The role of metallographic microscope in process control of PCB board technology
1. The role of metallographic microscope in PCB board slicing technology in process control
The production of PCB boards is a process in which multiple processes cooperate with each other. The quality of the product in the previous process directly affects the production of the next process, and is even directly related to the quality of the final product. Therefore, quality control of key processes plays a vital role in the quality of the final product. As one of the detection methods, metallographic sectioning technology plays an increasingly important role in this field.
The role of metallographic microscope in process control of PCB board slicing technology includes the following aspects:
2.1 Role in raw material inspection
As a copper-clad laminate required for the production of multi-layer PCB boards, its quality will directly affect the production of multi-layer PCB boards. The following important information can be obtained from sections taken with a metallographic microscope:
2.1.1 Copper foil thickness, check whether the copper foil thickness meets the production requirements of multi-layer printed boards.
2.1.2 Thickness of the insulating dielectric layer and arrangement of prepreg sheets.
2.1.3 In the insulating medium, the warp and weft arrangement of glass fibers and the resin content.
2.1.4 Laminated board defect information Laminated board defects mainly include the following:
(1) Pinhole
Refers to a small hole that completely penetrates a layer of metal. For the production of multi-layer printed boards with higher wiring density, this kind of defect is often not allowed to occur.
(2)Pockmarks and dents
Pitting refers to small holes that have not completely penetrated the metal foil; pits refer to the local dot-like protrusions of the pressed steel plate used during the pressing process, causing gentle subsidence on the surface of the pressed copper foil. The size of the hole and the depth of the subsidence can be measured through metallographic sections to determine whether the existence of the defect is allowed.
(3)Scratches
Scratches refer to thin and shallow grooves scratched on the surface of copper foil by sharp objects. Measure the scratch width and depth through metallographic microscope sections to determine whether the existence of the defect is allowed.
(4) Wrinkles
Wrinkles refer to the creases or wrinkles in the copper foil on the surface of the pressure plate. The existence of this defect can be seen through metallographic sectioning and is not allowed.
(5) Lamination voids, white spots and blisters
Laminated voids refer to areas where there should be resin and adhesive inside the laminate, but are incompletely filled and missing; white spots occur inside the base material, where the glass fiber and resin are separated at the intersection of the fabric, which is manifested as Scattered white spots or "cross patterns" appear under the surface of the substrate; blistering refers to the phenomenon of local expansion and local separation between the layers of the substrate or between the substrate and the conductive copper foil. The existence of such defects will be determined depending on the specific circumstances.
