The most problem i am having is when i use the dragging technique or soldering dragging, since its fine pitch pins it bends them and damages them because of the dragging

Another problem is it makes alot of solder bridging with the fine pitch

When i use the solder wick to remove the solder bridging it lifts up the pads because of the heat and the solder wick can stick to the pads and lift them up , it gets way worse when i use 'liquid rosin flux" because its very sticky stuff

When i use "Liquid Rosin Flux" not kester 44 rosin solder its liquid it makes the fine pitch pins so sticky and messy

When i use NO clean Flux" it leaves a salty white sticky , it leaves a white residue and sometimes it appears to be conductive if bridging leads

When i use "water soluble flux" its much better and its cleaner

 

"liquid Rosin Flux" RMA flux is most favoured one for surface mount reflow applications. The rosin fluxes can be cleaned by either aqueous or solvent methods
Rosin fluxes are used for both wave soldering and in solder paste for reflow soldering

My main point is that the "liquid Rosin Flux" is only used in solder wave machines or reflow machines NOT for fine pitch soldering is this true or not?



No-clean fluxes
1. Leave no corrosive residues
2. Leave a nontacky residue that does not collect dust
3. Be safe and must not degrade equipment
4. Allow penetration of probe pins for electrical testing allow visual inspection of joints
5. Provide excellent solderability
Cleaning "no-clean" flux
When cleaning NO-CLEAN flux with Isopropyl alcohol, it leaves a white residue and sometimes it appears to be conductive if bridging leads..


Process. Many technicians use alcohol with a brush, to scrub the residues and loosen them from the PCB. The problem is that this process makes it very difficult, if not impossible, to rinse the contamination off the board.

All proper cleaning processes require four steps: wet, scrub, rinse, and dry.


Well, circuit boards are the same way. If somebody is using the "dip-and-brush" method, they’re wetting the residues and loosening them, but they can’t rinse! If you can’t rinse, you can’t clean.
That’s why many companies use aerosol cleaners to flush and rinse after the scrubbing step.
Quality aerosols are available from Chemtronics, Miller-Stephenson, Micro Care and TechSpray, as well as smaller companies. In addition, Micro Care Corp. sells a convenient tool, the Trigger Grip system, that connects to aerosol cans and makes implementing the four cleaning steps fast and easy. Google “Trigger Grip” or “Microcare.com” to learn more.

Other Possible Causes. There are many other possible causes of conductive white residues. These can include improperly cured FR-4 substrates; solvent incompatibility with the no-clean flux, .

non-alcohol-based cleaner such as VeriClean™ from Micro Care, and use a better cleaning system, like the Trigger Grip, to eliminate these residue issues completely.

 

i just read that NO clean flux and LIquid Rosin Flux is only for wave soldering or oven reflow machines

No-clean fluxes leave flux residues that are not necessary to clean from the surface of the soldered assembly before final packaging.

flux residues that cause corrosion during operation.

Use a Can of No-Clean Flux Remover

 

Go matlab section of this site and search solding and desolding's.

 

Cleaning isn't vital, unless you need to preserve a high impedance. My old Heathkits I'm still using are 40 years old, never had the flux residue (abundant) removed, and show no signs of corrosion. Most flux cleaning is for appearance.

 

I thought the flux residue creates parasitic oscillations or resistances between the traces,pins and nodes

 

In tight spaces with high frequencies and impedances, that might be the case. There is no doubt that it looks tidier if you remove it.

 

beenthere

Have you used LIquid Rosin Flux on a fine pitch IC chip removing it with LIquid Rosin Flux and then tacking and soldering in a fine pitch IC chip with LIquid Rosin Flux ?

Have any of you guys done this? i'm having alot of trouble doing this its very sticky and messy

 

Never done anything like that. Can't see any situation in which I would want to use liquid solder flux.

 

I thought the liquid flux prevented solder shorts and solder bridging when soldering a fine pitch pins IC chips in

Because when you use the "drag techniques" dragging your soldering iron across the pins on a fine pitch IC chip it creates shorts and bridging from pin to pin , the liquid flux is suppost to prevent this

So you don't use liquid flux at all when soldering a fine pitch ic chip?

 

Possibly, a definition of "fine pitch" would be helpful. I would say that it would apply to anything less than 50 mils (.050", or 1.27 mm). I have no problem soldering leads with a spacing of .050, nor with handling SMD components of size 805 and up.

The only time I use what I would agree would be a "drag technique" would be during desoldering, when solder bridges would help in heating leads. I can't imaging how the technique would be anything but a disaster when attempting to solder a new component in place.

For through hole, you heat the lead and the pad. For SMD, you heat the pad and then the lead. One at a time is necessary for controlled work.

 

so how do you desolder through hole components? i use "solder pools" until the parts fall out

so how do you desolder and solder fine pitch ic chips?

 

I use solder wick and a solder sucker. Just wick for the SMD stuff.