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I am wondering if i ordered some aluminum pcbs that contain D2pak transistors and i want to solder a couple of them for testing is it possible using basic equipment or does it need an Reflow soldering Oven .

Equipment i have access to :

1. tempreture controlled soldering Station .

2. WHP 1000 prehating hot plate.

3. Solder leaded and lead free , with/without rosin core , flux , etc....

Questions:

  • Is soldering these PCB any different from ordinary (FR-4) PCBs ?
  • does the factory or assembly line use different procedure ( heat profile and temperatures ) ?
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    \$\begingroup\$ You dont need a reflow oven, but I dont think 'basic' equipment is gonna cut it either. What soldering station and tip do you have? \$\endgroup\$
    – Wesley Lee
    Oct 23, 2016 at 19:39
  • \$\begingroup\$ @WesleyLee , i donot remember the name of the soldering station ( it is in the university lab nearby ) , but i think it is American ( it can reach 450 degree Celcuis) and all the tips exist ( specifically the big wide one ) \$\endgroup\$
    – ElectronS
    Oct 24, 2016 at 7:58
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    \$\begingroup\$ Hmm, I ask because I've been able to relatively easily solder heavy packages on ALU PCBs with an ERSA i-con 1 and very thick tip, without pre-heating or reflow. I cant speak for other stations but its definitely doable. \$\endgroup\$
    – Wesley Lee
    Oct 24, 2016 at 8:54
  • \$\begingroup\$ @WesleyLee , how much was the temperature settings ? \$\endgroup\$
    – ElectronS
    Oct 24, 2016 at 14:36
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    \$\begingroup\$ I dont remember, but I rarely use more than 300ºC except if I really want to burn things (like remove coatings from enameled wire). \$\endgroup\$
    – Wesley Lee
    Oct 24, 2016 at 14:37

1 Answer 1

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The solder reflow heat mass is significantly greater. You may need some forced air for ramp-down and a thermocouple probe to "profile" a bare board to match the LED recommended ramp rates , peak liquidus dwell and cooling rates to prevent solder stress failures.

Assembly line process engineers do this with a thermally protected data collection module and slow down the conveyor speeds to absorb the higher heat mass and accelerate the temperature rise in the number of zones in their control, yet too slow is a reliability issue for LEDs and the overall time to ramp up and down must not be exceeded for this reason.

So do a dry run and get a digital timer.

If you do not have thermocouples , estimate the liquidus point when a tiny blob of solder melts and the duration it is melted. and your overall profile time from the datasheet. Avoid too slow and too fast as the wire bond may shear inside.

The main difference with FR4 is the massive heat sink effects of Alum. compared to FR4 requires a lot of power based on the 'C/W rating of the board. You can do the math for Watts and T rise.

Ideal process time 5 minutes, max 6 minutes

details

http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/XLamp%20Application%20Notes/XLampXBD_SH.pdf

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  • \$\begingroup\$ thanks , but i didnot mention anything about LEDs , the board is power supply with D2pak transistors ( 12 of them ) the size is 10cm x10 cm . I didnot catch in your answer if it is possible to solder the board using the equipment i have ?! and it look like a hassle to work with such boards \$\endgroup\$
    – ElectronS
    Oct 24, 2016 at 7:54

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