Heat sinks are the first thing people notice on most LED PAR lamps. Initially, production from the Far East had very little heat sinking, which meant all the heat from the diodes remained trapped inside the light bulb. This heat often did damage both to the drivers and the heat sink, which remain susceptible to heat. The first LED lamps were pretty low power and false claims. Retail stores offered 3 packs at low prices, but probably only all three combined equaled one 40 watt halogen in light output. The poor heat sinking was an attempt to keep production costs low, but ultimately left many customers with a bad taste in their mouth. The lights weren’t bright and didn’t last as claimed. It seemed like a recycled CFL curly cube light that didn’t meet expectations.
The heat sink has a single goal, extract heat from the junction point of the diodes. Using conductive adhesive further optimized performance. Some began to dabble in liquid, copper, and thermoplastics, but aluminum remains the most common and cost effective solution. The overall shape of PAR lamps provides natural room for a heat sink. While initially a little bulky, aluminum ultimately caught on and became mainstream with LED lighting.