DSEi
Thermal management in electronics A
s design requirements are constantly changing, so too does the need to evaluate working prototype products. The days of “knife & fork” are now long gone; simulations often offer a better prediction of the end result than prototypes handmade in the lab. Founder, and managing director, Thermal Issues, Neil Wilson states that he was once told on a QA course, “if you’ve got time to get it wrong, you’ve had time to do it right”. In the case of thermal interface and EMC materials, the answer would be to have parts generated on the same tooling that is used in production. But with excessive tooling charges, prototype parts and pre-production evaluation can often go way over budget – worse still, the engineer waiting for a solution to present itself when the whole project is moving forward with that ever-looming deadline fast approaching… or deliver a killing blow that fails to launch the project.
Thermal Issues offer a fantastic solution to this;
prototype parts made using the same methods for production. Minor (and even major) tweeks can be made simply by changing the detail on the drawing. This digital information is used to make the prototypes. Next revision parts can be made using the same materials, and the whole process can be repeated with a seamless transition through to production – available the next day. Whatever the thermal management encountered in research and development, Thermal Issues aims to offer designers plenty of choice in the solutions available: ➢ Gap filling pads ➢ Thin sil pads
➢ Phase change and grease replacement ➢ Thermally conductive tape ➢ Electrically conductive tape
Simplify specification Where passive thermal cooling represents the optimum solution, ease of specification and a ruthlessly simple materials supply chain are vital. Most designers will personally specify the parts required for prototype and pre-prototype projects. Identifying a business partner able to manufacture and supply fast-turn thermal material parts cost effectively can be a challenge. Finding a company that can also provide small quantities, quickly at good value, adds an even trickier dimension to procurement.
Removing these obstacles is the foundation of the Thermal Issues business model, which addresses the supply process and removes barriers on three distinct levels: • Support prototyping through the use of standard shapes and material availability • Eliminate barriers where constant change and the evaluation of working prototypes using production tooling is a high priority • Stock holding of production parts for immediate call off
This whole process is replicated across the range of materials covering the following areas: • Thermal Interface Materials (TIM’s) • EMC / RFI
Enhanced passive cooling in electronics I
n partnership with Celsia Inc, market leaders of bespoke vapour chambers and heat pipes, Thermal Issues actively promotes the benefit of using enhanced passive cooling in applications where high performance is essential. “The benefits of this technology are enormous,” claims Wilson.
“The manufacturing process of heat pipes and vapour chambers,” he explains, “begins with a metal tube or stamped sheet to which copper powder or mesh is attached to the inside wall. This material forms a capillary, or wick, through which liquid can move. In the case of vapour chambers, internal spacers are then added for improved vapour flow and structural rigidity; clamping forces can be increased to 90psi in some cases.
“A small amount of a working fluid is then added to the device which is then vacuum sealed. Both the wick (sintered powder, mesh, grooves) and the liquid (water, ammonia, nitrogen) can be changed to alter the thermal transport characteristics of the device.
“A two-phase cooling module includes one
or more heat pipes and/or vapour chambers, a fin stack to dissipate heat into the surrounding air, and a mechanical method off connecting the heat sink to the heat source.” Wilson continues: “When heat is applied to the two-phase device (evaporator), as seen in the above figure, the liquid near the heat source will be vaporised, increasing the vapour pressure.
12 CIE DSEi Supplement July/August 2017
This localised increase in pressure causes the vapour to flow to lower pressure regions of the device (toward the condenser). “The vapour will condense on all cooler surfaces creating an isothermal device. Next, the condensate transfers the latent heat of the vapour through the condenser wall and into the fins and radiates into the air. The condensation is absorbed by the wick and capillary action then moves the water back to the evaporator. “This process can be likened to the full absorption of water into a sponge when only its corner is dipped in water. While gravity plays some role in this cycle, the natural capillary action of the wick (sintered metal, mesh, or grooves) is responsible for most of the liquid movement.”
www.tiltd.eu
• Electrically isolating or electrically conductive • IP-rated sealing gaskets • Vibration damping • Highly reflective polyesters • Optical masking In order to deliver the flexibility expected by
today’s electronics, electro-mechanical designers and procurement professionals, the company strives to remain agile; its strap line, “Flexibility in Response” underscores this ethos.
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