FR2503526A1 - PACKAGE AND METHOD FOR MOUNTING AND INTERCONNECTING MEDIUM POWER SEMICONDUCTOR COMPONENTS IN A SINGLE PACKAGE. - Google Patents

Abstract

HOUSING FOR SEMICONDUCTOR COMPONENTS USING A CONNECTION GRID INCLUDING SEVERAL CONNECTION ARMS 21, 22, 23. THE UPPER PART OF EACH OF THESE ARMS IS INTENDED TO BE FOLDED IN ORDER TO LOCK FLUSHED NUTS PROVIDED ON THE UPPER PART OF THE HOUSING 31, OF THE HOUSINGS , 32, 33 LOCATED AGAINST THE THREADS OF THESE NUTS. AT THE LOWER PART OF THE ARMS ARE FOLDED BLADES 26, 27 AND 30 AND FOLDED PADS 25 AND 28. THE PADS ARE INTENDED TO BE USED AS A SUPPORT FOR SEMICONDUCTOR COMPONENTS, CERTAIN BLADES 27 AND 30 TO APPROACH CONTACT WITH VARIOUS TERMINALS FOR SEMICONDUCTOR COMPONENTS AND ONE OF THE SLATS 26 TO BE USED AS A SUPPORT FOR L-SHAPED CONNECTION ELEMENTS 44, 45 OF WHICH ONE BRANCH SERVES AS OUTPUT TERMINAL AND THE OTHER BRANCH FOR CONNECTION TO SELECTED TERMINALS OF THE SEMICONDUCTOR COMPONENTS. APPLICATION IN PARTICULAR TO BRIDGE MOUNTING OF MEDIUM POWER COMPONENTS.

Description

HOUSING AND METHOD FOR MOUNTING AND INTERCONNECTING COLIPOSANTS
SEMICONDUCTORS OF MEDIUM POWER IN SINGLE PACKAGE.

 The present invention relates to the assembly of medium power semiconductor components in boot formers, that is to say crossed by currents of the order of a few amps to a few tens of amps.

 Commonly, semiconductor components are arranged in parallel circuits, bridge circuits, or the like. Thus, semiconductor manufacturers, rather than providing independent components that the user must interconnect, frequently supply unique shoemakers comprising two or more elements. In particular, there are often single boot assemblies comprising two diodes in series, a diode and a thyristor in series, or two thyristors in series, access being provided at the connection point between the two individual components.

 At present, to achieve this type of interconnection, it tends to standardize a parallelepipedic shoemaker whose bottom consists of a conductive plate and carrying on its upper surface three main terminals in line, intended for fixing by screw, and, possibly in the extension of these three main terminals, two control terminals located on either side of the line connecting these three main terminals.

 The invention aims to achieve a mounting of components in such a case in a particularly simple and economical way by simplifying the manufacturing operations and by using as much as possible standard elements or conductive sheets, while minimizing the number of welds to carry out.

 To achieve this object as well as others, the present invention provides a parallelepiped casing for mounting several interconnected medium power semiconductor components. This housing comprises: as the underside, a metal base intended to be fixed to a radiator and of which the semiconductor components are thermally integral; as side walls, a plastic cover fixed to the base and intended to be filled with an encapsulation material; as a top wall, a plastic cover from which several main terminals and two auxiliary terminals come out, the main terminals comprising nuts embedded in the cover. The connection between the main terminals and the areas to be connected is ensured by plates or arms formed from a conductive sheet, these arms being folded at their upper part at the level of the cover to block the drowned nuts and being folded in the same direction at their lower part on different levels, possibly according to slats, to come in contact with the areas to be connected.

The auxiliary terminals consist of the end parts of L-shaped elements cut from a conductive sheet, the other ends of these L-shaped elements being close to the areas to be connected of the semiconductor components. These L-shaped elements are fixed by means of an insulating sleeve to a folded strip of one of the above-mentioned arms.

 According to the present invention, the method of mounting such a shoemaker consists, before placing the plastic cover and its cover, assembling the semiconductor components and connecting them to said arms or L-shaped elements while the arms are physically joined together. to each other by portions of the same plate S from which these arms are formed.

Various variants and applications of the present invention will be described in more detail below in the case of particular applications given by way of examples of a shoemaker according to the present invention in relation to the attached figures among which
Figure 1 shows the type of shoemaker that the present invention aims to achieve
FIG. 2 represents an embodiment of a base of a shoemaker according to the present invention
FIG. 3 represents a grid of connections suitable for mounting thyristors forming part of a bridge
Figures 4 and 5 show respectively in top view and in sectional view along the line IV-IV of Figure 4 an arrangement of thyristors according to the present invention
Figure 6 shows in perspective part of the assembly of Figures 4 and 5;
Figure 7 shows in perspective another part of the assembly of Figure 5;
FIG. 8 represents a shoemaker according to the present invention at an almost final stage of manufacture;
FIG. 9 partially illustrates a Darlington type parallel arrangement of transistors according to the present invention;
FIG. 10 shows in the form of an electrical diagram the assembly produced in material form in FIG. 9.

 It will be noted that between these various figures and within the same figure, no scale has been respected. In fact, the dimensions of the various elements may simply be chosen by the person skilled in the art according to existing standards or which is essential for the external configuration of the bootmaker.

 your Figure 1 shows the schematic external appearance of a shoemaker of the type of the present invention. This I bortier, of parallelepiped shape, comprises a metal base l intended to be fixed on a radiator, for example using fixing holes 2. On this base) is fixed a cover 3 provided with a cover 4 at the top of which three main connection terminals 5, 6 and 7 appear and two auxiliary connection terminals 8 and 9. Semiconductor components are arranged inside the case in thermal contact with the base 1 and their various terminals are interconnected and / or connected to the access terminals 5 S 9 in a chosen manner.

 The present invention relates more particularly to the constitution and the method of assembling the interconnection elements between the terminals 5 9 and the various semiconductor components contained in the case. The present invention also relates to specific embodiments of components of the bootmaker.

 FIG. 2 represents an embodiment of a base 10 which can replace the base 1 illustrated in FIG. 1. This base, unlike the use which consists in using a relatively thick, very conductive plate to ensure its rigidity, is formed from of a relatively thin and stamped sheet metal to present a bottom 11, longitudinal sides 12 and side sides 13. The side sides 13 are extended by ears 14 carrying bores 15 and intended to be folded along a line 16 indicated by dotted lines . After folding, the bores 15 are located opposite S-bores 17 hollowed out at the bottom of the case. This ensures the fixing of the base on a radiator. In the interval between the bottom of the base and the folded part of the lug 14, an extension of the plastic cover such as the cover 3 of Figure 1 to help maintain it and a metal spacer to improve the fixation. This stamped embodiment makes it possible to lighten the shoemaker, to use less material and to use a medium conductivity material, for example steel, instead of copper and therefore to reduce material colts twice. It also makes it possible to reduce the thickness of the base at equal rigidity, therefore to improve its thermal conductivity without other drawbacks.

 In a subsequent manufacturing operation, and in the particular case which will now be described in relation to FIGS. 3 to 8, of an assembly of two thyriators, the anode of one being connected to the cathode of the other, will have at the bottom of the base 10 one or two electrically insulating and thermally conductive plates, for example alumina plates, the faces of these plates being metallized to ensure their weldability. Next, on these plates, a connection grid 20 will be mounted, as shown in FIG. 3 and constituting an embodiment of a fundamental aspect of the present invention. This connection grid 20 is manufactured by cutting and folding from a sheet of a conductive material, for example copper. After cutting and folding, the part illustrated in FIG. 3 comprises three plates or arms 21, 22, 23. These three vertical arms are connected by transverse arms 24 in order to ensure the holding of the assembly. At their lower part, each of the arms is secured to a plate or a strip folded orthogonally to the general direction of the arm. For example, the first arm 21 is folded at its lower portion into a plate 25 and a strip 26 on different levels. The second arm 22 includes a folded strip 27, in slight transverse recess with respect to this arm in the example shown. The third arm 23 is extended by a folded plate 28. This plate 28 comprises a recessed segment 29 in the plane of the arms 21, 22, 23, this recessed segment 29 being extended by a folded strip 30. Each of the arms 21, 22 and 23 includes a bore 31, 32, 33 at its upper part. The dotted line 34 shows a cutting line along which, as will be explained below, the vertical arms 21, 22, 23 are cut to blow up the transverse arms 24 and make the various arms electrically independent.

 The plates 25 and 28 have the role of electrical conductor and thermal distributor. The lamellae 27 and 30 have an electrical conductor roll. On the other hand, the strip 26 has neither an electrical role nor a thermal role, but a mechanical supporting role for the mounting of other connection elements.

 The assembly of components on the grid 20 and the base 10 will be described and shown in more detail below in relation to FIGS. 4 to 7. In the top view of FIG. 4, the grid can be seen connection 20 welded or glued by its two plates 25 and 28 on the bottom 11 of the base 10 by means of electrically insulating and thermally conductive plates 40 and 41, for example made of alumina or a single insulating layer such as polyimide. On these plates 25 and 28 serving as a thermal distributor, the thyristor anodes 42 and 43 are welded. Thus, the arms 21 and 23 constitute anode connections. The thyristor cathode 42 is connected by an auxiliary connection element, an embodiment of which will be described in relation to FIG. 6, to the strip 30 and, by the hook element 29 to the plate 28. The thyristor cathode 43 is connected by a connection element, an embodiment of which is also shown in FIG. 6, to the strip 27. Thus, the arm 22 constitutes the connection of cathodes of one of the thyristors. The trigger of the thyristor 42 is connected by a connection wire to a connection element 44. Likewise, the trigger of the thyristor 43 is connected by a conductive wire to a connection element 45.

 FIG. 6 represents an enlarged view of the wafer 28 resting on an alumina wafer 41. The thyristor 43 is prepared so as to present an access wire to the trigger and a conductive sheet 47 which is welded to its cathode and to extend beyond the semiconductor surface. It is this overhanging part which is welded to the strip 27. Likewise, a cathode conductive sheet 48 of the thyristor 42 is welded to the strip 30.

 As best seen in FIG. 7, the connection elements 44 and 45 have, for example, an L-shape and will be called below, for the sake of rationalization, L-shaped elements, even if their shape may differ from this shape in L to meet specific geometrical conditions. These L-shaped elements 44 and 45 are fixed to the support strip 26 with the interposition of an insulating sheath 50 also having a function of positioning the L-shaped elements. In the example shown, the insulating sheath consists of a molded element in an epoxy resin and coming to stenclip on the strip 26. On the side of the arm 21, the insulating element comprises a guard 51. The L-shaped elements 44 and 45 are mounted on this insulating part 50, for example by openings of appropriate section provided near the corner of L. The elements in L 44 and 45 each comprise a first branch (horizontal), respectively 52 and 53, or connecting branch and a second branch (vertical), respectively 54 and 55, the upper part of which is intended to serve as a terminal to correspond to terminals 8 and 9 illustrated in FIG. At the level of these upper parts, provision will preferably be made for bores 56 and 57 intended for simpler connection of external connection wires, or else these upper parts will be conformed to established standards in order to be able to be plugged into female connectors of the type Faston. Similarly, at the horizontal branches, provision may be made for such bores (not shown) to ensure a more reliable connection with the trigger wires. The material constituting these elements in L 44 and 45 is an electrically conductive material, but not necessarily a very good conductor of electricity. These elements could for example be cut from steel sheets. Indeed, it is important that they have good rigidity and resistance to bending or S to torsion, but it is not necessary for their electrical conductivity to be excellent since they are only intended to convey currents of control, know the trigger currents in the example of a thyristor assembly.

 Once the connection grid 20 has been mounted on the base 10 and the semiconductor components have been appropriately connected to the various parts of the connection grid and L-shaped elements, the encapsulation of the bootmaker.

 your Figure 8 shows a subsequent intermediate assembly step. A cover 60 corresponding to cover 3 of FIG. 1 is mounted on the base 10. Resin is poured to fill this cover and, after cutting the horizontal connecting arms 24 along line 34 (FIG. 3), a cover 61 is placed on the cover, this cover comprising clean grooves allowing the arms 21, 22 and 23 and the vertical branches 54 and 55 to pass through elements L 44 and 45. This cover includes recesses suitable for containing and blocking the rotation of nuts 62 which are then trapped by folding the tabs 21, 22 and 23. A shoemaker of the type illustrated in FIG. 1 was then obtained, but of a particularly simple manufacture.

 The present invention has been described above in relation to an assembly of thyristors arranged in series with access to their interconnection terminal. However, this bootmaker is now susceptible to many other applications and may contain other types of components.

 FIG. 9 illustrates the mounting of several transistors connected as shown in the form of an electrical diagram in FIG. 10, namely three transistors 70, 71 and 72 in parallel and a fourth transistor 73 mounted as a pilot transistor for the assembly to function in Darlington editing. This assembly comprises main terminals of collector 74 and transmitter 75, a normal control terminal 76 and, optionally, an additional terminal 77 for direct access to the bases of transistors 70, 71 and 72.

 According to one aspect of the present invention, it is envisaged to mount four transistors already encapsulated in plastic shells 80 from which emerge basic connections 81, collector 82 and emitter 83, arranged on a metal base 84.

This metal base is for example at the potential of the collector 82. But, in certain cases, it could be transistors S isolated collectors, it will therefore be necessary to modify the assembly shown appropriately. In this figure 9, the same references have been used as much as possible as in the previous figures. The connection grid comprises only two main arms 23 and 21. The arm 23 is connected to the various bases or manifold connections (not visible in the figure). The arm 21 is folded back at its lower part into a transverse strip 85 to which the emitters 83 of the transistors 70 to 72 are connected.

The L-shaped element 45 is connected to the bases of the transistors 70, 71, 72 and to the emitter of the transistor 73. The L-shaped element 44 is connected to the base of the transistor 73. Each of the transistors is mounted on a ceramic or alumina wafer 86. In this embodiment, the connection grid has a shape distinct from that of FIG. 3, but there are found there the important fundamental characteristics of the present invention, namely on the one hand the mounting in grid various connection arms, on the other hand the fact that the control connections are secured to L-shaped elements fixed by means of an insulating part 50 on a support strip 26 secured to one of the connection arms 21.

 Thus, the present invention is susceptible of numerous variants and is not limited to the embodiments which have been explicitly described. On the contrary, it encompasses the generalizations included in the field of claims below.

Claims (4)

CLAIMS.  1. Parallelepipedic boot for mounting several interconnected medium power semiconductor components, comprising  - as the underside, a metal base (10) intended to be fixed to a radiator and of which the semiconductor components are thermally integral,  - as side walls, a plastic cover (60) fixed to the base and intended to be filled with an encapsulation material,  - As the upper wall, a cover (70) made of plastic from which several main terminals and two auxiliary terminals come out, the main terminals comprising nuts embedded in the cover, characterized in that the connection between the main terminals and the zones to connection is ensured by arms (21, 22, 23) formed from a conductive sheet, bent at their upper part at the level of the cover to block the nuts which are sunk and bent in the same direction at their lower part to come into contact or opposite zones to be contacted by plates (25, 28) or lamellae (27, 30) situated at various levels, and in that each of the auxiliary terminals consists of a branch (54, 55) of elements in L (44, 45) cut in a conductive sheet whose other branch (52, 53) is close to contact areas of semiconductor components, these L-shaped elements being fixed by means of an insulator (50) on a support strip (26) of one of the arms.  2. parallelepipedic boot according to claim 1 for mounting two thyristors in series with access to their connection terminal, characterized in that the first arm (21) carries a first connection plate (25) fixed to the anode face of the thyristor and a support strip (26), in that the second arm (22) comprises a first connection strip (27) intended to be connected to the cathode of the second thyristor, and in that the third arm (23) comprises a second connection plate (28) on which the anode face of the second thyristor is welded, and a second strip (30) integral with the second plate (28) to ensure the connection between this second plate and the cathode of the first thyristor , each of the L-shaped elements being connected to one of the triggers of said thyristors.  3. A parallelepiped boot according to claim 1, characterized in that the base (10) consists of a metal piece stamped so as to include a flat bottom (11) and sides (12, 13).  4. Parallelepipedic boot according to claim 1 for mounting several transistors in parallel with mounting Darlington, characterized in that these transistors are initially in encapsulated form and in that one of the L-shaped elements is connected to the base of the pilot transistor and the other L-shaped element is connected to the bases of the power transistors and to the emitter of the pilot transistor, a first arm being connected to the collectors of the transistors and a second arm being connected to the emitters of the power transistors.