is ICT dead? - Page 1
Forum section: electronics / general

author: ddavidebor
author_rank: Super Contributor
timestamp: November 01, 2018, 10:25:28 am
content: Hi Guys,Where I work for we usually do ICT testing and then functional testing. Not sure if there is AOI. The PCB are manufactured in europe from a huuuuuge fancy manufacturer.I'm looking towards Shenzhen for the future.It seems impossible to find someone that offers ICT. Some of them tells me ICT is out of the market since modern AOI is quite good.Is it true? what's your experience?For ICT i mean:* bed of nails* with populated components* machine measures RCL values in a matrix

author: Kjelt
author_rank: Super Contributor
timestamp: November 01, 2018, 10:55:23 am
content: Flying probetesters were used in my previous companies PCB manufacturer.A fixed bed of nails is expensive and static, is only beneficial with mass production numbers.

author: SMTech
author_rank: Frequent Contributor
timestamp: November 01, 2018, 11:03:24 am
content: I suspect they just don't want to do it/own the rigs/set it up etc. AOI is to catch manufacturing defects, mostly from the SMT process (THT inspection exists but it has its limitations), there are plenty of things it won't catch but that other procedures should prevent/reduce happening in the first place - board faults, wrong parts. Proper inventory management or Component verification on the pick and place for instance. Some places would put everything through ATE as std some rely on functional test or customer issued test equipment. ATE is certainly a thing you can readily buy so I don't see how you would call it out of the market. However you would expect flying probe to be the most common option as Kjelt says....

author: capt bullshot
author_rank: Super Contributor
timestamp: November 01, 2018, 02:17:22 pm
content: ICT is still done here, both bed of nails and flying probe style. JTAG / Boundary scan can replace a lot of otherwise time consuming discrete test points in a mostly digital circuit.AOI cannot catch a lot of faults, e.g. wrong component but looks the same, or some kinds of bad solder joints.However, if you inspect PCBs from random products carefully, one can find many that obviously have never been ICT tested (look for test points and / or needle marks). Apparently there are PCB assemblers out there that can deliver a good enough first time quality rate without ICT.

author: Neilm
author_rank: Super Contributor
timestamp: November 01, 2018, 07:57:53 pm
content: We still use ICT at work. My biggest issue with it is how much room thepest pointstest points take up. Flying probes take too long on even a medium complexity PCB.

author: capt bullshot
author_rank: Super Contributor
timestamp: November 01, 2018, 08:22:45 pm
content: +1 for pest^h^h^h^htest points

author: IconicPCB
author_rank: Super Contributor
timestamp: November 02, 2018, 01:47:20 am
content: The test points while bulky at times can be selected for various pitch components.From a few millimeter center to center distance, to 0.05" and smaller center to center distance.

author: SeamarkElectron
author_rank: Newbie
timestamp: November 02, 2018, 03:01:30 am
content: I knew some company still provide ICT test equipment, AOI, ICT or X-ray, you will always need one of them for deffects inspection.They can't be dead, most of the PCB assembly don't have enough quality rate without these equipment.

author: ddavidebor
author_rank: Super Contributor
timestamp: November 02, 2018, 09:26:02 am
content: Then where are the PCBA houses with ICT hiding in Shenzhen?

author: Gribo
author_rank: Frequent Contributor
timestamp: November 02, 2018, 02:14:33 pm
content: At my workplace, we still do ICT.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 02, 2018, 03:35:47 pm
content: ICT is significant investment, both from the equipment to the actual bed of nails. Which by the way, if you make a board revision and change the layout, it may require a non-trivial ICT change also. Therefore as others have mentioned, they make sense for medium to high volume products which are in the full production stage..In our company we do both bed of nails and flying probe ICT. Where the boards are packed too tightly for probing, we use both AOI and a diagnostics-firmware for self testing. Some boundary scan.It all depends on the product and its budget.

author: julianhigginson
author_rank: Frequent Contributor
timestamp: November 03, 2018, 03:01:08 am
content: ICT is definitely on the way out over the last 10 years. Modern AOI is very good (not perfect) but add that to modern process control, plus self test capability in most designs with reprogrammable processors and logic, and the benefits of ICT seem less and less, while the massive amount of work to enable it on modern high density SMT boards gets higher and higher.I'm sure big rigid businesses with it welded into their process still require it because everyone is too scared to allow it to be deprecated in case *something* happens and they get blamed. And I guess military and similar probably still want it... But in my experience, for the kind of things I work on, nobody wants it anymore. (And like you discovered, it's rarely even offered by EMS partners anymore, so if you really want it, chances are you're buying the whole system to do it, too)

author: julianhigginson
author_rank: Frequent Contributor
timestamp: November 03, 2018, 03:04:28 am
content: That said, a simple bed of nails to do basic functional testing and also programming the programmable bits is certainly still pretty common... You might add access to a few critical nodes in that case, and do some testing with access to internal signals on the board, but it's certainly nothing like high coverage measuring of everything in the board that traditional ICT is meant to be.

author: kkritsilas
author_rank: Contributor
timestamp: November 04, 2018, 10:58:35 pm
content: It really depends on the test strategy, how good the process is, and other influencing factirs (board density/layout, availability of qualified test program developers, and bed if nails vendors, and others).In a high volume scenario, ICT will be faster and most likely will be able to provide better fault infirmation. As well, if the data from the ICT is used properly, it can be used to improve the SMT orocess. However, in extremely high density designs, test probe access can be an issue. In RF type boards, test oads, and the use of vet small value components can also be a problem.Genreally speaking, ICT test times will be faster than AOI inspection times. Turning off component verification can speed pick and place rates, when a ICT is used.There are a lot if variables involved in optimizing any process, and the trade offs all need to be considered.

author: IconicPCB
author_rank: Super Contributor
timestamp: November 05, 2018, 02:58:32 am
content: I used to own a couple of MDA testers ( manufacturing defect analysers in old parlance) one was a universal grid based machine whihc was essentially a bare board grid machine with rudimentary in circuit testing of un powered boards ( hence MDA) made by Fastek od USA ( no longer in business) the other a flying probe bare board testing machine with much more sophisticated testing capability made by BSL - Bath Scientific Limited of UK.I have used the BSL machine a few times to test clients assemblies but that was the extent of it.Both ran on a 486 machine... long live DOS.BSL machine had a programmable source measurement unit which stored VI characteristics at a node in circuit and could be programed to guard adjacent nodes and evaluate component values at the node.The ROBOPROBE i understand started its life as a military bit of kit.

author: kkritsilas
author_rank: Contributor
timestamp: November 06, 2018, 09:38:12 am
content: Way back when, I used to run the ICT process at the Philips Montreal facility. Our products were PCs (386-486-original Pentium era). My 3 ICT testers were 2 Genrad 2287s and a 2282 (for a higher complexity/lower volume board). My test time for a complete motherboard was 18 seconds, and this was using a VAX 750 as a controller CPU. This included full shorts testing, all analog components for values, power up and verification, and IC (all Ics, including CPU and large chip set ICs) testing, as well as full memory testing.It was determined that there was significant time savings in turning off the component verifier on the Fuji chip shooters because the ICT could catch any incorrect components. We cut 2-4 seconds off the chip shooter placement time.This took time to develop. I spent time with the board layout guys to make sure that there was at least one test pad per net, and multiple test pads per voltage rail and ground. The manufacturing guys (pick and place, wave and convection soldering) also worked with the PCB layout guys to get good solder footprints and take into account the wake effect for the wave solder machines.Later on, I worked at a company in which ICT was used on a smaller board. Because the board used RF components, I had to test the very small value components (caps in the sub 100 pF range)with a flying probe tester. The design engineers did not allow test pads in the RF section, either, which made using a flying pobe tester mandatory. The slow test times of the flying prober were less of a problem due to the limited numbers of conmponents/nets that needed to be tested.If I were formulating test strategy today, I would need to add AOI/Xray into the equation. But, in a high volume environment, I still think that ICT would have a place. Something like AOI/Xray for BGA components, only, and ICT for everything else, or ICT plus a Flying Prober for any components not handled well by ICT. Everybody sees ICT as a test tool, and it is. What a lot of people don't look at is that ICT can be an excellent process monitoring tool when the failure data is fed back into the board assembly processes.