In the past, bonded fin heat sink was created due to fin ratio limitation for extrusion process. However, with technology advancement, we are able to produce extruded heat sink with high fin ratio of 30:1 (fin height to fin spacing) hence reduced usage of bonded fin heat sink. Today, we will only proposed bonded fin to our clients if heat sink size required is beyond our extrusion capability (W450 x H60 mm).
Main advantage of bonded fin heat sink is there is not limitation to the fin height and but we need to cater sufficient space for the grove to house the fins. Main disadvantage is the process of fins to base assembly with thermal epoxy might lead to inconsistency for heat transfer as the contact plays a vital role in effective heat transfer and you will have many variable should issue arise in your applications.
Our researched showed doubling your fin height doesn’t double your heat transfer rate, especially when your fin height is beyond 40mm. Your will see a high temperature gradient between heat sink base and tip of your fin.
We recommend skived fin heat sink to replace bonded fin as this will remove the production risk to control high fin to base contact and much more cost effective for our clients in long run.