RU81406U1 - MULTILAYER PRINTED BOARD - Google Patents

Abstract

The utility model aims to increase the reliability of interlayer contacts and reduce the complexity in the assembly of multilayer printed circuit boards. The indicated technical result is achieved in that the board is made of a dielectric substrate with double-sided metallization and has on the surface of each layer a pattern of conductors and contact nodes in the form of contact pads with solder, on each contact pad there is a hole in the metallized layer and the dielectric substrate layer on one side and both holes are filled with conductive material. 1 ill.

Description

The utility model relates to radio engineering, in particular, to the manufacture of multilayer printed circuit boards.

A known design of a multilayer printed circuit board [RF Patent No. 2056704, H05K 05 3/46 1996], which is a package of foil substrates in which holes are formed for the interconnects, the pattern of conductors and tinned contact pads located at the interconnects. Foil substrates are packaged by applying pressure (pressing) and exposure to temperature (heating). The holes for the interconnects are filled with electrically conductive material, and during the manufacturing process, the contact pads are placed above the holes for the interconnects with the formation of at least one gap between the corresponding wall section of each of the holes made in the dielectric substrate and the adjacent portion of the external contour of the contact pad. The dielectric substrate is made of material that is not wetted by the material filling the holes for interconnects.

The disadvantage of this design of a multilayer printed circuit board is the impossibility of producing pairwise through metallization in the inner layers and the impossibility of its use in cases where the size of the holes for the interconnects does not exceed 100 μm, and the number of layers in multilayer printed circuit boards increases to 10 or more.

The closest solution is the design of a multilayer printed circuit board [RF Patent No. 60296, H05K 3/46 of January 10, 2007], which has on the surface of each layer a pattern of conductors and contact nodes made in the form of contact pads with solder, and

holes in the dielectric substrate, the solder is deposited on a refractory ball (for example, balls for BGA-cases) installed on the contact pads in the holes in the dielectric.

The design of this multilayer printed circuit board has the following disadvantages:

- due to the fact that the diameter of the balls used is usually 0.1-0.6 mm, the final thickness of the multilayer board containing up to 20 layers will be about 0.6-15 mm;

- this design does not allow the use of bilateral foil materials;

- the resulting high complexity when assembling a multilayer printed circuit board, associated with the need to lay a large number of balls in all layers.

The objective of the utility model is to create such a design of a multilayer printed circuit board, which will provide high reliability of electrical contact and its group assembly, will allow to arrange 10 or more layers in a multilayer printed circuit board, and minimize its thickness to 2 mm.

The problem is solved in that in a multilayer printed circuit board made of a dielectric substrate with double-sided metallization and having on the surface of each layer a pattern of conductors and contact nodes made in the form of contact pads with solder, a hole in the metallized layer is made on each side of the contact pad on one side and a dielectric substrate layer and both holes are filled with conductive material.

Figure 1 shows the design of the contact node made on a dielectric substrate with double-sided metallization. A contact pad 2 is made on one of the metallization layers of the dielectric substrate 1. A contact pad 3 is made in the metallization layer on the other side of this substrate, which is located strictly

under the contact pad of the upper metal layer. Holes are made in this contact pad, both in the metal layer 4 and in the dielectric substrate 5.

Inside the hole in the dielectric substrate on the inner surface of the metal layer 2 is a layer of conductive material 6, deposited by an electrochemical method. The contact pads are covered with a layer of solder 7. Such printed circuit boards are stacked on top of each other, combined and interconnected by vacuum soldering

Example

Printed circuit boards are formed by photolithography on foil substrates from a polyimide film with double-sided metallization, creating a pattern of conductors, pads and holes in the dielectric substrate.

On one side of the printed circuit board pads, a layer of copper is deposited in the holes. Contact pads located on both sides are covered with solder. Printed circuit boards stacked on top of each other and interconnected by vacuum soldering under the influence of elevated temperature and pressure form a multilayer printed circuit board. Thus, a package of 20 layers with a thickness of not more than 2 mm can be assembled.

Due to the use of the proposed design when assembling multilayer printed circuit boards, the reliability of interlayer contacts is significantly increased, the thickness of the multilayer printed circuit board is small compared to the prototype with the same number of layers, and the laboriousness of its assembly is significantly reduced.

Claims (1)

A multilayer printed circuit board having on the surface of each layer a pattern of conductors and contact nodes made in the form of contact pads with solder and holes in the dielectric substrate, characterized in that the dielectric substrate has double-sided metallization and contact pads on both sides, with each contact the site on one side has a hole in the metallized layer and the dielectric substrate layer, and both holes are filled with conductive material.