Microscopic Verification of PCB Construction: Visual Inspection Revealing PCB Details
In the world of printed circuit board (PCB) manufacturing, quality and reliability are paramount for high-performance and critical applications. One essential method used to ensure these standards is the analysis of PCB test coupons through cross-section or micro-section analysis.
PCB test coupons serve as standardized samples that replicate the actual PCB's features, allowing for the evaluation of internal structural integrity and manufacturing quality. These coupons are designed following IPC standards like IPC-2220 to ensure relevant features, such as pad sizes, trace widths, and hole diameters, are accurately represented.
The process of creating and analyzing these test coupons involves several steps. First, test coupons are integrated on the PCB panel at specified locations to facilitate testing without impacting the functional PCB. After manufacturing, the coupons are selected and extracted for examination.
Next, the coupon is prepared by cutting it vertically (cross-sectioning), polishing to a mirror finish, and cleaning to remove contaminants. The coupon is then examined under a microscope to assess critical parameters, including barrel fill quality, copper plating thickness, presence of delamination or cracks, and other internal defects that could cause electrical failures.
Comparing findings against IPC-6012 quality requirements certifies the manufacturing quality and compliance. Optionally, complementary techniques like X-ray inspection, Scanning Electron Microscopy (SEM), and elemental analysis (EDX) may be used to escalate failure analysis if defects are found.
This controlled destructive examination allows manufacturers and engineers to verify process reliability, identify fabrication challenges early, and ensure the PCB meets stringent quality and reliability standards.
The peel strength of tracks test is another crucial aspect of the analysis, conducted only on 3mm conductor width. The sample is isolated, the edges are smoothened, and the conductor width is measured. The machine is validated with standard weights, and the selected conductor is peeled back at one end for a length of about 10mm. Traction is applied in a direction perpendicular to the plane of the PCB until the copper starts to peel off, and the force gauge utilized will have a minimum resolution of 0.1g.
At Sierra Circuits, we have the right infrastructure and experienced staff to perform these extensive cross-section analyses of PCBs. Through this process, we can detect and verify internal defects in PCBs, ensuring the highest quality and reliability for our customers.
Scientists in the field of data-and-cloud-computing may find value in studying the elaborate process of PCB manufacturing, as the analysis of PCB test coupons, including controlled impedance measurements and cross-sectional inspections, can provide invaluable data for medical-conditions that require high-performance, critical PCBs, such as pacemakers and imaging equipment.
In the event of PCB failure, technology like X-ray inspection, Scanning Electron Microscopy (SEM), and elemental analysis (EDX) can aid in discovering the root cause, ultimately improving manufacturing processes and preventing such occurrences in the future.
