Approved Component Substitution Process A component shortage forces a decision: wait, or use a part that is not the one on the drawing. The second option is legitimate and it has to be managed, because an unmanaged substitution is a design change made by whoever was at the desk when…

Stencil Cleaning and Solder Paste Residue Control Guide A stencil that is not clean will not print consistently, and the reason is simple: the paste left in the apertures from the previous print changes the volume that the next print can deliver. Stencil cleaning is therefore a process control rather…

Acceptance Class Selection for Electronics Manufacturing Every board is inspected against something. If the criteria are not written down, the inspector applies personal judgement, and the result varies between shifts, sites and customers. An acceptance class is a way to state in advance how much deviation is tolerable, so that…

Solder Paste Viscosity and Printing Window Control Guide Solder paste is a suspension of solder powder in a flux vehicle, and its viscosity is the property that decides how well it prints, how long it stays on the stencil and how much it slumps before reflow. Because the paste is…

Through Hole Soldering Method Comparison for Mixed Assemblies A board that carries both surface mount and through hole parts has to be soldered twice, and the second operation determines the quality of the through hole joints. Three methods are in common use: wave soldering with a masking pallet, selective soldering…

Pin in Paste Reflow for Through-Hole Components Pin in paste places the solder for a through hole joint as paste in the stencil, so that the joint is formed in the reflow oven rather than by a wave or by hand. It removes a process step and it puts a…

PCB Traceability Checklist: Key Process and Quality Checks Modern electronics depend on boards that are assembled correctly the first time. Every product – a phone, a charger, a medical instrument or an industrial controller – relies on thousands of solder joints that must conduct current for years. This article explains…

DFM Review Items Before PCB Release A design for manufacture review asks a short set of questions about a design before it is built, and the questions are the same for every board. They are asked at the point where the answers are cheap, which is before the artwork is…

PCB Traceability Improvement: What Buyers and Engineers Should Check Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB traceability improvement gives you a practical advantage when…

PCB Labeling Plan: What Buyers and Engineers Should Check Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB labeling plan gives you a practical advantage when…