# Ask Me Anything about In-Circuit Testing & Flying Probe Testing **URL:** \ **Category:** Ask Me Anything\ **Tags:** ict, in-circuit-testing, flying-probe-testing\ **Created:** [May 6, 2025, 4:41am UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151 "2025-05-06T04:41:04Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![lucy.sierracircuits](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/lucy.sierracircuits/32/8_2.png) [@lucy.sierracircuits](https://sierraconnect.protoexpress.com/u/lucy.sierracircuits)\ **Post date:** [May 6, 2025, 4:41am UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/1 "2025-05-06T04:41:04Z")
Join our next Ask Me Anything about **ICT and flying probe testing** where you can ask us questions on: - Test methods - Board size and complexity - Test points - And much more! ![calendar icon.png](https://global.discourse-cdn.com/sierraconnect/original/1X/ad6bc27950fafa568284d45f4ed2477f523717e4.png) **Post questions before** : May 14th Please, note that this is not a live event. We ask you to post your questions on the forum before the deadline. > **Ask Me Anything about In-Circuit Testing & Flying Probe Testing** > > **Starts:** May 14, 2025, 1:00pm (America/Los\_Angeles)\ > **Ends:** May 14, 2025, 5:00pm (America/Los\_Angeles) ---
**Author:** ![morgancole](https://avatars.discourse-cdn.com/v4/letter/m/77aa72/32.png) [@morgancole](https://sierraconnect.protoexpress.com/u/morgancole)\ **Post date:** [May 12, 2025, 9:13pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/2 "2025-05-12T21:13:55Z")
I saw on your website that you require ODB++ files instead of just Gerbers for flying probe testing. Is there a reason? ---
**Author:** ![steve.carney](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/steve.carney/32/50_2.png) [@steve.carney](https://sierraconnect.protoexpress.com/u/steve.carney)\ **Post date:** [May 12, 2025, 9:20pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/3 "2025-05-12T21:20:46Z")
I don’t work on the assembly side but I think I can take this one. Flying probe testing needs more than just the physical layout. It’s not enough to know where copper is. We also need to know _what_ it connects to. ODB++ (or IPC-2581 or native CAD files) includes rich data like netlists, component values, pin mappings, and layer stack-up info. These are essential for us to generate the flying probe test program. Gerbers only describe your board’s geometry, not the connectivity or component intelligence, so they can’t support full test coverage. Hope that helps. ---
**Author:** ![gigio](https://avatars.discourse-cdn.com/v4/letter/g/839c29/32.png) [@gigio](https://sierraconnect.protoexpress.com/u/gigio)\ **Post date:** [May 12, 2025, 11:25pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/4 "2025-05-12T23:25:02Z")
How small can the test points be for flying probe testing to still work reliably? ---
**Author:** ![atar.mittal](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/atar.mittal/32/49_2.png) [@atar.mittal](https://sierraconnect.protoexpress.com/u/atar.mittal)\ **Post date:** [May 12, 2025, 11:32pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/5 "2025-05-12T23:32:53Z")
Flying probe testers can handle very small targets compared to ICT. The minimum test point size is **6 mils** , though **20 mils is recommended** for best reliability. The minimum spacing between test points should be **10–20 mils**. Smaller targets are possible due to the precision of the probes and lack of bulky fixture constraints. ---
**Author:** ![Ryder](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ryder](https://sierraconnect.protoexpress.com/u/Ryder)\ **Post date:** [May 13, 2025, 3:43pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/6 "2025-05-13T15:43:43Z")
Do I need to add special test pads to my board if I plan to use FPT during assembly? ---
**Author:** ![atar.mittal](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/atar.mittal/32/49_2.png) [@atar.mittal](https://sierraconnect.protoexpress.com/u/atar.mittal)\ **Post date:** [May 13, 2025, 5:31pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/7 "2025-05-13T17:31:54Z")
Not necessarily. One of the big advantages of flying probe testing is that it doesn’t require dedicated test points. It can probe directly on component pins, vias, through holes and exposed pads. We recommend FPT for prototypes or dense designs where your real estate is limited. That said, you’ll get better test access and coverage if you follow good FPT design guidelines like exposing vias and ensuring probe clearance around components. ---
**Author:** ![BerndKruger](https://avatars.discourse-cdn.com/v4/letter/b/a5b964/32.png) [@BerndKruger](https://sierraconnect.protoexpress.com/u/BerndKruger)\ **Post date:** [May 13, 2025, 11:07pm UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/8 "2025-05-13T23:07:24Z")
I’d be curious to know how flying probe handles testing under BGAs or other leadless packages? ---
**Author:** ![atar.mittal](https://sea2.discourse-cdn.com/sierraconnect/user_avatar/sierraconnect.protoexpress.com/atar.mittal/32/49_2.png) [@atar.mittal](https://sierraconnect.protoexpress.com/u/atar.mittal)\ **Post date:** [May 14, 2025, 12:11am UTC](https://sierraconnect.protoexpress.com/t/ask-me-anything-about-in-circuit-testing-flying-probe-testing/3151/9 "2025-05-14T00:11:55Z")
Flying probe testers can test under BGAs, QFNs and other leadless devices using capacitive probing. It’s true that the probes can’t make direct electrical contact with hidden pads but capacitive coupling allows the tester to sense activity at those nodes indirectly. It’s not as thorough as boundary scan or X-ray inspection but it’s surprisingly effective for many use cases.