Common PCBA defects and how to prevent them
The PCBA defects that matter — tombstoning, bridging, cold joints, BGA voids — how a good assembler catches them, and how engineering review prevents them.
Quality is the real question for overseas buyers
Behind "can I trust a China PCBA supplier" is one real worry: will the boards arrive working and consistent? The reassuring answer is that the common PCBA defects are well understood — a good assembler catches them with inspection and prevents most of them before production even starts.
Below are the defects we watch for, how we detect them, and how engineering review stops them early.
The common SMT defects
Tombstoning — a small two-terminal part lifts on one end during reflow, usually from uneven heating or unbalanced pads. Solder bridging — excess solder links two pads that should be separate, common on fine-pitch ICs. Insufficient or cold joints — too little paste or heat leaves a weak connection.
Component shift, missing parts, wrong part, or reversed polarity round out the usual list. Most come down to paste volume, the reflow profile, placement accuracy, or a footprint issue — all controllable.
The defects that hide under the part
Some defects are invisible from the top. BGA and QFN solder joints can have voids or opens hidden beneath the component — we verify these with X-ray. Through-hole joints can also be cold or incomplete after wave or hand soldering.
This is why visual inspection alone is not enough for dense boards; the right mix of inspection methods matters.
How we catch them
The inspection stack depends on the board: AOI (automated optical inspection) checks placement and solder on every board; X-ray verifies hidden BGA joints; flying probe or ICT confirms electrical continuity; and functional testing validates the board against your criteria.
See PCBA testing and quality control for how the test scope is set per project.
How we prevent them up front
Catching defects is good; preventing them is better. Before production we run a DFM review of your files, inspect incoming components (IQC), dial in the reflow profile and stencil for your board, and confirm the test plan.
This engineering-review-first approach is exactly why we do not return instant black-box quotes — see our quality process and turnkey workflow.
Worried about quality on a China order?
A supplier that reviews your design and raises manufacturability questions before quoting is your best defense against defects.
Send your Gerber and BOM and we will review the design, flag any risks, and propose an inspection and test plan — reply within 24h.