IMHO:
1. In-circuit testing (ICT) just means that you're testing your board
after it is assembled, rather than testing the chips individually before
placement. For example, a node-impedance test would be an ICT test, and
so could a flying-probe test. In fact, I would also call a functional
test an in-circuit test, though I might be unusual in that.
2. A functional test makes sure that the product responds to simulated
real-life situations. Usually this means interacting with the board
through the pins it presents on its connectors. For example, you'd test
a serial port by connecting it to another serial port, or doing a
loop-back test.
3. A node-impedance test measures impedance at various points on a board
and compares the impedance signature with a golden-board sample.
4. A bed-of-nails simply refers to having an array of spring-loaded pins
that contact your board in various places. It can be used for either a
functional test or a node-impedance test.
- Berwyn
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Jack
Olson
Sent: Wednesday, July 26, 2006 9:44 AM
To: [log in to unmask]
Subject: Re: [DC] ICT testing
Maybe it is just a case of terminology,
but ICT *is* a bed of nails fixture,
where functional test uses the connectors or POGO
(or am I having a senior moment?)
Jack
On 7/25/06, Haldor Husby <[log in to unmask]> wrote:
>
> Hi Nagaraj -
> I don't know what you mean by Bed of Nails testing. People mostly talk
> about bed-of nails in connection to a functional test where the nets
are
> accessed through a matrix of pogo-pins. ICT (in-circuit Test) is in
> general not a functional test, but is in the simplest form a test
where
> the impedances of all accessible nets are measured to help detect
> manufacturing defects like shorts, opens, incorrect values, incorrect
> polarity etc. ICT is also referred to as Node Impedance Test (NIT).
> Modern ICT testers have many capabilities beyond just measuring
> impedance, such as boundary -scan and programming of non-volatile
> memory. Check also Agilent's testjet.
>
> Flying probe test is the prototype or low-volume version where the
> probes represent a very flexible fixture that can be programmed to hit
> all the nets in turn. ICT tester for higher volume will have a custom
> fixture for each board, with pogo-pins that connect to all nets
> simultaneously.
>
> Agilent and Teradyne are major vendors of in-circuit test equipment.
You
> can check their websites for more information
>
> http://www.teradyne.com/
> http://www.home.agilent.com/
>
> Med vennlig hilsen. Best Regards.
> __________________________________________
> Haldor Husby
> Senior Development Engineer
> Data Respons Norge
>
> [log in to unmask]
> www.datarespons.no
>
>
>
> On Mon, 24 Jul 2006 21:43:54 +0100, ert ert <[log in to unmask]>
wrote:
>
> >Hi All,
> >
> >I have studied and followed ICT testing on layout with constraint
> requirements like placing in grids, spacing b/w prope pads, component
to
> Probe pads spacing,..etc But I do wish to know how the ICT testting is
> carried out? Is it similar to Bed of Nails test and Flying prope test?
> >
> >If any one has any documents or have practical experience on this can
you
> help be understanding this.
> >
> >Thanks much in advance.
> >Nagaraj
>
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