Product category:
Electronics manufacturing: equipment, automation, software
News Release from: Kern-Liebers USA | Subject: Encapsulation dispensing system
Edited by the Manufacturingtalk Editorial
Team on 05 September 2002
Encapsulating ignition distributors
Encapsulating ignition distributors requires special materials and a dispensing system with precision temperature controls and exact material metering.
requires special materials and a dispensing system with precision temperature controls and exact material metering The requirements are very demanding: the encapsulating compound that fills the distributor modules must act as a high quality insulator protecting the electronics from continuous high voltage
This article was originally published on Manufacturingtalk on 5 Sep 2002 at 8.00am (UK)
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The material must not contain any air inclusions (bubbles).
Bubbles lead to sparking which destroys the printed circuit board in the distributor.
This encapsulating compound consists of two parts; one is filled with a glass fiber.
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Kern-Liebers Dispensing Technology developed a solution for this very difficult application in cooperation with the automotive component supplier.
During system development, attention is focused on temperature monitoring since acceptable results can only be obtained when specified temperatures are stringently maintained.
System temperature is continuously monitored at twenty measuring points and corrected if necessary.
Both material reservoirs are temperature-controlled, one at 80 degrees, the other at 60 degrees Celsius preventing the formation of bubbles and allowing the material reach the required fluidity.
A vacuum system used in the reservoirs reduces the pressure to 3 millibars removing trapped air bubbles.
The parts are pre-heated to 60 degrees Celsius, ensuring the mixed material retains it fluidity during dispensing.
The material is fed to the mixing unit by a reliable and proven media transfer system.
This system and all transfer hoses are temperature-controlled, keeping the material flowing properly.
A material ratio of 1:1 is precisely mixed with Kern-Liebers metering pumps ensuring an accurately mixed final compound.
Curing takes place in two, five-meter continuous furnaces, the first at 80 degrees and the second at 120 degrees.
Overly high temperatures are also not permitted since the module electronics are temperature sensitive and can be ruined by excessively high temperatures.
The system controller has the temperature indicators along with pressure sensors for the material reservoirs.
The operator keeps all system data in sight because it is displayed on a monitor at the loading and unloading position.
While the primary issue was handling the difficult encapsulating material in the ignition module application, another current project required speed as the key to success.
Foamed gaskets are applied to connectors in a system without a human operator; the cycle time is 2.8 seconds.
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