INSPECTION & TESTING PROCEDURES FOR PCB ASSEMBLY
Inspection & Testing Procedures for PCB Assembly
Testing Overview
Testing and inspecting PCBs throughout the PCB assembly process is crucial to ensure high quality products are delivered to customers. Emphasis should be on prevention rather the fixing mixing after the fact with rework. In this high-level article, read the most common types of testing and inspection performed by PCB assemblers.
Common Defects
Statistical analysis of common defects in PCB assembly reveals nearly one-quarter of them are of the nature of open circuits, about one-fifth caused by insufficient solder, and nearly one-seventh due to solder shorts. Other less frequently occurring defects related to solder paste are misaligned components and excess solder making up about one-twelfth and one-thirtieth of defects respectively.
| DEFECT | RELATED TO | RATE |
|---|---|---|
| Open | Solder Paste | 25% |
| Insufficient | Solder Paste | 20% |
| Shorts | Solder Paste | 14% |
| Excess Solder | Solder Paste | 8% |
| Misaligned Components | Pick and Place | 12% |
| Wrong Components | Pick and Place | 5% |
| Wrong Orientation | Pick and Place | 3% |
| Defective Components | Various | 8% |
Tailoring of inspection and testing methods is necessary for varying levels of effectiveness with each type of defect.
DFM / DFA Checks
DID YOU KNOW … 94% OF ASSEMBLY DATA IS ACCIDENTALLY SUBMITTED WITH ERRORS.
Most PCB fabrication and assembly companies have some form of design rule checking functionality. But these tools are not all created equally. Only trust your designs to true comprehensive design for manufacturing or assembly checks. Here are two of the best:
Debugging Your PCB
While working with reputable PCB fabrication and assembly partners greatly increases your chances of receiving PCBs that work straight out of the box, occasionally you will get a board that doesn’t work. When this happens, how do you start figuring out why?
Read this article for useful tricks and steps that will help debug your PCB.
Quality Testing
LEARN THE INS AND OUTS OF QUALITY TESTING
Today, PCBs are incredibly complex with tiny components and tight space restriction. For this reason, thoroughly testing completed boards for component compatibility and manufacturability is critical, especially during the prototype stage when speed and flexibility are a must.
Read this article for an overview of the types of testing methods used by PCB assemblers.
3D X-Ray
3D X-Ray machines can detect a number of problems that can not be seen by the human eye including solder joint shorts, opens and voids. Watch this video to see Advanced Assembly’s X-Ray in action.