Reworking a finished or near-complete PCB is a costly and inconvenient disruption to the Surface Mount Technology (SMT) production process. And in-service failures and product recalls are to be avoided at all costs.
The drive for consistent quality and performance makes rigorous testing and inspection throughout the PCB manufacturing process an essential investment. The ability to schedule new product launches with confidence and guarantee production volumes to meet demand all track back to one factor: effective inspection and testing during the SMT production process.
Three Steps to Product Integrity
This is only a very brief summary of the highly detailed inspection and test processes deployed in SMT manufacturing. It breaks down into three main phases as follows.
Pre-production
The road to reliability starts in pre-production and the Design for Manufacturing (DfM) review.
A thorough Bill of Materials review ensures that every component is correctly specified, identified and placed. Well maintained inventory and supply chain documentation is essential to ensure that component specifications are up-to-date and that they can be supplied to meet projected production requirements.
Designing-out potential problems covers a variety of factors including solder shadowing, uneven component heating during soldering and acid traps that can result in over-etching. Effective DfM reviews also aim to ensure adequate component clearance to avoid shorts, poor solderability or signal interference.
In-Process Inspection
In-process inspection identifies defects such as component misplacement or solder defects quickly and accurately. In modern SMT manufacturing this involves highly automated optical and X-ray inspection techniques.
Post-Production
The DfM process should ensure that signal test points are easily accessible and accommodate multiple test probes. This will speed up the test process.
Functional testing should simulate real world conditions such as the levels of temperature and vibration assemblies will be subjected to in service.
A rigorous inspection and testing regime ensures continuity of supply as well as product performance and reliability. It’s an area of our business where we continue to invest heavily, including the latest high resolution X-ray inspection (μAXI) equipment as part of our drive towards zero-defect, risk free manufacturing.
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