Testing a Cheap PCB Assembly
Flying Probe Test
Flying probe tests are done on low to mid volume PCB production. In the test, the PCB electronic components are accessed electro-mechanically. This test is commonly conducted to carry out signature analysis and examine analog circuitry, open and short circuits. In the flying probe test, the probe-ends access the electrical circuits through uncovered vias and pads of electronic components. If you are looking for a cheap PCB assembly test, then you should consider the following factors:
- The lead time for this type of testing is not more than a week and the fixture costs are low.
- The programming costs may vary from one circuit to another, depending upon the circuitry.
- In case of a product design change, you will only have to change the program – new fixtures are not required.
In Circuit Test
This test makes use of a bed of nails fixture to access multiple points for conducting circuit testing. The fixtures on the circuit board are usually placed on just the one side (mostly on the bottom side). Because there are so many test points, the in-circuit test performs testing of PCB assembly and circuitry at really high speed.
The bed of nails tester is a traditional electrical fixture that has copious amount of pogo pins. These pogo pins make a reliable connection with the circuitry of the device under test (PCBs in our case) whenever it is pressed in between the fixture of the tester bed. In terms of cost-effectiveness, for cheap PCB assembly testing, it is essential that the fixtures on the PCB are not double-sided.
This test is ideal for large batches. It is also relatively cheaper because it is quick. There are also multiple test options for integrated circuit PCB assemblies.
Environmental Stress Screening
In this test, PCB assemblies are checked to prove that the design is robust enough to be used in harsh environmental conditions. The test is done to improve the reliability of the PCB assembly and electronic components by stimulating such conditions that will reveal the hidden flaws. This is done in order to rectify the errors before the final PCB is shipped to the consumer. The test usually includes the following:
- Thermal cycling of the PCB assembly
- Fixed base vibration
For cheap PCB assembly testing while manufacturing PCBs in-house, an ESS system can be procured so that the corporate costs are reduced.
Automated Optical Inspection
The automated optical inspection is one of the key techniques to test PCB electronic components and assemblies during the manufacturing phase. The test is done to ensure that only high-end products leave the assembly line. The test performs visual inspections more swiftly and accurately than manual inspection. Following PCB assembly defects can be detected through this test:
- Scratches and stains
- Thinning of the solder
- Open and short circuits
In order to keep the cost of the integrated electronics as low as possible for cheap PCB assembly, this inspection is beneficial, as it detects the flaws on the assembly line earlier on.
Automated X-Ray Inspection
It makes use of the same principal, as that of the optical inspection but the range of application covered by the X-ray inspection is greater. The test makes use of pattern recognition and image processing software. This inspection is ideal for ball grid array PCB assemblies. The test is definitely not very cost-effective, but it checks even the hidden connections of the surface mounted chips.
Functional and System Test
Functional and system test is also a highly important test for testing PCB assemblies. The test is performed at the last stage of manufacturing and just as the name depicts, the test is done to check the behaviors and functionality of the final product. The procedures of functional and system testing varies from PCB to another. Hot mock-up is the most popular functional test. For cheap PCB assemblies, it is the responsibility of the equipment manufacturer to highlight the methods that can enhance the performance of the product.