Can silver conductive paint act as solder paste?...

Silver paint is not solder paste. Silver paint is Ag particles that rely on contact between particles for conductivity.

Solder is Sn/Pb that is melted and flowed into an alloy that is highly conductive compared to paint particles.

Do it right, or don't bother.

There's not an absolute answer. Some silver filled epoxies are also called silver paint, and you may (or may not) have one of those. The thing you have to look at is the thermal resistance of your "paint". If you don't know that, don't use it. If you do know it, do a calculation of the power you must pass across the junction and look at the temperature rise needed to achieve that.

Volume resistivity of E&C 56c electrically conductive adhesive is .00020 ohm-cm.

I stilll contend that you need solder paste and a reflow oven to do a proper job.

Silver paint does not contain silver, would be too expensive, it contains aluminium powder.The electrical counductivity of the paint would not be sufficient for use in any electrical circuit. Also the joints made by this paint will not last since the tensile strength of the paint would be nowhere near the solder strength.

The material to which I referred is indeed filled with silver (Ag) particles. For you to make such obviously uninformed claims is outrageous, and misleading.

Hey, I did not mean any offense, if I have hurt you while communicating, I am sorry. I think I have to improve upon my communication skills.

I just wanted to address the common misconception that I have come across while working on reflective coating for solar cooker. I am often told the coating/paint is either "silver" or mercury, and on enquiry, turns out to be aluminium.

I never knew there would be actually paint that contains silver. Any applications and data about costing? I want reflective coating for solar cooker.

Rajesh

Actually, I use silver paint a lot. Real paint (or ink), which is a colloidal suspension. It's expensive and a pain in the neck. It conducts really well the first short while, then falls off sharply with time.

I've also used a lot of metallic (aluminum, copper, ?) paints that were barely conductive.

I would never use paint to mount a component. In fact, I would never used somehing like e&c filled epoxy for a component. I have used the epoxy to move heat out of cryogenic coils and it requires a budget-busting cross section.

In short, go for solder.

I worked in a reliability/failure analysis lab for many years. I can tell you that metal filled organic conductors saved me countless hours of failure analysis. Just locate the joint in a product made with that material and chances were very high that I found the source of the failure. So, if you want to simplify the job of the failure analyst, I encourage you to use your conductive compound and stay away from the more reliable solder.

I suspect that the majority of those failures were the result of misapplication of the products, and not product failure.

The OP is a perfect example.

I suspect you are correct. The problem is that the people who sell these conductive materials try to convince all potential customers that their technology can solve problems and lower product cost without impacting reliability. Product engineers and their managers are often misled by these claims and test programs can fail to identify a reliability problem.

Silver paint is useful in some applications but is not strong enough to be loaded. If the LED being fitted by the OP has it's own mechanical fixing then silver paint or epoxy might be OK. My main concern is that the OP says 'high power' LED which suggests a high current device so a resistive connection could pose a problem.

We use silver epoxy to fit wires to platinum connections on optics which cannot be heated to more that 80°C & have found this to be very reliable if suitable care is taken in the application.

Thanks everyone..all your suggestion and ideas are really useful..

My work is on thermal characteristic of Light Emitting Diodes (1W).

During the measurement I will increase the junction temperature slowly which can exceed 150C. So I think I can't take risk by using Silver conductive paint as the solder paste..

So I will go for the real solder paste...and even I manage to get a reflow oven for the mounting process...

Thanks for your kind support everyone.