S8 Small scale production of functional circuits
This area of the audit has been marked at '1' meaning very little knowledge if not any at all.
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What I have learnt and what I understand now
Today we had a group tutorial on how to create a PCB and the processes within it. I have no past experience in this area of the audit so I found that it was was quite an interesting tutorial to watch also I was able to learn many new skills during this time that has supported me development so far within this section of the audit.
Dean gave us the option to either go away and recreate this process for our own work or use the examples that he had made previously. I set myself the challenge to go through the process again mainly because I wanted to learn more and understand whilst experimenting. I also knew that my knowledge was minimal within the area so I thought it was a good idea to insure that all of the key processes had been absorbed accurately which in turn will facilitate with developing my skills in the subject area.
First of all before I began to create my PCB, I wanted to actually find out what this meant!!
I now understand that the term PCB is short for 'printed circuit board' but also it can be referred to as a printing writing board. It is used in electronics to build electronic devices. I have also learnt that a PBC serves two purposes in the construction of an electronic device, it is a place to mount the components and it provides the means of electrical connection between the components.
Below is a sequence of the process of creating a PCB. I have captured this through photographs and I have also commented on the processes that I went through in order to create the PCB
- Initially a printed PBC was provided using a programme called Circuit Wizard and it was printed onto an acetate sheet. Within the circuit there is space for you to include some text, with the example circuit there was in fact some text and it stated ‘University of Brighton’. I learnt that an important point to remember is that when you place the acetate onto the UV light box you need to insure that the text appears in the reverse direction in order for it to be transferred correctly. I now understand as well that when you have completed this process you remove the protective photo-sensitive layer on the PCB revealing a black side to the board you need to insure that you do not expose this side to any light or as little as possible as it is UV sensitive and could damage the board. You then place the PBC on the UV light box with the white side of the board facing you and set the light box for three minutes.
- Once the board has been developed it will appear like this, I now understand that the yellow marks represent the circuit.
- The next step is to remove the rest of the copper that we do not need this in turn will reveal the circuit on the board. You do this by using 1 sachet of photoresist universal developer but first pour 500ml of warm water into a tray, then add the developer and tilt the tray back and forth in order for it to mix. I made note that this solution will last for half a day. I also think that it is important to wear protective gloves during this time.
- Place the PCB in the mix using prongs and wear protective gloves. I learnt that rocking the tray back and forth until the mask eventually disappears the mask will turn the water green. Then it is important to wash the PCB under water.
- This is how the board will look once it has been reacted with the solution. The next step now is to remove the rest of the copper in a bath of ferric chloride also known as an acid bath using a Bubble etch tank. The solution can stain clothes protective clothing could be a good idea! I did in fact get a little bit on my shirt so I have now learnt by this mistake.
- I now understand that the bubble etch tank will needed to be turned on prior to its usage, the reason being is because the solution takes 20 minutes to warm up. I forgot to do this so it ended up taking more time! Using the tongs fixate the board in the basket which in turn will immerse in into the heated solution of ferric chloride. I learnt quickly that you need to be careful with this because I actually dropped all of my PCB into the acid and therefore had to start all over again, I was not impressed but luckily I had a spare board so I just completed a few processes.
- The time on the machine normally is pre set however it usually will take a minute and a half for the copper to completely disappear also known as being etched away, Press the ‘U’ button to start the machine and check the board every so often. My board needed more time in the etching tank and therefore I had to wait a bit longer.
- Once etched this is how the PCB will appear insure the copper has been completely removed, take the board out using tongs and wash it thoroughly with water.
- I now understand that by using a guillotine cut the board it makes it easier to work with and also makes it look neater.
- The next step is to drill some holes to fit the components in the board using a pillar drill. I was able to discover that the drill actually self centres the holes so you merely need to careful place the drill on the board and it will automatically drill the whole in the centre. Therefore, it is very accurate if you are gentle. The first few times I did make some errors and as a result some of the holes were not central.
- This is the circuit that we were giving to mimic. It displays and labels the various electrical components and also shows where they need to be placed. I found this was a good starting point that helped me learn the basics.
- We fixate the components onto the PCB board by using a soldering iron. I realised after a while that you need to make sure that the soldering iron is always kept clean either using a damp sponge or wire. By placing the solder at the tip of the iron and place it on the leg of the component and track to feed in the solder and you only need a small bit of solder for it to hold and you must insure that the solder does not overlap onto another track as this can interfere with the circuit from functioning accordingly. Because it was my first time doing this I did in fact get some solder on the tracks and if this is the case then I now understand that you can use a solder sucker to remove it but you need to heat the solder before you do so.
- This photograph displays the finished PBC board with all of the components in the correct positions shown in the example.
- This is the other side of the board it shows the solder holding all the components all in place.
I have learnt a fair amount during this process, I have realised that it is so important to make sure that you are wearing gloves and protective clothing and be cautious at all times because the bottom line is some of the chemicals that you use can cause serious damage to yourself and pupils. I found that it was a very useful task as well for me to learn and go through again by myself as I know I shall be using this within my lesson as a teacher. I can now appreciate as well that each step in the process is important and if one section is completed incorrectly then it will have to be done again, there is no cover ups.
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Analysis of new gained knowledge and the next step
Prior to this course I had no knowledge in this area and for that reason I graded the section as a '1' meaning no knowledge if any at all.
I now feel that through this section of the audit it is clear that I have certainly developed and now understand a great deal more about the content hopefully this can be seen through my writing and the photographs that I have included.
As a learner I feel that I was most successful when I went away to recreate what Dean had taught us. Going through the processes again not only helped me to understand the sequence more but also made me realise the importance of each step in the making. Whats more, I noticed that I began to identify new aspects of making a PCB, for example taking in to account that you need to be careful whilst placing the board into the etching tank. Although, this is perhaps not a obvious measure to be cautious of, I myself made the mistake and dropped my work in the acid and as a result I had to start again. But now that I have learnt from my mistakes and most importantly I will consider these factors when teaching in the future. In my opinion, these factors allow you to be a successfully learner, although making mistakes are not ideal, you always learn from them and from that take away important factors which in turn helps you to develop within the content.
I feel that I was less successful at perhaps understanding why the certain procedures took place and how it worked. For example how the UV light printed a circuit diagram onto the PCB. I know that this is not necessarily crucial information to know, but I do realise and I am conscious that as a practicing teacher I should be aware that if I am going to ask such questions then students will be asking them as well. So I need to be prepared for knowing why and how certain things work so that I can explain it if need be.
My next step now is to perhaps design my own circuit design if I need to do so, with my own project in systems and control. I may just use the circuit that Dean has provided but if not I think it would be good practice to see how I can design something different using circuit wizard. Whats more, I can see if I am able to pick up any new tips and if I have learnt anymore if I was to go through the process of creating a PCB once again.
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Prior to this course I had no knowledge in this area and for that reason I graded the section as a '1' meaning no knowledge if any at all.
I now feel that through this section of the audit it is clear that I have certainly developed and now understand a great deal more about the content hopefully this can be seen through my writing and the photographs that I have included.
As a learner I feel that I was most successful when I went away to recreate what Dean had taught us. Going through the processes again not only helped me to understand the sequence more but also made me realise the importance of each step in the making. Whats more, I noticed that I began to identify new aspects of making a PCB, for example taking in to account that you need to be careful whilst placing the board into the etching tank. Although, this is perhaps not a obvious measure to be cautious of, I myself made the mistake and dropped my work in the acid and as a result I had to start again. But now that I have learnt from my mistakes and most importantly I will consider these factors when teaching in the future. In my opinion, these factors allow you to be a successfully learner, although making mistakes are not ideal, you always learn from them and from that take away important factors which in turn helps you to develop within the content.
I feel that I was less successful at perhaps understanding why the certain procedures took place and how it worked. For example how the UV light printed a circuit diagram onto the PCB. I know that this is not necessarily crucial information to know, but I do realise and I am conscious that as a practicing teacher I should be aware that if I am going to ask such questions then students will be asking them as well. So I need to be prepared for knowing why and how certain things work so that I can explain it if need be.
My next step now is to perhaps design my own circuit design if I need to do so, with my own project in systems and control. I may just use the circuit that Dean has provided but if not I think it would be good practice to see how I can design something different using circuit wizard. Whats more, I can see if I am able to pick up any new tips and if I have learnt anymore if I was to go through the process of creating a PCB once again.
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