RU2121774C1 - Radio electronic assembly - Google Patents

Abstract

FIELD: radio engineering, in particular, heat removal from heat-emitting planar-terminal electronic unit, which is mounted on printed circuit board in such housings as 4116.4-3, 4116.8-3 according to GOST-17467-89. SUBSTANCE: device has heat-conducting housing, printed circuit board which is located in housing and carries heat-emitting electronic unit, which has heat-removal base and planar terminals. Terminals are bent at right angle in opposite to heat-conducting base of electronic unit. They are located in holes of printed circuit board and soldered to its contact areas on its side which is opposite to mounted electronic unit. Heat-removal base of electronic unit engages with housing in which first and second groups of pins are anchored. Pins of first group are passed through holes which are made in support members of printed circuit board. Pins of second group are passed through holes which are provided in heat-removal base of electronic unit. They carry dielectric barrels which grooved lower ends are located in holes of heat-removal base of electronic unit. Upper ends of barrels are passed through corresponding holes in printed circuit board. Screw ends of pins which are extended over printed circuit board from its support members and from dielectric barrels are equipped with nuts turned on screw ends of screw joints. EFFECT: improved heat removal. 3 dwg

Description

 The invention relates to electronics and can be used in blocks of electronic equipment to solve the problem of heat removal from a heat-loaded electronic component located on a printed circuit board with planar leads.

 Radio-electronic blocks are known, described for example in [1], [2] and [3], in which the problem of heat removal from a heat-loaded radio-electronic component placed on a printed circuit board is solved using a heat sink plate of a radiator installed between a heat-sink, usually metal, base of the radio-electronic component and the surface of the circuit board. The cooling efficiency in such blocks depends on the area of the heat sink plate of the radiator placed on the printed circuit board, which requires the allocation of appropriate space on it. This reduces the area used on the printed circuit board for installing other electronic components. A feature of the blocks under consideration is that the thermal energy released on the radiator mounted on the printed circuit board is dissipated inside the block itself, which reduces the cooling efficiency of the heat-loaded radio-electronic component and increases the thermal load on other radio-electronic components of the block.

 Radio-electronic blocks are known in which the cooling efficiency of heat-loaded radio-electronic components placed on a printed circuit board is increased by using heat-conducting structural elements, such as a housing, as radiators. In this case, to transfer heat from heat-loaded elements placed on the printed circuit board to the case, special heat-conducting dielectric pastes can be used, as for example in the known solutions [4] and [5], or special heat-conducting buses made on the printed circuit board and having thermal contact as with the case cooled electronic component, and with the housing of the electronic unit, as for example in the known solutions [6] and [7].

 The use of heat-conducting dielectric pastes in the designs of the radio-electronic blocks to create the corresponding heat-removing bridges between the heat-loaded radio-electronic component and the block case complicates the manufacturing technology of the block, and the use of heat-releasing tires made on the printed circuit board for the heat removal from the heat-loaded radio-electronic component complicates the design of the printed circuit board and reduces the area used to install other electronic components.

 As a prototype, the design of the electronic unit described in [7] was chosen. The prototype block contains a heat-conducting housing with a housing frame and a printed circuit board mounted on the housing frame with a heat-loaded radio-electronic component with planar leads. A heat sink bus is made on the printed circuit board, having thermal contact with the frame. A heat-loaded electronic component with planar leads is mounted on a printed circuit board so that its heat sink base has thermal contact with the heat sink bus.

 The thermal contact of the heat sink bus of the printed circuit board with the case frame is ensured by tightly clamping it, followed by fixing the printed circuit board on the frame, for example, by soldering or screw connection. The thermal contact of the radio-electronic component with the heat sink bus of the printed circuit board is ensured by clamping it to the printed circuit board with subsequent fixation of this position by soldering the planar leads of the radio electronic component on the contact pads of the printed circuit board or by screw connection of the heat-removing base of the radio electronic component with the printed circuit board in those cases when the design of the heat sink base provides for the possibility of such a connection.

 The use of a prototype unit for the purpose of removing heat from a heat-loaded electronic component to the unit body of an appropriate heat sink bus running on a printed circuit board complicates both the design of the printed circuit board and the design of the unit, which is associated, in particular, with the need to ensure reliable thermal contact of the printed circuit boards with a block body. The use of a heat sink bus to remove heat to the block body reduces the area of the printed circuit board used to install other electronic components. In addition, when heat is removed using the heat-dissipating bus, part of the thermal energy discharged to the block body is dissipated inside the block itself, which reduces the cooling efficiency of the heat-loaded electronic component.

 The claimed invention is directed to solving the technical problem of providing heat dissipation from a radio-electronic component mounted on a printed circuit board with planar leads (the design of the heat-removing base of which provides for the possibility of screw connection) directly to the housing of the radio-electronic unit without the aid of the heat-removing bus performed on the printed-circuit board, providing assembly convenience disassembling the electronic unit.

 The solution of this problem allows for efficient cooling of the electronic component with planar leads installed in the electronic unit on the printed circuit board, without complicating the design of the printed circuit board and its fastening to the block body, without reducing the useful area of the printed circuit board used to install other electronic components, ensuring convenience assembly / disassembly of the electronic unit.

 The essence of the invention lies in the fact that in a radio-electronic unit containing a heat-conducting housing, a printed circuit board fixed in the housing with a heat-loaded radio-electronic component mounted on it with a heat sink and planar leads, the planar leads of the radio-electronic component are bent at a right angle to the side opposite to its heat sink base, placed in the through holes of the printed circuit board and soldered to its pads on the side opposite to the installation side of the electronic of the first component, the heat sink base of the electronic component interacts with the housing in which the first and second groups of studs protruding above the printed circuit board are fixed, the studs of the first group are passed through holes made in the supporting elements of the printed circuit board, and the studs of the second group are passed through holes made in the heat sink the base of the electronic component, and on the studs of the second group there are dielectric bushings, the hollowed lower ends of which are placed in the holes of the heat sink the base of the electronic component, and the upper ones are passed through the corresponding holes made in the printed circuit board, while on the threaded ends of the studs protruding above the printed circuit board from its supporting elements and from dielectric bushings, nuts are screwed.

 The invention, its feasibility and the possibility of industrial use are illustrated by drawings (Fig. 1 - 3), where Fig. 1 shows an example of a specific embodiment of the inventive electronic block in section (general view), Fig. 2 shows a general view of a radio electronic component with planar leads , Fig.3 presents a view of the electronic unit from the side of the printed circuit board.

 The inventive electronic block contains, see FIG. 1 to 3, a heat sink housing 1, a printed circuit board 2, a heat-loaded electronic component 3 mounted on a printed circuit board, having planar leads 4 and a heat sink base 5 in which through holes 6 are formed.

 In the considered example of a specific implementation of the claimed radio electronic unit, standard microcircuits are used as the electronic component 3, for example, type 142EH3 - 142EH16, 2D222BC, etc., implemented in cases of type 4116.4-3, 4116.8-3 according to GOST 17467-89 [8], in which the heat sink base 5 is made in the form of a metal plate with two through holes 6 (see figure 2, which shows an example of an electronic component with a housing type 4116.8-3).

 The planar leads 4 of the electronic component 3 are bent, see figure 1 at a right angle to the side opposite to its heat sink base 5, are installed in the through holes 7 of the printed circuit board 2 and soldered to its pads 8 from the side opposite to the installation side of the electronic component 3.

 In the housing 1, studs 9 of the first group and studs 10 of the second group protruding above the printed circuit board 2 are fixed (studs). Studs 9 of the first group are used to secure the circuit board 2, and studs 10 of the second group are used to secure the heat-removing base 5 of the electronic component 3 in the housing 1 electronic unit. The number of studs 9 is determined by the number of mounting points of the printed circuit board 2, and the number of studs 10 is determined by the number of holes in the heat sink base 5 of the electronic component 3 (in this example of a specific embodiment of the electronic unit, the number of studs 10 is two).

 The studs 9 are passed through the holes 11 of the supporting elements 12 of the printed circuit board 2, which in the considered example of a particular embodiment of the inventive electronic block are cylindrical racks mounted on the printed circuit board 2 by flaring their shanks 13 in the corresponding holes 14 of the printed circuit board 2. On the protruding above the printed circuit board 2 of the holes 11 of the support elements 12 of the threaded ends 15 of the studs 9 nuts 16 are screwed on, fixing the circuit board 2 in the housing 1.

 The height of the support elements 12 is selected such that when the nuts 16 are tightened, a gap is fixed between the printed circuit board 2 and the inner surface 17 of the housing 1; in which the heat sink base 5 of the electronic component 3 is in thermal interaction (contact) with the housing 1.

 The thermal interaction of the heat sink base 5 of the electronic component 3 with the housing 1 is carried out through a dielectric heat-conducting gasket 18, made, for example, of mica. The attachment of the heat sink base 5 of the electronic component 3 together with the dielectric heat-conducting gasket 18 to the housing 1 to ensure thermal interaction between them is carried out using studs 10.

 The studs 10 are passed through holes 19 made in a dielectric heat-conducting gasket 18, and holes 6 of the heat sink base 5 of the electronic component 3.

 On the studs 10 are installed dielectric bushings 20, made, for example, of PCB. In the dielectric bushings 20 there are central through holes 21 for mounting the bushings 20 on the studs 10.

 The bushings 20 are mounted on the studs 10 in such a way that the grooved lower ends 22 of the bushings 20 are placed in the holes 6 of the heat sink base 5 of the electronic component 3, thereby providing electrical isolation from the studs 10. The upper ends 23 of the dielectric bushings 20 pass through the corresponding process holes 24, made in the printed circuit board 2. The upper ends 23 of the dielectric bushings 20 in specific embodiments of the inventive electronic block or protrude above the printed circuit board 2, as shown in figure 1, either located at its level.

 On the protruding from the dielectric bushings 20 threaded ends 25 of the studs 10 nuts 26 are screwed.

 Metal washers 27 are mounted on studs 10 under nuts 26. Similarly, metal washers 28 are mounted on studs 9 under nuts 16.

 An additional window 29 is made in the printed circuit board 2 (Fig. 3) for inspecting the markings printed on the front surface of the electronic component 3.

 The assembly of the electronic unit is carried out in the following sequence.

 First, the forming of the planar findings 4 of the electronic component 3 is carried out. The molding is carried out by bending the conclusions 4 of the electronic component 3 at a right angle to the side opposite to its heat sink base 5.

 After that, the electronic component 3 together with the dielectric heat-conducting gasket 18 is placed on the housing 1 of the electronic unit on the studs 10. Dielectric bushings 20, washers 27 are installed on the studs 10 and the nuts 26 are screwed.

 Then, a printed circuit board 2 is installed in the housing 1 of the electronic unit.

 The printed circuit board 2 is installed on the studs 9, passed through the holes 11 of the elements 12 of the printed circuit board 2. The printed circuit board 2 is installed so that the formed terminals 4 of the electronic component 3 are located in the corresponding holes 7 of the printed circuit board 2. The printed circuit board 2 is fixed in the housing 1 with nuts 16 screwed onto the threaded ends 15 of the studs 9 protruding above the board 2.

 After tightening the nuts 16 securing the circuit board 2 in the housing 1 of the electronic unit, the nuts 26 are finally tightened on the studs 10, thereby realizing the required clamping of the heat sink base 5 of the electronic component 3 to the housing 1. After that, the terminals 4 of the electronic component 3 are soldered to the corresponding pads 8 circuit board 2.

 With this assembly, the uniformity of the pressure of the heat-removing base 5 of the electronic component 3 to the housing 1 of the electronic unit is ensured, distortions when fixing the electronic component 3 and the possible mechanical stresses in its structural elements are eliminated.

 The radio-electronic unit assembled in this way provides efficient cooling of the heat-loaded radio-electronic component mounted on the printed circuit board by removing heat directly from it to the unit case without the use of heat-releasing buses on the printed circuit board.

 The design of the electronic unit provides the ability to conveniently disassemble it, for example, to repair a printed circuit board, and subsequent assembly with preservation of all thermal and structural characteristics of the unit.

 When disassembling the electronic block, the nuts 26, washers 27 and dielectric bushings 20 are turned off and removed from the studs 10. Then, nuts 16 with washers 18 are fastened and removed from the studs 9, fastening the printed circuit board 2 with the housing 1. After that, the printed circuit board 2, as well as the dielectric the heat-conducting gasket 18 is removed from the housing 1.

 The reassembly of the electronic unit is carried out in the reverse order: first, the dielectric heat-conducting gasket 18 and the printed circuit board 2 are installed in their place on the studs 10 and 9, after which the printed circuit board 2 is fixed in the housing 1 using washers 28 and nuts 16, and then installed in their places dielectric bushings 20, washers 27 and nuts 26 are screwed, fastening the heat sink base 5 of the electronic component 3 with the housing 1 of the electronic unit.

 Thus, from the above it is seen that the claimed invention is industrially applicable and solves the technical problem.

 The inventive design can find application in the design of small-sized blocks of electronic equipment using heat-loaded electronic components with housings similar to housings of type 4116.4-3, 4116.8-3 in accordance with GOST 17467-89, while solving the problem of efficient heat dissipation in a minimum structural volume, providing ease of assembly / disassembling the electronic unit.

Sources of information
1. USSR author's certificate N 586515, cl. H 01 L 23/36, published. 12/29/77.

 2. USSR author's certificate N 658798, cl. H 05 K 7/20, published. 04/25/79.

 3. Copyright certificate of the USSR N 1679666, cl. H 05 K 7/20, published, 09/23/91.

 4. Application of Great Britain N 2270207, CL H 05 K 7/20, published 02.03.94.

 5. US patent N 5109317, CL H 05 K 7/20, published 28.04.92.

 6. Copyright certificate of the USSR N 764160, class H 05 K 7/20, published. 09/15/80.

 7. The layout and design of microelectronic equipment / Ed. B.F. Vysotsky, V. B. Pestryakova, O. A. Pyatlin. -M.: Radio and Communications, 1982, p. 104-106, Fig. 5.25.

 8. GOST 17467-89. Integrated circuits. The main sizes.

Claims (1)

 An electronic block comprising a heat-conducting body, a printed circuit board fixed in the body with a heat-loaded radio-electronic component mounted on it with a heat sink base and planar leads, characterized in that the planar leads of the radio electronic component are bent at right angles to the side opposite to its heat sink base, placed in through holes printed circuit board and soldered on its pads from the side opposite to the installation side of the electronic component, heat the leading base of the electronic component interacts with the housing in which the first and second groups of studs protruding above the printed circuit board are fixed, the studs of the first group are passed through holes made in the supporting elements of the printed circuit board, and the studs of the second group are passed through holes made in the heat-removing base of the electronic component moreover, dielectric bushings are installed on the studs of the second group, the hollowed lower ends of which are placed in the holes of the heat sink base of the radio the electronic component, and the upper ones are passed through the corresponding holes made in the printed circuit board, while on the threaded ends of the studs protruding above the printed circuit board from its supporting elements and from the dielectric bushings, nuts are screwed.

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