Defining X-ray solder-void acceptance for SMT busbars

Locate each target attachment on the drawings

We recommend mapping solder regions, holes and overlapping double-sided features using hardware, pad and assembly drawings. Retain orientation and coordinates to distinguish designed openings and board features from suspected solder defects. Comparison samples should share revision and assembly state.

Nordson's PCB inspection information describes 2D transmission, oblique and CT acquisition, with voiding, bridging and insufficient-solder checks. The task determines the method; that capability description does not qualify every inspection program for a particular busbar.

Establish whether the interface is distinguishable

Have the inspection provider assess metal thickness, overlapping layers and distinguishability of target solder from background. Where 2D interpretation is unreliable, review oblique, layered imaging or approved cross-section confirmation. Nordson describes CT reconstruction of a target volume followed by layer inspection.

Use representative samples to establish detection of agreed defects before freezing acquisition, regions and review rules. CT still needs target-layer and identifiable-feature definitions. An equipment name cannot guarantee visibility of all defects. Review radiation exposure where sensitive electronic devices require it.

Connect image metrics to product validation

Define the denominator region, total projected void area, largest void or spatial distribution, and whether results are 2D or 3D. Specify treatment of designed holes, background and uninterpretable regions. Results from different programs otherwise may not be comparable.

Use adopted standards, customer requirements and actual attachment validation, not a void percentage borrowed from another package. Temperature rise, mechanical strength and required reliability tests need their own evidence. Confirm uncertain regions under an approved plan rather than adjusting thresholds simply to remove alarms.

• Map coordinates, target interfaces and designed holes
• Validate the method and retain images and settings
• Agree statistics, acceptance and abnormal-result confirmation

Frequently asked questions

Does a good-looking fillet remove the need for hidden-joint inspection? Follow the approved plan. Visible fillets do not fully describe the underside interface.

Does a clean X-ray prove adequate strength? No. Imaging, mechanical, electrical and reliability evaluations serve different purposes.

RFQ inputs for attachment inspection

Provide hardware and pad drawings, copper thickness, paste, reflow and rework processes, existing images and failure locations. Identify incoming, first-article or post-assembly inspection responsibilities. Agree representative samples and reporting, then establish detectability before freezing acceptance.