Contact Through Silver Particles in Ink

May 06, 2008
Contact Through Silver Particles in Ink
Printed conductor paths connect a flow sensor (below) with the contacts on a circuit board (above). Credit: Fraunhofer IFAM

Modern cars are full of sensors. The optimum quantity of air in the intake tract of a combustion engine is regulated by thermoelectric flow sensors, for instance. They measure which quantities of a gas or a liquid flow in a particular direction. Another application for sensors like these is in medicine, where they regulate tiny quantities of drugs.

These thermoelectric sensors depend for their correct function on the right contact: The measuring sensors, consisting of a silicon wafer and a membrane, are embedded in a printed circuit board. So that the necessary current can flow between the contacts of the sensor and the printed circuit board, a conductor path has to be created – experts speak of ‘contacting’.

Researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM in Bremen (Germany) are working on a special technique: “Up to now, contacting was usually done with wire bonds – thin wires, that is,” explains IFAM project manager Christian Werner. “But wire bonds stick out, and thus impair the flow behavior of the gases and liquids. That can affect high-precision measurements.”

The researchers have therefore developed a new technique: INKtelligent printing®. What is different about this technique is that the researchers print the conductor paths instead of wiring them. This is basically a contactless aerosol printing method. The secret lies in the ink: “The suspension contains nano silver particles in a special solvent,” says Werner. “This enables us to print extremely thin-layered conductor paths.” Subsequent thermal treatment activates the electrical conductivity of the paths.

The researchers have tried and tested these conductor paths together with colleagues from the Institute for Microsensors, -actuators and -systems IMSAS in Bremen. Altogether, the engineers have solved one of the main problems of thermoelectric sensors. In contrast to wire bonds, which have an overall height of 1 to 1.5 millimeters, the printed conductor paths are a mere 2 to 3 micrometers high, or almost five hundred times thinner than wire bonds. This enables the sensors to make far more accurate measurements.

Source: Fraunhofer-Gesellschaft

Explore further: New device could spell the end of no balls

Related Stories

When temperature goes quantum

Mar 06, 2015

A UA-led collaboration of physicists and chemists has discovered that temperature behaves in strange and unexpected ways in graphene, a material that has scientists sizzling with excitement about its potential ...

The quest for efficiency in thermoelectric nanowires

Feb 02, 2015

Efficiency is big in the tiny world of thermoelectric nanowires. Researchers at Sandia National Laboratories say better materials and manufacturing techniques for the nanowires could allow carmakers to harvest ...

Pantograph monitoring for the eHighway

Jan 13, 2015

Siemens is developing an automatic monitoring system for pantographs. Designed initially for electric and hybrid trucks on eHighways, the system uses cameras and sensors to check the condition of pantographs ...

Recommended for you

Defusing bombs by color

May 22, 2015

This March, Cambodia held its first national-level science festival at the Royal University of Phnom Penh, attracting over 10,000 young students to the science booths over the course of three days. At one ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

DGBEACH
not rated yet May 07, 2008
Wire bonds are much more able to withstand the rigorous automotive environment than would any "painted-on" connection...I can see this coming, an exponential increase in servicing requirements for the next generation of vehicles because some misguided "researchers" thought it would be a good idea.
This so called new-technology has been used to make flexible anti-shoplifting and RFID tags for quite sometime now. The only reason this story ended up here is because the word "nano" appears within the text!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.