WEEK 11

with

BISMILLAHIRRAHMANIRRAHAIM

INTRODUCTION

In this week i will explain how i did etching for my project's PCB. in order to install all components permanently.thus, i used UV board to custom my board at PCB to sketch the circuit i am using Proteus Ares 7. for sketching the circuit, i think that i dont need to show it as its simple procedure like usING multisim (just take component then put the connection). but for etching, the procedure really rare as student not really use it. so, i will skip to the etching state.

ETCHING

PROCEDURES / METHODS

In my project I used a simple method to build my PCB

The mask is printed on a transparent paper or foil, exposed and developed on the laminate with a UV lamp.

The laminates have a coating that is sensitive to light - by shining a light on them, we can transfer an image of the design to be created onto the board.  Where light strikes the board, the coating weakens and creates an area of copper that will be dissolved away by the etching acid. 

You will need a UV imaging frame and a photo development kit. Follow these steps:

•       Export your PCB layout from Ares using File > Export > Etchable PDF/SVG. If you like, you can now edit and enhance the graphics in a graphics software.
•  Print the file in highest resolution, first on white paper, and when satisfied, on a transparent paper or foil. Be careful to set the printer options to NOT "scale to fit".
•  When printing on foil, use either a special toner or a toner dissolver spray to heighten the density and get the print tone overall even.
• The spray should be used directly after printing, and care should be taken not to cause any drops. After the toner dries, place the foil in the imaging frame, toner side up.
•  Peel the protective blue film off the laminate and place it in the imaging frame copper side down, on top of the transparent film. Make sure not to expose the light-sensitive layer to too much light during the development process.
•       Close the lid of the imaging frame, set the timer for 4 minutes and press the knob to start the exposure.

UV board type

The mask is printed on a transparent paper 

UV scanner

•   Once the imaging process finishes, place the board in the development tank for 1-2 minutes and shake it once in a while (be careful not to leave it too long, otherwise it will damage the traces).
• Place the board in the rinse tank containing destillated water for a few seconds

shack the UV board(board already scan) with sodium till the circuit line come out

Etching

Different machines and chemicals can be used for etching, which will affect the comfort, duration and quality of the result.

Two Acid types that can be used for etching are ferric chloride (Eisen-3-Chlorid) and Sodium Persulfate (Natriumpersulfat - Feinätzkristall).

Although etching can also be done in simple plastic boxes, the quality of the results will improve dramatically when using a machine that controls temperature and constantly keeps the fluids in motion. There are small etching tanks with heating and air pump and there are small spray etching machines which can handle bigger PCBs and even the development and cleaning processes involved.

To get rid of all unwanted copper follow these etching steps:

  Put the board in the acid tank for about 20 minutes until the copper traces are completely etched. You can tell that it's finished when the board turns from opaque pink to transparent yellow

shacking the PCB with the chemical 

the copper is appear

Robbing

Using steel brush to rob the PCB

• If unwanted copper still there, rob the PCB with steel brush till all unwanted copper is clear but beware with the wanted copper
• Dry the board with a cloth.

robbing the PCB