how many times have you read a press release or an announcement for this great solution to all of our thermal management problems and have tried to get your hands on it? and, how many times have you heard that you cannot get a sample (even when you are willing to pay good dollars for it) or even some reasonable performance data? some start up firms even ask you to sign an nda (non disclosure agreement) just to provide you with some performance data.
this is obviously not helpful if you think that you could really use that great heat sink, cold plate, interface material. the desire by the some vendors to put a stake in the ground by pre-announcing a product even before a prototype is built is understanable. as thermal engineers, however, we should insist on the availability of useful performance data if they want our business.
for example, these days you hear many claims about a super performing cold plate (a water block) but when you visit the vendor's web site, all you see are a few images and many unsubstantiated claims. when it comes to a cold plate you usually know what kind of resistance you need for your device. unless the active area of a given cold plate is exactly the same size as the heat dissipation area, you need to start with calculating your desired thermal resistivity. thermal resistivity is the ratio of the approach temperature difference to the heat flux. this measure of performance eliminates the effect of the surface area and allows you to pick the right cold plate. starting with the thermal resistivity, you should shop for a cold plate that has the lowest flow requirement and the lowest pressure drop. both of these requirements help you to reduce the size of your pump and reduce cost. in addition low flow rate results in lower velocities in the flow channels leading to less erosion problems. so, you need to require at least two graphs from your vendor. the first one is a graph of flow rate (per unit area) versus the thermal resistivity and the second one is the graph of pressure drop versus the thermal resistivity. unless you have similar graphs from all vendors, your job of comparing them would be very tough.
the same principle applies to other components such as interface materials. we must insist on some standard performance data and also require to know the testing procedure used by the vendor for obtaining the performance graphs.
if the thermal management community consistently insists on getting reliable performance data from all vendors, the vendors will begin to get the message and back their claims with scientifically sound performance data. when this happens, a lot of time and disappointment will be saved.