Coils on small seperate fiberglass boards

[Sjokolade]

Why are some coils mounted on to small seperate fiberglass boards before they are fitted to circuit boards ?

Less coil whine ? easier to fit ?

[sahko123]

Why are some coils mounted on to small seperate fiberglass boards before they are fitted to circuit boards ?

Less coil whine ? easier to fit ?

this may be that the coils are tuned or preselected.

[amyk]

It keeps the leads aligned for easy insertion.

[T3sl4co1l]

It keeps the leads aligned for easy insertion.

^

There may also be reasons for insulation/isolation, which the green square in the second pic is doing.  Keeps the wires away from the components on the facing PCB.

The one on the right, second pic, might also have insulation between windings.  This is common with common mode chokes:
http://www.digikey.com/product-detail/en/triad-magnetics/CMT-8120/237-1373-ND/2783628
They may also be molded in, like
http://www.digikey.com/product-detail/en/wurth-electronics-inc/744834101/732-3402-ND/2794422
Or they simply use spacer tape:
http://www.digikey.com/product-detail/en/bourns-inc/8107-RC/M8902-ND/775441


Tim

[station240]

Also consider magnetic coupling, by using separate and differently orientated PCBs, they can reduce the interaction between unrelated parts of the circuit.

[BravoV]

It keeps the leads aligned for easy insertion.

Also if you watch the windings, all are secured/soldered/glued to that piece of plastic, without it, the coil will unwind or get loose before they were assembled into the board, cmiiw.