Reel Storage: 6 Rules for Moisture Sensitive Parts Reel storage is a set of rules for keeping moisture sensitive components dry between the supplier and the placement machine. Plastic packages absorb water from the air, and that water turns to steam at reflow temperature. The result is internal stress that…

Snap Off: 6 Rules for Clean Paste Release Snap off is the small gap left between the stencil and the board during printing, and the speed at which the two separate afterwards. The gap keeps the foil from touching the solder mask as the squeegee passes, and the separation speed…

Paste Warm Up: 6 Rules Before Opening a Jar Paste warm up is the wait between taking solder paste out of cold storage and opening the container, and it exists because paste is a suspension of alloy powder in flux. Cold paste is stiff, and its behaviour on the stencil…

Soak Zone: 6 Rules in a Reflow Profile The soak zone is the flat band a reflow profile holds between the initial climb and the spike, usually somewhere between 150 C and 180 C for a lead-free paste. It is the part of the curve where the board stops gaining…

Panel Warpage: 5 Causes Before the Reflow Oven Panel warpage is the loss of board flatness across a PCB array, and it is measured as the maximum distance between the panel and a flat reference. It matters long before the finished product, because a panel that is not flat does…

Carbon Treatment: 6 Steps to Restore a Plating Bath Carbon treatment is the standard way to remove organic contamination from a plating bath that has drifted away from the deposit quality it was made to produce. Powdered or granular carbon is added to the tank, allowed to adsorb the organic…

AOI Lighting: 6 Setup Rules to Cut False Calls AOI lighting is the arrangement of light sources that illuminates a board for the inspection camera, and it is the part of the machine that decides what the software is allowed to see. A solder joint that is never lit correctly…

Pumice Scrubbing: 5 Rules for Brush and Slurry Pumice scrubbing is a mechanical surface preparation step that runs before lamination, before oxide treatment and before some coating operations. A slurry of fine pumice is fed onto rotating brushes that pass over the copper, removing oxide, handling soil and the residues…

Exposure Energy Control: 5 Checks With a Step Wedge Exposure energy is the amount of light the photoresist actually receives, and it decides whether the pattern that leaves the developer matches the artwork on the film. Too little energy leaves resist at the bottom of the exposed area, so the…

Turbulent Wave: 6 Setup Rules for Through-Hole A turbulent wave is the second, rougher wave in a wave soldering machine, and it exists to push solder up into plated barrels and around tall leads. The first wave is laminar and fast, and it does most of the wetting. The turbulent…