Solder Paste Jetting: Design Rules and Process Limits Printing paste through a stencil is a batch process: one tool, one setting, and the whole board printed at once. Jetting deposits paste through a valve that moves over the board, one deposit at a time, and it changes which problems are…

Conductive Adhesive Instead Of Reflow: When It Works Most of the board is assembled in a reflow oven, and the oven is efficient, well understood and cheap to run. Some assemblies, however, contain parts that cannot go through it. A camera module with a plastic lens barrel, a focus coil…

Supercapacitor Backup Power Design Guide A supercapacitor sits between a battery and a conventional capacitor in the way it stores energy. It holds far more charge than an electrolytic of the same size, delivers it far faster than a battery, and tolerates hundreds of thousands of cycles. Those properties make…

Etch Compensation: Holding Line Width Through the Etcher Etch compensation is the correction applied to artwork so that the conductor that comes out of the etcher matches the width the designer asked for. The etchant removes copper sideways as well as downwards, so a trace drawn at a nominal width…

PCB Thermal Pad Compression: Squeezing the Gap 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 thermal pad compression gives you a practical advantage when you…

Shielding Methods for High-Speed PCB Design Signal integrity is not the only property that degrades as edge rates rise. The same fast edges that make a high-speed link work also make the traces more sensitive to the fields around them, so a design that ignores interference can pass bench tests…

Tin Whiskers in Lead Free Assemblies: Risk and Growth Tin whiskers are thin conductive filaments that grow out of a tin or tin alloy surface over months and years, and they are capable of bridging a gap that was designed to be a permanent open circuit. The problem was understood…

Moisture Sensitivity Level And Why Dry Storage Matters Plastic packaged components absorb water from the air. It is a slow process and an invisible one, and it matters only when the part is heated rapidly, which is exactly what a reflow oven does. The water turns to steam inside the…

SMT Placement Machine Faults and How to Trace Them When a placement machine begins placing parts off centre, rotating them or dropping them altogether, the first instinct is to edit the program. Most of these faults originate in the machine, the board support or the feeder, and a disciplined sequence…

Flip Chip Bumping and Copper Pillar Interconnects Flip chip assembly turns the die face down and connects it to the substrate through an array of bumps rather than through wire bonds around the perimeter. The change shortens the electrical path, improves thermal performance and allows far more connections on the…