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Capt. Cave Man Capt. Cave Man is offline
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Default Light bulb - Light-bulb.jpg (0/1)

On Thu, 25 Jun 2009 22:28:13 -0400, legg wrote:

On Thu, 25 Jun 2009 11:40:39 +0100, Raveninghorde
raveninghorde@invalid wrote:


Here is my new light bulb, minus reflector.

168 112 lumen leds in 14 strings.

The main problem is the aluminium of the pcb is not earthed causing
problems with current control presumably due to much higher stray
capacitance than we had on FR4. Just got to find a neat way of
earthing it.


Why the 'S' pattern, and why copper-free areas (if thermals are an
issue)?

Must be a really hefty pre-heat for reflow. Are the leds compatible to
this fab step, at all?

RL



SMT LEDs are SMT capable (duh). That means a 500 F heat bath (or more
for RoHS). It can handle it, and likely more than one cycle.

The preheat remains the same. It is not like he used an 0.090" thick
PCB.