FR2782573A1 - Metal support for electronic power components comprises parallel rails offering support and attached section for thermal contact with heat sink - Google Patents

Abstract

The device is of constant thickness throughout, using a common metal base. The metal support for electronic power components comprises a band of material which is cut and folded to define two regions. A dog-leg section (1d) links together the two parts of the support. The first region comprises three parallel prongs (1a) for the mounting of the electronic components. The second region comprises a frame defining three sides of a rectangle (1b). This region is intended to be attached a heat sink component (2), which has grooves (2a,2b) cut into its upper edges to receive the frame elements. The support is cut from a sheet of metal of constant thickness - typically 0.5 mm.

Description

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  METAL SUPPORT, ESPECIALLY FOR COMPONENTS

ELECTRONICS OF POWER

  The invention relates to the technical sector of power microelectronics. The invention finds a particularly advantageous application for the continuous production of electronic power components among which

  Mention may be made, without any limitation being implied, of the TO 220, TO 251, TO 253 ...

  The constituent parts of the electronic components, namely essentially the connection tabs, the electronic chip support, and a part capable of acting as a heat sink, are obtained continuously from a metal strip previously cut and folded. Generally, this type of

  product is known by the English term "leadframe".

  In most cases, taking into account the envisaged application, the metal strip has, over its entire length, at least two parts of different thicknesses. Thus, the part of thinner thickness, of the order of 0.5 millimeter, is reserved for the production of the connection lugs, while the other part, of greater thickness, of the order of 1.5 millimeter, is reserved for the realization of electronic chip carriers and heat sinks. This difference in thickness can be carried out according to different methods, in particular by removing material, by a milling operation.

for example, or by rolling.

  Such operations are relatively difficult to perform and represent a high cost price. There is also a break in the homogeneity of the fibers, in particular in the case of the rolling operation, capable of generating

  problems of subsequent deformation during assembly.

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  It therefore appears that the fact of using a metal strip having at least two different thicknesses poses real technical problems. However, this difference in thickness is necessary when it is desired that the electronic power component is mounted in combination with a part acting as a heat sink. The object of the invention is to remedy these drawbacks so

  simple, safe, efficient and rational.

  One of the first important problems which the invention proposes to solve is to use a metal strip of constant thickness, while having the objective of ensuring, effectively, the function of heat sink and supports

  chip or electronic components.

  To solve such a problem, a metal support has been designed and developed, in particular for electronic power components, in the form of a strip cut continuously to constitute in particular a zone delimiting a series of electrical connection tabs and a zone. for mounting a series of electronic components as such. According to a basic characteristic of the invention, the strip is of constant thickness at the level of the two zones, the zone for mounting the series of electronic components being shaped to ensure the coupling of a series of added elements independent of thickness greater than that of the strip and able to receive said components

  by acting as heat sinks.

  From this basic design, consisting in using an attached element acting as a heat sink and as a support for electronic components, various embodiments can be envisaged at the level of the zone.

  corresponding mounting of said components, presented by the strip.

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  In a first embodiment, the zone for mounting the series of electronic components has a series of cutouts formed in the thickness of the strip to delimit, in a manner corresponding to each series of components, a plurality of forks formed in continuity with the corresponding connection lugs, each of said forks having

  arrangements for mounting one of the added elements.

  In a second embodiment, the area for mounting the series of electronic components is completely cut out to reveal, for each series of components, at least one protruding connection tab

  having arrangements for mounting one of the added elements.

  To solve the problem posed of facilitating the electrical connection of the component with the various connection lugs, and in the first embodiment, each fork is connected to the corresponding connection lug by a curvature capable of positioning said fork in a plane horizontal

  lower than that of the area with the connection tabs.

  To solve the aforementioned problem and in the second embodiment, the arrangements of each protruding connection lug consist of a curvature capable of cooperating with a complementary part of the element in order to ensure its fixing in a horizontal plane less than that of the area presenting

the connection lugs.

  Another important problem which the invention proposes to solve is to significantly reduce the production costs for the production of these electronic power assemblies from a metal strip.

  suitably cut and folded.

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  Indeed, according to the state of the art, one works in the direction of the length of the fibers of the metal strip. In other words, the zones delimiting the electrical connection tabs and the zones for mounting the electronic components are arranged parallel to the longitudinal edges of the strip, so that the cutting and folding operations are carried out perpendicular to said longitudinal edges, that is to say perpendicular to the direction of the fibers. The strip thus produced is then cut in the form of independent plates successively presenting, at regular intervals, the various constituent parts of each electronic power component. Each plate must then be brought independently to different mounting and connection stations for electronic components. Generally, these operations are manual and require the use of personnel with the appropriate capacities.

  to handle this type of component, very small in size.

  To solve the aforementioned problem and remedy the above drawbacks, the different zones are obtained by cutting and folding operations carried out in the lengthwise direction of the fibers of the plate, so that said

  zones are arranged perpendicular to the direction of said fibers.

  Given these characteristics, this results in a significant reduction in the wear of the cutting and bending tools, without weakening the support.

  metallic, since we work in the direction of the fibers.

  Another important problem which the invention proposes to solve is that it no longer works in the form of independent plates. To solve such a problem, the strip has over its entire length a plurality of series of zones, said strip having arrangements to be packaged in rolls in order to be unrolled linearly to be subjected, continuously, to

  different work and processing stations.

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  The invention is set out below in more detail with the aid of the figures of the appended drawings in which: - Figure 1 is a plan view of a metal support assembly for

  electronic power components according to the characteristics of the invention.

  - Figure 2 is, on a large scale, a partial perspective view of the constituent parts of the electronic power components before mounting

  the added element according to a first embodiment.

  - Figure 3 is a view corresponding to Figure 2 after mounting of the insert. 1 o - Figure 4 is a view of the type illustrated in Figure 2 showing a variant

of achievement.

  The metal support, in particular for electronic power components, is established in a known manner in the form of a strip (1) cut continuously, 1 5 to constitute a zone (A) delimiting electrical connection lugs (la) and a zone (B) for mounting the electronic power components as such, not shown. The different zones (A) and (B) are executed by any known and appropriate means, in particular by cutting and folding, so that the zone (B) is located in a horizontal plane less than that containing the different

connection lugs (the).

  The strip (1) is of constant thickness at the level of the two zones (A) and (B). For example, this thickness corresponds to the smallest thickness accepted according to the state of the art, namely approximately 0.5 millimeter, without excluding a slightly greater or lesser thickness depending on the applications.

specific plans.

  According to the characteristics of the invention, the area (B) is determined to ensure, in correspondence with the different series of connection lugs,

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  the coupling of added elements (2) of thickness greater than that of the strip. These various elements (2) are intended to receive the electronic power components and to act as a heat sink. From this basic design, different technical solutions can be envisaged to ensure the coupling of the insert (2) with one of the lugs

connection.

  In the embodiment illustrated in Figures 2 and 3, the area (B) has a series of cutouts formed in the thickness of the strip (1) to delimit, so

  corresponding to each series of components, a plurality of forks (lb).

  Each fork (lb) consists of two lateral arms (lbl) (lb2) joined at one end by a common transverse arm (lc), itself joined to the central connection lug (lal), located by example between two other legs

(la2) (la3).

  The whole of the fork (lb) has any type of arrangement for mounting the insert (2). For example, these arrangements can be of the drawer type, presenting a profile in dovetail section cooperating with two complementary grooves (2a) and (2b) that the added element (2) has. Obviously, this mounting example is given as an indication, and should not be

considered limiting.

  To each fork (lb) is connected the central connection tab (la) by a curvature (ld) capable of positioning the fork (lb) in a horizontal plane lower than that of the zone (A) presenting the connection tabs. In a perfectly known manner, these provisions make it possible to connect in perfect conditions the

  electronic component in two end tabs (1 a2) and (1 a3) for example.

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  In the embodiment illustrated in Figure 4, the area (B) is completely cut out to reveal, for each series of components, the median connection lug (lal) which projects and which has arrangements for mounting the insert. (2). In this case, the free end of the connection tab (lai) is bent in (le) to be engaged and fixed by any known and appropriate means in a slot (2c) that has the insert (2). These arrangements also make it possible to position the whole of the element (2) in a horizontal plane less than that of the zone (A) having the tabs of

  connection for the reasons indicated above.

  Given the independence of the added element (2) which acts as a radiator and as a support for electronic components as such, the latter

  can be made of a material different from that of the entire plate.

  The element (2) may also have a different coating. Its thickness is

  adapted to specific application cases.

  To ensure the function of heat sink, the element (2) is drilled in (2d).

  It is also advantageously emphasized that the element (2) can be previously equipped with the electronic component, and therefore be subjected beforehand, before its mounting in the arrangements of the area (B), to the various specific operations for processing electronic components

as such.

  According to another important characteristic of the invention, the different zones (A) and (B), as defined, are arranged perpendicular to the lateral sides of the strip (1), that is to say perpendicular to the direction of the fibers of this band. It follows that the different zones (A) and (B) are subjected to the operations of cutting and / or folding in the direction of the length of the fibers of the

band metal (1).

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  As shown in FIG. 1, the strip (1) has, over its entire length, a plurality of series of zones (A) and (B), each series itself being composed of several assemblies (connection tabs, support of electronic components and heat sinks) regularly distributed and spaced across the width of the strip. In the example illustrated, each series of zones (A) and (B)

presents ten sets.

  In view of these provisions, the strip has arrangements for being packaged in rolls with a view to being linearly unwound in order to be subjected continuously to various work and processing stations. These arrangements are for example constituted by solid lines of separation (le) appearing between each series of zones. These lines have perforations spaced apart according to a

not determined.

  The advantages are apparent from the description. In particular, we underline and

  recalls: - the use of a strip of constant thickness, - the arrangement of the connection and support areas of the electronic components perpendicular to the direction of rolling of the strip, so that the cutting and folding operations are carried out in the direction of the length of said rolling, - the packaging and handling in rolls of the strips arranged for mounting the electronic power components, - the possibility of using a support and heat sink in different

  thicknesses and in different materials.

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Claims (1)

  -1- Metal support in particular for electronic power components in the form of a strip (1) cut continuously to constitute in particular a zone (A) delimiting a series of electrical connection lugs and a zone (B) for mounting a series of electronic components as such, characterized in that the strip (1) is of constant thickness at the level of the two zones (A) and (B), the zone (A) for mounting the series of components electronic, being shaped to ensure the coupling of a series of independent added elements (2) of thickness greater than that of the strip (1) and capable of receiving said components by acting as heat sinks. -2 Metal support according to claim 1, characterized in that the zone (A) 1 5 for mounting the series of electronic components, has a series of cutouts formed in the thickness of the strip to delimit, in a corresponding manner for each series of components, a plurality of forks (lb) formed in continuity with the corresponding connection lugs, each of said forks (lb) having arrangements for mounting one of the reported items (2).   -3- Metal support according to claim 1, characterized in that the zone (A) for mounting the series of electronic components is completely cut out to reveal, for each series of components, at least one protruding connection tab (lal ) having arrangements (the) for mounting of one of the added elements (2).   -4- Metal support according to claim 2, characterized in that each fork (lb) is connected to the corresponding connection lug (lal), by a 2782573   curvature (ld) capable of positioning said fork (lb) in a horizontal plane   lower than that of the area with the connection tabs.   -5- Metal support according to claim 3, characterized in that the arrangements of each protruding connection tab (lai) are constituted by a curvature (the) capable of cooperating with a complementary part (2c) of the element (2) with a view to securing it in a horizontal plane lower than that   of the area with the connection tabs.   -6- Metal support according to claim 4, characterized in that the   fork arrangements (lb) are of the drawer type.   -7- Metal support according to claim 1, characterized in that the different zones (A) and (B) are obtained by cutting and folding operations carried out in the direction of the length of the fibers of the plate, so that said zones (A) and (B) are arranged perpendicular to the direction of said fibers. -8- Metal support according to claim 7, characterized in that the strip (1) has over its entire length, a plurality of series of zones (A) and (B), said strip (1) having arrangements for be packaged in rolls to be rolled out linearly to be continuously subjected to   different work and processing stations.   -9- Metal support according to claim 8, characterized in that the arrangements consist of solid lines (1 e) of separation between each series of zones, said lines having perforations spaced apart according to a determined pitch.