soldering 16mm copper LED pcbs to a piece of flat copper

[amlu]

Hi
got some new leds to mount in a floodlight enclosure, they are mounted on their little pcb bases, rather than mess around with drilling and screws i thought it may be a good idea to get a chunk of flat copper strip, solder the pcbs to it, then mount the strip on aluminium heatsink with thermal paste applied.
 
https://www.aliexpress.com/item/2pcs-5W-5050-Ultra-Violet-UV-Purple-XML-365nm-380nm-390nm-420nm-High-Power-LED-Emitter/32676633451.html?spm=a2g0s.9042311.0.0.31584c4d2rbNwJ
https://www.ebay.co.uk/itm/3-MM-thick-COPPER-SHEET-PLATE-guillotine-cut-many-sizes/273239735520?hash=item3f9e5b7ce0:rk:5:pf:0&var

something along the lines of heating the copper from the bottom with small blowtorch, spreading some solder on it, placing the leds on, letting it flow for a bit then taking off the heat...
doable? will it cool quickly enough not to damage the leds?