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2007-09-22 Manufacturing News
New engineering plastics
for electronic components
New engineering plastics developed by BASF markedly reduce the risk that
electronic components will malfunction due to contact with moisture or
oil.
The electrical conductive paths of these components can easily be overmolded
with the new specialty polyamide Ultramid* Seal-Fit for tight overmolding
of metal inserts. This is a transparent, non-reinforced copolyamide (PA)
that forms a tight seal.
It stands out for its very good adhesion to metals on the one hand and
to plastics such as Ultramid (PA) and Ultradur* (PBT) on the other hand.
This product has been specially developed for the tight overmolding of
metal inserts, thus accounting for an optimal bond in the component. Many
approval samples have already been successfully tried out and the first
serial applications are in the planning stage. The material is now already
available in commercial quantities.
Injection molding instead of gluing or pre-coating
Until now, the limited adhesion of the housing plastics to the metal as
well as the differing thermal expansion of these two materials have made
it difficult to attain a really tight covering of metal inserts. Complicated
sealing methods involving silicone adhesives, hot melts, impregnation
or pre-coating of the metal were necessary. Thanks to Ultramid Seal-Fit,
a tailor-made technical solution is now on hand that can be completely
implemented via injection molding technology.
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Overmolding of metal inserts
with Ultramid* Seal-Fit. Click
Here for High resolution image. photo: BASF |
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Fits like an injection molded glove (pictured at right)
BASF’s new plastics Ultramid Seal-Fit, a transparent copolyamide,
can be used in a simple, two step injection molding technique to manufacture
gas-tight mechatronic composite parts consisting of metal and plastics.
The metal inserts of the electronic component are first premolded with
the new copolyamide, a process in which they are simultaneously fixed
in place and tightly sealed. The second step is overmolding with the conventional
housing materials Ultramid or Ultradur Ultramid Seal-Fit adheres very
well to the metal as well as to the plastics used for the housing and
compensates for the difference in thermal expansion of these two materials.
As a result, processors have a high degree of design freedom that allows
them to cost-effectively manufacture controls, sensors and plug-in connectors
that are sufficiently sealed against oil, water and gas.
Tight overmolding: sealing by means of injection molding in two steps
In the first step, the material insert is partially premolded with a precise
fit and subsequently, in the second step, conventionally overmolded with
a classic housing plastics such as Ultramid A3EG6 or Ultradur B4300 G6.
Wherever metal inserts are premolded anyway, the first process step even
offers an additional benefit: with Ultramid Seal-Fit, the electrical conductive
paths are not only affixed in place but also tightly sealed at the same
time.
Metal parts thus overmolded are sufficiently sealed against water, oil
and gas, as the experts of the Plastics Institute in Ludenscheid, Germany
have demonstrated in comprehensive temperature-shock tests on special
test components. Among all of the other materials tested, this new BASF
plastics best meets the requirements of the automotive industry. Application
areas are sophisticated mechatronic components such as transmission and
brake controls, sensors and plug-in connectors, especially in automotive
construction.
* Ultramid and Ultradur are registered trademarks of BASF Aktiengesellschaft.
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