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Standard terminology in this field.

Source: 40+ years of professional experience +:

http://www.linguee.fr/francais-anglais/traduction/plaquette ...

Here, I believe 'circuit' really refers to 'the electronic circuitry' = 'the electronics'. Unless the wider context indicates that any other specific distinction is being made, I think this should be understood as simply 'the board carrying the electronic circuitry'.

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Note added at 10 heures (2015-01-17 07:46:35 GMT)
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I fear a lot of people are missing the point here. The source text does not specify that this is a 'printed circuit board', and to do so in our translation amounts to over-interpretation. Yes, we all know on the basis of our own knowledge and experience that this is of course a likely possibility — but if it isn't specifically stated in the souirce text, who are we to introduce it in the translation?

In certain contexts, it would be stated: "Start by mounting all the components onto the PCB" (the term 'printed circuit board' in full is relatively rare in technical jargon, other than in more formal documents, patents, etc.)
But when talking on a different level, to engineers and techniciens who may not be specifially electronics engineers, one might read "Install the circuit board into the housing and check all connections are sound."
Here, the emphasis is on the function of the board: it carries the electronic circuitry, rather than on its particular construction (it is a printed-type circuit board).
'PCBs' are a subset of 'all circuit boards' — but the converse is not implicitly true.
It is all a question of nuance and feeling for the source text, which probably explains the clear-cut divergenece of opinion here between native-speakers of the source language and the target.
In my FR > EN translation work, I very often encounter my suggested term in my source texts, and also observe the distinction I am seeking to make here, used within a same document.