What is Screen Printing?



Hey guys! I know this is early in the week, but this is a post to explain the process of screen printing. A few people two weeks ago asked what exactly the screen printing process was, and I wanted to hold off answering that question so I could post this blog. I know what some of you are thinking right now, "this post is late, late, LATE!" And that I didn't post last week. But last week was technically my week off (I had to go to Texas Wednesday through Saturday and couldn't go to the lab to get all my required hours). I started working on this post last week, and I'm sorry that is so long. But there was a lot I wanted to talk about and share with you guys. So here it goes! :) 

What is screen printing? And how does one make screen printed electrodes? Well, screen printing is a technique in which an individual uses a stencil to spread ink onto a surface to get a desired design. And in my case, the desired design would be an electrode. In my previous post, I compared the screen printed process to baking. So I will continue using that analogy and list the "ingredients", steps, and baking time of each part of the screen printing process. So let's start, shall we?

First off, here are the materials needed in this process.

Materials Used

1. Stencils                        

2. Conductive carbon ink

3. Conductive Sliver        

4. Oven                             



                           

 Below is an outline of the screen printing process in the lab that I intern at. Dr. LaBelle created this so his students would know where the stencils of each part are, as well as know the steps of the process so no confusion ensues. Now I'll break each step down for you.

Step 1and 2  

Before I start the process, I go to the oven and set it to 100 degrees Celsius (it takes a really long time to bring the temperature up to that mark).

 So in the first step, I take the stencil #1 --which looks somewhat like a bunch of trees-- and put it on printer paper. Then I take the conductive carbon in, a black, thick substance, and spread it on the stencil. During this process, I make sure to keep a constant pressure spreading the ink across the stencil. This is to ensure each electrode made (the stencil makes 4) have the same amount of ink and bake properly.

Now I head over to the oven, place the paper with conductive ink on a metal rectangular sheet, and put it in the oven. And I bake it for 1 hour.

Here is a closer look at the stencil I used in step one.

Here is a closer look at the stencil I used in step one.

Here is the product of step 2

Step 3

Step 3 is exactly the same as step 2, except with a different materials. I use conductive silver, instead of conductive carbon ink; and I use the stencil shown below, instead of the one above.  I still scoop up the silver and use constant pressure when spreading it across the stencil. The most difficult part of this task is lining up the stencil on the electrode, and making sure the conductive silver doesn't run off due to its liquid form. After that, I go back to the oven and bake it for 1 hour at 100 C.

I need to line the stencil up to lines 3, 6, 9, and 12 of the electrodes.

Step 4

After step 3, I must now take the insulating ink and repeat what I have been doing for the past 3 steps. I take the stencil, line is up, spread the ink on, and then bake it for 1 hour in the oven.  

Insulating ink is a lot stickier than the previous inks, so I need to be careful spreading it on so that the stencil won't move while I spread it onto the stencil.

Step 5

 I know by now you think the screen printing process sounds really tedious. And you probably already know the next step I have to do: the same as step 4! I must complete my insulating circle on the electrodes by doing the same exact thing as step 4 and bake it for an hour. 

And finally, after 4 hours, I have my screen printed electrodes. So there you have it, the screen printing process. If you guys have any further questions about it, just ask in the comment section bellow. Until next time guys!

- Tina Smith