second layer of the foil between the first and second substrates; and firing the composite of the first and second substrates under reducing conditions, whereby a layer of bonding glass bonds the substrate and foil layers to the multilayer circuit composite (85). (27) at least one through hole (76) through the first and second substrates and a layer of bonding glass disposed thereon;
and filling the at least one through hole with an electrically conductive material (78) to electrically couple at least the first and second layers of foil.
The method described in Section 6. (28) providing a bonding glass comprising disposing at least one essentially non-porous preform of bonding glass between each substrate surface and an adjacent thin layer; 28. The method of claim 27, including the steps of bonding a body to the surface and the foil layer. (29) providing at least first, second and third ceramic substrates (88); at least first and second layers of copper alloy foil selected from the group consisting of deoxidized copper alloys and oxygen-free copper alloys; a bonding glass (90) forming a flowable body at temperatures below about 1000°C;
02) on both sides of the first ceramic substrate, a third layer of the bonding glass on at least one surface of the second ceramic substrate, and a fourth layer of the bonding glass disposed on at least one surface of the third ceramic substrate; at least the first and second layers of foil disposed on opposite sides of the first substrate; the first and second layers of foil; The combination of the first and second layers of glass and the first substrate is fired under reducing conditions such that the first and second layers of glass are the same as the first and second layers of foil. forming a circuit in the first and second layers of foil, bonding the first and second layers to opposite sides of the first substrate; and a third base such that a third layer of glass disposed on the second substrate faces the first layer of foil and a third layer of glass disposed on the third substrate four layers opposite the second layer of foil, and heating the assembly of the first, second and third substrates;
A method for manufacturing a multiphase circuit composite (109) comprising steps, whereby the bonding glass layer bonds the substrate and the foil layer into a multiphase circuit composite (109). (30) The steps to provide the bonding glass (90) have the general composition MO-B_2O_3-SiO_3 (wherein MO=A
l_2O_3, BaO, CaO, ZrO_2, ZnO,
30. A method according to claim 29, characterized in that it comprises the step of providing the bonding glass from a borosilicate glass (Na_2O, SrO, K_2O or mixtures thereof). (31) drilling at least one first through hole (96) through the first substrate and the foil layer bonded thereto; and at least one second through hole (107) through the second substrate and the glass layer disposed opposite thereto; ), drilling at least one third through hole through the third substrate and the glass layer disposed opposite thereto, and filling the at least first, second and third through holes with a conductive material; 31. The method of claim 30, further comprising the steps of electrically coupling at least the first and second layers of the foil. (32) providing a bonding glass phase in the form of a plurality of essentially non-porous preforms and heating the assembly to bond the glass preforms to the foil layer and the substrate surface to create a porous circuit; 32. The method of claim 31, comprising the steps of: (33) A ceramic substrate (157) having a cavity therein, a copper alloy circuit foil (152) having a first surface bonded to the ceramic substrate, the group consisting of an oxygen-free copper alloy and a deoxidized copper alloy. a copper alloy circuit foil (152) selected from a ceramic layer (152) disposed on a second surface of said circuit foil;
54) a first layer of bonding glass (155) between the ceramic substrate and a first surface of the circuit foil; and a bonding glass (155) between the ceramic layer and a second surface of the circuit foil; 15
5) a second layer for bonding the foil between the ceramic layer and the ceramic substrate;
0). (34) The bonding glass (155) has a general composition MO-B_
2O_3-SiO_2 (in the formula, MO=Al_2O_3,
BaO, CaO, ZrO_2, ZnO, Na_2O, S
34. The side brazed package according to claim 33, characterized in that it is a borosilicate glass of 30% oxidation (rO, K_2O or mixtures thereof). (35) The side braze package of claim 34, further comprising a sealing ring (152) bonded to the ceramic layer with a third layer (160) of bonding glass. 36. The side braze package of claim 35, further comprising a conductive wire (164) coupled to the circuit foil.