Soldering a 3030 led

[6PTsocket]

I have to replace an led. The small pc board that it sits on appears to be some sort of heatsink material, as well. The problem is the solder pads are completely under the led. Do I use solder paste? Hot air from the back? Hot air from the front? The areas next to the led have a lot of perf holes. Can I stick the led in place with paste and apply an iron with a blob of solder next to the led pads and hope it conducts enough heat? I have never dealt with hidden pads before. The only hot air gun I own is a big unrestricted blower, not a soldering device. Hooefully I can use an iron. This is just a one shot problem. It is the light fixture from my freezer. Kitchenaid wants $70 for the fixture(led, pc board, lens cover and connector). Mouser wants under a buck for the led. The old led worked on the bench but cut out as soon as it got cold. It was probably a bad solder joint but it is off the board and destroyed and too late to worry about that now.

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[Totalsolutions]

Try the heat from a 50 watt halogen lamp. Purch the pcb on top of lamp and the heat could melt the solder. Other wattage lamps are available as well as 12 volt types. YMMV 


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[thinkfat]

If you don't have a hot-air gun or something, try putting the PCB in an old pan on some sand and put it on the stove. You don't need paste, just tin the pads on the PCB and put the LED on. But you'd need some extra flux or it'll probably not flow nicely.

Or use an iron? You know, the kind used to flatten clothes. Put it downside up on some fixture, put the PCB on top and heat it up. No idea if that would work, though, normally those irons don't get hot enough before tripping some safety device.

[Totalsolutions]

Good tips there. Another, the diode / led is directional ie only goes one way round.  There will be an identifying mark. 

[6PTsocket]

Good tips there. Another, the diode / led is directional ie only goes one way round.  There will be an identifying mark.

These are polarity indicated by one pad on the led being larger than the other.

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[6PTsocket]

Thanks everyone for the good suggestions. What I have concluded from them is that the heat should be aoplied from the back. I have an IR thermometer so I can keep tabs on the heat source. The bulb or sand  sound like good ideas.

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