Original equipment manufacturers (OEMs) may want their assemblies potted for a number of reasons, but typically it is carried out to protect against shock and vibration, or to stop moisture or corrosive agents from getting near the electronics. Here's our guide to getting it right.
Potting is the process of filling or submersing a complete electronic assembly using a compound material. While the process may sound quite simple - just a case of pouring liquid resin into an enclosure - it can actually be a real challenge for those carrying it out. To achieve the "perfect pot", there are a number of factors to take into consideration, to ensure that the dispensed potting material is consistent and repeatable
In this blog post, we will look at six steps that should be followed, in order to achieve a consistent result. Also included are some hints and tips for those involved in carrying out the process within electronics manufacturing.
It is important to heat the resin up before the potting process starts. This allows the potting mixture to flow better through the system when production begins. Due to the wide range of resins available, it’s important to consult the supplier of the resin so they can advise what the optimum flow temperature should be.
For some resin and hardener systems, the weight ratio can be varied to produce cured material with differences in properties, usually in flexibility or hardness. Again, we recommend you consult with the supplier to determine if the mixing ratio is fixed or if some variation is possible. To achieve the optimum result for your own application, you may need to run a number of trials before production volumes commence.
Broadly speaking, there are two types of potting methods available.
Once the ratios have been controlled the resin and hardener require mixing together. This operation is typically achieved using a detachable mixing nozzle. It’s important the nozzles are detachable as once the mixing process has taken place they have a short life span. The curing process means they need regularly replacing.
Mixing nozzles ensure optimum performance by dividing and recombining the materials into a homogeneous stream. It's generally accepted that the longer the nozzle, the better mix of material.
It is important for the materials to be mixed at pressure so that they are combined effectively. If there is too little pressure, then this can result in an uneven mix. If you are unsure of the exact pressure you need or have experienced issues with your current settings, contact the supplier of the materials for advice.
The required volume or weight of the mixed material can be achieved in multiple shots or one single controlled shot. Much depends on the size of the electronic assembly that is being potted. A cylinder-piston method can be adjusted to regulate the dispense amount but is limited by the cylinder size. As a result, in most cases multiple shots are required. In contrast, a machine with a gear pump allows a single continuous shot, which can be set and controlled electronically.
This will be closely related to the force of mix and the required volume/weight. Of course, from the operator's perspective, the speed that the mixture is dispensed must be at a rate they are able to cope with on the assembly line in a controlled manner.
In addition to the above steps, here are some further hints and tips, many of which are the result of our very own blood sweat and tears!
So there you have it: some of the more critical factors to be aware of in order to consistently achieve the "perfect pot"!