PCB Electrical Testing
Bittele Electronics performs 100% electrical testing on all bare PCBs produced at its facilities as per IPC-9252 specifications. We either use the Bed of Nails Fixture method or the Flying Probe method to perform the testing in our circuit board manufacturing process.
To test the PCBs, we require the NETLIST file. Although we create a reference netlist from the customer’s original Gerber data during PCB Fabrication, we always prefer to receive the CAD file based on the netlist for comparison. Since a CAD-based netlist is generated before PCB routing, it provides another layer of checking (against the Gerber output). This allows us to catch any PCB Faults introduced in the event of an error in the Gerber files. For Complete PCB Assembly projects, this helps to ensure that the boards are 100% correct before any components are installed.
The preferred netlist format is IPC-356 since all CAD software packages are capable of loading this format.
TESTING CAPABILITES AND TYPES
Our testing capabilities are listed in the following table:
|Minimum Continuity Resistance||0.1 Ohms|
|Maximum Test Voltage||1000 Volts|
|Maximum Isolated Resistance||25 M Ohm - 2 G Ohm|
|Electrical Test Pitch (Fixture)||0.020"|
|Electrical Test Pitch (Flying Probe)||0.004"|
Depending upon both the design and the cost, our testing methodology will either be:
- The Bed of Nails Fixture method, or
- The Flying Probe method
Sometimes customers are unclear about the difference between Fixture (Bed of Nails) vs. Flying probe testing, as well as the costs associated with them. The following example will clarify the difference between the two methods, as well as the cases in which one or the other might yield a more efficient PCB Assembly Process.
For this example, let’s assume there are 3,500 test points with 750 nets.
TEST FIXTURE (BED OF NAILS)
Electrical Test Pitch = 0.020"
Setup time: 30 minutes
Learn time: 0 minutes
Debug / check for missing pins: 10 minutes
Test time per board: 40 seconds
All points are tested simultaneously.
However, this process involves both setup time to create the fixture and additional costs associated with the cost of materials.
Electrical Test Pitch = 0.004"
Setup time: 0 minutes
Learn time: 20 minutes
Test time per board: 6 minutes
The points are tested one at a time.
There is no setup time because the machine learns the program as it operates.
If Fine Pitch is not a concern (depending on the design), our threshold is 15 manufacturing PCB Panels. So, we would select a testing method based on the following thresholds:
Flying Probe: less than 15 Manufacturing Panels
Test Fixture: greater than 15 Manufacturing Panels
Upon request, we supply the following reports free of charge: