Feeder Calibration and Pickup Accuracy on SMT Lines A feeder presents a component to the nozzle at a position that the machine believes it knows. If that belief is wrong, the nozzle picks the part off centre, at an angle, or not at all, and the placement machine spends the…

Reflow Soak Profile And Void Formation A reflow profile has four parts: a ramp, a soak, a spike to the peak and a cool down. The soak is the part that engineers most often remove in the name of speed, and it is also the part that decides how much…

Solder Paste Flux Activation In Reflow Solder paste is a mixture of metal powder, flux and a solvent, and the flux is there to remove the oxide that covers both the powder and the surfaces being joined. The chemicals that do that work are the activators, and they only function…

PCB Supplier Qualification Guide Supplier qualification is the work of establishing, before the first production order, that a supplier can make what is required, repeatedly, and that there is a written basis for expecting it to continue. It is often treated as a purchasing formality, and it is more accurately…

Nozzle Crash and Placement Head Damage Prevention on SMT A nozzle crash is the moment when the placement head drives a nozzle into something that should not be there, and it is usually the most expensive event of the week. The nozzle bends or breaks, the head may be knocked…

PCB Incoming Inspection: Verifying Materials Incoming inspection is the last point at which a defect can be stopped before it enters the production flow, and the first point at which supplier quality becomes visible as a number. The temptation is to inspect everything, which is impossible, or to inspect nothing,…

Annular Ring Calculation and Breakout Limits in PCB Design The annular ring is the ring of copper that surrounds a drilled hole on a printed circuit board. It is what connects the barrel of the hole to the trace and what holds the pad together, and its width is the…

Underfill And Corner Bonding For BGA Packages Underfill is an adhesive that is dispensed along one edge of a ball grid array after reflow and allowed to flow by capillary action until it fills the space between the package and the board. It reduces the strain that thermal cycling puts…

ACF And Hot Bar Bonding For Flex Connections A hot bar bonding machine joins a flex tail to a rigid board by pressing a heated blade onto the joint while the adhesive between the two parts cures. Where the connection is made with anisotropic conductive film, the film carries current…

Root Cause Analysis in PCB Manufacturing Root cause analysis is the method a board shop uses to stop a defect from coming back. It is not a meeting and it is not a form; it is a short investigation that ends with a change that can be verified. Most failed…