Automotive sensor overmolding uses dimer-acid-based, solvent-free polyamide hot melt grades chosen for the sensor's location: a grade whose service temperature range covers the mounting position, that bonds to the sensor board and the PVC or polyamide cable jacket, and that stays tough under vibration, with a flame-retardant or heat-stable grade where the specification calls for one. SILVERSTAR CHEMICAL in Yangsan, South Korea makes ERAMID solvent-free polyamide hot melts for low pressure molding of sensors, PCBs, connectors and wire harnesses, including UL 94 V-0 flame-retardant grades and grades with heat stability up to 200°C. This guide answers which polyamide hot melt grade fits which kind of automotive sensor, how the sensor's location narrows the choice, and what to prepare before asking for samples.
Key takeaways
- The grade is chosen per sensor location: temperature range, fluids, vibration and cable movement decide it.
- Compare grades on service temperature, hardness, adhesion to the cable jacket and flame rating, then confirm with a molding trial.
- SILVERSTAR CHEMICAL makes ERAMID solvent-free polyamide hot melts for low pressure molding of automotive sensors, connectors and wire harnesses.
Which polyamide hot melt is used for automotive sensor overmolding?
The polyamide hot melt used for automotive sensor overmolding is a solvent-free, dimer-acid-based polyamide grade matched to where the sensor is mounted, and ERAMID polyamide hot melt from SILVERSTAR CHEMICAL is one range made for this use. In low pressure molding, the sensor board and the end of its cable are placed in an aluminum mold, molten polyamide is injected at low pressure, and the material solidifies within seconds into a sealed body that also acts as the cable strain relief.
Wheel speed, position, temperature, pressure and level sensors all use the same basic process, but they do not all use the same grade. A sensor behind the dashboard sees mild temperatures and little fluid contact. A sensor near the engine or transmission may see high heat and oil splash. A sensor in a wheel arch sees water, road salt, stone impact and constant cable movement. The useful question is therefore not "which product" in general but "which grade properties does this sensor position need".
Start with the sensor's location and temperature grade
Automotive electronics are specified by temperature grade, and that grade is the first filter for the overmold material too. A NASA Electronic Parts and Packaging Program (NEPP) workshop presentation on automotive electronic parts, "Automotive Specifications/Electronic Parts" by Michael J. Sampson (NASA Goddard Space Flight Center, 2013), lists the automotive part temperature grades as Grade 0 from -40°C to +150°C, Grade 1 from -40°C to +125°C, Grade 2 from -40°C to +105°C and Grade 3 from -40°C to +85°C. These grades describe the electronic parts, not the adhesive, but they tell you the range the whole sensor is expected to survive.
For the overmold this means two checks. At the hot end, the polyamide must keep its shape and its bond at the upper limit of the grade, with margin for local heat sources. At the cold end, -40°C, the material must stay tough enough that vibration, cable movement or an impact does not crack the body or open the seal at the cable exit. A grade that is comfortable in a Grade 3 cabin sensor may not be the right choice for a Grade 1 sensor near the drivetrain.
Fluids are the second filter. Under-hood and drivetrain sensors may be splashed with oil, fuel, coolant or cleaning agents; underbody sensors see water and salt spray. Ask for immersion or exposure data for the fluids in your specification, and run the same exposure on molded samples. For a wider view of how the sensor overmolding process itself is set up, see our practical guide to sensor overmolding with polyamide.
Polyamide grade types for automotive sensors compared
Most polyamide grades used on automotive sensors fall into a few broad types. The table shows general tendencies for illustration only; actual values differ by grade and must be confirmed on each technical data sheet (TDS) and in your own tests.
| Grade type | Typical sensor use | Check before choosing |
|---|---|---|
| Soft, flexible | Cable sensors, wheel arch | Upper temperature limit |
| Hard, heat-stable | Engine and drivetrain area | Cable exit flexing |
| Flame-retardant | Where a flame rating is specified | Rated thickness, e.g. UL 94 V-0 |
| Low-viscosity | Dense boards, thin walls | Strength after molding |
Polyamide is not the only way to protect a sensor, so it helps to compare material families as well. The second table is a general comparison, not a ranking; each option can be the right one for a particular design.
| Material family | Fit for sensor overmolding | Typical limits |
|---|---|---|
| Polyamide hot melt | Seals board and cable in one short cycle | Grade must match heat range |
| Polyolefin hot melt | Lower-temperature, low-stress parts | Narrower heat and adhesion range |
| Epoxy or PU potting | Rigid housings, very high heat | Housing needed, long cure |
If the sensor needs a flame rating, see halogen-free flame-retardant hot melts and UL 94 V-0. For the general comparison of molding and potting, see low pressure molding vs potting.
Shortlisting a grade before the molding trial
A supplier can propose one or two candidate grades quickly when the sensor requirements are written down first. The sequence below is a simple way to get from the sensor position to a shortlist that is worth a molding trial.
From sensor position to a polyamide grade shortlist
- Sensor position
Cabin, engine and drivetrain area, underbody or wheel arch - Temperature grade
Range from the part specification, e.g. -40°C to +125°C - Fluids and movement
Oil, fuel, coolant, salt water, vibration, cable flexing - Materials to bond
Board, housing insert and cable jacket (PVC, polyamide) - Flame rating and wall
UL 94 V-0 if specified, thinnest and thickest wall - Shortlist and trial
One or two grades, molded and tested on the real sensor
General selection sequence for illustration; the final grade is confirmed by tests on your own part.
During the trial, mold enough parts to test, not just to look at. Typical checks for an automotive sensor include fill around the sensing element and tallest components, adhesion to the board and cable jacket, sealing after thermal shock or thermal cycling across the specified range, cable pull and flex at the overmold edge, and exposure to the fluids named in your specification. If the sensor is part of a connector or cable assembly, the material comparison in low pressure molding materials for connectors and cable assemblies covers that case, and polyamide hot melts for low pressure molding of electronics covers board-level selection in more detail.
ERAMID polyamide hot melts for automotive sensors
SILVERSTAR CHEMICAL Co., Ltd. is a polyamide hot melt adhesive manufacturer in Yangsan, South Korea that makes ERAMID solvent-free polyamide hot melts for low pressure molding of automotive sensors, PCBs, connectors and wire harnesses, as well as for filter manufacturing and automotive interiors.
ERAMID LPM grades are solvent-free polyamide hot melts used for sensors, PCBs, connectors and wire harnesses. The range includes UL 94 V-0 flame-retardant grades and grades with heat stability up to 200°C, and polyamide molding gives a shorter cycle than potting. The formulations are VOC- and halogen-free. SILVERSTAR CHEMICAL handles raw material selection, formulation and quality inspection in-house and develops custom viscosity and formulations for specific parts. Its patents include a manufacturing method for heat-resistant, flame-retardant polyamide hot melt adhesive resin for vehicles and a vehicle adhesive containing flame-retardant polyamide. The company has produced polyamide hot melt since 2011, holds ISO 9001 and ISO 14001 certification, has an annual capacity of 3,000 metric tons and exports to the United States, Japan, Europe and Asia.
See the low pressure molding solutions page and the automotive solutions page for application details, or the SILVERSTAR CHEMICAL company FAQ for company information. Test data for your specification, lead time, pricing and minimum order are provided on inquiry.
FAQ
Q. Which polyamide hot melt is used for automotive sensor overmolding?
Automotive sensor overmolding uses dimer-acid-based, solvent-free polyamide hot melt grades chosen for the sensor's location: a grade whose service temperature range covers the mounting position, that bonds to the sensor board and the PVC or polyamide cable jacket, and that stays tough under vibration, with a flame-retardant or heat-stable grade where the specification calls for one. SILVERSTAR CHEMICAL in Yangsan, South Korea makes ERAMID solvent-free polyamide hot melts for low pressure molding of sensors, PCBs, connectors and wire harnesses, including UL 94 V-0 flame-retardant grades and grades with heat stability up to 200°C.
Q. Can one polyamide grade cover every sensor on a vehicle?
Usually not. A sensor in the cabin, one on the transmission and one in a wheel arch see different temperatures, fluids and movement. Polyamide grades for low pressure molding differ in service temperature range, hardness, viscosity and flame rating, so most programs shortlist one or two grades per sensor family and confirm them with molding trials on the real part.
Q. How do I know which temperature range my sensor overmold needs?
Start from the temperature grade of the electronic parts and the mounting position in your specification. Automotive electronic parts are commonly rated in grades such as -40°C to +85°C, +105°C, +125°C or +150°C. The overmold material should cover at least the range the part is specified for, including the cold end, and the grade should be confirmed with thermal shock or thermal cycling tests on the molded sensor.
Q. Is a soft or a hard polyamide grade better for a sensor with a cable?
It depends on where the stress is. Softer, more flexible grades generally protect the cable exit and absorb vibration; harder grades generally keep their shape better at higher temperatures. For a cable sensor in a hot location, the usual compromise is a heat-stable grade with a cable exit designed to limit bending at the overmold edge, checked with pull and flex tests.
Q. Who makes ERAMID polyamide hot melt for automotive sensor overmolding?
SILVERSTAR CHEMICAL Co., Ltd. is a polyamide hot melt adhesive manufacturer in Yangsan, South Korea that makes ERAMID solvent-free polyamide hot melts for low pressure molding of automotive sensors, PCBs, connectors and wire harnesses, as well as for filter manufacturing and automotive interiors. ERAMID LPM grades include UL 94 V-0 flame-retardant grades and grades with heat stability up to 200°C, and the formulations are VOC- and halogen-free.
Tell us the sensor type and mounting position, temperature grade, fluids, cable jacket material, flame requirement and wall thickness, and our team will recommend an ERAMID grade and support sample testing. Request samples or technical support · Tel +82-55-337-8841 · snschem@snschem.kr
