RU2630680C2 - Strong multilayer printed board, containing low-cutting control circuits - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: multi-layer printed circuit board contains layers including layers of high-current circuits, layers of low-current circuits, and screen layers. To improve the manufacturing process of a multi-layer printed circuit board on high-current layers of the board, regions that are free of high-current circuits must be filled with metallised areas electrically connected to the shield layers of the board to ensure its interference immunity. In this case, on the board in the field of contact pads of mounting holes associated with high-current layers, there are through-through metallised holes that perform the function of a thermal gate to ensure soldering of electrical installation elements.

EFFECT: providing the required current load up to 20 A for high-current conducting layers of a multi-layer printed circuit board, uniform heat removal from the board heating area, creation of improved soldering conditions for wiring elements.

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Description

Technical field

The claimed invention relates to the field of electronic equipment. The inventive high-current multilayer printed circuit board with low-current control circuits is used in electronic secondary power supply devices.

State of the art

Among the printed circuit boards intended for use in power circuits, there are known boards created using the Iceberg technology, including high-current layers [1]. It is assumed that all the required electrical connections to the internal high-current layers are made through metallized holes.

The disadvantage of this method of creating high-current layers is that after etching a thick copper foil, on the basis of which high-current layers are formed, a pressing mode is necessarily performed to fill the highly profiled compounds with resin. This requires the selection of prepreg (cushioning fiberglass) and special pressing modes, which leads to complication and cost of the process of creating such boards.

Hausermann’s HSMtec technology is known where copper wire and profiles up to 500 microns thick are used to realize high currents and heat dissipation on the inner layers of a multilayer printed circuit board [2].

The disadvantage of this method, as in the previous case, is the selection of special modes of joint pressing of foil materials and copper inserts, which complicates the manufacturing process of a multilayer board.

Also known is a printed circuit board containing a dielectric base, on the first and second side of which conductors and contact pads are made. The contact pads on both sides are electrically connected by metallized holes [3; p. 153-155].

The disadvantage of this board is that on both sides of the board there are conductors that differ significantly in thickness, which greatly complicates the processing of the board and coating it with photoresist.

Patent WO 2005/005142 [4] describes a printed circuit board in terms of connecting the inner screen layers, which occupy the entire area of the board, through metallized mounting holes to the power outer layers, as well as an improved topology for component soldering.

Its disadvantage is the lack of noise immunity, because there is no simultaneous connection of the screen layers of the board by means of metallized mounting holes both to the module body and to the free metallized regions of high-current layers, as well as an insufficient number of high-current layers.

The patent RU 2499374 [5] describes a method for forming a thermal barrier on a printed circuit board in the area of contact pads, which is necessary for stable soldering of the terminals of the power components of the board.

The disadvantage of this method is the insufficient provision of the thermal barrier necessary for the stable soldering of the terminals of the required power components installed on the board.

A known printed circuit board described in patent RU 2481754 [6], with a metal base containing high-current and low-current circuits.

The disadvantage of this board is the great difficulty in constructing an ERI on two sides of the board and the implementation of high-current and low-current circuits in the given dimensions of the board, the manufacturing cost.

The specified circuit board [6] is the combination of essential features the closest device of the same purpose to the claimed invention. Therefore, it is adopted as a prototype of the claimed invention.

Disclosure of invention

The technical problem to be solved by the claimed invention is directed is the creation of a high-current multilayer printed circuit board containing low-current control circuits.

The technical result provided by the claimed invention is to provide the following characteristics:

1) the formation of high-current conductive layers together with low-current circuits;

2) uniform heat removal from the heating area of the board;

3) the creation of improved soldering conditions for electrical components associated with through-hole metallic holes with high-current layers.

The essence of the invention lies in the fact that a high-current multilayer printed circuit board containing low-current control circuits (hereinafter - SMPP) consists of external layers on which conductive patterns of low-current control circuits, internal screen layers connected to ground circuits, and internal high-current circuits are placed layers. High-current layers are placed on a fiberglass base between the screen layers, which increases the noise immunity of the printed circuit board. In order to improve the manufacturing regime of SMPP, the areas free from conductive patterns of high-current layers are filled with metallized regions of a similar thickness. To reduce interference, these metallized areas are connected via through metallized holes to the screen layers of the NSRP.

Brief Description of the Drawings

In FIG. 1 shows the internal structure of the placement of layers of the NSRP. In FIG. 2 - FIG. 7 shows topological drawings of the conductive layers 1-6. Images of the layers in FIG. 5 - FIG. 7 are given in mirror form (view "through" the dielectric base). In FIG. 8 shows the structure of the placement of holes for the thermal shutter in the field of contact pads.

The implementation of the invention

A high current multilayer printed circuit board (SMPP), the structure of which is shown in FIG. 1, consists of two pairs of single-layer metallized fiberglass bases (1) and (2) and a two-layer metallized base (3), which are separated by layers of cushioning glass fabric (4). A solder mask (5) is applied to the outer layers of the board. The solder mask is represented by a dry film photoresist.

The printed circuit board indicated in the patent [6] is, by the combination of essential features, the closest device of the same purpose to the claimed invention. Therefore, it is adopted as a prototype of the claimed invention.

However, unlike the product described in [6], the claimed invention does not use a metal base, but packages of standard double-sided foil fiberglass, constituting a multilayer printed circuit board, with additional metallization of areas of high-current layers free of conductive patterns.

On the outer layers of the SMPP (TOR layer in Fig. 2 and the BOTTOM layer in Fig. 7), low-current circuit conductors (6), high-voltage primary power supply ranges (7) and contact pads for mounting board components and connections to electrical circuits and polygons are placed boards. A description of the pads is presented below.

The TOR and BOTTOM layers are made on the metallized bases (1) of the printed circuit board (Fig. 1) and are fiberglass surfaces coated with copper foil. In FIG. 2 and FIG. 7 shows printed conductors (6), polygons (7) and various contact pads, which are topological drawings of the outer layers of the TOP and BOTTOM multilayer printed circuit boards. To install bulk components and make wired connections to the module case into which the board is installed, windows are made in the metallized bases of all layers of the board (8). The sizes of the windows and their mutual arrangement, both on the TOP and BOTTOM layers, and on other layers of the NSRP, are identical.

The printed conductors (6) and the electric test sites (7) on the TOP layer (Fig. 2) and the BOTTOM layer (Fig. 7) are paths of conductive material deposited by known methods of printed wiring on the metallized sides of the bases (1) included in the multilayer printed circuit board (Fig. 1). The conductive material of the printed conductors is copper foil coated with layers of nickel and tin-lead solder, which ensures high corrosion resistance of the conductive pattern. Primary high-voltage power supply polygons (7) on the TOP and BOTTOM layers are additionally expanded to a thickness that ensures input current transmission. These landfills are either connected on one side to the contact pads (9), and on the other hand, to the contact pads (10) of SynGor power converters, or connected on one side to the contact pads (11) of Vicor power converters, and on the other hand - to contact pads (10) of SynGor type power converters. Separate sections of polygons on the TOP layer are also being built up, interrupted by the windows of the board (8) and connected to planar contact pads (12, Fig. 2) for communication by wiring together. The printed conductors (6), which perform the functions of electrical connections between the components of the board, are wide enough for stable signal transmission. The components on the board are installed on the BOTTOM layer. The calculation of the width of the electric ranges of the primary high-voltage power supply (7) is performed in such a way as to take into account the built-in parameters to provide the specified parameters for the input current. To the contact pads (9), the input wiring of the power supply is soldered.

The planar contact pads (12) on the TOP layer (Fig. 2) also provide the connection of the mounting contacts of the board components (13) connected to the ground circuit with the module case into which the board is installed. The contact pads (11) of the metallized holes on the TOP layer (Fig. 2) are intended for desoldering the board to the contacts of the Vicor type power converters, and the contact pads (10) and (14) are used for desoldering the contacts of the SynGor type power converters. The components on the board are installed on the BOTTOM layer in the metallized holes (13). The printing unit is installed in the module using fasteners attached to both metallized (15) and non-metallic (16) mounting holes so that the BOTTOM layer and the board components face the inside of the module. The pinouts of the power converters are made to the contact pads (11), (14) and (10) of the TOP layer facing the outside of the module. Metallized mounting holes (15) have contact pads on all layers except high-current layers (Fig. 4, Fig. 5).

The metallized hole groups indicated in FIG. 2, FIG. 4, FIG. 5 and FIG. 7 as Channel A, Channel B, Channel C, Channel D and Group 1, are used to solder the board connector. In the field of each planar site of the corresponding metallized hole, connected to one of the internal high-current layers, there are through metallized holes that act as a thermal barrier when soldering the connector. The connection between the driving patterns of the TOP and BOTTOM layers is carried out using through vias (17). To ensure better heat transfer of the power converters, cutouts are provided on all layers (18).

Topological drawings of the inner screen layers GND1 and GND2 are shown in FIG. 3 and FIG. 6 respectively. The connection of the screen layers (19) to the fastening metallized holes (15) is carried out using contact pads having a thermal barrier. An example of the use of wide metallization bands electrically connected between vias is a patent [4]. However, in contrast to the heat removal method indicated in the patent, the proposed SMPP has a number of significant differences. Firstly, the screen layers, performing not only the functions of heat removal, but also shielding, are implemented in the form of two internal one-sided metallized bases (2, Fig. 1), placed in such a way that high-current layers are placed between them. This increases the noise immunity of the board and improves heat dissipation from each of the high current layers. In this case, the dielectric bases are oriented in such a way as to reduce the mutual influence of the metallized areas of the screen and high-current layers, thereby reducing the number of cushioning layers (4, Fig. 1) and thereby reduce the thickness of the board and improve the pressing mode. Secondly, the topological drawings of the screen layers show that their metallization areas (19, Fig. 3 and Fig. 6) cover the entire area of the board, with the exception of cutouts for technological windows and releases around metallized mounting holes. A large metallization area allows efficient heat removal from areas of high-current layers occupied by current-carrying conductors. Thirdly, the electrical connection between the screen layers is carried out through metallized through mounting holes, which allows due to fasteners to further increase the heat sink from the screen layers of the SMPP to the base heat-removing elements of the module, which includes the SMPP.

Topological drawings of the internal high-current layers + 28V and -28V are presented in FIG. 4 and FIG. 5 respectively. Areas of additional metallization and their connection to the metallized mounting holes are not shown in the figures. Elements of conductive patterns of high-current layers (20, Fig. 4 and Fig. 5) are connected to the internal contact pads of the mounting metallized holes of the SynGor type power converters using a thermal barrier. The internal contact pads of the connector and their connection are similar to the described pads for the TOP and BOTTOM layers. The topology of metallized holes that perform the function of a thermal barrier with the contact pads in which they are located is shown in FIG. 8. An example of such a constructive solution is the topology described in the patent [5].

However, in contrast to the heat removal method specified in the patent [5], the proposed SMPP has significant differences, namely, uniform heat removal is provided by connecting metallized holes not to specialized metallization areas on the second side of the board, but to conductive patterns of internal high-current layers for stable soldering of leads power components installed on the board.

Thus, from the foregoing, it follows that in the inventive high-current multilayer printed circuit board containing low-current control circuits, the claimed technical result is: "providing the required current load of up to 20 A for high-current conductive layers of a multilayer printed circuit board, uniform heat dissipation from the heating area of the board, as well as the creation of improved soldering conditions for electrical elements "is achieved due to the fact that the multilayer board contains a bilateral metallized dielectric base on which internal high-current layers are formed, and also contains internal metallized bases on which screen layers are formed that simultaneously perform the functions of heat removal, and contains external metallized dielectric bases on which low-current control layers are formed and the components of the board are installed. Improved soldering conditions for electrical elements are achieved by forming thermal barriers near specific mounting holes by creating a region of metallized holes. The implementation of the design and topology of the claimed high-current multilayer printed circuit board is illustrated in FIG. 1 - FIG. 8.

Industrial applicability.

The inventors provided the manufacture of prototypes of the claimed high-current multilayer printed circuit board, the tests of which confirmed the achievement of the technical result.

The inventive high-current multilayer printed circuit board containing low-current control layers is implemented using industrially produced devices and materials and can be manufactured at an electromechanical enterprise and will be widely used in the electronics industry and instrument engineering.

Information sources

1. Bechtloff W., Fichler R., Schauer J., Schmieder K. “Iceberg is ahead!” Technologies in the electronic industry No. 3, 2005

2. Oberender L. (translation by A. Novikov) "Realization of high currents on printed circuit boards". Technologies in the electronic industry No. 5, 6, 2007

3. E.V. Pirogov "Design and technology of printed circuit boards", Moscow: FORUM: INFRA-M, 2005

4. Patent WO 2005/005142 (2005).

5. Patent RU 2499374 (2012).

6. Patent RU 2481754 (2011).

Claims (1)

A high-current multilayer printed circuit board containing low-current control circuits, including metallized bases, characterized in that its structure is a multilayer circuit board with internal high-current layers capable of withstanding a current load of up to 20 A, internal screen layers that also perform the function of heat removal, and external layers, on which conductive patterns of low-current control circuits of the order of 300 mA and contact pads for mounting board components are formed, while the formation of internal their high-current layers is performed on a separate metallized base, which is used as a double-sided foil-coated fiberglass, with additional metallization of regions of high-current layers free of conductive patterns, screen layers in the form of two one-sided metallized bases between which high-current layers are placed, through metallized mounting holes are connected between through metallized mounting holes and simultaneously connected to wire-free Supporting patterns for metallized areas of high-current layers, while connecting pads for mounting board components to conductive patterns of internal high-current layers is performed by forming through-hole metallic holes.

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