How to make your own PCB design in 10 steps

 

1. Draw circuit

    Requirement:    i) Desktop or Laptop Computer

                              ii) PCB circuit design software

                             iii) Photosensitive PCB board

     In the first process, PCB circuit design software is required to design your PCB circuit.  There are numbers of designing software available in market such as OrCAD, Protel, Circuit Creator ant etc. But the simplest software that I had used and also for beginner or student is Engle 5.0 which you can download from here. The guideline on how to use the software in drawing circuit can be obtained here, This software is quite easy to be used in terms of simple interfacing. What should be taken into consideration when design circuit is always make sure track size, gap between track and driller pad size.

     Refer to the figure below, recommended size for track (blue) is 12.5mil up to 25mil according to respective suitability. Then, gap between tracks is 12.5mil, more far more good. For driller pad (green), Vias (through linking holes): 50mil (1 mil = 1 / 1000 inch, 50mil = 0.05”).

     Remember, for a better safety and if there is still have space on your PCB board, adjust as spacious as possible because it is easier when we want to drill a hole. Besides, do not forget put together your project name in TEXT form. Make sure the text is in mirror Text (text could be read into mirror). You are also encouraged put screw hole in your every angle of your PCB and also frame border (if necessary). Lastly, compile your design to prevent any error.

2. Print circuit

    Requirement:        i) OHP transparencies

                                ii) Laserjet printer

                                iii) A4 Paper (2 pieces)

                                iv) Photosensitive PCB board

     OK, for printing, OHP transparencies are needed, this is not like any transparent plastic that we always used as folio or report cover. That type of transparent plastic cannot to be used because it is does not have quality enough and the ink cannot stick on the transparent plastic.  It also required using quality printer such as laserjet type. 

     Please remember, print your design on A4 paper first before print on OHP. Then, take your PCB board and measure the printed circuit on A4 paper with your PCB board. This measurement is done to determine whether your circuit size is suitable and fit into PCB board. After that, look back at the track size and the drill pad. Because the size printed on A4 is actual size that will be established on PCB board later. If the results are not satisfied, go back to the first step to adjust the width track and drill pad. This is the reason why I recommended you to provide 2 pieces of A4 paper.

     After finishing everything and satisfy with your design, print it on OHP transparencies.

 

3. UV Exposure

    Requirement:        i) UV light

                                ii) scissors

                                iii) sellotape

                                iv) Photosensitive PCB board

     In Exposure UV process, you need to be careful, because of mistakes will be giving effect and shatter the whole process. Sometimes you are required to buy a new Photosensitive PCB board and repeat back the first process. Perhaps, sometimes you might have the intention to give up. Mistake might be keep happening when your circuit is upside down on PCB board after this process. If you discover the mistake, the only solution is to throw away your PCB board into garbage.

     Ok, the first step you should do is taking the printed OHP and lay down the OHP on table or flat surface. From here, make sure our mirror Text (mentioned at 1st step) that only can be read through mirror. If you can read it in normal letters, please overturning your OHP until it reverse condition.

     Next, take your photosensitive PCB board then take off the plastic film (as shown in the figure below) which covered photosensitive surface. Please ensure the photosensitive part is not exposed to any lamplight or sun.  When take off the plastic film, quickly topple unexposed part on printed circuit board on OHP. Hopefully the PCB board fit enough to cover the whole circuit on OHP. This is the reason why we measured it first in the second step. (in my opinion, Photosensitive and Photo-resist is a same type of PCB board).

 

     For your information, Photosensitive PCB board consists of 4 layers of material, first layer is plastic (PCB platform), second is Copper layer, third was Photosensitive layer and last is plastic film that protect photosensitive from light source.

      What we should do next, take cellophane tape and stick at every edges of your PCB board (as shown in figure below).  It is better when half of cellophane tape sticks on PCB board and in the other half on OHP. This method has been taken to ensure the OHP will be fixed properly and orderly below PCB. After done the sticking process, use scissors to cut over the waste OHP.

 

     After cutting off, the PCB board attached with OHP can be put inside UV light box. Make sure the OHP side is facing the UV light. Shut the door of UV Light Box and set the timer. Usually, heat it for 7 – 10 minutes.

4. Develop circuit on PCB

    Requirement:        i) Sodium metasilicate pentahydrate Na2SiO3*5H2O (Universal Developer)

                                ii) Container or tapeware

                                iii) Warm water

                                iv) Gloves

     In step 4, it has been  explained on how to remove photosensitive which was expose by UV light.

     Firstly, wear a pair of glove and prepare a container which is filled with warm water, if possible, the warm water should not be too hot to avoid immediate reaction.  For safety sake, use plain water but the reaction will be longer. Ok, fully fill the container with water, then put 2 ½ teaspoon or 3 spoons of Universal Developer powder (depend on volume of water) into the container. After that, shake the container until the powder  is dissolved.

     After PCB board is cooked, take it out from UV light box and take off the OHP and cellophane tape from PCB board slowly and carefully. After that, you will see circuit on PCB. Don’t worry, after going through UV process, it can be exposed with any light.

     After removing all cellophane tape and OHP, dip PCB into the container and shake slowly. Make sure the circuit is upper side, so that you can see the development of PCB progress. Shake the container until your circuit is completed than take it out from the container. Then wash the PCB board using plain water and dry it off.

     Make sure the only things left on your PCB board are circuit (dark blue) and copper. And now you can read mirror text (if any).

      If you notice there are any insufficient track or drill pad not solid enough, don’t worry, you can use permanent maker pen for touchup (draw) the insufficient track or drill pad. Make sure this drawing to be done before etching process.

 

5. Etching

    Requirement:        i) Ferric chloride acid

                                ii) Etching container

                                iii) glove

                                iV) Warm water

     In etching process, ferric chloride acid is used to remove unwanted copper to get track and drill pad. This process is quite dirty, please wear suitable attire if possible.

     Firstly, fill in the warm water into container, same like previous process, the warm water to accelerate Ferric chloride acid's reaction. Water need to be filled on flat level of container. Then, put Ferric chloride as much as 5-7 teaspoon depends on water's volume. Avoid acid from hand.

      After completed preparing the acid, put the PCB board and shake the container slowly. Make sure facing up the circuit so that you can see PCB board progress. Shake the container until unwanted copper is being removed and only left your circuit and PCB platform as shown in figure below.

 6. Cleaning

     Requirement:       i) Thinner

                                ii) Tissue

     In cleaning process, thinner has been used to clean up remaining photosensitive that may stick on track. Please use tissue or cotton, pour a little thinner to tissue and brush slow and carefully on circuit surface.

     After the cleaning process, your PCB will be seen as figure below.

7. Tin Plating (skip this process)

    Requirement:    i) Tin Plating

    Tin Plating is used to prevent copper from oxidized or copper become rust. But this process costly to small industry and education. So, you can skip this process.

8. Drilling

    Requirement:    i) Driller

    Small driller is needed in this process to punch hole on PCB. This hole will be used in soldering components later. Make sure you use suitable sizes of drill bit for pad, this method has been taken to avoid damages to our PCB.

    The correct way for drilling is the drill bit should be situated angular 90 degrees from PCB surface. Remember, let the drill do its job and don’t give force pressure from your hand. It is to prevent drill bit from being broken.

9. Soldering components

    Requirement:        i) Toolbox

                                ii) Mask (if any)

     So, this process challenges your patience for soldering all the components. This process gives advantage to simple design due to not much components are being soldered.

 

10. Testing

      Requirement:    i) Multimeter

      Please test your circuit connectivity using MultiMeter (MM). If any circuit disconnected, you can touch up using step 9.

 

That all for now, thanks - "Practice makes Perfect"