Metallographic sectioning (also called microsection) is one of the main methods for metallographic analysis of materials for PCB. The usual sampling methods for sectioning include: solid sealing, grinding, polishing and other processes. After all the steps are completed, photos of the morphology and structure can be provided, and data such as the size of the metallographic cracking layer and the size of the sample can be analyzed. The corresponding metallographic section analysis report is obtained by observing the metallographic section through a stereo microscope or a metallographic microscope, including observation of connection parts and solder joints, observation and analysis of micro cracks, cross-sectional compound morphology and intermetallic compound morphology and size measurement for testing report.

01 The role of raw material inspection As a double-sided or multi-layer printed board production required copper clad board or laminate, its quality will directly affect the production of multi-layer printed boards. The following important information can be obtained through metallographic section:

(1) Thickness of copper foil and substrate. Check whether the thickness of copper foil and substrate meets the production requirements of printed boards.

(2) The thickness of the insulating dielectric layer and the arrangement of the prepreg.

(3) In the insulating medium layer, the warp and weft arrangement of the glass fibers and the resin content.

(4) Laminate defect information

02 The role of quality control in the production process Metallographic section technology plays an important role in the process control of printed circuit board production. After the completion of different processes, sample the process board and conduct metallographic section analysis to detect the quality of the printed board after the process is completed; Quality plays a role in guarantee. It is mainly manifested in the following aspects:

(1) Detection of hole wall roughness after drilling process

(2) Detection of coincidence degree after multilayer printed board lamination process

(3) Detection of desmearing and etch-back effects on the hole wall

(4) Detection of hole metallization status

(5) Evaluation of electroplating ability

03 The role of product reliability test After the multilayer printed board is manufactured, the reliability test of the finished printed board is required according to the requirements of different customers. The following is a brief introduction to the role of metallographic section technology in reliability testing:

(1) Coating thickness measurement

(2) Thermal stress test

(3) Thermal shock test

(4) Metalized holes simulate repeated welding tests.