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: Wireless sensor transmits tumor pressure

add to favorites email to friend print save as pdf

Related Stories

Copper shines as flexible conductor

Aug 22, 2014

Bend them, stretch them, twist them, fold them: modern materials that are light, flexible and highly conductive have extraordinary technological potential, whether as artificial skin or electronic paper.

Recommended for you

Wireless sensor transmits tumor pressure

Sep 20, 2014

The interstitial pressure inside a tumor is often remarkably high compared to normal tissues and is thought to impede the delivery of chemotherapeutic agents as well as decrease the effectiveness of radiation ...

Seeing through the fog (and dust and snow) of war

Sep 19, 2014

Degraded visibility—which encompasses diverse environmental conditions including severe weather, dust kicked up during takeoff and landing and poor visual contrast among different parts of terrain—often ...

The oscillator that could makeover the mechanical watch

Sep 18, 2014

For the first time in 200 years the heart of the mechanical watch has been reinvented, thereby improving precision and autonomy while making the watch completely silent. EPFL researchers have developed an ...

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!