| PCBA sides to be probed |
The number of PCBA sides which the fixture must make electrical contact with (Top, Bottom or Both) |
Single side probing is recommended. |
Probing of both sides of a PCBA is possible but should be avoided if the DUT design permits. |
Accuracy and Maintenance: Probing of both sides of a PCBA increases the risk of misalignment and may require more frequent fixture maintenance.
Cost: Fixtures will generally cost more as two precision probe plates are required as opposed to one. |
| Probe Contact Spacing |
The distance between the center-point of the nearest contacts to be probed on a PCBA |
0.1” (2.54mm) Probe Point Spacing is recommended and considered standard |
0.05” (1.27mm) Probe Point Spacing minimum is possible but should be avoided if the DUT design permits. |
Accuracy and Maintenance: Probing with smaller pitch probe contacts (and therefore smaller contact targets) increases the risk of accuracy issues. Smaller spacing probes are more fragile and may require more frequent maintenance.
Cost: Smaller spacing probes are more expensive. |
| Probe Contact Target Size |
The dimensions of the PCB contact test point which are to be probed |
>=0.04” (1.01mm) |
0.03” (0.76mm) diameter contact test points minimum |
Accuracy and Maintenance: Probing of very small diameter test points may cause inconsistent testing as each DUT and fixture itself will have mechanical stackup variations. |
| Probe Contact Distance to Components or PCB Edge |
The distance of the probe centerpoint to the edge of a nearby component of PCB edge |
>=0.1” (2.54mm) distance minimum is recommended |
>0.075” (1.9mm) distance minimum is possible but not recommended |
Accuracy and Maintenance: Probing very closely to a nearby component or PCB edge may risk unexpected electrical contact to component sides. |
| Probe Voltage and Current Limits |
The voltage and current of any one contact test point on the DUT |
<= 30V DC, <=1.0A DC |
<= 60V DC, <=2.0A DC.
Higher voltage/current is possible but not recommended without special contact probes. |
Accuracy and Maintenance: Higher voltage and higher current contacts may cause premature failure of spring loaded contacts
Cost: Higher voltage/current probes are more expensive. |
| Quantity of Probe Contact Targets |
The quantity of total PCBA locations to be probed by the fixture |
<=50 |
<100 |
Accuracy and Maintenance: The cumulative force of large quantities of pogo pins may stress the fixture itself.
Cost: Smaller spacing probes are more expensive.
DUT: High quantities of spring loaded contact probes may cause the DUT to flex and damage components or the PCB itself. |
| PCBA Manufacturing Clean Process |
The specified cleaning process of a PCBA after solder/reflow |
Recommend clean process |
“No Clean” is possible but not recommended |
Accuracy and Maintenance: Flux residue on a PCBA which has not been cleaned can interfere with probe contacts, and worse can reduce the lifetime of test fixture probes. |
| PCB Thickness |
The maximum thickness of the DUT PCB |
0.063” (1.6mm) standard PCB thickness recommended |
0.039” (1.0mm) PCB thickness is possible but not recommended |
DUT: Thinner PCB’s will tend to flex and deform more when the force of spring loaded contact probes are distributed across the PCB.
Cost: Additional fixture components may be necessary to adequately protect thinner DUT’s from mechanical stress or damage. |
| Locating Features |
Mounting or tooling holes in a PCB which the test fixture can use to accurately locate and align the DUT |
2 Non-Plated Through Holes, 3.0mm diameter or greater |
1 Non-Plated Through Hole, 3.0mm diameter or greater |
Accuracy and Maintenance: At least one non-plated through hole is required to locate the DUT for consistent probing. |
| PCBA Dimensions |
The maximum dimensions of the target PCBA |
<= 47mm x 105mm |
<= 65mm x 105mm |
Cost: Additional fixture fabrication steps may be required to accommodate larger PCBA’s Abnormally shaped PCBA’s may further limit the space which can be probed. |
| PCBA Component Height |
The maximum component height permitted from either side of the PCB |
<3.0mm maximum component height from either PCBA side |
<=4.5mm maximum component height from either PCBA side |
Cost: Additional fixture fabrication steps may be required to accommodate taller components |
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