SAN DIEGO --- Just about everybody has dropped a cell phone at one time or another. The engineers at Nokia's testing lab in San Diego have seen and heard all the phone disaster stories and have designed hundreds of tests with the idea of improving Nokia cell phone quality.
On a tour for journalists attending the International CTIA conference yesterday, Nokia engineers demonstrated sophisticated tests on many of its devices, including smartphones and more traditional cell phones.
The engineers dropped, twisted, steamed, dunked, scraped, vibrated and generally tried to destroy the phones to show the processes that Nokia uses in 10 device testing labs around the world.
In one test, a small piece of plastic used for what is termed a "window" on a phone display was propped up on a stand with pressure precisely applied from a metal bar above. Nearby computers measured and recorded what pressure was applied, bending the window to the point of breakage, which sounded like a quick 'pop.'
The precisely applied pressure on the window is like "an elephant wearing a stiletto standing on a phone," said Mike Myers, a mechanical test engineer at the lab.
Other tests involved robots that continuously pushed phone buttons, opened slider phones or scraped surfaces to find out when painted-on numbers started to fade.
There were also a varoety of drop tests: A pendulum swung around to bash a Nokia 6650 phone, while another box-like device rolled phones for hours. In a more sophisticated drop test, a robot arm lifted a phone to a height of about 7 feet, dropping it into a chamber where it landed on a concrete pad. A high-speed camera recorded the drop to record how the phone hit the pad for clues to what could cause breakage.
"We test things to failure," Myers said, noting that the button-pressing robots will speed up the use of a phone by an average user, applying hundreds of thousands of button pushes over five days.
Nokia has developed many of its own tests atop a group of international standards used for testing phones and small electronic devices. One of the more unusual tests involved pieces of cloth pockets that rotated in a drum, in which the engineers placed a phone with keys and pennies to simulate what might be happening in a man's trouser pockets while carrying a phone.
Chris Rubie, manager of the environmental testing lab, showed an enclosed tray that was made to vibrate violently, with dust thrown in with cell phones that danced like jumping beans.
"What happens for most of us is that we come home and pull the phone out of our pockets and toss it on the table," Rubie said. "So we're interested in seeing how dust and cotton from clothing gets into the seams of a phone."
Nokia also simulates more commonly reported problems, including a user dropping a phone in a toilet or making a call in the rain, but the testing devices employed don't resemble bathroom fixtures. One device applies heat and steam to simulate jungle swelter at 95% humidity. Another simulates a downpour while other tests chill and bake phones from minus 40 degrees Farenheit to 250 degrees Farenheit, Rubie said.
A separate failure analysis lab is designed to look at problems in phones at the microscopic level, making use of equipment including a scanning electron microscope that can detect cracks in solder joints as tiny as 300 nanometers. A single piece of paper would be about 250 times as thick as a crack of that size, said Mike Wellborn, manager of the failure analysis lab.
"Sometimes a failure is too small to see," Wellborn said.
Wellborn showed an actual case he investigated over several days where testing engineers had noticed the repeated failure of a hinge on a flip-style phone under development. Microscopic 3-D analysis was able to show that air packets inside the molded magnesium hinge area were weakening the hinge. Nokia passed on this information to its supplier for
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