Z270 PCH Reballing help needed pls

[petemanuk]

I'm trying to reball a Z270 PCH, i've got the right stencil for the PCH and it's direct heat type.

I initially tried using 0.3mm solder balls (leaded type) but am having lots of problems with the balls not wetting to the chip, basically some of them just wont solder to the pads.

I'm making sure the chip is as clean (using ipa) then putting a thin layer flux on then putting in in the holding jig with the stencil on. I'm the heating to about 400degC with minimal airflow (4% on my Atten) but some balls just refuse to stick!!

I've repeated the above using solder paste and am getting similar results.

Anyone got any ideas were i'm going wrong??

[diif]

Re: Z270 PCH Reballing help needed pls

Which Atten,? 400c seems low, are all the balls melting?

[petemanuk]

Re: Z270 PCH Reballing help needed pls

Atten ST862D.

I'm not sure if its the flux i'm using Kingbo RMA, i read somewhere if you overheat the joint you can burn off the flux and then the two surfaces become oxidised so wont solder together?

Could you recomend any fluxes worth a go.

[diif]

Re: Z270 PCH Reballing help needed pls

I use genuine Amtech 599

[dellxps15]

Re: Z270 PCH Reballing help needed pls

i use atten 8586 and kingbo flux, but my kingbo is the original from usa and i pay 30 dollar for 100g has no green stick on top of it and i use i regurally from 5-6 years without any problem. for soldering themp i set 380° celsius and after a while solder ball solder perfectly.
remember solder ball size is written on the stencil and the amount of flux is just a thin layer otherwise ball will sta y hight, and also check bga for some dusto or paper residue after cleaning because it wont make ball stick fine.

[maninashed]

Re: Z270 PCH Reballing help needed pls

after cleaning off the balls, then cleaning with IPA, refresh the bga pads with a fibreglass pen.

599 isn;t a great flux for reballing, burns off too fast in my opinion. pick up a tube of amoe, it's dirt cheap and the best performing flux I've found to date, including both flavours of amtech.

https://www.aliexpress.com/item/4000249740671.html

also, 400/5% is way too low, I do 420@30% on my 862D.