Board Warpage Control Through Reflow A board that leaves fabrication flat does not necessarily stay flat. The reflow process heats it above the glass transition temperature of the laminate, where the material becomes soft and the internal stresses that were built in during lamination are free to relax. The result…

Stencil Design: Area Ratio and Step Stencils The stencil is the tool that turns a design into a deposit, and it is the only part of the printing process that is made specifically for the product. Its thickness, its apertures and the way it is tensioned all determine how much…

X-ray Inspection of Area Array Solder Joints An area array package has its joints under the body, so the only practical way to look at them without destroying the assembly is with X-ray. The image shows a lot and it does not show everything. What the Image Shows A two…

Bend Test and Flex Testing Methods for Assembled Boards Bending is the most common way an assembled board is damaged, and it is also the least noticed. A board flexes when it is snapped out of a panel, pressed into a housing, clamped in a fixture or simply picked up…

Production Floor Zoning for ESD, Cleanliness and Humidity A production floor is divided so that the conditions a product needs can be maintained in the places where they matter and not everywhere. The division is a design decision about the space, not a policy statement. Why Zone at All Maintaining…

Wire Harness To Board Connector Interface Design Where a wire harness meets a board, the electrical connection is only half of the problem. The harness is a mechanical object with mass, stiffness, and a routing path, and every movement of the product, every thermal cycle, and every pull on the…

Projector Mainboard Design for Compact Projection Products A compact projector fits a display engine, a battery and a processor into a space the size of a book. Projector mainboard design is dominated by the light source, because the led driver and its power loop set the size, the heat and…

Drop Testing and Shock Resistance for Electronic Assemblies Dropping a product is one of the most severe mechanical events it can experience, and it happens in a fraction of a second. The acceleration involved can exceed a thousand times gravity, and the whole event is over before any protection circuit…

V2X Module Board Design for Vehicle Communication A module that lets a vehicle talk to other vehicles and to the road infrastructure is a radio product in a harsh environment. V2X module board design combines radio frequency layout with the electrical and thermal requirements of automotive electronics. What V2X Communication…

Reflow Defect Troubleshooting in a Structured Sequence Troubleshooting a reflow defect is easy when the cause is obvious and slow when it is not. A structured sequence keeps the investigation from moving to the least likely cause first, which is usually where time is lost. Start With the Defect Class…