How much do you know about the length of 1 μm (micrometer)?
μ is 1mm 1/1000. For example, the thickness of hair is said to be 60 to 80 μm, and the size of cedar pollen, which bothers many people in spring, is said to be 30 to 40 μm.
As you can see, μm has an image of being very small, but it is an important unit for screen printing.
μ is 1mm 1/1000. For example, the thickness of hair is said to be 60 to 80 μm, and the size of cedar pollen, which bothers many people in spring, is said to be 30 to 40 μm.
As you can see, μm has an image of being very small, but it is an important unit for screen printing.
The plate used for screen printing is coated with a resin called emulsion. This emulsion has the role of forming the print pattern and the role of controlling the thickness of the print pattern. The thickness of this emulsion is about 5 µm when it is thin and about 100 µm when it is thick. When I say thick, it's about the thickness of a human hair. This thickness is set in units of 1 μm according to the pattern shape and ink to be printed.
1 μm control! Some of you may be wondering if you need a control smaller than pollen. But this is the point.
A long time ago, I had an experience like this.
It happened when an electric circuit was printed on a polyester film with a conductive paste. Using a plate with an emulsion thickness of 15 μm, we made 10 samples and submitted them to a customer. Shortly after, I was informed that the evaluation was over, and went to a meeting.
The customer's answer was, "The sample is well made. However, the electrical resistance is a little high."
I replied, "We will double the emulsion thickness to 30 μm and increase the film thickness of the conductive paste to lower the resistance value."
It happened when an electric circuit was printed on a polyester film with a conductive paste. Using a plate with an emulsion thickness of 15 μm, we made 10 samples and submitted them to a customer. Shortly after, I was informed that the evaluation was over, and went to a meeting.
The customer's answer was, "The sample is well made. However, the electrical resistance is a little high."
I replied, "We will double the emulsion thickness to 30 μm and increase the film thickness of the conductive paste to lower the resistance value."
When I made 10 samples for the first time, I was able to make them in half a day. So I called the customer and said, "The new version will arrive this morning, so I'll make a sample this afternoon and send it to you." Then, when I went to the factory to make a sample, the reply was, "I'm busy today, so the printer won't be available until after 17pm." However, since the last printing took about an hour, I thought that there would be no problem, so I started making samples in the evening.
But I can't print! Even though the same paste is used, the print is scratched off. When the paste is thinned, the paste bleeds. There is no change even if the conditions of the printing press are changed. While repeating this, the night finally dawned. Was it easy to print before?
But I can't print! Even though the same paste is used, the print is scratched off. When the paste is thinned, the paste bleeds. There is no change even if the conditions of the printing press are changed. While repeating this, the night finally dawned. Was it easy to print before?
I changed the paste, changed the conditions, didn't sleep at all, and finally made 10 samples and delivered them to the customer.
After some experimentation, it was found that the thicker emulsion prevented the paste from passing through the plate, which made printing impossible. Just changing the thickness of the emulsion by just 15 μm made the difference between heaven and hell. It was the moment when I experienced firsthand that a difference of a few μm in the thickness of the emulsion can make a big difference in printability for screen printing.
After some experimentation, it was found that the thicker emulsion prevented the paste from passing through the plate, which made printing impossible. Just changing the thickness of the emulsion by just 15 μm made the difference between heaven and hell. It was the moment when I experienced firsthand that a difference of a few μm in the thickness of the emulsion can make a big difference in printability for screen printing.
For screen printing, it's just μm, but μm.
If you are having trouble printing, pay attention to the thickness of the emulsion.
If you are having trouble printing, pay attention to the thickness of the emulsion.
