DE29620595U1 - Socket for an integrated circuit - Google Patents

Description

&igr; GR 96 G 4469 DE

Description

Socket for an integrated circuit

The invention relates to a socket for an integrated circuit according to the preamble of claim 1.

Highly complex and costly integrated circuits, e.g. processors, are offered as components in high-pin, standardized housings, e.g. PGA (Pin Grid Array) or SPGA (Staggered Pin Grid Array). For assembly on a circuit board, connection elements of the integrated circuit, so-called pins, are either connected directly to connection elements on the circuit board by soldering or the integrated circuit is detachably inserted into a socket, which is itself soldered onto the circuit board and creates the electrical connections between connection elements of the integrated circuit and connection elements on the circuit board. The greater effort involved in using a socket as an additional component has the advantage that the integrated circuit can be easily replaced later, e.g. for repair or to upgrade with a more powerful component. With an integrated circuit soldered directly in, this would not be possible or would only be very complex.

Such a socket is known from DE-GM 87 16 007, which, in addition to cooling on the top of the integrated circuit, is equipped with a heat sink that is snapped into a carrier frame.

GR 96 G 4469 DE

A shielding housing is known from DE 39 22 461 C2 that can be used to house various circuits. The housing is essentially cuboid-shaped and has an open side that is closed by a circuit board when it is mounted on it. The shielding housing is attached to the circuit board by inserting four mounting legs formed on the lower edge of the shielding housing into mounting openings in the circuit board and bending them or soldering them. Circuits housed in the shielding housing are soldered directly to the circuit board. This shielding housing makes the already difficult replacement of installed components even more difficult. A further disadvantage is that the encapsulation of the components has a negative effect on heat dissipation, which must be guaranteed especially in complex integrated circuits.

The invention is based on the object of creating a socket for an integrated circuit which enables improved heat dissipation of the integrated circuit with a low installation height above the circuit board.

To solve this problem, the new base of the type mentioned at the outset has the features specified in the characterizing part of claim 1. Advantageous further developments are described in the subclaims.

The invention has the advantage that the surface area active in heat dissipation is increased without having to change the height of a heat sink above the circuit board.

GR 96 G 4469 DE

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Both heat sinks can be designed as shielded housings.

A further advantage is that the socket allows for easy replacement of integrated circuits despite good electromagnetic shielding, the integrated circuit is accessible after opening the housing cover and can be removed from the socket insert - possibly with the help of a simple lifting tool.

To make it easier to open the cover, it can be secured with screws, clips or a snap-in connection. The electrical connection technology of the socket insert can be implemented as with conventional connection forms and is not subject to any additional restrictions. For example, on the integrated circuit side, connection elements can be implemented using through-hole technology and on the circuit board side, the connection elements can be implemented as BGA (Ball Grid Array) or SGA (Stud Grid Array). In particular, if SMD (Surface Mounted Device) connection technology is used on the circuit board side, it is advantageous to secure the socket insert in its position using the socket frame, which is attached to the circuit board. This prevents the extraction forces that occur when the integrated circuit is removed from acting on the electrical contact points of the socket insert and damaging them. Even when the socket insert is installed using press-in technology, the press-in pins should not be subjected to excessive pulling force. A slope on the inside of the base frame allows easy access to the integrated circuit for a lifting tool.

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If a screwdriver, for example, is used as a lifting tool, the base frame advantageously serves as a counter bearing close to the component with good leverage. In addition, the design of the base frame is such that a special lifting tool, which can also be used to press in the component, can be used. A base frame made up of several parts makes it possible to build different types of frames in a modular manner using a modular principle. This does not have a negative effect on the shielding properties of the housing with regard to electromagnetic or electrostatic influences if the parts overlap at the joints. To ensure good thermal contact between the cover and the integrated circuit, the cover rests positively on the top of the integrated circuit, possibly thermally coupled by a thermal paste. The use of a thermal paste is also advantageous between the cover and the frame. Additional measures on the circuit board, e.g. large copper surfaces on both sides, which are connected to one another with as many through-holes as possible, can further improve heat transfer and ground connection. A recess in the base plate can be used to ensure that connection elements protruding through the circuit board are not short-circuited. Such a base plate can also serve as a counter bearing when assembling a socket insert with press-in contacts. With a BGA or SGA design of the socket insert, the base plate is designed to be flat, i.e. without a recess, for better heat dissipation and as a counter bearing. SMD connection technology on the circuit board side also has the advantage of

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Advantage that integrated circuits with PGA or SPGA connection forms, which are actually designed for through-hole mounting, can also be mounted on a circuit board using pure SMD (Surface Mounted Device) technology without having to break the SMD principle. With this socket, integrated circuits for through-hole mounting can also be mounted on circuit board technologies that do not allow through-hole connections as connection elements. This is the case, for example, with circuit boards with multiple surface wiring, where the number of signal layers is drastically reduced by partial through-hole connections to connect lines in different layers. The now possible use of pure SMD technology eliminates the process steps that would be required with a mixed technology for assembling and soldering components in through-hole mounting. This means that an assembly no longer has to be taken to a manual assembly station and through a wave bath during the manufacturing process. The manufacturing effort is thus significantly reduced.

The invention as well as its embodiments and advantages are explained in more detail below with reference to the drawings, which illustrate an embodiment of the invention.

Show it:

Figure 1 shows a base in an exploded view, Figure 2 shows a sectional view of a base, Figure 3 shows a base insert with force-locking clamping of a contact element in a sectional view, Figure 4 shows a base insert with form-locking clamping,

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Figure 5 a base insert with force and form-fitting

Clamping of a contact element, Figure 6 a base insert with connection elements for press-in technology,
Figure 7 shows a socket insert for through hole mounting in solder

technology and
Figure 8 shows a base insert in SGA design.

Identical parts are provided with the same reference symbols.

According to Figure 1, a base for an integrated circuit 1 essentially consists of a cover 2, a frame composed here of four parts 3, 4, 5 and 6, a base insert 7 and a base 8. The cover 2 is designed as a heat sink and is provided with cooling fins on its top so that it can be optimally aligned according to the air flow in the device in which a circuit board 9 equipped with the components shown is to be used. The cover is attached to the base frame with four screws 10 ... 13 arranged in the area of its corners. For this purpose, openings with internal threads corresponding to the screws 10 ... 13 are provided in the parts 3 ... 6 of the base frame, of which only the openings 14, 15 and 16 are visible in Figure 2. To ensure that the shielding housing is also radiation-tight at the joints between the cover 2 and the base frame, parts 3 ... 6 each have a collar 17, 18, 19 or 20, which protrudes slightly laterally over the cover 2 at the associated edge sections. For economic reasons, the base frame can also be designed as a one-piece frame with fewer fastening points on the line.

GR 96 G 4469 DE

terplatte. When assembled, the cover 2 rests flat on the top of the integrated circuit 1. This already achieves good thermal coupling between the integrated circuit 1 and the cover 2. To further improve the thermal coupling, the top of the integrated circuit 1 can be provided with a thermal paste or a similar agent, e.g. thermally conductive foil, during assembly. In order to enable good thermal coupling between the base frame and the cover 2, two recesses are made in each of the parts 3 ... 6, which serve as a depot for thermal paste. In Figure 1, only recesses 21 ... 27 are visible. The parts 3 ... 6 of the base frame are provided with overlaps at the joints so that no electromagnetic or electrostatic interference can penetrate the shielding housing via these joints. The base frame is fastened with eight screws, which are passed through openings in the circuit board and screwed into corresponding holes with internal threads in the base 8. In Figure 1, only the screws 28 ... 31, the openings 32, 33 and 34 as well as holes 35 ... 40 are shown. The base 8 is also designed as a heat sink and provided with cooling fins. On its upper side it has a recess 41, into which any protruding connection elements of the base insert 7 on the underside of the circuit board 9 can protrude without touching the base 8. The base 8 can also be used as a support or counter bearing if a base insert 7 with press-in pins is used or with contact elements that are clamped in their guides by pressing the base insert 7 against the circuit board 9.

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If the thermal coupling between the base 8 and the socket frame is not yet sufficient across the eight fastening screws and the contact points on the circuit board 9, further recesses (not shown in Figure 1) can be made on the top of the edges of the base 8 and on the underside of the parts 3 ... 6 of the socket frame as a depot for thermal paste. Since heat sinks are provided on both sides of the circuit board 9, the total height of the base is distributed over both sides of the circuit board 9. Thus, only a small height above the circuit board 9 is required on each side to realize the heat dissipation of the integrated circuit 1. In certain cases, this can be of decisive importance, for example if only a small height is permitted on the component side of the circuit board 9, which would not be sufficient for heat dissipation with just one heat sink on the component side in fanless operation. For easy removal of the integrated circuit 1, e.g. B. for repairing or upgrading the electronic device, there are diagonally extending recesses 42, 43, 44 and 45 on the parts 3 ... 6 of the base frame, into which a lifting tool, for example a screwdriver blade, can be inserted in such a way that it grips the underside of the integrated circuit 1. At the same time, the parts 3 ... 6 may serve as a counter bearing to create a lever effect. To secure the position of the base insert 7, i.e. so that it is not detached from the circuit board 9 when the integrated circuit 1 is pulled out, the parts 3 ... 6 of the base frame each have webs, which are hidden in Figure 1, which, when mounted, are almost completely wrapped around the base insert 7.

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running edges - in Figure 1 only the edges 46 and 47 are visible.

In Figure 2, a sectional view of an assembled base according to Figure 1, the overlap described above of the collars 18 and 20 of parts 4 and 6 of the base frame on the sides of the cover 2 is particularly clearly visible. The distribution of the total height of the base on both sides of the circuit board 9 is also clear, whereby a low height is achieved on the top and bottom with good heat dissipation of the integrated circuit 1. By placing contact points on the circuit board 9 in the area of the base frame, the base structure can be integrated into the ground concept, i.e. the routing of the shield and reference ground in the electronic device.

Figures 3, 4 and 5 illustrate different variants for clamping a contact element in the base insert after it has been pressed onto a circuit board 55. The situation immediately before pressing is shown in each case. Contact elements 56, 57 and 58 are each provided with a contact spring 59 for contacting the connection element of an integrated circuit to be inserted. The contact elements 56, 57 and 58 are inserted from above into a plastic body 60 or 62 and secured against falling out in their final position by a snap connection. The plastic bodies 60, 61 and 62 are pressed onto the circuit board 55 and secured there with a frame 63 that can be attached directly to the circuit board. To explain the tolerance compensation, dimensions A, B, C and D are shown in Figure 3.

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The contact elements 56, 57 and 58 can be moved in their guides by dimension A in all three variants of clamping in order to compensate for height tolerances of the connection elements on the circuit board 55. The dimension B determines the distance by which the contact elements 56, 57 and 58 are moved from their end position in the plastic body 60, 61 or 62 when the base inserts are pressed against the circuit board 55 in order to create a clamping effect in the guide. To secure the position of the base insert in the base, a web 48 is attached to the frame 63, the underside of which rests on the top of an edge of the plastic bodies 60, 61 or 62 of the base inserts. To compensate for manufacturing tolerances and to generate a defined pressure force, roof-shaped extensions 49 pointing upwards are provided on the top of the edge of the plastic bodies 60, 61 and 62. When the base inserts are pressed against the circuit board 55, the height D of the extensions is reduced by the dimension C to compensate for tolerances by deforming the extensions. In the variant according to Figure 3, a force-locking clamping of the contact element 56 in the plastic body 60 is achieved by a circumferential collar 64 of the contact element 56 pressing into a conical bevel 65 of the plastic body 60 when pressed and being held there by mutual clamping. A positive clamping is achieved in the variant according to Figure 4, in which an initially hollow conical collar 66 rests against the shaft of the contact element 57 and is deformed by a circumferential collar 67 of the contact element 57 when pressed against the circuit board 55. This creates a positive connection to the collar 67 in the plastic part 61. In the variant shown in Figure 5

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In the third variant shown, the contact element 58 is provided with a circumferential, deformable pointed collar 68, which presses into the plastic part 62 and causes a positive and non-positive clamping. In all three variants shown in Figures 3, 4 and 5, it is thus ensured that when an integrated circuit 1, which can be designed as a PGA or SPGA component, is pulled out, no forces act on the soldering points on the circuit board 55.

According to Figure 6, a base insert for press-fit assembly has press-in pins 51 with spring elements in their shaft area, which press against the inside of the hole when pressed into a fully metallized hole in a circuit board. A soldered connection is not required for this. In contrast, in a base for through-hole assembly according to Figure 7, connection pins protruding through the metallized openings in the circuit board are electrically connected to conductor tracks on the circuit board by soldering. Connection elements 53 of the base insert shown in Figure 8 are also soldered to connection surfaces on the circuit board, although these are only located on the surface of the circuit board. With the SMT (Surface Mounted Technology) used here, it is advantageous if the base insert is positioned precisely before the soldering process using centering pins 54, to which the circuit board has corresponding holes. Such centering pins are also helpful in the embodiments according to Figures 6 and 7. For tolerance compensation, the 0 SGA version according to Figure 8 or a BGA version can be

GR 96 G 4469 DE

Connection elements 53 are mounted floating in the direction of insertion of the centering pins 54. By appropriately designing the connection elements and the base insert, the latter can be pressed onto the circuit board by the base frame or another tool after the soldering process. For example, the connection elements can be additionally secured in their final position in the base insert by means of a clamping effect. Pulling forces then no longer act on the solder connections.

Since the shielding housing of the base and possibly a ground layer in the circuit board form a hermetically sealed "island" with respect to electromagnetic and electrostatic influences, which can be either firmly integrated into a ground concept or coupled inductively or capacitively, additional components that are critical with regard to electromagnetic shielding, e.g. quartz, VCO or clock circuits, can be integrated into the shielding housing with a modified shape with an enlarged interior of the base or in the free space 55 within the base insert 7. This is particularly advantageous for components that are functionally assigned to the integrated circuit.

To avoid excessive extraction forces when removing the integrated circuit 1, socket inserts can be used which are designed as ZIF (Zero Insertion Force) or LIF (Low Insertion Force) versions on the integrated circuit side.

Advantageously, the socket can be replaced by replacing only the socket insert 7 for integrated circuits.

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different housing designs and different electrical connection elements can be used.

Claims (10)

GR 96 G 4469 DE 14 Protection claims 1. Socket for an integrated circuit suitable for mounting on a printed circuit board, - with a base insert (7) through which electrical connections can be made between connection elements of the integrated circuit (1) and connection elements of the circuit board (9), and - with a first heat sink (2 ... 6) provided with cooling fins on the top side of the integrated circuit, characterized in that that a second heat sink (8) is provided for mounting on the side of the circuit board (9) opposite the first heat sink, which, in the mounted state, is thermally coupled to the integrated circuit through recesses (32, 33, 34) in the circuit board. 2. Base according to claim 1, characterized in - that the first heat sink is designed as a shielding housing open on one side towards the circuit board (9) with a frame (3 ... 6) and a cover (2) for accommodating the integrated circuit (1) and the socket insert (7), whereby the cover (2) can be opened to remove the integrated circuit (1), and - that the second heat sink is designed as a base plate (8) in such a way that the base can be secured by clamping the circuit board between the base frame and the base plate. GR 96 G 4469 DE ··■ t« · &igr; 3. Base according to claim 2, characterized in that the base frame and base plate can be screwed together with screws (28 ... 31) projecting through the circuit board. 4. Socket according to claim 2 or 3, characterized in that the base plate has a recess (41) for connection elements of the socket insert (7) protruding through the circuit board. 5. Base according to one of claims 2 to 4, characterized in that the base frame (3 ... 6) secures the base insert (7) in its position in the assembled state. 6. Base according to claim 5, characterized in that the base frame for securing the position of the base insert on its inside is provided with a substantially circumferential web (48), on the underside of which, in the assembled state, the upper side of a corresponding circumferential edge (46, 47) of the base insert (7) rests. 20 7. Base according to one of claims 2 to 6, characterized in that the base frame is provided on its inner side with at least one recess (42 ... 45), in particular a slope, which allows access for a lifting tool, in particular a screwdriver, to lift out the integrated circuit (1). 8. Base according to one of claims 2 to 7, characterized in that the base frame is rectangular and consists of several 0 essentially along the straight edges GIS. 96 G 4469 EN extending parts (3 ... 6), the parts overlapping each other at the joints located in the area of the frame corners. 9. Base according to one of claims 2 to 8, characterized in that the base frame has chambers (21 ... 27) for thermal paste for thermally coupling the frame and the cover on the support surfaces of the cover. 10. Base according to one of claims 2 to 9, characterized in that the base frame and cover overlap each other at the joints.