RU2824175C1 - Connection of electric circuits of printed circuit boards through elements of device circuit - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the design of radioelectronic equipment and can be used in the design of small-sized items consisting of two or more printed circuit boards, which require connection of electric circuits to each other. Connection of electric circuits of printed circuit boards through elements of the device circuit includes printed circuit boards and connection elements. Connection is provided between at least two printed-circuit boards with connection elements installed between them. Connection elements are represented by smd-components of the circuit with a soldered surface on two opposite sides of the element. At the same time connection of connection elements with electric circuits of printed circuit boards can be carried out both by soldering and by means of current-conducting glue.

EFFECT: creation of reliable, low-resistance, with improved weight and size characteristics of the final device for connection of electric circuits of printed circuit boards through elements of the device circuit with the possibility of two-sided mounting of components on the printed circuit board.

1 cl, 1 dwg

Description

The invention relates to the design of radio-electronic equipment and can be used in the design of small-sized products consisting of two or more printed circuit boards that require connecting electrical circuits to each other.

A multilayer and multifunctional printed circuit board is known (US 2002070835 A1, published 11.12.2000), consisting of several printed circuit boards, each of which has four or six layers and includes one winding. One set of windings is made in the form of an inductor, and the second set of windings is made in the form of a transformer. The printed circuit boards are laid with an offset so that the pins connecting one set of windings on the printed circuit board or printed circuit boards to the main printed circuit board do not penetrate the printed circuit board or printed circuit boards, including another set of windings.

The disadvantage of this device is the need to use third-party parts (connecting pins, pos. 506, 507 and 515) to connect printed circuit boards, which do not participate in the operation of the device, which reduces reliability and increases the overall dimensions of the product (area and volume).

The closest to the proposed solution is a module for double-sided mounting of components on a board (RU 2033710 C1, published 20.04.1995), consisting of two multilayer ceramic boards with single-sided mounting, electrically connected to each other, both boards are installed on a common base made with through slots for electrical connection of the boards and simultaneously serving as a heat sink, on its opposite surfaces mirrored relative to each other, and each of the boards has a built-in heating device.

The disadvantage of this device is the use of third-party parts (common base, pos. 5) for connection, which do not participate in the operation of the device, which reduces reliability and increases the mass and dimensions of the product (area and volume). Also, this technical solution does not provide for double-sided mounting of components on a ceramic board (only single-sided mounting).

The technical result consists in creating a reliable, low-resistance connection of electrical circuits of printed circuit boards that does not increase the mass and dimensions of the final device (improving the mass and dimensions of the device) through elements of the device circuit with the possibility of double-sided mounting of components on the printed circuit board.

A connection of electrical circuits of printed circuit boards through elements of a device circuit, including printed circuit boards and connection elements, characterized in that the connection is provided between at least two printed circuit boards with connection elements installed between them, wherein the connection elements are SMD components of the circuit with a solderable surface on two opposite sides of the element.

In this case, the connection of connection elements with electrical circuits of printed circuit boards can be carried out either by soldering or by using conductive glue.

The essence of the proposed invention is explained by drawings, where Fig. 1 shows an example of connecting printed circuit boards using elements of the device circuit, in particular capacitors.

In Fig. 1 the following designations are used:

1 - printed circuit board;

2 - circuit elements (connection elements);

3 - open areas of contact pads;

4 - vias;

I - the first pair of printed circuit board connections;

II - the second pair of printed circuit board connections;

N - n-th pair of printed circuit board connections.

The design shown in Fig. 1 is a printed circuit board 1 made on a glass-textolite, ceramic or metal base, on the open sections of the contact pads 3 of which solder paste is applied, the composition of the solder paste can be absolutely any (for example, Sn63Pb37 or SAC305), subject to the selection of the optimal thermal profile and reflow environment. Solder paste is applied using screen printing or drop inkjet. Then, the elements of the circuit 2 of the device are installed on the contact pads exposed from the solder mask. All smd components (surface mounted device, from English - device for surface mounting or surface-mounted components), which have a soldered surface on two opposite sides of the body (for example, CHIP capacitors, CHIP resistors, CHIP inductors and others), electrically connected to each other, can act as circuit elements.

The installation of the circuit elements 2 is performed automatically using modern equipment (e.g., automated surface mount component installers), manual installation is also allowed. This solution provides the ability to install components from both sides. Then, solder paste is dosed onto the upper pads of the circuit elements 2 of the device using a dosing unit. The optimal dose is calculated and the repeatability of the applied dose is controlled. Then, also using an automated installer or manually, the second printed circuit board is installed, which has mating open areas of the contact pads 3, opening from the solder mask and having a solderable finish coating, to organize a soldered connection. Instead of a soldered connection, it is allowed to use a connection using conductive glue (e.g., TTK, EKT-9S or OTKz). Next, the entire structure goes through a melting stage, where the open areas of the contact pads 3 are melted and provide a reliable soldered connection with the printed circuit boards, thereby connecting the electrical circuits to each other, forming a pair of printed circuit board connections I. This assembly procedure can be repeated N times, within the limits of technological capabilities.

In a static state, this solution is a rigidly connected printed circuit board and circuit elements of the device using solder paste. This connection ensures a reliable connection under mechanical impacts on these areas. Reliability is comparable to the classic soldered connection of a surface-mount component to a printed circuit board. Due to the small tolerance for the manufacture of the copper pattern of the printed circuit board (about ±50 μm), precise positioning of printed circuit boards 1 relative to each other is achieved, which allows using this solution in tasks with high-precision requirements.

In working condition, this solution provides reliable electrical connection between elements of circuit 2 of the device and connected printed circuit boards 1. The current flow path is movement through copper parts of printed circuit board 1 to elements of circuit 2, also known as connection element, then current flows through connection element 2. When passing through connection element 2, the signal can change, since the element can have certain electrical characteristics, then the signal gets through vias 4 in printed circuit board 1 to the next element of circuit or connection element 2. Transitions can be performed N-th number of times, in accordance with the number of pairs of connected printed circuit boards 1, depending on the requirements and the task.

An example of using the connection of printed circuit boards through the elements of the device circuit is its use in step-down voltage converters (hereinafter referred to as converters). In particular, in converters up to 50 W, printed circuit board connections are used, consisting of 3 pairs of printed circuit boards connected to each other by soldering through capacitors.

Claims (2)

1. A connection of electrical circuits of printed circuit boards through elements of a device circuit, including printed circuit boards and connection elements, characterized in that the connection is provided between at least two printed circuit boards with connection elements installed between them, wherein the connection elements are SMD components of the device circuit with a solderable surface on two opposite sides of the element. 2. Connecting electrical circuits of printed circuit boards through elements of the circuit of the device according to paragraph 1, characterized in that the connection of the connecting elements with the electrical circuits of printed circuit boards is carried out using conductive glue.

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