SMT subtractive high-density packaging multilayer circuit board structure and its manufacturing method

Abstract

The invention relates to an SMT subtraction high-density packaged multilayer circuit board structure and a manufacturing method thereof. The structure comprises an inner circuit layer (1) and an outer circuit layer (3), connecting copper columns (2) are arranged between the inner circuit layer (1) and the outer circuit layer (3), local etching is conducted on the middle of the inner circuit layer (1) to form a fill area (4), tin layers (5) are arranged on the surface of the inner circuit layer (1) etched locally, elements (6) are arranged on the tin layers (5) in a surface-mounted mode, the inner portion of the fill area (4), the peripheries of the tin layers (5) and the peripheries of the elements (6) are filled with epoxy resin (7) and the surface of the outer circuit layer (3) and the periphery of the outer circuit layer (3) are coated with light-sensitive insulating materials (8). The SMT subtraction high-density packaged multilayer circuit board structure and the manufacturing method of the SMT subtraction high-density packaged multilayer circuit board structure have the advantages that a solid surface-mounted welding area formed through tin cream coating is replaced, and therefore high-performance electric connection and good reliability are realized on the basis of high-density circuit design and manufacturing.

Description

technical field [0001] The invention relates to an SMT subtractive high-density packaging multilayer circuit board structure and a manufacturing method thereof, belonging to the technical field of semiconductor packaging. Background technique [0002] The current surface mount process of high-density substrates is mainly to use stencil printing or injection coating solder paste on the wiring layer pad on the surface of the substrate, and then perform surface accurate mounting of components in the solder paste area, and finally reflow soldering . [0003] The multilayer circuit board structure of the conventional solder paste process is as follows: Figure 35 As shown, the above-mentioned current high-density substrate surface mount technology has the following deficiencies and defects: [0004] 1. The tin powder or tin particles in the solder paste have a certain size, which limits the printing spacing to a certain extent. The printing accuracy depends on the size of the me...

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Problems solved by technology

[0004] 1. The tin powder or tin particles in the solder paste have a certain size, which limits the printing spacing to a certain extent. The printing accuracy depends on the size of the metal component in the solder paste. The conventional capacity can reach 50um, and it is difficult to achieve high density. design and manufacture;

[0005] 2. The coated solder paste layer is liquid (softer) and thicker (generally 70-80um), which is not conducive to controlling the dimensional stability of surface mount components;

[0006] 3. Solder paste is a paste-like substance mixed with various substances, and its fluidity is relatively poor. After reflow soldering, it is easy to form bubbles in the welding area, which reduces the electrical stability;

[0007] 4. After the reflow soldering of the mounted components, the solder paste softens and the components collapse in the solder paste layer, which may easily cause the gap between the components and the circuit layer to be too small and cause the problem of unfilled subsequent packages;

[0008] 5. There is a certain thickness drop between the circuit area of ​​the high-density substrate and the border. It is difficult to place and remove the printed stencil during the process of brushing the solder paste, and it is easy to cause the offset of the printed stencil and the local unevenness of the solder paste, thus will degrade the electrical performance of the connection

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