This blog post addresses custom user interface testing in terms of functional test schemes that are completed prior to shipment. Generally, the first user interface assemblies shipment are for First Article acceptance testing where customers fully examine the first units for mechanical and electrical compliance to all engineering drawing and specifications.
When designing PCBs in a multi-up array, most designers choose v-score (also referred to as v score, v cut, or v groove) as the singulation method over traditional rout and breakaway tabs. The benefits of v-scoring pcb range from effortless removal of parts from panel form to realized cost savings with better utilization of panel area. When designing a circuit boards in array with v-scoring, there are two areas of concern - the angle of the cut, and the depth of the cut.
For rigid-flex printed circuit boards (PCBs), the space joining rigid material to flex material (Transition Zone) sometimes contains imperfections that, although acceptable, could impact effectiveness of the final part. Transition zone imperfections can include any of the following:
- Adhesive squeeze-out
- Protruding dielectric materials
When a blow hole defect occurs during the assembly process as a result of the PCB card, the primary culprit tends to be entrapped moisture or air. With moisture, any non-plated and non-masked areas on a bare circuit board that expose internal laminate can be suspect to absorbing moisture. Absorption can occur both during board fabrication and during improper storage. Examples of highly suspect areas include non-plated drilled holes and routed features.
It is not recommended to bake boards with an Organic Solderability Preserve (OSP) finish. Although baking a printed circuit board with an organic solderability preserve finish can have negative consequences, the process itself can have positive performance in specific applications. OSP is a very thin protective layer of material placed over exposed copper, typically using a conveyorized process to protect the copper from tarnish.
Generally pads are small round or square areas of copper which are normally used to make a connection to a component pin. If these pads are not sitting correctly or are lifted, it can cause the connection between the printed circuit board (PCB) and the component to fail.
Printed circuit boards (PCBs) with immersion finishes such as electroless nickel immersion gold (ENIG), immersion tin, silver, and OSP are appealing because they are lead-free. However, when handled improperly, these materials are susceptible to oxidation and corrosion from exposure to moisture and humidity. This oxidation causes dewetting after soldering, which can lead to poor joints at assembly and ultimately lead to failure of the board.