PCB Assembly Testing and Inspection
Testing is crucial to ensure high quality products are delivered to customers. Thankfully board assemblers offer multiple layers of testing and inspection to ensure high-quality, assembled Circuit boards are produced and delivered to customers. Despite all efforts to prevent errors, printed circuit board assembly is a complex process and defects sometimes occur relating to a variety of issues from incorrect component loading to failures in SMT equipment. Thorough testing and inspection occurs throughout the production process to ensure problems are captured early on, ensuring high quality and yield.
Visual Inspection of Solder Paste
Visual inspection is a vital element in ensuring problems are captured and corrected as early in the process as possible, reducing the time and cost associated with rework and wastage. Visual inspection begins with the solder application. Inspection at this stage checks for correct deposition of solder paste on pads to ensure components reflow properly. Here testing helps prevent solder bridges, open circuits or fragile joints prone to failure.
Pre and Post Reflow Inspection
Pre and post reflow inspection are important elements in quality control. Pre-reflow inspection catches placement errors at a point where they are easy to repair, avoiding repetitive mistakes early in the process. This is important with products like automotive boards where regulatory compliance require that boards cannot be reworked. Components and boards are heat sensitive and detection of errors at this stage can avoid their damage or destruction. Post-reflow inspection can be manual or with AOI.
A ‘first article’ inspection is performed on a run to ensure all SMT feeders are set up correctly and that there are no issues like worn vacuum nozzles or alignment of the vision system. Board assemblers can offer a special ‘First Article Service’ that enables a rapid and cost effective pre-production process by expediting a production of a few boards to designers for testing prior to a full run.
Post reflow BGA inspection and testing, along with other leadless parts require special considerations as the component package shadows solder joints making inspection impractical without special equipment. Inspection can be conducted by a range of devices including: computed-tomography (CT) scanning, specially angled optics microscopes, endoscopes and X-ray machines.
Flying Probe Testing
Flying probe testing is good for where a PCB test jig is prohibitively expensive. Flying probe has relatively low setup cost and a test procedure can be designed and implemented in a single day. Assembled PCBs with all components placed are compared electrically against the measurements from a golden board for verification. It can conduct open, short, orientation and component value circuit checks. This can help verify correct component placement and alignment.
For PCB assembly, in order to ensure high quality, we do and provide related testing and inspection, include:
IQC: Incoming Materials Inspection
First Article Inspection for every process
IPQC: In Process Quality Control
QC: 100% Test & Inspection
QA: QA based on sample inspection plan
Quality Management based on ISO9001:2008, ISO13485:2003, ISO/TS16949:2016 and ISO14001:2004
Automatic Optical Inspection (AOI)
In-circuit Test (ICT)
Functional test (FCT)
Burn in test
Thermal cycle test