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PCB Tech

PCB Tech

PCB Tech

PCB Tech

Multi-Stage HDI Rigid Flex Composite Board Structure
2021-07-22
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Author:Evian

The utility model relates to the technical field of Multi-Stage HDI Rigid Flex PCB, in particular to a multi-stage HDI soft hard bonding board structure, which comprises a soft board, on which a non flowing adhesive sheet, a copper clad core board and a multi-layer laser coating are successively arranged, the copper clad core board comprises a core board layer and a copper clad layer, the none flowing adhesive sheet is provided with a rigid flex window, and the copper clad layer on the copper clad core board is provided with an annular isolation groove, The copper-clad layer is surrounded and separated by an annular isolation groove to form a copper patch. 


Background technology:

Printed circuit board (PCB) is an important electronic component. It is the support of electronic components and the provider of electrical connection of electronic components. At present, with the rapid development of PCB industry, its application is more and more widely. From electronic equipment to electronic watch, calculator, general-purpose computer, communication electronic equipment, military weapon system, as long as there are integrated circuits and other electronic components, the electrical interconnection between them will use PCB. In the traditional manufacturing method of directly opening windows for rigid boards, both before laser drilling and after mechanical drilling need to be expanded or degummed, especially for HDI (High Density Interconnect) boards with multiple boards, which need to be expanded or degummed for many times, causing great corrosion to the substrate of flex boards and the surface of the covering film, causing the surface of the covering film to change color and have no luster. If it is serious, it will cause the problem of line exposure; In addition, HDI PCB board needs to be laminated for many times, and each laminate needs to be windowed. The windowing of each laminate needs to be compensated by measuring the rise and fall after the completion of the secondary outer circuit, so the production process is long and the production cost is high; In addition, during alignment, the glue overflow may be too large due to alignment deviation, covering the flex board area of small windows.

HDI Rigid Flex PCB

HDI Rigid Flex PCB

Contents of the utility model:

The purpose of the utility model is to provide a multi-stage HDI soft and rigid combination board structure aiming at the shortcomings of the existing technology, which simplifies the production process, reduces the production cost, and improves the production efficiency and accuracy of the product.


In order to achieve the above purpose, the technical scheme adopted by the utility model is as follows:

A multi-stage HDI rigid-flex board structure comprises a flex board, on which a copper-clad core board and a multi-layer laser cladding layer are successively arranged, the copper-clad core board is bonded with the flex a none flowing adhesive sheet, the copper-clad core board comprises a core board layer and a copper-clad layer respectively arranged at the upper , and lower end faces of the core board layer, and the non flowing adhesive sheet is provided with a soft board window at the position corresponding to the window opening area of the soft board, The copper clad layer connected with the none flowing adhesive sheet on the copper clad core board is provided with an annular isolation groove corresponding to the windowing area of the soft board, and the position on the copper clad layer corresponding to the windowing area of the flex board is surrounded and separated by the annular isolation groove to form a copper patch.


Noted: 

Above flex board is provided with a covering film at the position of the soft board window.

The laser adding layer comprises a medium layer, a copper foil layer and an electroplated copper layer from the inner layer to the outer layer.

The thickness of the dielectric layer is less than or equal to 0.3 μ M.

Preferably, the thickness of the dielectric layer is 0.05 and 0.2mm.

The outer surface of the outermost laser layer is provided with a solder resist ink layer.

There are holes drilled in each layer, and the holes of two adjacent layers are staggered.


The utility model has the advantages : the utility model comprises a soft board, the flex board is successively provided with a copper-clad core board and a multi-layer laser coating, the copper-clad core board is bonded with the soft board through a none flowing adhesive sheet, the copper-clad core board comprises a core board layer and a copper-clad layer which is respectively arranged on the upper and lower ends of the core board layer, and the none flowing adhesive sheet is provided with a soft board window at the position corresponding to the window opening area of the flex board, The copper clad layer connected with the none flowing adhesive sheet on the copper clad core board is provided with an annular isolation groove corresponding to the windowing area of the flex board. And the position on the copper clad layer corresponding to the window area of the soft board is surrounded and separated by the annular isolation groove to form a copper patch. The utility model only needs to windowing the none flowing adhesive sheet attached to the soft board, and other layers do not need to window. The follow-up process can be completely in accordance with the production process of the hard board, without measuring the rise and fall of the secondary outer layer and window of each layer. After the completion of the outer layer graphics. The window of the soft board area of the rigid and soft bonding plate can be completed by mechanical and laser blind milling. At the same time, the copper at the edge of the board can be etched during the etching process, so as to avoid the residual copper phenomenon at the edge of the hard and soft bonding board, and the production process and production cycle are short. The soft and rigid joint area has uniform glue overflow, low production cost and high production efficiency and precision; Moreover, the copper patch can block the laser burn covering film, and at the same time, it can also fall off together with the waste after the window opening, which simplifies the manufacturing process.


Specific implementation mode:

1. The soft plate I is successively provided with a copper clad core plate and a multi-layer laser additional layer 5. The copper clad core board and the soft board I are bonded through a none flowing adhesive sheet . The none flowing adhesive sheet 2 is a non flowing semi cured sheet. The copper clad core board comprises a core board layer 4 and a copper clad layer 3 respectively arranged on the upper and lower end faces of the core board layer 4, The none flowing adhesive sheet 2 is provided with a soft plate window 21 at the position corresponding to the soft plate window opening area. The copper clad layer 3 connected with the non flowing adhesive sheet 2 on the copper clad core board is provided with an annular isolation groove 31 corresponding to the soft board window opening area. The copper clad layer 3 is located at the position corresponding to the soft plate window opening area and is surrounded and separated by the annular isolation groove 31 to form a copper patch 3

2. The copper patch 32 can block the laser, Limit the laser drilling depth to avoid laser damage to the substrate. The soft board I is provided with a covering film 6 at the position of the soft board window 21 to protect the soft board I.


The window opening method of flex and rigid combined board is to use mechanical depth control blind milling to a certain depth, and then use laser blind milling to open the window. It is mainly used for products with two or more stages. The flex and rigid combined HDI products with a total thickness of more than 0.25mm from soft board I to outer layer and more than 8 layers are the most suitable. Mechanical blind milling uses pin positioning, while laser blind milling needs to design laser target at the corresponding level of copper patch 32, and use the target of this layer as the alignment basis to ensure the accuracy of laser position. The production process of the utility model is simple, and the utility model is very suitable for the production and design of high-order HDI products of soft and hard combination boards; The inner soft board I and the outer hard board are processed and manufactured at the same time on the outer layer. The manufacturing process of the outer layer is basically the same as that of the ordinary rigid board. At the same time, it can effectively protect the covering film 6, soft board 1 and golden finger from being polluted by the liquid medicine during the manufacturing process; It can be used for products with small inner groove and can not be completed by mechanical milling.


The utility model only needs to open the window on the non flowing adhesive sheet 2 pasted into the soft board I, and there is no need to open the window on other layers. After the first pressing board, the subsequent process can be made in full accordance with the manufacturing process of the rigid board, and there is no need to measure the expansion and contraction of the secondary outer layer and open the window on each layer. After the outer layer graphics are completed, the window making of the flex board I area of the soft board can be completed by mechanical and laser blind milling. At the same time, in the etching process, the copper at the edge of the board can be etched away to avoid the phenomenon of residual copper at the edge of the combination of soft and rigid. 


Of course, the above is only the preferred embodiment of the utility multi-stage HDI rigid flex model, so any equivalent changes or modifications made according to the structure, features and principles described in the scope of the patent application of the utility model are included in the scope of the patent application of the utility model.