I am making my own circuit board.
When i solder components on pcb. There is flux presents in pcb and some blackish colour parts is present.
I want to clean pcb with contact cleaner spray.
So, which is good contact cleaner spray for pcb?

I saw many mobile shop with Falcon 530 contact cleaner spray.

You must sand the PCB well before etching and also do light sanding after etching. Once done, manually tin the pads with solder before exposed copper gets oxidized. Use Rosin core solder wire - always. Heat the pads and apply solder on the pads (area where the soldering tip touches the pad) but not on the soldering tip.

The issue seems to be oxidized copper pads or component leads or both. Try keeping soldering tip on pads for a few seconds more or clean the oxidized surface.

If black residue it present on your soldering tip then you must clean your tip properly or replace it. You can lightly sand the tip and area near it with a high grit(~600) sand paper - but be careful or you might damage the tip.

In my opinion, you don't need Falcon 530 when making new PCBs at home. I am not sure what Falcon 530 does exactly so cannot comment more.

I need contact cleaner because when i solder, some flux and blackish thing present on the pcb which is unburnt flux.

Never ever do this. You will definitely damage your tip. There is a way to maintain a clean soldering tip.

The black residue is that of the flux. It will become black when flux is heated multiple times. It is often recommended to clean the excess flux once you solder a component.

For cleaning PCBs you need isopropyl alcohol. Don't use this fancy term just ask for PCB cleaner they will give it.

1. Soldering iron rod needs to be cleaned regularly when used, after the rod gets heated use stainless steel mesh(which we use for vessel washing in kitchen) and rub the tip on it gently on the mesh.

2. Use Isopropyl rubbing alcohol to clean the flux in PCB, easily available in medical shop, use ear buds dip it in rubbing alcohol and clean the PCB, flux will get removed slowly, since it contains alcohol it gets dried up easily, remove all power connections while cleaning the PCB.

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Its a 600 grit sandpaper not 180 grit or lower. It will polish the surface rather than grind it. I have done it multiple times (also with 400 grit sand paper) on old soldering iron tips and never have had any issues (And yes, not to sand on the coating of the soldering iron). Though alcohol + steel mesh works good but sometimes it might not able to clean the tip completely.

I assumed OP is using Soldron or similar soldering iron and not Hakko or similar. Don't do this on Hakko anyways. 

@Balakrishn_Reddy @Purush @Power_user_EX
Thanks for reply
Steel mesh never works. I use rehti to clean my soldering iron and rehti  works.
I will try to purchase isopropyl alcohol solution for medical shops.

@taksh
Steel mesh works...using for more than a year...first you need to make the rod hot..

This is also used to remove excess lead from the rod too....

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Use IPA, iso propyl alcohol available at chemist to remove extra flux and black residue from soldered joints

Really guys are you using steel meshes and reti (file) to clean your solderig irons? There is no better way to ruin the tip. Your iron will seeming work nice for a while and then start to give up again. I have been soldering for over 25 years using various gear. The last time i changed a tip was 5 years back. Pleae follow these guidelins and please do not file or sand or scrub those tips. they loose their coatings and will give you more pain than pleasure

1. Keep a damp sponge (with RO water) always by the side. gently wipe after each solder. no need to press hard, just gently wipe. You do not need to use any chemicals or any hard substance to remove that residue.
2. if you're soldering iron is idling for a while (while you setup stuff), wipe on sponge and tin again before first solder
3. everytime you wipe, your iron tip should shine and not have yellowish tar or gray shineless solder on it. It must be shiny always when you use it solder
4. Never dip your solder iron tip in flux in an attempt to clean it
5. Shake exceesive solder off yoru iron by giving it a quick tug
6. You never melt the solder wire on the iron tip and apply that to the joint. You always heat the joint to be soldered and try to melt the wire directly on the joint. At places you cant do this, use the iron as a sculpting tool to flow the molten metal around the joint.
7. Use generous amount of flux at solder joints (yes dollops). Excessive flux can always be cleaned using IPA or acetone. I cant stress this more. If you want solder joints that will last very logn and not dry up, please use lots and lots of flux. I use normal flux for simple joints and indium flux for smd's
8. tin your wires before you solder them. During tinning, the idea is to cover the part with solder (the part which will form the joint). Do both sides separately and finally bring them together and solder them
9. Everytime you heat your iron, tin it again, and shake off the excess. Do this everytime the soldering iron is heated up.

The art to solder is the fact that molten solder will melt all solder that touches it. If there are impurties in the mix, the thermal transfer is not enough to melt more solder. So yea tin everything that needs to be soldered.

Hope this helps everyone and you do not have to sand any of your solder iron tips for a long long time

Thanks  Girish Bhaiya for reply.
I have one more question. Which cloth is better for cleaning pcb?
I saw mobile shop person used microfiber lint free cloth for cleaning.
But i don't have microfiber lint free cloth for cleaning pcb?
Any alternative?

A clean cloth.