DE1953678A1 - Circuit carriers for electrical circuit elements and components, as well as processes for its production - Google Patents

Description

and components, as well as processes for their production

The invention relates to a formwork support for electrical circuit elements and components, in particular for connecting diodes, transistors and monolithic circuits, as well as a method for their production

In the manufacture of electrical circuits, one usually connects the circuit elements e.g. resistors, Capacitors, diodes and transistors, by soldering their connection wires to a printed circuit board. The card is made of insulating material, has a thickness of approx. 1 mm, and is provided with a conductive foil on one or both sides. The latter is in using a mask and etching technique taken the form of a circuit network or a conductive pattern. Is the card on both sides with a conductive If the pattern is visible, it is drilled through at suitable points and a conductive connection is provided according to a known electrolysis process.

With the invention of integrated circuits that have a large number of circuit elements on a small tree,

00 * 8 U / 1298

the printed circuit cards must have considerably more connectivity options. In order to meet these requirements Z ₁₁ , the circuit cards are provided with a large number of conductive layers. It is also possible to reduce the width of each individual conductor and thereby gain space for more conductors. However, this poses two problems. Firstly, the connection areas must be adapted to the connections of the tieη circuit elements enclosed in a housing and thus take up a lot of space, and secondly, the resistance value of the individual conductors can become too high if their length is not reduced at the same time.

By making a circuit network or conductive pattern with the width and length of the Head is adapted to the connection areas of not introduced into the housing circuit elements and are used in the insulating and connecting materials that a Allowing a direct connection between the circuit network and the respective circuit element, a circuit carrier can be achieved in which the available tree is fully utilized. In addition, the structure can be changed at will because the manufacturing cost of the novel Circuit patterns are relatively low.

By using semiconductor components that are not placed in housings or capsules, you can however, problems arise with regard to the protection and heat dissipation of these elements.

The main aim of the invention is a circuit carrier or a card for a printed circuit in which the available tree is optimally used and in which for several

- 3 -009818/1298

Circuit elements or üalbleiterbauteile a common Protective or heat dissipation surface can be provided *

Another object of the invention is manufacture a conductive pattern with high electrical conductivity, great metallurgical stability against 'the connecting metals, high corrosion resistance, as well as perfect Adhesion to the card and the adhesive layers used to attach the individual semiconductor components to the film. According to the invention, a conductive pattern is also to be created that is easy to manufacture and by means of ultrasound is weldable

The circuit carrier according to the invention is distinguished in particular by a flexible sheet of insulating material, which is provided with an electrically conductive pattern and on the .at least a single circuit element is brought into permanent contact with the conductive pattern.

J) a the insulating material or the carrier provided with the conductive pattern consists of a flexible film the surface of the circuit elements facing away from the film, regardless of existing thickness fluctuations of the elements, cemented or glued onto a common plate. Thanks to the flexibility of the foil, different games play Strengths don't matter. The plate serves as a protective and / or heat dissipation surface for the entire or any part of the circuit carrier and for this reason not every individual elements can be provided with a housing and if all or some of the elements are placed in capsules s ~ in <i, this has the advantage that, due to the improved heat dissipation, they can be arranged closer to one another and a lot of space can be saved in this way.

- 4 -009811 / 1 * 98

According to a further development of the invention are Circuit elements attached to the circuit carrier by means of an adhesive layer · This has the advantage that during the fastening of the element, the KIe temittelschicht is pressed out and wraps around the edges of the elements and so can encapsulate the surface of the circuit element provided with the electrical connections. Just this one The element surface must be protected most urgently from the surrounding atmosphere. That way needs Due to the adhesive layer, no special housing or capsule should be provided for the individual elements. The other surfaces of the element can be protected by a known passivation method.

The invention further relates to a method for manufacturing such a device, which is very well suited for automatic series production of circuit carriers. This method is characterized in particular by this from providing a thin, flexible sheet of insulating material with a conductive oyster, the individual electrical circuit elements remaining in a certain position attached to the foil and then brings the connection points of the individual elements into contact with the conductive pattern

Further details, features and advantages of the invention emerge from the following description. On the Drawing the invention is shown by way of example, namely show Fig. 1 is a perspective partially sectioned view an embodiment of the circuit carrier according to the

Invention with provided on one side of the card

Ladders, Fig. 2 is a perspective partially sectioned view a card with - ^ pus arranged on both sides and with

009818/1298

connections made between the side surfaces,

3 shows a plan view of a circuit carrier according to the invention with semiconductor components fastened thereon,

4 shows a cross section through another embodiment of a circuit carrier attached to a heat dissipation plate,

^ 'ig. 5 shows a plan view of a modified embodiment of the circuit board,

6 shows a cross-section through the circuit carrier from Hg. 5 in a plane VI-VI,

7 shows a circuit carrier with a carrier substrate, and

^ ig. 8 shows a modified embodiment of the circuit carrier from ^ 'ig. 7 without carrier substrate.

Hg. 1 shows a circuit carrier with a transparent film 10 made of insulating material, which has conductors 12 on one side in the form of an electrically conductive pattern. On the other side of the film 10, semiconductor components 11, for example silicon wafers, are connected to contact areas 13. The contact areas 13 are connected to the conductive pattern of the first side of the foil

FIG. 2 shows a circuit carrier in which the film 10 is provided with conductors 12 on both sides. The ladder 12 on the different sides of the film are connected to one another via continuous connections 14. Like the figure shows, cross conductors can also be provided

A particularly suitable insulating material for the film is Jfolyatmid, especially the polyimide available under the trade name "KAPTON".

009818/1298

This material has a great flexibility and can be treated ⁰ C at temperatures up to 40O. The foils made of this material can be coated with a metal layer with high electrical conductivity and high corrosion resistance, which is suitable for direct connection with the contact areas of the circuit elements and can then be reinforced by an electrolyte coating. For perfect adhesion between the gold layer and the foil, an active metal, for example Cr or Ti, is introduced between the foil and the old layer. It can also be vapor-deposited or dusted. Other metals suitable for the metal layer are Al, Cr, Mb, Ti and W.

The connections drawn in Fig. 2 between the conductors on the two sides of the film can be made by making holes in the film or by locally Break the foil insulation at certain points and then arrange a galvanic connection penetrating the foil by means of vapor deposition, sputtering, electrolysis or a combination of these processes For example, the holes can be formed by blowing a thin jet of abrasive powder through a metal mask, by alkaline etching or by spark machining. Carefully controlled spark or adhesive discharge can break the foil insulation in places. In the latter case, the conductivity can be increased through the broken layer by means of a gold layer applied by electrolysis.

The conductive connection between the semiconductor components and the conductive pattern is obtained by removing the metal foil layer and the contact areas of the semiconductor components.

- 7-009811 / 1298

parts press against each other and for example by ultrasonic vibration under heat or laser beam action Supplies energy. The use of a transparent film makes it easier to arrange and align the semiconductor components with respect to the conductive pattern of the film. at Using laser radiation with visible light, only the metal areas absorb energy.

Should be the connection between the conductive pattern on the foil and a semiconductor component at the holes are made in the foil, it is advantageous to use a% gel, e.g. made of Au or Al, which is applied simultaneously to the conductive metal pattern of the foil and the Contact area of the conductor component is pressed on and supplies energy in one of the ways described.

u'ig. 3 shows a circuit carrier according to the invention, on which lead components 15 are arranged, whose contact areas 16 are connected to the conductive pattern applied to the film 10 · On a tape is the posture bracket with connection contact surfaces 17 for connection to external circuits.

As described above, it is important that the circuit board, and in particular the separate circuit and the semiconductor components of the circuit board have adequate heat dissipation. This is according to the invention achieved by placing the entire circuit on a substrate or a plate made of a material that conducts heat well, e.g. Al or A ^ Oz ceramics glued or cemented on becomes, or the circuit or the circuit elements

00981t / 1218

in an environment that conducts heat well, e.g. epoxy resin with an addition of ALjOy powder or a similar compound be stored or encapsulated. The circuit is advantageously glued to an anodized aluminum plate. To further improve the thermal conductivity between the circuit containing the semiconductor components and the Al plate To increase, plastic is used for gluing, which is mixed with a metal powder, e.g. made of Ag. The advantage the flexibility of the foil provided with the conductive pattern is increased by gluing on the circuit carrier a heat dissipation plate can only be seen particularly clearly · "I Due to the flexibility of the foil, the circuit carrier namely can be easily glued to a flat surface, regardless of the thickness of the individual semiconductor components all elements provided on one side of the film are in contact with the heat dissipation surface because the film which absorbs height differences thanks to its flexibility.

In the case of a small semiconductor component with an area of less than 1 mm, the semiconductor body must be on a Metal plates with an area of at least 1 mm are soldered or welded to ensure adequate heat dissipation To achieve this, this heat dissipation plate can then be glued onto a large, common heat dissipation plate will·

Fig. 4 shows a ^ chaltungsträger which is adhered to a heat transfer plate 18 made of aluminum, which all albleiterbauteilen ⁿ 15 of the circuit carrier is in common. Since the film is flexible 10, both the surfaces facing away from the film reach the Halbleiterbq _U tei3s and the film seist in contact with the heat transfer plate 18 made of aluminum. Those heads who are on the side of the for

009818/1298

Aluminum plate facing foil are arranged, must Of course, they can be provided with an electrically insulating layer if the adhesive used to attach the circuit carrier to the sheet is not sufficient for proper electrical insulation. The connecting foil 10 is around a band of the heat dissipation plate 18 bent around and on this curvature of the film, the terminal contact surfaces 17 are provided for the circuit carrier to this by simply plugging in the complete To connect the circuit carrier in a plug to external circuits.

When the üalbleiterbauteile are placed even between the heat transfer plate 18 made of aluminum and the film 10 15, (Fig. 4), there is effectively a casing for each ^u albleiterbauteil.

5 and 6 show a circuit carrier according to the invention with a film 10, which is used in particular for the connection of individual diodes, transistors or monolithic platelets. A semiconductor component 19 consists of a Si plate that is manufactured using planar technology and has diffusion areas 20, 21 of different conductivity types that form diodes, transistors or complete integrated circuits.The electrical contact for these areas is through metallized areas 22 on one side of the Ensures semiconductor wafer, which is provided with the exception of the areas 22 with an insulating oxide layer. The semiconductor die 19 is connected to a conductive pattern 23, 24 in contact, which is etched using the ^r hotowiderstandstechnik and applied to the film 10 of plastic. The contact is through metal supports

- 10 -

009813/1298

25 »26 ensured, made of solder, e.g. from SniPb or pure metal such as Au or Al. Furthermore, an adhesive layer 27 is introduced between the semiconductor component 19 and the film 10. This serves as attachment, as insulation, so that the conductors of the foil do not come into contact with the conductor component can, and also as a cover for the side of the semiconductor component provided with the contact areas.

Fig. 7 shows a flexible sheet 32, preferably made of "KAPTON" and having a conductive pattern 33 to 35 is provided with a silicon wafer 43 with n- and p-conductors attached to the film Areas as well as with a conductor 38 applied to a carrier or a base 31 is connected. That Conductive patterns can consist of a single layer of aluminum, chromium, molybdenum, titanium, or tungsten. In the embodiment shown, however, it consists of a multilayer composite. That of the flexible ones Layer 33 closest to the film is made of titanium, chromium, molybdenum or tungsten and has a Gold layer 34 covered, on which in turn a layer 35 made of chromium, molybdenum or tungsten is applied. The base 31 is preferably made of aluminum oxide

The guiding pattern still has contact conditions 37f 39 at those points where from the conductive pattern 33 to 35 to the conductors 38 on the carrier 31 or to the silicon wafer 43 a contact is to be established. The contact conditions 37 »39 exist on those Places where contact with the silicon wafer 43 is desired, made of gold or aluminum, and on

- 11 -

009811/1198

those points at which a connection to the base is to be created via the conductor 38 Gold. The silicon wafer 43 is glued to the flexible film 32 with the aid of a suitable adhesive 40 and attached in any way, e.g. by an adhesive or a soldering point 44, to the base 31

At the contact points, the silicon wafer 43 has a metal layer 41. The wafer is with the exception covered with an oxide layer 42 at the contact points

An insulating photoresist layer 36 is coated over the conductive pattern. The photoresist material Also serves as a mask if contact pads made of gold or aluminum are deposited by means of electrolysis.

Jf'ig. 8 shows a device according to FIG according to Fig. 7-

A foil 57 is provided with a conductive pattern 56, that- never mentioned above - either from a simple one Metal or a metal layer composite and covered with an insulating photoresistive layer 58 is. On the left side of the drawing is a contact pad 59 made of gold for a connection between the conductive pattern arranged on the film and a conductor provided on the carrier · On the On the right side of the drawing, a silicon wafer 51 can be seen, which is a diode, a transistor or a may contain monolithic circuit. This silicon wafer is provided with an insulating layer 52, which for example consists of silicon dioxide (SiO2). It also has a metal layer 53, which is on the outside of gold

- 12 009818/129 8

or aluminum, as well as a contact pad 55. It is attached to the film with the aid of an adhesive layer 54 attached, which also acts as a cover for the conductors and switching elements on the side of the silicon wafer facing the foil serves *

The silicon wafer is used as a contact metal Aluminum and in certain cases gold applied »Palladium-gold and gold compounds are used on thick film supports and gold on thin film carriers.

The gold and aluminum can be ultrasonically welded onto these areas. The contact pads on the contact areas of the base should preferably consist of gold; In contrast, both gold and aluminum can be used on the silicon wafers. In order to obtain a high level of metallurgical stability with respect to the terminal metals, aluminum is used for the contact pads in contact with the metallized silicon wafers. In this case , however, a connection point between the aluminum and the gold must be provided somewhere on the foil, which must not be metallurgically unstable, because otherwise brittle gold-aluminum connections can form.

Metals such as gold, molybdenum, tungsten and chromium have good corrosion resistance, but aluminum does not, ^ hrom, Molybdenum, titanium, tungsten and aluminum have good adhesion to the film and to the adhesive layer, But not gold «,

- 13 -

009818/1298

These metals can be easily deposited by a conventional vapor deposition and spraying process. Chrome and gold can also be relatively easily deposited by electrolysis · The various forms of the conductive pattern can ufsprühverfahren using metal masks in connection with vapor deposition and either ^A, or be applied by means of photoresist technology.

A circuit carrier according to the invention can for example can be produced in the following way: On those surfaces of the semiconductor that are covered with the foil in If you want to come into contact, an adhesive layer is applied, for example rolled on «Estiat has proven to be special Proven to be advantageous if the adhesive consists of 100 parts of the commercially available under the name "Epoy-Novolac D.E.N. 438 ", available epoxy resin, 101 parts of nadicmethyl anhydride and 1 part of S-methyl-benzyl-dimethyl-amine. After the adhesive has been applied to the semiconductor components, the latter are pressed against the film; arranging the elements is lightened when the film is transparent. When the component and film are pressed together, this becomes Adhesive squeezed away from the contact surfaces consisting of the supports. The conditions were previously through Dip-tinning the contact surfaces of the semiconductor components or by plating the foil contact surfaces. If the semiconductor components are precisely arranged, between the contact surfaces of the semiconductor components and the corresponding contact surfaces of the conductive pattern of the film by heating, soldering or ultrasonic vibration flawless electrical connection established.

- 14 -

009818/1298

Experience has shown that this is even possible when the adhesive is heated and has already started to solidify. After a flawless electrical connection has been established, the entire system is subjected to the heat treatment necessary to solidify the adhesive. The heat treatment may consist in that the whole Scnaltungsträger for two hours at a temperature τοη 95 ⁰ C, 4 hrs. Is maintained at 165 ⁰ C and 16 hrs. At 205 ⁰ C. After hardening, the circuit board can withstand large temperature changes. The adhesive has a high strength even at 315 ⁰ C. Furthermore, the adhesive layer has perfect insulation characteristics and, according to previous experience, only favorable properties in general with regard to the semiconductor components. If necessary, the circuit board can be glued or soldered onto a heat sink. However, if the conductive pattern of the plastic film is made of Cu, the heat dissipation through the conductive pattern is sufficient in many cases without a special heat dissipating surface being necessary.

With the help of the method described, the semiconductor components can easily be applied to the circuit carrier and an easy connection between the contact surfaces of the semiconductor components and the corresponding contact surfaces of the conductive pattern can be achieved. As described above, this is also obtained for the semiconductor components or at least for their most important surfaces a housing consisting of the applied adhesive layer, which is used in At least pressing the semiconductor components onto the film. partially is squeezed out and thereby forms a wall, which is the side facing the foil of the üalbleiterbauteiie surrounds. This wall, which adheres perfectly to both the film and the semiconductor component, forms a housing

- 15 -

009818/1298

for the semiconductor component, so that the individual semiconductor components do not have to be introduced into the housing or that / further introduction into the housing can be partially replaced _{by simply passivating the other surfaces of the tialbleiterba u.} This method is particularly suitable for automatic production, in which case the film is then produced in the form of a strip and the various areas are arranged along the strip.

For example, in the above description reference is made to the manufacture of circuits based on films are upset. However, the invention can also be used at a later date can be applied. Furthermore, the circuit carrier can be combined with plates made of A ^ O ^ ceramic, for example by means of Grid printing processes are provided with metallic conductors, resistors and capacitors. This allows the flexible connection foil as a connection between the semiconductor components and the elements of the printed circuit be used. You can also arrange some foils on top of one another and connect them to one another. The semiconductor components can also be attached to openings penetrating the plates.

- 16 009818/1298

Claims (14)

Patent claims: (Circuit carrier for electrical switching elements, characterized by a flexible sheet (10) of insulating material having an electrically conductive pattern (12, 13; 23 | 24) is provided and on which at least one single circuit element (11, 15 »19) in contact with the conductive Pattern is permanently attached. 2. Device according to claim 1, characterized in that that the individual circuit elements (19) are attached to the film by means of an adhesive layer (27) which completely surrounds the edges of the elements facing the film and serves as a housing. 3. Apparatus according to claim 1 or 2, characterized in that ei§e heat dissipation plate (18), the several individual circuit elements (15) is common to the surfaces of the individual circuit elements facing away from the film (10) is attached. 4. Device according to one of claims 1 to 3, characterized in that the film (10) is transparent. 5 device according to one of claims 1 to 4 / that ' the film (10) provided on both sides with a conductive pattern and from! «festers (14) for mutual connection of the conductive Pattern is interspersed. 6. Device according to one of the preceding claims, characterized in that the conductive pattern consists of a metal layer applied to the foil and made of aluminum, chromium, molybdenum, titanium or tungsten. - 17 - 009818/1298 7. Apparatus according to claim 6, characterized in that that the applied to the foil metal layer (33) with a layer (34) of gold and this with a Layer (35) is made of chromium, molybdenum or tungsten 8. Apparatus according to claim 6 or 7, characterized in that the conductive pattern at the connection points Has contact pads (37, 39) which at the connection points for the semiconductor components (43) made of aluminum or Gold, and for the connection points to external circuits (38) are made of gold 9. Device according to one of claims 6 to 8, characterized in that the conductive pattern with an insulating Layer (36) is provided from phioresistive material. 10 »Method for producing the circuit carrier according to one of claims 1 to 9» characterized in that that one on a thin, flexible film (10) made of insulating material, which is provided with a conductive pattern (23,24), individual electrical circuit elements (19) permanently arranged at certain points and the points for the electrical Brings connection of the individual elements into contact with the conductive pattern «, · 11. The method according to claim 10, characterized in that the points for the electrical connection of the individual circuit elements (19) are provided with elevations (25, 26) so that the surface facing the film is applied the circuit elements applies adhesive, the circuit elements pressed against the film and in their corresponding - 18 - 00981871298 Position to remove the adhesive from the areas of the To squeeze out electrical contact and thus to a housing around the strips to be directed towards the film. form, and that at the same time as the adhesive is squeezed out, the areas are in contact with corresponding areas of the guiding pattern. 12. The method according to claim 11, characterized in that to connect the contact areas, the film during the gluing of the circuit elements or afterwards a heat or ultrasonic treatment and then subjected to a heat treatment to solidify the adhesive. 13.Verfahren according to any one of claims 10 to 12, characterized characterized in that the surface of the individual circuit elements (15) directed away from the film on a joint carrier or a heat dissipation surface {18) glued on » 14. The method according to claim 13, characterized in that the film (10) on the carrier or the heat dissipation surface (18) and the conductive pattern of the film on the edges of the carrier or the heat dissipation surface with connection contacts (17) for external connections. 009818/1298