Solder Paste Powder Size: 6 Rules for Choosing Type 4 or Type 5 Solder paste powder size is the classification that describes how large the alloy particles are, and it is written as a type number from 1 to 8. The number rises as the particles get smaller, so a…

Component Lot Codes: 6 Controls for Traceability A lot code is the identifier that ties a unit of material to a batch, and it is the smallest piece of information that makes traceability work. Without a lot code, a quality alert from a supplier cannot be acted on, because there…

Core Baking Before Lamination: 6 Rules for Dry Prepreg and Core Core baking is the drying step that removes absorbed moisture from inner layer cores and, where the process requires it, from prepreg before the stack goes into the press. It is a short operation with an outsized effect, because…

Self Alignment: How Reflow Pulls Components Into Place Self alignment is the tendency of a component to move into the centre of its pad pattern while the solder is molten. Molten solder forms a fillet with a defined surface area, and surface tension drives the system toward the shape with…

Mask Window Design: 5 Rules for Solder Mask Openings A mask window is the opening in the solder mask that exposes the copper pad, and its size decides how much bare metal the process leaves around the joint. Too small a window and solder cannot wet the full pad; too…

Immersion Heater Failure: 5 Signs in a Solder Pot An immersion heater is the element that melts and holds the alloy in a solder pot, usually housed in a tube of stainless steel that sits in the bath. Heat passes through the tube wall into the alloy, so the tube…

X-Ray Tube Ageing: 5 Signs Image Quality Is Falling An x-ray tube ages from the first shot, and the change is gradual enough that a line can lose inspection capability without anyone noticing. The focal spot grows, the output falls for the same settings and the image becomes softer. Void…

Barrel Cracks in Plated Holes: 6 Causes After Thermal Cycling A barrel crack is a fracture in the copper plating inside a plated through hole, usually running around the circumference or along the length of the barrel. It appears after thermal cycling rather than at manufacture, which is what makes…

Silkscreen Ink Curing: 6 Controls for Legible, Durable Legends Silkscreen ink is the last layer applied to a bare board, and it carries the information an assembly line and a service technician rely on. It has to be legible at the size the design allows, it has to bond to…

Plating Additives in Copper Plating: 6 Ways to Hold the Balance Plating additives are the organic chemicals that turn a simple copper sulphate solution into a bath capable of plating a smooth, fine grained deposit into a drilled hole. They are present in very small concentrations, they are consumed continuously,…