I am carefully practicing into SMD circuits now, from many years of confident DIP sized soldering & builds. I see on youTube video people are squirting this gel/paste solder that appears to flood the area and work well with the copper-wick to absorb the solder in small places. I want to order some of this solder-flux wax greese/gel stuff, but am lost - can anyone help guide me? I just want to get some cheap eBay samples before I buy a big thing of something before I know I will use that.
On top of cheap eBay search "flux paste" is "NC-559-ASM-UV" and "Rma-223", which I am ok with trying for $1 entire dollar for 10cc squeeze plastic. Can anyone advise me on other options, or would I probably be ok with 90% practical use for either of 559 or 223 ?
Invest in a vinyl cutter! I use my gerbers to make my own solder paste stencils to lay over my PCB's (usually from iTead or Elecrow... as they are cheap for small boards in qty of 10!)
lay the stencil over the pcb...
smear some solder paste over it..
remove stencil
populate board with parts
pop into $17 toaster oven from wal-mart!
They turn out great!
Biggest investment is the vinyl cutter!
I have only used FLUX when I need to remove parts... or when I soldering to a 'sensitive' component, and can apply to much heat for long to it..
You can also get OSHStencils to laser cut stencils for you from polyimide - these are reusable many times (they also do stainless for a somewhat higher fee).
This will be the next flux I try after working through the stuff I have now: https://store.rossmanngroup.com/index.php/amtech-nc-559-v2-30-cc-16160.html
I bought some Chip Quik flux paste but it leaves a residue that is extremely difficult to remove. Louis Rossman lays that Amtech 559 on super thick as a full time job so I'm thinking it's worth giving their choice of flux a try.
I'm not a soldering expert so don't take this as the "final word".
The solder paste or regular wire-type wire solder (normally) contains flux.
There are 3 kinds/categories of flux used for electronic soldering -
Regular-old rosin flux. This seems to work the "best" but it requires "strong nasty" chemicals to clean. For that reason it's not popular in industry. I believe it's "inactive" when cooled so you don't have to clean the board, but it's ugly and it may be slightly-conductive so it can cause problems with some "sensitive" high impedance or RF circuits.
Water soluble flux. It doesn't seem to be as effective but you simply wash the board with (preferably with deionized or distilled water after soldering (and heat-dry or blow-dry before powering up). It may remain active when cool so it's always recommended that you clean. At one place I worked we just used tap-water and a dishwashing brush and we dried with compressed air... We were using an outside PCB assembly house, but we used this process in-house for rework/repair.
No-clean flux. It's clear so it's not so ugly and it's non-conductive. I don't have much experience with it.
Typically, if you are buying some additional flux you'll use the same flux that's in your solder. But, you may want something more "aggressive".
P.S.
In the past I've used "low melt" solder for rework/removal. We had a special [u]rework station[/u] to heat-up the board, but it an be used without the special heater. You heat-up the board to below the melting temperature for the regular solder, then you flow-on the low-melt solder on the leads you want to unsolder. You "glob on" quite a bit, "shorting-out" all of the leads, etc. No flux is needed for the removal step. The low-melt solder somehow blends with the existing solder, all of it melts, and the component comes loose (at the lower temperature) while the other parts remain soldered. After removing the part you use a solder-sucker and a Q-tip, etc., to clean-up the pads. The removed part is a mess with extra solder but presumably you are going to discard it anyway. [u]This video[/u] shows the process.
Thank everyone for the information. I make a little mistake, I am not up to that stage yet. I was just looking for the flux-paste / gel that helps me de-solder SMD components, with the copper braid.
I ordered some kester stuff before, it arrived in two bottles #951 and #186. One brown liquid and one clear liquid. It was thin, more like water. It kind-of works. But I saw on youTube videos where people were using a more jelly-like consistency and thought that stuff probably works better. This thin stuff appears to vaporize really quick.
In order for me to make SMD boards, I have to go and re-buy the entire collection I have from the past 15 years in DIP size - which is depressing. My prototypes never really get past the 1 or 2 models, before I find myself re-doing them again anyway. I am not really in a rush to make things smaller, more difficult to see for my own self.
I do not even have machine to etch, develop boards. I am working on a galvo-laser UV resin system, gantry or a LCD exposure, but who knows when I get that to actually work.
I just got two flux pens. They look like paint markers loaded with flux. I’ve used it a couple times to resolver smd components. I really like it. Wish they made them refillable.
