Solder Mask Viscosity Control: Mixing, Thinner and Pot Life Solder mask viscosity decides how the ink behaves in the screen printer, and it changes from the moment the can is opened. It affects the thickness of the printed film, the definition of the openings and how the ink behaves when…

Solder Balling in Reflow: Profile and Paste Drivers Solder balling is the ring of small spheres that appears on the solder mask around a reflowed joint. Each sphere is a droplet of paste that melted but did not merge with the main fillet, and it was left behind when the…

Reflow Zone Temperature Verification: Beyond the Profile A profile is a measurement of one assembly on one day. The zone controllers report their own temperature, the board passes through, and the thermocouples produce a thermal profile that is filed with the product record. What that curve cannot show is whether…

Copper Foil Profile After Etching: Width, Angle and Undercut The copper foil that remains after etching is not a rectangular bar with vertical walls. The etchant attacks the top surface and the sides at the same time, so the cross section has a trapezoidal shape with a sloped wall and…

Reflow Oven Belt Speed: Verification and Process Control Reflow oven belt speed sets how long a board spends in every zone, so it is the variable that converts a temperature profile into a time at temperature. The zones decide the shape of the curve and the belt speed decides the…

PCB Panel Vacuum Chuck Control: Holding Boards Flat for Drilling A vacuum chuck holds a panel flat on the machine table while it is drilled or routed, and it does the job with air pressure rather than with clamps. That makes it fast, repeatable and almost invisible, which is exactly…

PCB Etch Factor Improvement: A Practical Manufacturing Guide 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…

PCB Etch Factor Traceability: Following One Board 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 PCB…

Paste Inspection Frequency: Sampling and Trend Analysis Solder paste inspection measures the deposit after printing and compares it with the stencil aperture, so that a print problem is found before components are placed on top of it. How often that measurement is made is a decision about risk rather than…

Wave Solder Preheat Zone: Flux Activation and Board Temperature The preheat zone in a wave soldering machine does two jobs at once: it activates the flux so that it can remove oxide, and it brings the board to a temperature close enough to the solder that the wave does not…