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Engineering notes on PCBA process control
Written by the process engineering team that runs our SMT, THT and inspection lines. Every note starts from a measurement or a standard clause, says where the number came from, and stops there: no customer names, no direct quotes, and no product pitch dressed up as engineering.
WHAT THESE NOTES COVER
What we write about
The process engineering team writes these notes from our own SMT, THT and inspection data. Where a limit belongs to a standard it is cited by number, and where a figure is published industry research it is labelled as such rather than presented as ours.
| Coverage | What the notes give you | Where the numbers come from |
|---|---|---|
| Process windowsprint, place, reflow | Stencil aperture geometry, print parameters, reflow windows and the limits we write into the inspection program | IPC-7525B for stencil design; our own SPI programs for the limits |
| Defect mechanismscause, not symptom | Insufficient paste, bridging, slumping, solder balling, BGA voiding and head-in-pillow, each traced to the step that produces it | IPC-A-610 and IPC-7095 for the criteria; our AOI and X-Ray records for the patterns |
| Acceptance criteriaclass-based limits | What a class 2 or class 3 build accepts, how the percentage is measured, and which questions have to be settled before a batch is judged | IPC-7095 for voiding; IPC-A-610 Class 2 and Class 3 for assembly workmanship |
| Component supply & lifecycleNRND, EOL, LTB | Lifecycle status, long lead items, counterfeit risk, last-time-buy quantities and the rules that govern a substitution | J-STD-048 and J-STD-046 for notice periods; AS5553 and AS6081 for anti-counterfeit practice |
Each note carries its own measurement basis. Where a build figure is quoted as ours, it is defined in the same sentence — for example, first-pass yield measured at final inspection before any rework or retest on SMT and THT production lots.
THE NOTES
Three starting points
Solder paste printing: the defects that start upstream
Industry estimates put 60–70% of SMT assembly defects at the printing step. The aperture criteria from IPC-7525B, four defect mechanisms, and the SPI loop that feeds the printer back.
Reading BGA voiding on X-ray
IPC-7095 puts Class 2 at ≤25% in a single joint and ≤40% in total, Class 3 at ≤10% and ≤25%. What a 2D image can support, and why head-in-pillow is a different failure.
Component obsolescence and last-time-buy planning
Semiconductor life has fallen from about 30 years to about 10 while the equipment runs for 20–30. The BOM risk scan, the J-STD-048 notice clock and how to size a last-time buy.
HOW WE SOURCE THESE NOTES
What you can check
Standard clauses are cited by number. Where a limit comes from a standard, the note names it: IPC-7525B for stencil design, IPC-7095 for BGA voiding, J-STD-048 for discontinuance notice.
Industry figures are labelled as industry illustration, in the sentence where they appear. They are never presented as measurements taken on our own lines.
Only a production lot we built and measured is written up as our data, and the measurement basis is stated next to the number — 98.5% first-pass yield is defined at final inspection before rework or retest.
No customer names, logos or quoted sentences. Every case is reduced to customer type, region, constraint and result; there are no company names, no logos and no quoted sentences attributed to anybody.
GO DEEPER
Where to take this next
Capabilities
Seven SMT lines and two THT lines on one 10,000 m² site, from 01005 (03015 metric) placement and 0.4 mm pitch through to box build.
Quality and inspection
How the criteria are applied and reported, including first-pass yield of 98.5% or better measured at final inspection before any rework or retest.
Design and DFM guides
Put the criteria on your own drawing: a process edge of 5 mm or more, fiducials, land patterns and a first-pass DFM report inside 24 hours on prototype boards.
HAVE A DEFECT WE HAVEN'T WRITTEN ABOUT?
Send the board and the failure
Describe the defect, the board and the volume. A process engineer reads it and replies with the measurements worth taking first — not a brochure.
Reply within one business day