Abstract:
A heat transfer housing for a printed circuit board, which has an electrical component having a thermal contact area, includes an extruded section having a contact area and contours for receiving the printed circuit board. One of the walls of the housing is initially formed displaced outwardly through an angle. When the printed circuit board is installed in the housing, the outwardly displaced wall is rotated inwardly and held in place by a cover. The wall includes a portion which bears against the printed circuit board and forces the thermal contact area of the electrical component to bear against the contact area of the housing for efficient heat transfer.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of housings and, more particularly, to a heat-dissipating housing for electrical or electronic components. 
     PRIOR ART 
     The prior art related to housings for semiconductors having thermal contact elements which are connected to the inside of the housing for the purpose of heat dissipation includes German Patent Application DE 36 29 552 A1. In order to attain reliable heat transfer, the semiconductor components are screwed to one of the side portions of a U-section. Instead of the screw joint, spring pressure elements may also be provided as is shown in German Patent DE 92 13 671 U1. It is also known to solder correspondingly constructed power semiconductors to heat sinks. 
     In general, the known connecting techniques for establishing a thermal contact in a housing require, irrespective of whether they function in a mechanical-force locking manner or in a manner connected by a material joint, result in an increased outlay in terms of components and assembly cost with the consequent risk of additional fault sources being introduced in the design. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a heat-dissipating housing for electrical or electronic components which equipped with at least one printed circuit board on which electrical or electronic components are mounted and having a portion which can be deformed or moved in a way such that thermal contact between the electrical or electronic components can be established without the need for assembly of any additional parts. 
     Another object of the present invention is to provide a heat-dissipating housing which can be manufactured economically as a unitary structure. 
     The foregoing and other objects and advantages of the present invention will appear more clearly hereinafter. In accordance with the present invention there is provided a heat-dissipating housing for electrical or electronic components which consists of a light-metal section preferably on three peripheral sides which has at least one side which either is already integrally formed in a displaced fashion or rotated in the course of extrusion or which can be displaced by being bent in the course of assembly. After the introduction of the populated printed circuit board with the electronic or electrical components which are mounted thereon and which have respective thermal contact elements, the displaced side is rotated into a final or installed position which is generally perpendicular to the base of the housing. 
     Thermal contact between the thermal contact elements of the relevant components on the printed circuit board and a contact area inside the housing is established, at the same time, by the rotated side of the housing pressing the thermal contact elements of the components against a heat-dissipating contact area on the housing either directly or indirectly via an intermediate element. For this purpose the geometrical dimensions are chosen such that the contact pressure obtained is one which minimizes the thermal contact resistance between the thermal contact elements of the components to be cooled and the contact area inside the housing. At the same time, this thermal contact can additionally be utilized to produce potential equalization between the printed circuit board and the housing with corresponding potential equalization protective contacts. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Other important objects and advantages of the present invention will be apparent from the following detailed description taken in connection with the accompanying drawings wherein like numerals refer to like parts and in which: 
     FIG. 1 is a cross-sectional view of a heat-dissipating housing for electrical or electronic components with the housing cover shown removed; 
     FIG. 2 is a cross-sectional view similar to FIG. 1 showing a printed circuit card installed in the housing and showing the cover in place; 
     FIG. 3 is a cross-sectional view similar to FIG. 2 showing an alternative embodiment of the present invention; and 
     FIG. 4 is a cross-sectional view similar to FIG. 2 showing another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, wherein like reference numbers designate like or corresponding parts throughout, there is shown in FIGS. 1-4 a heat-dissipating housing  100  for electrical or electronic components, made in accordance with the present invention. 
     FIG. 1 shows an essentially U-shaped extruded section  1  composed of light metal, such as aluminum. Section  1  can be referred to as a box section because it constitutes the basis for a box-type housing which has the shape of a cuboid or of a parallelepiped and consequently, after the insertion of end sides all around, is closed by four sides each at right angles to one another. 
     The U-shaped box section  1  has a base side  2  and flange sides  3 ,  4  integrally formed in one piece longitudinally on said base side  2 , the left-hand flange side  3  in the illustration being oriented at right angles to the base side  2 . The right-hand flange side  4  of the U-section  1  is displaced somewhat outwardly in the starting position shown in FIG.  1  and is at a slightly obtuse angle with respect to the base side  2 . As a result, a very acute angle W is produced between the perpendicular to the base side  2  and the planar flange side  4 . The angular position of the flange side  4  relative to the base side  2  can either be provided in the course of extrusion or it can be produced by subsequent deformation in the transition region between these two sides  2  and  4 . 
     The displaced flange side  4  can be connected to the base side  2  via a cross-sectionally weakened wall portion  5 , for which purpose a continuous indentation  6  is made in the inner comer between the flange side  4  and the base side  2 . The wall portion  5  in the transition region can thus assume the function of a plastically deformable film hinge and, for the purpose of elimination or resetting of the angle W of inclination, permits the flange side  4  to be pressed in the direction toward the interior of the U-section  1 , with the result that the flange side  4 , in its final position, lies parallel to the second flange side  3  of the U-section  1 . 
     In the region lying toward the base side  2  the flange side  4  has on its inner side a projecting pressure part  7  in the shape of a transverse web, the function of which is shown in FIG.  2 . 
     An inwardly directed projection  16  having a triangular cross-section is formed on the base side  2 , which projection is integrally formed in one piece. The shorter side of this triangular cross-section forms a contact area  15 , the function of which will be explained with reference to FIG.  2 . This contact area  15 , which is perpendicular to the base side  2 , has to resist a mechanical pressure which is applied up near the upper edge of the projection  16  at the level of the pressure part  7  on the flange side  4 . For this reason too the cross section of the projection  16  on the side remote from the contact area  15  gradually decreases down to the base side  2 . 
     FIG. 1 additionally shows a groove  10  which is formed in the base side  2  on the inside of the housing  100  at a relatively short distance in front of the contact area  15  of the projection  16 . As is further shown in FIG. 2, in this regard, a printed circuit board  12  can be inserted into this groove  10 . The printed circuit board  12  may be populated with a multiplicity of electrical or electronic components for which there is space inside the U-section  1  but which are not represented in the drawing. This is because the electronic components of concern here are primarily those electronic components  13 , such as power semiconductors, which are equipped with thermal contact elements  14  on the housing side or housing area of the respective component  13 . When the printed circuit board  12  is inserted, these components  13  are arranged proximate to the base side  2  of the U-section  1  at the level of the pressure part  7  which is formed on the flange side  4 . 
     During the insertion of the printed circuit board  12 , the pressure part  7  initially maintains a distance from the printed circuit board  12  as a result of the inclined starting position of the flange side  4 . Once the printed circuit board  12  is seated in the predetermined installed position, the initially inclined flange side  4  of the U-section  1  is directed, that is to say is brought into the position perpendicular to the base side  2  and parallel to the opposite flange side  3  by being pivoted about the deformable wall portion  5  in the transition region, which consequently forms the pivot axis. After this, the pressure part  7  on the inside of the flange side  4  bears upon the printed circuit board  12  at the level of the components  13 , or rather their thermal contact elements  14 , but on the side remote from the components. As a result, the thermal contact elements  14  of the components  13  are pressed against the contact area  15  situated on the projection  16  of the base side  2 , whereby there is very good thermal contact for dissipating the heat loss from the components  13  into the projection  16  on the base side  2  and thus into the entire U-section  1 . Electrical potential equalization between the printed circuit board  12  and the U-section  1  can also be produced in the same way. 
     The housing side situated opposite the base side  2  of the U-section  1  is formed by a covering hood  8  which has a groove  11  between two webs on its inner side, the groove  11  being situated opposite the groove  10  in the base side of the U-section  1  in such a way that the printed circuit board  12 , in parallel alignment with the directed flange side  4 , can engage therein for the purpose of further mechanical securing. The covering hood  8  engages over both flange sides  3  and  4  on their outer sides, the covering hood  8  and the flange sides  3  and  4  having latching elements  9  that correspond with one another in the overlap region, in order that the covering hood  8  can be latched onto the open housing in a simple manner. 
     FIG. 3 shows an alternative embodiment of the present invention  200 , the external structure of which is generally similar to the structure of FIG.  2 . The embodiment  200  incorporates a pressure component  7 ′ on the flange side  4 ′ which can act directly on the component  13 ′ and brace the component against the projection  16 ′ on the base side  2 . Component  13 ′ is connected via lengthened connecting lugs  17  to the printed circuit board  12 , which is arranged near the non-directable flange side  3  and is also parallel thereto. The contact area  15 ′ of the projection  16 ′ on the base side  2 ′ extends in a plane perpendicular to the flange side  3  as well as to the directed flange side  4 ′. In FIG. 3 the pressure part  7 ′ on the directable flange side  4 ′ functions as a lever and acts upon the component  13 ′ on the top side remote from the base side  2 ′ of the U-section  1 . When the directable flange side  4 ′ is pivoted, a torque is produced at the end of the pressure part  7 ′. The torque generates the pressure force by which the thermal contact element  14 ′ on the component  13 ′ is braced against the contact area  15 ′. In order to keep the bending stresses in the pressure part  7 ′ on the directable flange side  4 ′ within limits, the pressure part  7 ′ is arranged on the inside of the directable flange side  4 ′ in such a way that it is arranged in a manner inclined toward the component  13 ′ when the flange side  4 ′ is in the directed end position. Moreover, it is also possible to provide an angular portion  18  on that end of the pressure part  7 ′ which acts upon the component  13 ′, the angular portion being directed perpendicularly to the thermal contact element  14 ′ of the component  13 ′ and perpendicularly to the contact area  15 ′ on the projection  16 ′ of the base side  2 . 
     FIG. 4 shows another alternative embodiment of the invention  300  which is generally similar to the embodiment  200  of FIG.  3 . 
     The component  13 ′ to be cooled is acted upon directly in order to brace it against the contact area  15 ′ in the housing. In FIG. 4, however, the extruded section forming the box section  1  is constructed such that it is essentially C-shaped, which means that the fourth peripheral side  19  is integral with the remaining peripheral sides. Thus, in this case too, there is a base side  2 , a first side  3  situated at right angles thereto, the side  4 ′ arranged in a directable manner on the base side, and a covering side  19  opposite the base side  2 . In principle, the covering side  19  of the C-shaped box section  1  replaces the covering hood  8  of the U-shaped box section  1  according to the previous figures. Accessibility to the interior of the C-shaped box section  1  is ensured by a correspondingly large opening angle W of the directable side  4 ′. For the rest, the pivoting of the directable side  4 ′ with the simultaneous production of the heat-dissipating contact for the component  13 ′ is affected in the same way as in the designs described above in connection with FIG.  3 . 
     In FIG. 4 the directable side  4 ′ can be latched to the covering side  19  and latching means  9 ′ are correspondingly present on the free ends of the directable side  4 ′ and of the covering side  19 . Consequently, the covering hood  8 , that can be attached separately, can be omitted in this design. 
     The foregoing specific embodiments of the present invention, as set forth in the specification herein, are for illustrative purposes only. Various deviations and modifications can be made within the spirit and scope of this invention, without departing from the main theme thereof.