The role of metallurgical microscopy in the process control of PCB board slicing technology
1 Role in the incoming inspection of raw materials As a copper-clad laminate required for the production of multilayer PCB boards, the quality of its good or bad will directly affect the production of multilayer PCB boards. Through the metallographic film taken by the slice can get the following important information.
1.1 Thickness of copper foil, to check whether the thickness of copper foil meets the production requirements of multilayer PCB.
1.2 Thickness of the dielectric layer and the layout of the semi-cured sheet.
1.3 Olympus metallographic microscope insulation medium, glass fibre warp and weft arrangement and resin content.
(1) pinhole
Refers to the complete penetration of a layer of metal holes. For the production of higher wiring density of multilayer printed circuit boards, is often not allowed to appear this defect.
(2) Spots and pits
Numbness refers to the small holes that do not completely penetrate the metal foil: pit refers to the pressing process, may be used to grind the steel plate local point-like protrusions, resulting in pressure after the surface of the copper foil appeared to ease the phenomenon of subsidence. The size of the hole and the depth of subsidence can be measured by metallographic section to decide whether the existence of the defect is permissible or not.
(3) Scratch
Scratches are shallow grooves made by sharp objects on the surface of copper foil. The width and depth of the scratches are measured by metallurgical microscope sections to determine whether the presence of the defect is permissible or not.
(4) Wrinkle
Wrinkles are creases or wrinkles in the copper foil on the surface of the platen. The existence of this defect can be seen through metallographic sectioning is not permitted.
(5) Laminated voids, white spots and blisters
Laminated cavity is the laminate should have resin and adhesive, but filling is not complete and there is a lack of area; white spot is occurring inside the substrate, in the textile interweaving at the glass fibre and resin separation phenomenon, manifested in the substrate under the surface of the dispersed white spots or "crosses"; blistering refers to the substrate of the interlayer or the substrate and conductive Between the layers of the substrate or substrate and conductive copper foil, resulting in local expansion caused by the phenomenon of local separation. The existence of such defects, depending on the specific circumstances to determine whether to allow.
