FEATURE EMC & THERMAL MANAGEMENT
Engineered tapes for insulation, shielding and cooling in electric vehicle batteries
Specialist adhesive tapes from Techsilare meeting the requirements of the electric vehicle industry T
here is no denying that electrical and hybrid vehicles are growing in
popularity, being cheap to run, quiet and smooth to drive. Automotive manufacturers are keen to improve the power to weight ratio by using lighter materials such as composites and weight saving bonding, joining and fixing solutions. Double sided tape and single sided
self-adhesive tapes offer an attractive alternative to traditional mechanical fastening methods and have a key role to play in the manufacture of electric cars, vans and public vehicles. From structural bonding tapes, and anti-noise tapes to prevent rattles and squeaks through to closed cell foam tapes to provide waterproof seals and thermal management tapes for electronics; there are many options.
ADHESIVE TAPES FOR ELECTRIC VEHICLE BATTERIES Techsil has just introduced a specialist adhesive tapes range designed specifically for Lithium ion (Li) automotive battery applications that meets the stringent requirements of the Electric Vehicle industry. This range of electrical tapes offers properties such as EMI shielding, Thermal & Electrical Insulation, Flame Retarding and Heat Sink Optimisation. The range is manufactured by ITW Stokvis Tapes and includes: Stok-Therm – a range of thermally conductive interface tapes that can give electrical insulation or act as a thermal cooling bridge to the cooling unit
ITW Formex – a range of tapes that offer mechanical protection, electrical insulation and EMI shielding to battery covers and busbars and can be used as a battery cell separator
Stok-Seal – a range of PU and silicone adhesive foam pads that are used for cushioning, thermal insulation, sealing of housings and connectors against water ingress and as compression pads giving compensation for cell expansion
THERMAL INTERFACE TAPES Developments in electric vehicle battery design involve producing ever-higher
32 OCTOBER 2018 | ELECTRONICS
any thickness between 0.25 and 3mm. Formex is a range of hard wearing customisable tapes that can be formed into 3-dimensional shapes and used to make a number of different battery components including: Battery covers offering mechanical protection, electrical insulation and EMI shielding
Brackets offering electrical insulation and contact corrosion protection
energies and capacities and heat dissipation is a key consideration. Lithium-ion battery cells can suffer from a high cell thermal resistance. Under an aggressive duty cycle, this resistance can result in the formation of large in-cell temperature gradients and high hot spot temperatures, which are known to accelerate ageing and further reduce performance of the battery. Thermal resistance can be reduced by:
1. Improving the wetting (contact area) of the TIM, the softness and choice of polymer and thickness has influence on this.
2. By the right choice of fillers, a mix of smaller and bigger conductive particles will increase the contact points Vehicle batteries can have many differences - in air gaps, surface roughness, flatness and size. To enable the best thermal path the Stok-Therm range has tapes that vary in: Thickness, Softness (compression), Thermal conductivity and Adhesion performance They fall into 2 categories a hard TC range and a soft TPS range that come in three different tTechsil hermal conductivities of 1.5, 2 and 3 W/mK and
Figure 1: Electric vehicle
Spacers and cell covers offering electrical insulation between cells; for top and bottom insulation and busbar insulation This range has a flammability rating of UL 94 VTM-) to V-0 and can operate in temperatures from -40°C to 125°C and to a short term temperature of 150°C.
Figure 2:
Polyurethane foam adhesive tapes and silicone foam gaskets are used for water sealing between the battery cover and housing and also to seal connectors against water ingress
STOK-SEAL BATTERY SEALS, GASKETS AND COMPRESSION PADS Stok-Seal is a range of polyurethane foam adhesive tapes and silicone foam gaskets that are used for water sealing between the battery cover and its housing and also to seal connectors against water ingress, compression pads for cell expansion in the battery unit, and cushion pads underneath the battery unit for dampening and vibration control. The silicone foam tapes have the following properties: Flammability rating UL 94V-0, CSA 0.6 V-0
Temperature range -40 to 150 Short term temperature 200 Hardness from soft to hard Shore A 40 to 70 In partnership with ITW Stokvis, Techsil can also offer Laminating and Die-Cut services. Laminating - to make proprietary products self-adhesive or laminating different tapes onto each other creating unique easy to apply materials
Die-Cut Services – to engineer new shapes and new combinations of materials to reduce application time and find a creative fixing solution
Techsil
www.techsil.co.uk e:
technical@techsil.co.uk / ELECTRONICS
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