Adaxo Case Study

Case Study: Probe

Design reqirements

The probe is the heart of the instrument. Its operating principle is to measure the change
in characteristic impedance of a transmission line at very high frequency (VHF).
The transmission line is created on flexible printed circuit. In use it is pressed against the
surface being measured. Intimate contact is vital and this is ensured by moulding a
silicone pad onto the substrate.
A small low cost housing was needed to accept the completed flexi-rigid PCB assembly.
The probe has a limited life so the manufacturing cost of the final product
had to be as low as practicable.

The solution

The rigid PCB with surface mounted components sits on guides in the moulding. The flexible section constitutes the active part of the probe. It is mounted on a silicone pad which is bonded to a platform, formed as part of the moulding.
The complete probe. Features are included to allow the user to orient the probe easily and to protect the connector pins. Tooling cost is low as the moulding can be made in a single, dual cavity open and shut tool.

Comments

ADAXO has had considerable experience in sourcing parts from the Far East
and has relationships with injection moulding suppliers in Southern China.