ALUMINUM FILLED, HEAT SINK BONDING RESIN
CC3-450 is a medium viscosity, aluminum filled, bonding resin that has gained wide-spread acceptance as the primary bonding resin used in the assembly of heat sink components and the attachment of heat sinks to sources of heat or cold. This resin system is the most widely used bonding agent in the heat sink industry with a history of many varied applications over the last thirty years. There is real industry acceptance for this product at all of the major heat sink suppliers for their bonded heat sink requirements.
In the typical bonded fin heat sink the contribution of the bonded fin joint to the overall thermal resistance of the full heat sink is from 1 to 3%. The primary contribution to the thermal resistance of bonded heat sinks is the convective contribution between the air and the finned surface. The second most significant factor is the base spreading conductive resistance and the fin conductive resistance. Good joint design and clean, rough surfaces produce superior joints that generally exceed the mechanical requirements of the application while remaining an insignificant contributor to the overall thermal resistance of the bonded fin heat sink.
Fin-to Base: High thermal conductivity at the joint. The slot depth should be three times the fin thickness with a top chamfer of 20/25% of the slot depth. The slot width should be fin thickness plus 0.005/0.010". For maximum bond strength, vapor blast the slot and the fin edge followed by a proper degreasing process. Fins should be 1100H14 aluminum alloy and bases 6063T5 for maximum conductivity. This design, properly cured, will produce a bond strength that exceeds the shear strength of the fin in a typical tensile test.
Folded Fin High thermal conductivity for all minimum bond line joints. This is accomplished by setting
Set-To-Base: weights on the fin sets or clamping the crested ends. Fin sets are best ordered with the flat crested ends. This insures the maximum contact area with the base for optimum heat transfer. The fins sets should fit into a recess (.025/.035" deep) to secure their position during cure.
Bent Wire Complex shapes and very high omni-directional performance heat sinks can be assembled from
Pin Fin pin fin segments bonded to the base with this high thermal conductivity filled epoxy system. The
Set to Base: same rules of cleanliness, surface preparation and clamping are also required in this application.
Cold Plate The thermal joint between a cold plate and the extruded aluminum base is the single major
Tube-To- source of overall thermal resistance of this style of design. Careful attention to tube design and
Extruded crimping details to minimize the glue line can make a large difference in the thermal
Base: performance of this economical cold plate design.
High The glue line joint is the most important contributor in cold plate design. Therefore, it is essential
Performance to minimize the glue line, which is accomplished by pressing the tubes into the mechanical
Cold Plate aluminum plates. There are two basic design types, tubes-up to face the heat load for the very
Tube to Base: best performance and tubes-down to spread the cooling over the entire heat sink surface. Optimum thermal conductivity is an absolute necessity for this application.
* The thermal conductivity of CC3-450 cured with H-7 Hardener is 4.54 W/m’C. However, the thermal conductivity of an assembled heat sink can approach the thermal conductivity of the basic metal depending upon design and construction.
CHOICE OF HARDENERS:
H-1 Hardener: Rigid, good dimensional stability, fast cure.
H-7 Hardener: Resilient, excellent mechanical and thermal shock, low viscosity,
good air release, fast cure.
Ancamine Z: Resilient, excellent mechanical and thermal shock, plus high heat
distortion, long pot life.
H-10LV Hardener: Variable hardness, excellent impact properties, long pot life
ROOM TEMPERATURE CURE:
H-1 Hardener: Cures overnight at room temperature or 30 min. at 65’ C.
Do not heat cure if the mass exceeds 2 pounds.
H-7 Hardener: Cures overnight at room temperature or 45 min. at 65’ C.
H-10LV Hardener: Cures overnight at room temperature or 3 hrs at 65’ C.
Ancamine Z: Cures overnight at 65’ C or 2 hrs at 125’ C. For best physical and electrical properties, a slow cure for 16 hours at 65’ C followed by a post cure for
3 hours at 125’ C is recommended.
Mix CC3-450 thoroughly in it’s shipping container to insure a uniform consistency. Weigh out the desired amount of resin in a clean container. Add the hardener accurately by weight in the proper proportion as specified above. (ie. 4.9 grams of H-1 Hardener and 100 grams of CC3-450 for a total mix of 104.9 grams) Mix thoroughly. Use in a well ventilated area and avoid contact with eyes and skin.