Rigid-flex composite circuit board and manufacturing method thereof

Abstract

The invention discloses a soft-hard composite circuit board, the structure of which comprises a flexible substrate and at least one rigid substrate, the flexible substrate is embedded in the outer edge of the rigid substrate in the horizontal direction, and a first conducting hole penetrates through An insulating layer on the rigid substrate is electrically connected to a conductive pattern layer and the rigid substrate, and a second via hole penetrates the insulating layer and electrically connects the conductive pattern layer to the flexible substrate .

Description

technical field [0001] The present invention generally relates to a rigid-flex composite circuit board structure and a manufacturing method thereof, more specifically, the present invention relates to a rigid-flex composite circuit board structure and a manufacturing method of an embedded flexible board (e-flex) design . Background technique [0002] In the field of printed circuit boards, if two rigid substrates (referred to as rigid boards) are to be connected, in the past, flexible substrates (referred to as flexible boards) and connectors were mostly used as the connection structure between the two. Nowadays, the industry has developed a design in which a flexible board is directly fabricated between two hard boards, which is the so-called rigid-flex composite circuit board (Rigid-Flex) structure. This structure can not only improve the reliability of the connection between the hard board and the soft board, but also save the subsequent process steps of making the soft-...

AI Technical Summary

Problems solved by technology

[0005] However, in some customized e-flex designs, especially Figure 1A The structural design of an additional electromagnetic shielding layer 150 is provided on the flexible substrate 110 shown in , the thickness of the flexible substrate 110 will increase due to the addition of this additional layer-up structure

At the same time, if the rigid substrate 120 to be connected is produced by using the technology of Every Layer Interconnection (ELIC), considering the technology used in this technology, the center of the rigid substrate 120 is used as the hard core film of the core layer. The thickness of 121 should not be too thick, otherwise the hole filling process of the subsequent via hole 124 will cause uneven hole filling due to the excessive thickness of the core layer, resulting in reliability problems

Therefore, in this ELIC process, the thickness of the rigid substrate 120 must be reduced, such as from Figure 1A Standard 100µm thickness scaled down to Figure 1B 60μm thickness, resulting in a thickness drop between the flexible substrate 110 and the rigid substrate 120

[0006] It can be seen from this that if the e-flex design is combined with the ELIC process to manufacture the soft-hard composite circuit board, the thickness difference between the flexible substrate 110 and the rigid substrate 120 will be too large, so that the flat surface cannot be obtained after the two are pressed together, forming like Figure 1B Composite panel structure with surface drop shown

This uneven surface will make the subsequent photolithography process of patterning the conductive pattern layer 142 impossible.

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