'J' lead SMD ram soldering

[foft]

I was trying to make a new RAM board for my Falcon. I received the PCBs and the chips and am trying to solder them. I finding the 'J' lead ram chips really hard to solder on. I've tried with the iron and hot air - also with lots of flux, also tried with paste. It just doesn't seem to stick to the leads of the ram chips properly so I'm clearly doing something wrong.

My joints look nothing like the acceptable ones on here, in fact some of the chips even entirely fell off when I thought I'd tried pretty hard to do a good job!
https://workmanship.nasa.gov/lib/insp/2 ... kages.html

Any tips for these?

[exxos]

Sounds like the PCB isn't getting hot enough. A hot plate is how I do them. With paste.

[DoG]

I use a soldering iron with knife edge tip. Tacky flux and drag soldering. Then go back and fix the pins that needs it with the tip. Or braid if excess solder do exist between legs. 320°C-350°C.

I have also used hot air but more often to desolder them. But it takes a while. You should be able to see when the solder melts. 60/40 gets more shiny when it is melted. Lots of tacky flux is needed if it doesn't exist enough in the paste.

[exxos]

Coating the PCB with solder first helps. Soak it up after with braid and flux. It will help the solder stick then. A PCB oven is the best way.

A smaller version of course.. viewtopic.php?p=43116#p43116