DE3925604A1 - Contacting housing-less semiconductor circuits or substrate - forms depressions in substrate such that circuit surfaces lie in substrate surface plane - Google Patents

Abstract

The semiconductor circuits (2) are formed on a flat substrate (1) of insulating material, supporting conductive tracks (9). In the substrate are formed depressions such that the semiconductor circuit surfaces lie in the surface plane of the substrate, with the semiconductor circuit firmly secured in the depression. Between the substrate and the semiconductor circuits is formed a gap coated with an insulating layer (7). Then further conductive tracks (8) are applied for contacting the contact faces (3) with the first conductive tracks. Pref. the extra conductive tracks are applied by screen printing. USE/ADVANTAGE - For hybrid circuits or circuit plates, with simple application and no need for a special form of the semiconductor circuits.

Description

The invention relates to a method according to the preamble of Claim 1 and a hybrid scarf produced thereby tung.

In hybrid circuits, the planar is generated Structures such as conductor tracks, crossovers and resistors in the usual thick-film or thin-film technology on ceramic or glass substrates. The structures can be one or be applied on both sides. Vias are also used possible.

The use of unhoused semiconductor circuits on hybrid circuits or printed circuit boards gives the following advantages:
good thermal coupling between the semiconductor circuit and the substrate results in high heat dissipation;
the space required for unhoused semiconductor circuits is considerably less than that for packaged ones;
the missing designation on the unhoused semiconductor circuits results in increased protection from replication.

The most common methods for contacting the semiconductor scarf connections with the conductor tracks of the hybrid circuits or conductors boards are as follows: The chip-and-wire process, each Connection must be bonded individually, and critical interme metallic connections, such as the purple plague, between the gold wire and the pads of the semiconductor circuits Aluminum can arise.

The tape automated bonding process, in which a special Build-up of bumps on the semiconductor scarf device is required, and chip-specific, etched conductors web spiders are required.  

The flip-chip assembly process, which also bumps on the semiconductor are required and joints below the chip, so that no complete optical control is possible.

The beam lead bonding process, in which special ribbons, the so-called beam leads, on the semiconductor circuit are such.

The invention has for its object a method of Specify the type mentioned that is easy to carry out and no special embodiment of the semiconductor circuit is required different.

This object is achieved by the in the patent claim 1 specified features solved.

An advantage of the method according to the invention is that all semiconductor circuits on the substrate in one work can be contacted (simultaneous contact procedure ren).

The method according to the invention also makes a very good one thermal coupling of the semiconductor circuit to the carrier sub strat reached. Additional heat sinks are easy to install ren. The thermal resistance between the junction of the semi-lead terschaltung and the heat sink can be kept very low who the.

The method according to the invention can be used both in hybrid circuits conditions as well as standard housings.

In the following, the invention is illustrated by one in the drawing described embodiment described. Show  

Fig. 1 in cross-section a substrate having an indentation lying in a Ver semiconductor circuit,

FIG. 2 shows a detail from FIG. 1, conductor tracks being applied,

Fig. 3 is a plan view of the substrate with semiconductor scarf device and conductor track, and

Fig. 4 additionally attached heat sink.

In Fig. 1, a substrate 1 made of insulating material (it can also be a printed circuit board) is shown in cross section with a recess, not specified, into which a semiconductor circuit 2 (for example an IC) is inserted. In order to be able to contact contact surfaces 3 of the semiconductor circuit 2 using conductor tracks made in thick-film or thin-film technology, the upper surface of the semiconductor circuit 2 must form a plane with the surface of the substrate 1 . These depressions in the substrate 1 can be produced, for example, with an excimer laser. By using appropriate diaphragms in the laser beam, the manufacture of all depressions is possible simultaneously when using several semiconductor circuits 2 . If the tolerances of the semiconductor circuit 2 require it, the dimensions of the depressions can be adapted to the respective dimensions of the semiconductor circuit 2 via a variable aperture.

The exact dimensions of the semiconductor circuit 2 can be measured using an optical system, this system advantageously being computer-coupled to the excimer laser.

The depth of the depression is above the removal rate, for example or other measuring devices, e.g. optically or with ultra sound, to determine. After reaching the required Depth, the measuring device used for this gives a signal to Switch off the laser. Another way of making the deepening is this in so-called green To produce ceramics.  

The semiconductor circuit 2 is fixed in the recess with an adhesive 4 . A conductive or insulating adhesive (epoxy die bonding) can be used as the adhesive 4 . The adhesive 4 is then cured.

Any necessary electrical contacting of the rear side of the semiconductor circuit 2 can take place via one or more plated-through holes 5 in the remaining substrate 1 under the semiconductor circuit 2 to the rear side of the substrate 1 .

Referring to Fig. 2, the next steps are tert erläu.

A gap 6 present between the semiconductor circuit 2 and the substrate 1 is covered with an insulating layer 7 . This insulating layer 7 can be produced by applying an insulating paste by means of screen printing. To achieve high accuracy, it is also possible to use etched metal masks instead of the usual screens. The curing of the insulating paste or an insulating adhesive must be below the max. permissible junction temperature of the semiconductor circuits 2 used . In order to avoid pinholes, it may be necessary to perform this print twice.

The application of the insulating layer 7 is necessary in order to avoid short circuits between the non-passivated edge of the semiconductor circuit 2 and a contact conductor 8 applied in the next operation.

The actual connection of the contact areas 3 to a circuit conductor track 9 applied to the substrate 1 takes place with the contacting conductor track 8 . These conductor tracks 8 who executed the with a conductive paste or a conductive adhesive in screen printing technology. If high demands are placed on the accuracy or if the track width is <100 µ, etched metal masks can be used instead of the sieves. With a single screen printing process, all connections between the circuit tracks 9 on the substrate 1 and the contact surfaces 3 of the semiconductor circuit 2 can be produced. The curing must again below max. permissible junction temperature. Due to the usual passivation of the surface of the semiconductor circuit 2 with silicon nitride or silicon oxide, no short circuits occur. Instead of a printing process, a thin film process can also be used.

After the semiconductor circuits 2 have been contacted, an electrical test is generally carried out. If defective semiconductor circuits 2 are detected here, they can be removed in a space-selective manner using an excimer laser. A new semiconductor circuit 2 is then fixed and contacted by space-selective execution of the necessary method steps.

The conductor tracks 8 , 9 including the semiconductor circuits 2 can be protected from environmental influences by means of a resist. This lacquer can also be applied by screen printing because the surface of the circuit is flat. The hybridization places of any components that are still required are to be kept free. Another possibility of passivation is sputtering (sputtering) of, for example, silicon oxide. In this case, the hybridization sites are then cleared again, for example by etching or using the lifting technology.

Are additional ge for the function of the hybrid circuit housed components required (integrated circuits, Kon capacitors, diodes, transistors, etc.), so this construction parts assembled with electrically conductive adhesive, for example will. The adhesive can either be applied using standard methods (at for example with a numerically controlled dosing device) or applied using screen printing technology. The latter is only possible that with the method according to the invention flat surface of the hybrid circuit is reached.  

The semiconductor circuit 2 embedded in the depression can be seen in plan view in FIG. 3. Next, the contact surfaces 3 with the circuit traces 9 connecting to contacting traces 8 are shown, which are placed over the insulating layer 7 .

Be additional to improve heat dissipation for cooling elements 10,11 shown in Fig. 4 is required, the assembly of these elements 10, 11 is possible on the front or back of the substrate 1. The cooling element 11 on the front of the substrate 1 must be applied with a good heat-conducting insulation adhesive 12 . In order to maintain a defined distance between the cooling element 11 and the substrate surface, a filled adhesive, for example with ceramic granules, is preferred. Since the temperature-generating barrier layer of the semiconductor circuit 2 is on the surface, a very low thermal resistance between the barrier layer and this cooling element 11 can be expected.

The cooling elements 10 , 11 additionally prevent harmful environmental influences from the hybrid circuit.

Claims (5)

1. A method for electrical contacting of unhoused semiconductor circuits ( 2 ) on a plate-shaped substrate ( 1 ) made of insulating material with conductor tracks ( 9 ) applied thereto, characterized in that
Depressions are produced in the substrate ( 1 ) so that the surfaces of the semiconductor circuits ( 2 ) lie in the surface plane of the substrate ( 1 ),
the semiconductor circuits ( 2 ) are fixed in the depressions,
an insulating layer ( 7 ) is applied to a gap ( 6 ) between the substrate ( 1 ) and the semiconductor circuits ( 2 ), and
further conductor tracks ( 8 ) for contacting the contact surfaces ( 3 ) with the conductor tracks ( 9 ) are applied. 2. The method according to claim 1, characterized in that the further conductor tracks ( 8 ) are applied using screen printing technology. 3. The method according to claim 1, characterized in that the further conductor tracks ( 8 ) are brought up with a thin film process. 4. Hybrid circuit characterized by
at least one semiconductor circuit ( 2 ) embedded in a recess of a substrate ( 1 ),
by an insulating layer ( 7 ) covering a gap ( 6 ) between the semiconductor circuit ( 2 ) and the substrate ( 1 ), and
by conductor tracks ( 8 ) to contact the contact surfaces ( 3 ) of the semiconductor circuit ( 2 ) over the insulating layer ( 7 ) with circuit conductor tracks ( 9 ) located on the substrate ( 1 ). 5. Hybrid circuit according to claim 4, characterized by at least one applied to the hybrid circuit cooling element ( 10 , 11 ).