Conductive Paint

Conductive Paint for Circuit Boards

What is Conductive Paint for Circuit Boards?

Perhaps you’re unsure of what conductive paint is.

In this post, we talk about it in terms of how it is used in circuit boards or PCBs.

This is not a very sophisticated hard-to-understand product.

It can be said to be very simple to use. One form of it is readily available directly to consumers.

Similar to super glue, it is a widespread commodity, although its only use is in electronics.

We aim to provide you with all the pertinent information you require for your electronics projects, or for understanding circuit boards in general.

Then let’s begin.

Why Use Conductive Paint for Circuit Boards?

The simplicity of the product makes it useful for PCB professionals and PCB hobbyists alike.

Mainly, the paint is used for repairs. So you do see it sold in small amounts by retailers online such as Amazon.

Additionally, the product is quite helpful for prototyping PCBs due to its additive action, compared to subtractive action as with PCB etching.

Meaning, when you use conductive paint, you add a design by painting it on.

When you use PCB etching, the traditional way traces are made, you remove (subtract) copper traces to make your PCB design possible.

Conductive Paint Applications for PCBs

Conductive Paint Applications for PCBs

We’ll identify the applications for this product in this section:

• Typically, this product is used to fix PCB traces.
• Conductive paint reconstructs printed circuit board (PCB) paths for low-current applications.
• You can use it to fix PCBs in your piano, calculator, remote control, and other devices with tactile buttons and broken traces.
• Another major use, as mentioned earlier, is for PCB prototyping purposes. For example, you are just starting with a PCB design.

In this scenario, you are still learning what functions well and what doesn’t.

Likely, you’re prone to make errors, so an easy fix is to apply the paint in areas that you need to redo.

Here’s a video where conductive paint is used to repair a remote control:

Types of Conductive Paint Products for PCB

We can broadly classify the types into two major categories

Classified according to product form:

• Conductive Ink sold in small quantities (bottle form)
• Conductive Pen sold in pen-shaped squeezable containers
• Conductive Paint sold by liter to PCB manufacturers of fabricators

Classified according to conductive material used:

• Carbon – this is the most common active ingredient. It is lightweight, versatile, adaptable, and stable for use in inks. It also possesses high electrical conductivity.
• Graphite –This black substance, which can be seen in pencils, is a type of carbon. It has high conductivity as well. However, its bendability is a bonus. This substance is already found in touchscreens, Li-ion batteries, and LED lighting. It follows that it is a good material for Carbon Paint.
• Nickel – It is a good conductor of electricity with a thermal conductivity of 90.7 W/m.K. The best thing about nickel is that you can put it in water-based Carbon Ink products. This makes the item safe to use by children.
• Silver – The attraction of using silver versus carbon is that even at 90 °C, you can already get it to conduct electricity. There are also plenty of compatible inkjet printers that can shoot the silver-containing ink onto designs. This renders silver Conductive Ink or pain suitable to flexible circuit boards. You can even print circuits on hard paper for school projects.
• Gold – Once this product was available, but because carbon and graphite produce better results, there are no gold-containing inks available in the market anymore

How to Use Conductive Paint in PCBs

How to Use Conductive Paint in PCBs

These are the general procedures:

1. You must collect the necessary components.
2. The component you wish to fix, PCBA parts, electrical tweezers, paint, conductive tape, several paint brushes, or cotton swab sticks would all go under this category.
3. Ensure that your PCB design or schematic is in front of you so you can easily refer to it.
4. Next, practice before you speak! Make sure you become proficient with utilizing the paint (either the pen time or the brush-on type).
5. If you want to keep your lines straight, use the tape.
6. Remove the tape before the paint has finished drying.
7. Compare your design against the schematic to ensure it is sound.
8. Test and adjust accordingly. If you made mistakes, simply wipe off the paint with water, then repeat the application of paint.

Conductive Ink Pen & Conductive Ink Paint

Meanwhile, here are the primary ways you can use Conductive Paints and Conductive Inks. The applications are valid whether you use the pen-type or the brush-on type.

• Repair remote controls and other push-button controllers
• Automotive applications (e.g. windshields anti-frost)
• Logistics utilization
• Medical/laboratory diagnostic devices
• Modify push buttons or repair them
• Photovoltaic cells/ Li-ion/ batteries
• PCB projects for students/ PCB hobbyists
• RF tags in clothing, food, beverages, etc.
• Touch screen displays of all sized
• Wearable devices/ IoT circuit boards/ flexible circuit boards

Pros and Cons of Using Conductive Paint in PCBs

The Pros:

• It is cheap, relatively speaking.
• Using this material is easy, even children and teenagers can learn how to use it.
• You can’t argue with the results—it’s effective!
• Electromagnetic Interference (EMI) shielding takes effect almost immediately.
• If you make an error, you can erase the paint with water and start over again.
• The time spent on repairs is shortened.

The Cons:

• Main drawback: it does not last very long.
• There’s a tendency for the pain to rub off if the application is not done properly
• Great for a temporary solution, but after 12 months, conductivity wears off as the product has a shelf life.
• The conductivity level achieved using paint is significantly lower compared to conductivity levels of solid (not liquid) material, like copper
• If you need to keep reapplying, the cost will add up.

Conductive Paint vs. Conductive Ink

Conductive Paint vs. Conductive Ink

Confused about the difference between conductive paint and conductive ink? Then, we will tell you what sets both apart:

Conductive Ink

• This type of product uses conductive materials like carbon, graphite, silver, and gold
• It is packaged in small quantities such as 0.3ml, 0.4ml, 0.5ml up to 1ml
• Sometimes, it can be called “conductive glue”
• Another form it is sold is in a pen form. Usually with 6ml – 12ml variations

Conductive Paint

• This product also makes use of conductive materials like gold, silver, graphite, and carbon like the carbon ink
• But it is used in large-scale industrial applications
• A PCB manufacturer uses large quantities of conductive paint, applying the product to circuit boards produced by the thousands
• Conductive paint is directly applied on the PCB substrate (FR4, FR5, CEM-1. CEM-3, etc.)

The topic of this blog is conductive paint. But we also talk about how you can use conductive ink. Our intention is to capture a broad scope of the topic.

Kinds of PCBs Suitable for Conductive Paint

What Kinds of PCBs are Suitable for Conductive Paint?

You can use the Conductive Paint on a variety of circuit boards. However, some are incompatible with this product.

Here are the boards you can use the paint on:

• Rigid PCB – the material is compatible with most PCB substrates, especially FR4.
• Flexible PCB (FPC) – polyimide materials are also a good match with the paint
• Rigid-Flex PCB – you can apply it on both the rigid or the flex parts
• Multilayer PCB – any layer of PCB would be suitable
• Single-sided PCB – like PCBs for USB sticks, power banks, etc.
• Double-sided PCB – same as above
• ENIG PCB – the gold color will not be affected by the paint
• Controller PCB – such as remote controls for garage doors, TV remotes, Xbox controllers, Nintendo controllers
• Keyboard PCB – this covers mechanical keyboards and digital keypads

Here are the boards you cannot use the paint on:

• PCBs that are exposed to harsh environments (the ink can evaporate)
• High Tg PCBs that are exposed to temperatures as high as 180 degrees Celsius
• HDI PCB (to a certain extent of time the ink will work, but for prolonged use, you may need to replace the board if the traces are effective)
• Long-term EMI shielding on PCBs (again, if you use it as a short-term/quick fix, the ink will work fine)
• Military PCB – due to rigorous demands on quality compliance
• Medical PCB – in a pinch, you can use the ink for repairs, but medical PCBs are precision tools and need to be handled cautiously

Conclusion

At first, we explained what Conductive Paint essentially is.

Then, we set out the most popular applications in which this product is deployed in.

After that, we dived into the different materials that make it effective.

We were also able to cover Conductive Paint as differentiated from Conductive Ink, technically speaking.

Most importantly, we discussed this item in the context of the circuit board industry.

This article is brought to you by PCBMay. We’re a Chinese PCB company well-versed in the use of Conductive Paint in PCBs.

No matter what kind of PCBs you need, we make the, And we assure you that the ink we use for your boards are high-quality and top-class.

If you have more questions about this product, please let us know. Contact us any time, and we’ll answer.