Micro-Etch Before Plating: 6 Control Points A micro-etch is the short, controlled etch that runs immediately before plating or oxide treatment. It removes the oxide layer that formed while the panel waited, roughens the copper surface on a microscopic scale, and leaves a topography that the next deposit can key…

Cavity Stencil Design: 7 Rules for Step Height A cavity stencil is a printing foil with a milled pocket that thins the metal around selected apertures, so two paste volumes can be printed in one stroke. Full thickness stays where standard pads sit, while the pocket lowers the local foil…

Cupric Chloride Etching: 7 Bath Control Checks Cupric chloride etching is the workhorse chemistry for copper removal on inner and outer layers, and it is preferred because the etchant can be regenerated rather than replaced. A line running this chemistry holds a stable etch rate only while the copper loading,…

Fume Extraction: Preparation, Placement and Process Control Fume extraction on a reflow oven removes the flux vapour that the paste releases as it heats, together with the condensate that forms when that vapour cools. Without extraction the vapour condenses on the coolest surfaces inside the oven, which are usually the…

Pot Skimming: Preparation, Placement and Process Control Pot skimming is the removal of the oxide layer that forms on the surface of a molten solder bath, and it is the task that decides how much dross the wave carries onto the boards and how much alloy is lost in a…

Drill Accuracy on a PCB Line: 6 Checks Before a Tight Job Drill accuracy is the ability of a machine to place a hole where the program says it should be, and to do it the same way on every panel. It is not one property but the sum of…

Dispensing Needle: Preparation, Placement and Process Control A dispensing needle is the last few millimetres of the solder paste path, and it is where most dispensing problems start. The paste has to pass through a bore that is only a few hundred micrometres across, and the behaviour of that passage…

Line Changeover: Preparation, Placement and Process Control Line changeover is the interval between the last good board of one product and the first good board of the next, and it is one of the largest hidden costs on an SMT line. It is not only the machine time; it is…

Mask Window: Preparation, Placement and Process Control 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 large a…

Impedance Coupon Design: 6 Rules for a Coupon You Can Trust An impedance coupon is a set of test traces built into the panel border that lets the fabricator and the customer measure the controlled impedance the process actually produced. A well built test coupon is the only practical way…