By Dr. Aysegul Kascatan Nebioglu and Chris Morrissey
Elements on printed circuit boards or digital modules in electrical autos are sometimes required to be lined with polymeric encapsulants to guard them in opposition to environmental circumstances comparable to moisture, chemical substances, and fast and excessive temperature adjustments, whereas offering mechanical assist and electrical insulation.
It’s essential for encapsulants to induce minimal stress on chips, wires, and different elements for the reliability of the digital assemblies. Liquid encapsulants are usually based mostly on epoxies, silicones, or light-curable supplies. Epoxy formulations are inflexible and make the most of excessive a great deal of mineral fillers to decrease bulk coefficient of thermal growth (CTE) to match CTE of the substrates. Nevertheless, because the natural epoxy has the next CTE than the mineral fillers, it may possibly transfer filler particles in opposition to the wires and create an abrasive impact on the wires, lowering the reliability of the elements. Silicones and light-curable encapsulants are usually extra versatile and have low modulus than epoxies, due to this fact creating much less stress on the parts, wire bonds, and solder connections, together with these present in circuit boards used within the operation of battery administration techniques (BMS).
A brand new dual-curable (gentle and moisture), 100% solids encapsulant that reveals a superb steadiness of properties is now out there. Whereas the important thing benefit of light-curable encapsulants is the power to make use of a non-solvated, “inexperienced” (100% solids) materials, secondary moisture remedy permits curing of the fabric in shadow areas not out there to UV gentle. This one-component materials may also be shipped and saved at ambient circumstances, so it doesn’t require chilly delivery and storage. Mild-curable encapsulants may present important advantages over typical applied sciences, together with very quick, tack-free curing, decrease working prices pushed by decrease labor wants, area financial savings, decrease vitality demand, and better throughput. This materials doesn’t require heating to remedy, which makes it a really perfect alternative for heat-sensitive substrates and really well-suited for wire bonding functions in EV BMS.
A white paper options the outcomes of a examine carried out on liquid glop-top encapsulants which might be positioned over PCB parts and wire bonds as a protecting layer. The efficiency of this new dual-curable encapsulant in opposition to different light-curable supplies and varieties of encapsulants in reliability exams, comparable to warmth and humidity resistance (85oC / 85% RH), thermal shock resistance (-55oC to +125oC) and corrosion resistance in opposition to salt spray and chemical substances, is printed intimately.
Go to Dymax dual-cure EV encapsulant to obtain your copy.