plastics - The customer magazine from BASF 2/2007

Markets and products
New plastic specialty protects
circuits against moisture.
Same method,
better bond
“Our broad product line certainly contains
plastics that bond well to metals. Our task
was merely to further optimize this important
property,” explains Gall. The breakthrough
came with the new Ultramid Seal-Fit, which
flows so easily that it actually fills every nook
and cranny of the microscopic structures
of the metal surface. “The special feature
of these granules is that they can still be
processed in conventional injection-molding
machines like almost any other thermoplastic.
This means that processors do not
have to deal with a new process,” says Gall.
And what is even more, there is no longer a
need for complex pre-treatments involving
materials that are not suitable for injection
molding but that had been used up until now
to affix the printed-board conductors so that
they would not get all tangled up during the
subsequent injection molding of the housing.
“This bond is now simply created by Ultramid
Seal-Fit,” is how Gall describes the
advantage of the new solution. Fedler adds,
“That’s
the beauty
of it: you simply
use the existing injection-molding
method but with
a new material.” Okay. But are the printedboard
conductors that are overmolded this
way really tightly sealed? The engineers
are all fired up that this is indeed the case
and to prove it, they even put the material
specimens into the oven. “We subjected
the specimens one after the other to all of
the usual climatic cycling tests as well as
to harsh temperature-shock experiments,”
says Fedler, describing the rigorous testing
they conducted in-house. “Here, the parts
had to withstand temperature fluctuations
from -40°C [-40°F] to +50°C [122°F] within
less than 10 seconds.” And they still had to
be tightly sealed after this. Ultramid Seal-Fit
firmly clings not only to the metal but also to
the polyamide housing. “Polyamides adhere
extremely well to each other, creating a tight
seal here as well,”
according to Gall.
Besides, Ultramid Seal-Fit
is somewhat softer then the
fiberglass-reinforced material of the
housing, so that it can also absorb the
stresses that occur between the metal and
the housing upon exposure to heat. “The
combination of our material know-how with
the extraordinary technical testing competence
of the Lüdenscheid Plastics Institute
allowed us to come up with an innovation
that benefits everyone,” summarizes BASF
expert Gall. “Manufacturers of electronic
components can now make much better
products without having to expend more effort
and the OEMs can put safer cars on the
market – with the result that the nightmare of
electronic system failure is becoming a thing
of the past.
Further information:
www.ultramid.com
www.kunststoff-institut.de
25