Conductive adhesive for ultrasound catheter
Connect, no.76, May 1996 Intravascular Research Ltd has been working with TWI's Centre for Adhesive Technology (CAT) to assess the use of electrically conductive adhesives to join two components of a catheter tip.
The tip is part of an ultrasound imaging device for quantitative and diagnostic analysis of coronary arteries.
Piezoelectric (PZT) transducer rings were bonded to tungsten carbide (WC) tubes using silver-loaded epoxy adhesives. Selection of adhesives was based on the following requirements:
- good adhesion to both PZT and WC
- rapid, low temperature curing
- ease of manual or automated dispensing
- electrically conductive (resistivity of about 1.4 X 10-3W)
- zero or low volatile emission during cure
- thermal stability: 1000C continuous, 1500C intermittent
- low shrinkage (0.5% or less) on curing
- coefficient of thermal expansion compatible with PZT and WC
- ability to withstand sputter-coating and machining processes
Adhesive dispensing and curing have been optimised to provide a void-free, 80mm conducting layer with required acoustic properties.
Catheter tips assembled using conducting adhesive have been taken through mechanical testing to clinical trials.
Further information is available from Gareth McGrath: gareth.mcgrath@twi.co.uk
