Manufacturing Process of Potting
The process of potting a device in a low cost manner requires the potting compound, equipment
and method to work together. Therefore, the process of potting device needs to be done first before the potting compound is
selected. The first step is to determine if the process is to be a continuous
or a batch process.
If a continuous production line then the number of devices to be potted per minute and the space available will determine if they are potting one or multiple
devices at a time. After deciding the length of the conveyor and its speed the time to travel to the end of the conveyor can
be calculated. The potting compound will have to gel in this time. If the potting compound selected does not gel fast enough
then a different one will be required or heat will have to be used. Some times other critical properties will dictate that a slow
gel potting compound must be used. Then tunnel IR or convection ovens can be used to speed the gel.
The diagram below is a continuous system which includes all the
elements need for high speed low cost production. The diagram is courtesy
of Sealant Equipment & Engineering, Inc.
If a batch process is chosen then a choice of hand pouring the potting compound or machine meter-mix-dispensing is made.
Machine processing can use a faster gelling and odd ratio potting compound were as the hand pour works better with a simple
ratio and a long gel time.
Machine processing in a batch process requires trays or racks to hold the parts in an upright position until the potting compound gels.
Is common to have a dispensing gun connected to the MMD machine with hoses. The person potting the units
positions the gun over the part and pulls the trigger to dispense the potting compound. They can have complete control over how much and where to
dispense the potting compound or the machine can have a shot size control that allows
only a certain amount to be dispensed. Companies who have high production use bakers racks on castors so after the devices are potted the rack can be rolled out of
the way to gel and the next rack rolled in place.
Hand pouring processing is normally done by weighing out the resin and hardener and then mixing together for about 1-2 minutes and the
pouring in to the devices. This can have problems if after mixing the resin and hardener the mixture is not poured in to another cup
and mixed again before pouring in to the part. Many times the volume of devices to pot are small so they are put on a bench top and
left to harden overnight.