Fixtureless PCB Testing
Electrical TestingAt Bittele Electronics, we guarantee 100% electrical testing on all PCBs that leave our facilities. We make this guarantee in order to ensure both the quality of our work and the satisfaction of our clients. Electrical testing, in the world of PCB manufacturing, is the process of checking the electrical conductivity of a finished PCB against the NETLIST file that was defined during the project’s design stages, before the PCB layout was created. Using the NETLIST from the design stages offers protection not only against discrepancies which may occur during production, but also against those which may occur during PCB layout or Gerber file generation.
The Flying Probe MethodThe Flying Probe Method is a type of electrical testing that is largely reserved for small-volume production. During this procedure, electro-mechanically-controlled test probes are moved through the board, testing for expected electrical values at various predefined test points, in sequence. This testing method has existed nearly as long as the more well-known “Bed of Nails” In-Circuit Test (ICT), but it did not enjoy widespread industry adoption until the early 2000s. Low-cost and open-source PCB design software was beginning to allow for smaller businesses and even hobbyists to design boards for professional production. Meanwhile, professional designers were looking for a cost-effective solution for the fabrication and assembly of their prototype runs.
Going FixturelessThe largest barrier to low-cost, low-volume PCB fabrication and assembly was the cost of designing and building a fixture to be used during ICT. A unique fixture must be created to test each new PCB design, and these fixtures can present complex devices which incorporate numerous preciselyplaced testing and tooling pins. The time and resources required for PCB manufacturing facilities to build these fixtures, relative to the number of PCBs being assembled, is simply not viable for many designers.
This untapped corner of the market, not being served by the industry at large, prompted many facilities to take a second look at the Flying Probe’s possible advantages.
Advantages in Cost and EfficiencyThe Flying Probe offers a superb solution for low-volume production by eliminating the cost of fixture design and production from the equation. Though each individual board test may take marginally longer using the Flying Probe, the time savings incurred by avoiding fixture creation will more than compensate for this fact, so long as order quantity remains low. The removal of fixture cost from lowvolume PCB assembly services has opened the market to many new avenues, and the widespread adoption of Flying Probe testing has allowed for some additional benefit in terms of functionality as well.
Advantages in FunctionIn addition to its advantages in terms of price and time requirement, this procedure also offers some functionality that cannot be achieved by the “Bed of Nails” ICT. First of all, the probes are capable of making precision connections at a tighter pitch than the ICT is able to achieve. High-accuracy flying probes boast an incredible electrical test pitch of 0.1mm, compared to the standard ICT’s 0.5mm pitch, allowing for greater coverage on small and/or HDI (High-Density Interconnect) PCBs.
The Flying Probe can also employ automated optical inspection (AOI) to allow for some specific tests that are not possible using a Bed of Nails. AOI-assisted Flying Probes can catch polarity reversals, low-value components, and individual components in parallel; none of these tests can be performed using a standard ICT fixture.
The Best of Both WorldsAt Bittele Electronics, we offer both Flying Probe and “Bed of Nails” ICT electrical testing, and our expert staff will work with you every step of the way to determine the best fit for your particular project. For low-volume and prototype assembly projects, we are happy to offer Flying Probe testing to save you those fixture costs. For some high-volume projects, you may want a Flying Probe test to be performed in addition to the ICT for added functionality, and in this we are also happy to oblige. Depending on the specifics of your design and the quantity of your order, as well as your own personal preference, we will select the most cost-and-time-efficient method to ensure the quality and accuracy of every PCB that leaves our facility.
- Manufacturing Defect Analysis (MDA) Testing
- Bittele's Essential Design for Testing (DFT) Tips for PCB Assembly
- Bed of Nails PCB Testing
- PCB Netlist Files and Their Use in Printed Circuit Board Fabrication
- PCB Electrical Testing