Automated assembly equipment typically requires that the board being assembled move along a track. The actual board sits on two chains on either side of the track. As the chain moves along the assembly line the board is moved along with it from station to station. If components are close to the board edge they may interfere with how the board sits on the chain. Hence the need for rails.

Rails are extensions of the pcb that are attached and later removed after the board is assembled. Rails are added for handling purposes and to provide clearance for components that may be close to the board edge.  It is common practice for anyone that assembles printed circuit boards with components to (more…)

There is an old saying, “A picture speaks a thousand words.” To help understand what a fabrication drawing is, I have posted several views along with brief explanations. The first view is a full size view of a fabrication drawing (more…)

In this post I shall provide a listing of sample fabrication drawing notes that may be used on any fabrication drawing for a pcb. Fabrication drawing notes typically specify materials and finished requirements in a text outline form. Critical requirements shall be specified in the note structure.

Notes: (more…)

Not clearly specifying information may result in errors along the manufacturing supply chain. For example, one of my customers had an old legacy design they needed to have built. The fabrication drawing called for FR4 as the material the board was to be built on. The original designer specified a high volume resistivity requirement in an email sent to the previous manufacturer. The requirement was never added to the the fabrication drawing. The company that used to build the pcb went out of business. The original designer retired. My company built the design. A contract manufacturer assembled the boards. The customer installed it into their rack. None of the assemblies worked.

To make a long story short, (more…)