Board notes
Substrate Check
A practical note on PCB substrate checks, for teams that want to catch bow, finish and handling issues before placement begins.
Before paste, placement and reflow, the bare board still needs a proper check. Warpage, finish condition, panel damage and drill or routing defects can all waste line time later. Substrate Check is a straightforward note on what electronics teams should verify before a PCB enters SMT.
Substrate Check is written for PCB inspection before solder paste goes down. The note focuses on board flatness, edge damage, finish condition and storage signs that often show up on assemblies headed for Gauteng, KwaZulu-Natal and Western Cape lines.
Checks logged before paste print
- Laminate type and thickness noted
- Top and bottom board photos taken flat on a bench
- Drawing revision or fab reference recorded
- Inspector name and line role listed
After this note, move to the linked process material that follows the board through printing, placement and oven entry. The journal side stays with recurring shop issues, while the equipment pages cover the machine limits that make a warped or damaged PCB harder to run.
How Substrate Check starts with FR4, aluminium and flex
Substrate Check covers the board conditions worth checking before placement starts. It focuses on PCB bow, surface finish and handling marks that can upset printing, pickup and alignment on the SMT line.
Begin with the substrate family and the defect that can stop stable placement. FR4 panels, aluminium core boards and flex circuits each behave differently when they arrive from storage or freight. Coastal humidity, inland dust and power interruptions can all affect how long boards sit exposed before they reach the stencil printer.
Capture the incoming condition before boards are split, wiped or stacked near the line. A quick image of corners, rails and finish can settle later questions about whether damage came from packing, handling or depanelisation. That record matters when fiducials, edges or solderable pads no longer match the drawing.
What the inspection should confirm
The aim is a short record that says whether the PCB is fit for SMT loading. It should identify bow or twist, scratches in the finish, damaged tooling holes, poor route tabs and any contamination around pads. One clear pre-run check is worth more than a longer note written after components start skewing.
Use Substrate Check alongside the related reflow and board handling notes when the issue may continue beyond incoming inspection. Before boards are released, confirm pack condition, panel count and any visible substrate defects that should follow the lot record. SMT line enquiries should name the board type, the placement volume and the machines already on the line.
- Board release based on visible condition
- Warp or twist captured before loading
- Findings sent with the inspection record
Conditions seen on South African sites
Freight, storage and weather can all change how bare boards present at goods-in. Panels moved through OR Tambo cargo, Durban humidity or long inland warehousing may show oxidation, packaging rub or moisture exposure before the first setup starts. That is why this note favours direct checks on finish, flatness and edge integrity rather than assumptions from the fab pack alone.
Coastal air can dull exposed metal faster when packs are opened too early. Dry inland sites often show more dust on unpacked panels, which matters around fine-pitch pads and fiducials. During outage-prone periods, boards may wait longer between receiving, inspection and print, so handling marks and storage discipline need closer attention.
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Points to record on Substrate Check
A practical note on PCB substrate checks, for teams that want to catch bow, finish and handling issues before placement begins.
File the substrate note while the lot is still at incoming or kitting. It pairs well with the project record and any process sheet used to trace defects from the bare board into placement and reflow.