What is Low Pressure Molding?
Low Pressure Molding is a low pressure molding process with hotmelt adhesives. It can achieve superior sealing, better protection of electrical/electronic components with higher productivity compared to those materials widely used in current sealing processes e.g. 2-component casting/potting resins or silicones. This notable process is environmentally compatible and contributes to total cost reduction due to improved productivity.
Process Flow Advantage of Low Pressure Molding
Traditional Casting/Potting Process Flow
Low Pressure Molding Process Flow
Encapsulates fragile/delicate components• No damage to components
No chemical reaction: single-component material • Simple and clean process
• Fast cycle times (10 – 50 seconds)
Water-tight encapsulation with adhesion:
Excellent electric insulation and water resistance
Chemical resistance:
Depending on their chemical basis, the molding products are resistant to gasoline, oils, alcohols, acids and alkalis
Excellent thermal durability characteristics:
Thermal cycle resistance, cold resistance, temperature resistance (from -40 °C to +150 °C)
Based on non-toxic and renewable raw materials:
Environmentally compatible
Application Case – Sensor: 2C Casting vs. Low Pressure Molding
Current
Technology Low Pressure Molding
Adhesive
Consumption/unit 16 g / unit (Casting) (PA Hotmelt)4 g / unit
Cost of Adhesive/kg € X € 2X
Adhesive Cost/unit € Y € Y/2
Production Cycle/unit 2 hours < 1 min
Production Space Required
Occupies space for case storage &
curing
No space for case storage nor curing Results after changing to Low Pressure Molding:
• Adhesive cost saving = 50 %
• Saving in production time
• Saving in production space
• Saving in component and energy costs
• Much better water-proof quality
Highlighted Features
2-Component
Casting Resins Low Pressure Molding
Process Time Hours – Days Seconds –Minutes
Machine
Maintenance Every day Once a week
• Eliminates traditional housings and cases used in potting. • Saves energy by eliminating the heat curing process. • Uses less adhesive for PCB encapsulation.
• Mold made of aluminum helps to reduce cost.
Above data are taken from a real reference case Injection Molding
Low Pressure Molding
Injection temp: 180-240 °C Injection pressure: 5-40 bar
Injection pressure (bar)
Injection tempera ture (°C) 400 400 600 800 1000 1200 1400 300 200 200 100 0 0
Superior Material Properties
Mold Case
Encapsulate Setting or Vacuum Cure Test
Palletize ElectronicsInsert Preheat
Insert
Electronics Overmold Test
Low Injection Pressure
Improved Productivity
Moldability:
Flexible and miniaturized product design
Low flammability:
UL94 V-0 available
Polyamide Polyolefin
Product Macromelt® OM Macromelt® Q
Service Temp (°C) -40 to +150 -30 to +100
Molding Temp (°C) +180 to +240 +180 to +200
Viscosity range (mPa.s ) 1,000 to 7,000 5,000 to 15,000
Shore Hardness A80 to D50 A60 to A90
Outstanding Properties Superior adhesion to plastics e.g. ABS, PBT, PVC Superior adhesion to PP, PE, PET
UL 94 V0 V2
Low Pressure Molding Applications
Low Pressure Molding can be applied to various automotive electronic systems and devices, such as tire pressure monitoring systems (TPMS), PCBs for seat occupant sensors, belt lock sensors, ECUs for motorcycles, air quality sensors, antennas for RF devices, smart entry (E-Key) systems, etc.
1. Water-tight connector
3. Absolute angle sensor 4. Intelligent battery sensor
2. Micro-switch
5. Air quality sensor
Connector potting
Hotmelts are used for sealing the plug and also for cable strain relief.
Grommet injection molded in place
The molding process can be used to mold grommets in place. This eliminates the time-consuming process of slipping the grommet on, which can cause repetitive strain injury. The molding can also include strain relief, which also enhances its esthetics.
Electronic component encapsulation
It is the low pressure applied during the molding process that prevents damage to the sensitive electronic components and elements. The molding protects the electronics from external influences (moisture, mechanical stressing, etc.) and is capable of serving as a housing.
Three Main Application Groups of Low Pressure Molding Products
6. Temperature sensor
What is Low Pressure Molding?
Low Pressure Molding can be applied to the mobile phone battery, antenna, strobe flash, and other delicate components that require water-tightness, protection or encapsulation.
Low Pressure Molding Applications
Automotive Electronics
Mobile Phone Applications
PCB Overmolding
Grommets / Sockets
Molded connectors / Sensors with water-tightness & strain relief
7. Other kinds of sensors 8. Antenna coil
9. GND terminal
The molding system consists of the molding product, the mold set, the machine, and the melting unit. The melting unit for the hotmelt is usually used for injection of the hotmelt adhesive into the mold set at lower pressure compared to conventional injection molding machines. The mold set, which is usually made from aluminum, facilitates the process to trial stage as it is lower in cost compared to conventional ones.
Aluminum can be used as the material for making the mold set for Low Pressure Molding due to
• Lower injection pressure of the process • Better thermal conductivity of aluminum • No abrasive ingredients, e.g. fillers, glass fibers,
contained in hotmelt
Steel can also be used as the material for the mold set. If the component to be over-molded has steel or hard glass filled components, it is recommended to have steel inserts in this area of the cavity.
There are many types of molding machines available: • For small-scale production with manually opened
mold set.
• For production that needs higher productivity and output, with a sliding stage or rotary table for the mold set. Further details about molding machines are available from our machine partners in each country.
Henkel supports customers throughout project development, from initial sample-making with a trial mold set to consultancy on designing complete packages for mass production based on long experience with this low pressure molding technology.
Supply System Supply Molding Product
Molding Machines Mold Sets Hotmelt Adhesives
Technical Support
Melting Unit Supplier Customer
Molding Machine & Mold Set
Select right hotmelt
• Check requirements • Spot test, if required • Develop new
product
• Trial with mold set • Produce molded
samples for eval uation
• Environmental resistance • Chemical resistance • etc.
• Check requirements • Decide right
specifi-cation
• Supply hotmelt and machines • Start production
Prototyping Evaluation bycustomer for productionPrepare completionProject
Mold Set
Molding Machines
System Solution
Technomelt Polyamid Hotmelt
Product Test Method PA 653PA 658 BLACK PA 6208 PA 6208 BLACK PA 633 PA 638 BLACK PA 646
BLACK PA 648 BLACK PA 676 BLACK Properties
Colour - AmberBlack AmberBlack AmberBlack Black Black Black
Service Temp
Range (°C) - -40 to +100 -40 to +100 -40 to +130 -40 to +130 -40 to +130 -50 to +140 Softening Point (°C) ASTM E28 +160 +155 +175 +175 +175 +190
Viscosity at +210 °C
(mPa.s) ASTM D3236 4,500 3,000 3,500 7,000 7,300 7,500 Shore Hardness ISO 868 / 15s A77 A82 A90 A92 A93 A89
Creep Resistance (°C) Henkel Method MH11 +125 +130 +155 +155 +155 +165
Cold Flexibility (°C) ASTM D3111 -50 -40 -30 -35 -30 -55
Special Properties hydrolyse good resistance
RTI-Value for 6208 S: 95 °C,
UL-V0 UL-V0 UL-V0 UV-stablelized
Very good cold flexibility, very good temp resistance
Adhesion Properties Substrate
PA6.6 good good moderate moderate moderate moderate
PVC good good good excellent moderate moderate
ABS good good moderate moderate moderate moderate
Macromelt products are thermoplastic hotmelt adhesives based on natural fatty acids. They show good adhesion to plastics like PA 6.6, ABS and PVC, low temperature flexibility, a wide service temperature range, and superior molding properties.
Technical Information
Product Range for Low Pressure Molding
A variety of adhesive values – spot tests, peel strength, shear strength – are available on request or can be supplied after testing by our technical customer service team. Old names – Macromelt OM XXX – New Names Technomelt PA XXX
Old names: Macromelt Q – new names Technomelt AS * Development Product – properties could change The data above is based on our knowledge and experience. Due to different materials and conditions of application which are beyond our knowledge and control we strongly recommend carrying
out sufficient tests and consulting of our technical customer service. Except for willful acts any liability based on such recommendations or any oral advice is hereby expressly excluded.
Technomelt Hotmelt
Polyolefin Transparent
Product Test Method AS 5375 AS 5361* AS 4226*
Properties
Colour - white – light-beige white – light-beige transparent, colourless, clear
Service Temp Range (°C) - -30 to +85 -30 to +100 -40 to +85
Softening Point (°C) ASTM E28 +141 +155 +165
Viscosity at +210 °C (mPa.s) ASTM D3236 2,400 4,000 45,000
Shore Hardness ISO 868 / 15s A50 A68 D45
Creep Resistance (°C) Henkel Method MH11 +90 +130 +110
Special Properties Broad adhesion range Broad adhesion range, UL-V2
Transmission rate at 2 mm thickness:
Wavelength: Transmission rate:
450 nm 89,0 % 600 nm 90.5 % 800 nm 91,0 % 850 nm 91,5 % Adhesion Properties Substrate
PA6.6 good good moderate
PE good good
-PP excellent excellent
-ABS good good
-PVC moderate moderate good
PC moderate moderate good
Electrical Properties:
Volume Resistivity DIN IEC 60093 ~ 1012 Ω cm
Dielectric Strength DIN IEC 60243-1 ~ 20 kV / mm
® designates a trademark of Henkel AG & Co. KGaA or its affiliates, registered in Germany and elsewhere © Henkel AG & Co. KGaA, 2013
The data contained herein are intended as reference only. Please contact Henkel Technical Support Group for assistance and recommendation on specifications for these products.
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