PCBA Process
Nowadays, PCB, short for Printed Circuit Board, has played a significant role since technology has kept growing and has been everywhere in our daily life. PCBs are used in almost every electronic device to help us lead a better life.
We can divide the PCB Assembly process into the steps below.
- Bare Boards & Laser Markings: Mark a unique serial number on each board.
- Screen Printing: Apply solder paste onto PCBs through the stencil.
- Solder Paste Inspection, SPI: Ensure the solder paste be applied well.
- Pick & Place: Pick & place PCB components on the board.
- Visual Inspection: Validate correct components placement.
- Reflow Oven: Attach SMC, which stands for surface mount components, to PCBs. It will divide into various chambers such as preheat zone, thermal soak zone, reflow zone, & cooling zone.
- Automated Optical Inspection, AOI: Validate placement & correct soldering of all components.
- Through Hole & Manual Assembly: Place additional components & solder to the board
- Electrical Testing — Bed of Nails Test: For electrical function. It also called ICT (In-Circuit Test), is a non-Standard Test to test the online components to check PCB manufacturing defects and bad components using the electrical properties of the auxiliary fixtures.
- Electrical Testing — Flying Probe Test: Validate electrical function.
- X-Ray: Make sure soldering status.
- PCB Cleaning: Eliminate the erosive/toxic substances to guarantee the reliability and electrical functions of electronic products.
- Functional Test, FCT/FVT: Verify the function on PCBs.
- Final Manual Assembly
- Packaging & Delivery
SMT, Surface Mount Technology
Actually, step 1 — step 6 can be regarded as SMT. SMT is a technology to assemble SMC (Surface Mount Component) onto PCBs by using SME (Surface Mount Equipment). You might get confused by those abbreviations. No worry! The picture below has clearly explained what are they and what is the relationship between them.
AOI, Automated Optical Inspection
AOI is an automated visual inspection methodology used primarily to test for defects in printed circuit board assemblies (PCBAs). AOI autonomously scans PCBAs with cameras and detects two types of failures:
- Catastrophic failures, such as missing components
- Quality failures, such as misshapen fillets or components that are skewed
ICT, In-Circuit Test/ MDA, Manufacturing Defects Analyzer
Manufacturing Defect Analyzers (MDA) and In-Circuit Testers (ICT) are two popular electrical testing technologies for PCB manufacturers. Both use a Bed-of-Nails type test fixture facilitating connections between the nets of the PCB and the test system instrumentation. While similar in design, they differ greatly in terms of costs, capabilities, and test coverage.
The main difference between MDA Testing and ICT is that MDA Testing only tests for connectivity on the board, while ICT checks specific voltage and current levels throughout the PCB.
FCT/FVT, Function Verification Test
FCT/FVT is a testing method to ensure that all functions of PCBA are acting in accordance with pre-determined requirements. It is the quality control test at the final stage of the production line before shipping the PCBA to the customers.
Know more about FCT in NPI Process.
Packing
Finally, finished products are packaged to protect them during shipment and handling before use at the packing stage.
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