What is Low Pressure Molding
Low pressure molding, refer as LPM, is a a "new" molding technique that marry plastic injection and traditional potting that offers a fast and convenient packaging solution that both encapsulates and forms the housing of the device. LPM molding eliminates the number of processes that associates with traditional potting without the enormous pressure from the plastic injection.
LPM is utilizing low pressure, typically 3 to 35 bar and lower temperature at 180 to 230 deg C for molding, made possible by the properties of the specially developed unfilled polyamide. These polyamides, polyolefin and PUR hotmelt provide adhesion to give a water tight feature that is uncommon with other plastics.
Engineering plastics like PA6, PA6.6 and PA11 requires pressure from 400 bar at 230 - 300 deg C. These plastics possess much higher viscosity that requires a screw feeder to move the molten plastic. The higher the content of the filler i.e glass fibre, so does the pressure. Hence, the mold of steel or Be copper generally, is subjected to take “beating” of high pressure and more tear to the mold to expect. Common practice is the mold undergoes a hardening treatment to stiffen up the hardness. Mold maintenance is costly.
The size and design of the molding also the determinant factor of the amount of pressure.
What is LPM for
Therefore, LPM is useful where the particular molding requires
- low pressure due to delicate and fragility of the insert
- low temperature resistance of the insert and
- water tightness
The limitation of LPM is the size of molding, a mere smaller than a name card size. Minimum thickness is 0.6mm, subjected to trial.
How did LPM start
LPM started in early 70ties at IBM for an undisclosed application. However, LPM only started making waves with its success on water tight connector at Peugout in the late 80ties.
Pause for a thought
Have you ever experienced the jerking and lose of drive-ability of car when driving in a rainy day? The cause is water has slipped into your electrical system and has caused a short circuit.
Who is LPM for
Automotive industry proves to be the most strident industry for technology penetration. It requires years of qualification, inspection and tested under severe environment.
LPM has slowly making an in road to electronics applications in the mid 90ties. LPM is particularly welcomed in insert molding, overmolding and as an encapsulant. This greatly reduces the cycle time and improves production yield compares with potting technology. Lower cost per unit can achievable from LPM especially true to mass production like cell phone lithium ion battery. Molding of battery control board is by far the biggest market for LPM to date. Yield and cost is the name of the game in electronics industry, it determine the sustain-ability of the company.
Pause for a thought
Ever wonder there are many companies in Penang aka Malaysian Silicon Valley relocating to low production cost country like China?
There are clear signs that electronics has picked up in momentum in the field of automotive industry. The latest keyless system of Mercedes Benz that recognize its owner and new BMW 5 series features intelligent battery sensor that indicates precise knowledge of the battery state, which obtained from variables such battery current, voltage and temperature, are made possible via LPM. Other electronics like tyre pressure monitor, air quality sensor, seat occupant sensor, micro sensor etc had been incorporated into the premium cars. We expect these features will be rolled down to “working man” cars in time to come.
What is the next big thing for LPM
LPM does not stop here. RFID is the latest and most exciting technology that the industry is waiting for. An RFID tag is an object that can be applied to or incorporated into a product, animal, or person for the purpose of identification using radio waves. Most RFID tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and demodulating a (RF) signal, and other specialized functions. The second is an antenna for receiving and transmitting the signal. RFID used is in enterprise supply chain management to improve the efficiency of inventory tracking and management.
The encapsulation of active RFID tags performs several very valuable functions, including protection from the environment and business processes, and creating the necessary offsets required to mount on metal. The trick here is the packaging must be compatible with the radio frequency (RF) performance of the tag.
