METHOD AND DEVICE FOR POSITIONING AND RETAINING MICRO-BUILDING-BLOCKS

Abstract: In order to simplify handling and mounting of chips or chip-like structures/micro-blocks, a method and a device have been developed, by which, depending on the area of use, one or more chips can be assembled to act together and/or act together with other chip-like structures such as micromechanical building elements or micro-optical elements. The actual retention of a micro-building-block (1) is achieved by micromechanical tongues (4) acting across holes or cavities (2) in a carrier material (3). Silicon tongues can, for example, be both flexible and sufficiently strong to retain a chip. In this manner, there is assured both precise vertical and horizontal positioning and mechanical retention. Electrical connection to the chip can be effected either by thin film technology or by more conventional wire-bonding.

Description: Method and device for positioning and retaining micro-building-blocks Technical field The present invention relates to a method of positioning and retaining micro- building-blocks and a device for positioning and retaining micro-building-blocks, the term "micro-building-block" comprising electronic microcircuit elements/chips, micromechanical elements or opto-elements. Background art Within opto-electronics, there has arisen an interest in micromechanics and micro- structure technology. This interest is based on the knowledge that micromechanical structures can today be made with very high precision. Micromechanical structures can provide exact positioning of components. For example, it is possible with etched V-grooves in silicon to achieve alignment of optical fibers. With the aid of microstructures it is also possible to achieve alignment when hybrid-mounting opto- components and micromechanical mirrors for angling light. It is also known to use small mechanical holders to hold securely and guide opto fibers in V-shaped groups in silicon substrates (see Swedish Patent Application No. 9501591-5). Description of the invention In order to simplify handling and mounting of chips or chip-like structures/micro- blocks, a method and a device have been developed, where, depending on the field of use, one or more chips can be assembled to act together and/or act together with other chip-like structures, such as micromechanical building elements or microopti- cal elements. The basic idea for the actual retaining of a micro-building-block is to use micromechanical tongues across holes or cavities, which can be etched in silicon (see Fig. 1). These silicon tongues can be both flexible and sufficiently strong to retain a chip, for example, which trials have shown. In this manner, it is assured that there is achieved both precise positioning, vertically and horizontally, and mechanical retention. Electrical connection to the chip can be achieved either by thin film technology or by more conventional wire-bonding. Description of the figures Figure 1 shows a side view, partially in section, of a micro-building-block inserted and retained in a cavity in accordance with the invention. Figure 2 shows the micro-building-block in Figure 1, connected electrically by wire- bonding. Figure 3 shows, from above, a niicro-building-block inserted and retained in accordance with the invention, by means of silicon tongues. Preferred embodiments Figures 1-3 show in simplified form how a micro-building-block/chip is inserted into a cavity 2 or a hole in a silicon material 3, where the holder structure consists essentially of micromechanical tongues 4 acting across the cavity 2 on one or two sides. Opposing sides 5,6 without tongues can consist of reference edges/sides for exact positioning of the chip together with the bottom 7 of the cavity. When insert- ing the chip 1 into the cavity 2, the elastic tongues 4 will be bent down and press with their points the chip against the reference edges 5,6, thereby providing both a precise positioning and retention of the chip. As an alternative to the resilient tongues, resilient leaves lying at the bottom could be used. In a system with one or more rows of cavities, as in a grid, it is possible to position a plurality of different cooperating micro-building-blocks and then join them to achieve a cooperating microsystem. Several methods of contacting are possible. Figure 2 shows how wire-bonding 8 has been used but thin film technologies can also be used, since the building method renders the chip on the same level as a surrounding substrate with a conductor pattern. In hybridization, for example of electronic, optical and mechanical components, a method of mounting in accordance with the invention can be of crucial importance since much importance is placed on increasing the integration of various functions at "chip level". There is still no really good method of integration and it is difficult today to manufacture integrated microsystems on the same substrate. With the microsystem according to the invention, the various parts of the system can be manufactured individually by existing methods and thereafter be brought together and placed in their respective cavities in a carrier material. By packing chips together in this manner, the design and shape rules for supply lines and contact surfaces can be further refined. By using the cavity for mounting opto-components/opto-chips, these can be passively aligned with a waveguide Uthographically defmed relative to the cavity. In the same manner, opto-components can be passively aligned with opto-fibers in litho- graphically defmed guide structures in a carrier. Multichip modules (MCM) consisting of a plurality of chips linked together by a plurality of strip wires, can be replaced by a carrier with a plurality of cavities, in which the individual chips are placed to be subsequently linked together by li ho- graphically defmed methods/thin film technology. By using this technology, grids of chip structures can be built up and linked together, thus providing very complex systems with individually replaceable micro-building-blocks. The cavity structure can also be used as a test fixture for MCM-chips enabling the entire chip set for an MCM to be tested prior to mounting by using a cavity structure where each chip has its own predetermined position. A connecting fixture adapted to this purpose could temporarily link all the chips so that an electrical evaluation could be made. Instead of using silicon as a carrier material, plastic could be used and especially so-called replicated plastic, which could provide extremely good positioning of the micro-building-blocks set in place by its precisely defined reference edges and its bottom with or without inlaid grooves for waveguides/optical fibers in the surface of the carrier material between the cavities. When using replicated plastic for manufacture of carrier materials, instead of resilient elements acting against the chip, non- elastically acting deformable projections arranged in the plastic could be used instead, which would fix the mounted chip against the reference edges when the chip is pressed into the cavity.

Claims: Claims 1. Method of arranging at least one micro-building-block, such as a chip, in a carrier material, characterized in that there is arranged in the carrier material at least one space provided with means for positioning and with means for retaining the micro- building-block, and that the micro-building-block is placed in the cavity, whereupon it is precisely located. 2. Device for arranging at least one micro-building-block, such as a chip, in a carrier material, characterized in that in the carrier material (3) in at least one arranged space (2) there are arranged means (5,6) for positioning and means (4) for retaining the micro-building-block (1), whereupon on placement of the micro-building-block (1) in the space, the micro-building-block will be precisely located and retained. 3. Device according to Claim 2, characterized in that if there are a plurality of spaces, the spaces are arranged in a row or a plurality of parallel rows forming a grid. 4. Device according to Claim 2 or 3, characterized in that the means for positioning comprise one (5) or two walls (5,6) at an angle to each other, and a bottom (7) of the space (2). 5. Device according to Claim 2 or 3, characterized in that the means for retaining comprise one or more means (4) acting to press the micro-building-block (1) against one (5) or more walls (5,6) 6. Device according to Claim 4 or 5, characterized in that non-elastically acting deformable projections are arranged to fix the micro-building-block against one or more walls. 7. Device according to Claim 2 or 3, characterized in that on the carrier material there are arranged means (8) for electrical connection to one or more micro- building-blocks. 8. Device according to Claim 2 or 3, characterized in that on the carrier material there are arranged means for optical connection to one or more micro-building- blocks. 9. Device according to one of Claims 2-8, characterized in that the carrier material (3) is of silicon type with one or more etched-out spaces (2). 10. Device according to one of Claims 2-8, characterized in that the carrier material (3) is made of plastic material, such as replicated plastic with one or more spaces (2).

Inventors: BAECKLUND YLVA, STRANDMAN CAROLA, BAECKLUND, YLVA, STRANDMAN, CAROLA
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1997
Main classification: H05K7
IPC codes: B81B3, B81B7, H01L21, H01L23, H05K7