Replacing LGA CPU sockets

[dicky96]

I've tried this several times but I just seem unable to solder the new LGA socket.

I have no problem removing the old socket with broken pins, but using the same profile (or a bit hotter one) to fir the new socket results in a socket that is firmly attached to the board but just using the multimeter and checking continuity between Vcc pins (or ground pins) it is obvious the new socket is not soldered properly. I find maybe the outer pins and the next row may solder but not the inner ones and not all around the socket either

I've tried about half a dozen times now on various boards with various profiles and get the same result

I am using the technique - remove old LGA1151...
clean PCB with leaded solder ball and then braid
use paintbrush to apply this layer of Amtech 559 to the PCB
use optical alignment to set the socket position
solder

I've now come across this other method, on a very similar machine to mine, where they don't use flux, not any that it mentions anyway, and use a stencil and solder paste instead

https://www.youtube.com/watch?v=zEPNmOXjy4Y

Has anyone tried this method, and did it work?

Rich

[dicky96]

Re: Replacing LGA CPU sockets

Hmm well it seems I am pretty much on my own with this one then - I've ordered a direct heating 1151 stencil so I can try this for myself.

For sure the method I am currently using does not work

[SMDFlea]

Re: Replacing LGA CPU sockets

What sort of nozzles do you have,are the ones with "nets" better for a more even airflow .

[dicky96]

Re: Replacing LGA CPU sockets

The bottom nozzle has the 'net' or mesh, but the top one does not

[dellxps15]

Re: Replacing LGA CPU sockets

sorry for the late answer.

1) always use flux.... a good one.... without flux u wont be able to remove the socket even at 245°.
2) when lifting the socket use 2 tweezer... one on the right one on the left and lift it as much clean as possible
3) make picture of the pads on mainboard after socket lift..... are all pads with same amount of residual solder?

if when u lift the socket all pads had same amount of solder on them... then the temperature is right.
bebore solder new socket, check if pcb is 100% in orizontal position and pcb didnt make any curve.

if pcb is good, profile is good ( dont go too fast with temperature ... i take approx 7-8 minutes to remove the socket with an ir rework station.) cover also the capacitor near the socket ( generally they are in 3-4 side) cover with one strip od kapton and one of alluminium. it happened on first try that some of those can explode if u dont cover them properly.

if mainboard didnt get any damage from booting with shorted pins, u can make it work again.


look in the picture how much flux i use for removing the socket. when i solder it back i apply just one thin layer on the pads with a brush.
look also the residual solder on pads after removing the socket... all have same amount.



edit: i forgot to mention that old socket dont have any support to prevent socket touch the pcb, while all new socket have them... so if pcb is not perfect straight, it wont solder some ball because that spessor wont allow the socket to touch properly the zone.