Large Area/Array Coolers

Micro-Impingement Coolers

MC2 offers a line of high performance water-cooled copper heatsinks for high power electronics, laser diode arrays, and general high heat flux cooling needs. These heatsinks incorporate advanced micro-impingement cooling circuits to dramatically improve thermal performance. These coolers offer:

  • Extremely Low Thermal Resistance: Thermal resistances as low as 18 K-cm2/kW have been meaured using water as a coolant.
  • Low Pumping Power: Pumping power is typically 0.1 - 3% of the dissipated power.
  • Scalable to Large Areas: The dimensions of a cooler can be expanded without affecting the thermal performance of the cooler, since the internal cooling circuits are repeated throughout the cooling zone.
  • Rugged Construction: The coolers are nominally fabricated using Glidcop, a dispersion-strengthened copper alloy, though a variety of materials can be used. The coolers are compact, tough, and easy to work with in a military, laboratory or industrial environment.
  • Conventional Attachment to Flow Systems: Soldering and brazing to the coolers is not a problem - they can survive extended exposure at temperatures up to 1500°F. Coolers are routinely threaded for bolted attachment.
  • Ease of Customization: Various materials, coolants, passage designs, and internal & external geometries can be employed.

Micro-impingement coolers are currently available in a variety of external packages, with cooled areas ranging from 0.31 cm2 to 400 cm2. The internal cooling passage widths can vary from 25 microns up to 250 microns, though widths of 25 and 50 microns are considered "standard." These are designated as "A" and "B" cooling designs, respectively. Thermal performance values for these designs are provided in the figure below. To first order the thermal performance values will apply to any cooler in this class.

The flow performance, by contrast, will depend on the specific external geometry, as well as the internal cooling circuit design. The allowable thickness, port size & location, and flow distribution uniformity requirement typically drive the pressure drop of the cooler. The flow performance in the chart below is for the SA-2 package with 1 cm x 2 cm cooled area.

A Note on Thermal Resistance. The areal thermal resistance used in our specifications is defined as the temperature difference between the average surface temperature and the coolant inlet temperature, divided by a uniform heat flux. The geometries used in performance measurements ensure that there is no thermal spreading, so the heat transfer geometry is truly 1D.
A Note on Flow Rates. MC2 uses an areal volumetric flow rate in its performance charts. This flow rate is the total flow divided by the cooled area. Using the areal definition allows you to quickly compare performances and flow rate requirements of coolers with large size differences. For example, if you desired a thermal resistance that could be achieved with an areal flow rate of 1 LPM/cm2, you can quickly determine that the total flow for a 2 cm2 cooled area would be 2 LPM, and for a 30 cm2 area would be 30 LPM.

Common Large Area/Array Cooler Packages

Typical packages are listed in the table below. The SA-2A is normally the only cooler kept in stock. All other packages require a 10-week lead time.

Package Mounting Area


2 cm x 1 cm


7 cm x 1 cm


14 cm x 1 cm

Notes on Usage


Component Mounting. Typical installations involve soldering or brazing a component or component carrier to the surface of the cooler. The coolers can be processed at temperatures up to 1500 °F, and thus are compatible with conventional soldering and brazing processes. Due to the grain structure of the copper alloy, it is advisable to plate the interface with copper or nickel prior to brazing with silver-based brazes to prevent migration of the silver into the cooler (depleting the silver at the braze joint). If excessive mechanical loads are applied to the cooled surface, it is possible to deform the surface, crushing the internal channels. This may be avoided by either: 1) limiting loading on the surface to less than 1000 psi, and/or 2) requesting a custom design with a more robust surface.

Installation in Flow Systems. MC2's micro-impingement cooler packages require special mating manifolds. These manifolds are designed to allow coolers to be closely arrayed without interference from the manifolds or the coolant lines. The coolers are bolted to the manifolds, with o-rings sealing the inlet and outlet ports. Manifolds and manifold arrays can be custom-designed for the users' applications, or may be fabricated by the users themselves.

A common question during installation is: Does it matter which way the coolant flows through the cooler? The answer is yes, it does matter - flowing the wrong way will yield higher pressure drops and higher thermal resistance values. Even with the flow reversed, however, the coolers are still likely to outperform any competing products.

Filtering and Cleaning. Upstream filtering should be provided for the coolers as follows: Type A < 10 µm, Type B < 20 µm, and Type C < 50 µm. Flow lines between the filter and the cooler should be cleaned prior to use of the cooler. Sealing aids such as teflon tape should be avoided as much as possible between the filter and the cooler. The coolers have integral internal filters which are slightly larger than the designated upstream filtering values. Periodic backflushing may clear these filters and improve flow performance.

Long Term Performance. To date only limited long-term performance data is available on MC2's micro-impingement coolers. Continuous testing for 1200 hours has resulted in only a modest increase in the flow rate of the coolers. The coolers should be resistant to clogging, given proper filtering and periodic backflushing. Copper and its alloys are also known to be inherently resistant to biofouling, although a UV filter is suggested for long-running systems. If in an application corrosion is determined to be a problem, a commercial additive such as OptiShield (Opti Temp, Inc., Traverse City, MI) may be introduced into the cooling water.