Friday, 20 April 2012

MPhil 2 Months in

These months I have been reading up on power electronics, how it works, how to change from a AC current to a DC current and visa versa. There is a heck of a lot of information, I did start reading books on it, which is boring so what has the web have to offer I found out about PEEB It is also on power electronics, It has the same information as a book but there is in some chapters, experiments, haven't tried them but it is a nice idea.

The project I'm working on which is on wire bonds is in collabration with University of Nottingham, so we all the people who are involved with project RODENT meet up for a preliminary on what the proposal is for the project.

After I had a look at power elecronics, I thought I'd have a look at what the proposal meant I had to do. I did a bit of research on some papers and got some information.

Damage mechanics-When searching on wikipedia it redirect to Tribology. Which has something to do with the exposed suface of a solid interacting with materials or environment may result in loss of material from the surface. Tribology come from greek tribo-"I rub".

Wire bonding is the primary method of making interconnections between an Intergrated Circuit (IC) and a printed circuit board. Bond wires ususally consist of one of the following materials:

  1. Aluminium (Al)
  2. Copper (Cu)
  3. Gold (Au)
There are 2 main classes of wire bonding:
  1. Ball Bonding
  2. Wedge Bonding
Ball Bonding is usually restricted to gold or copper wire and usually requires heat. Wedge bonding can use either gold or aluminium wire, only gold requires heat. Both types the wire is attached using a combination of heat, pressure and ultrasonic energy to make a weld.

MOSFET stands for Metal Oxide Semiconductor Field effect transistor. This is an IC. MOSFET are fast switches which are turned on and off by applying a voltage to a gate terminal. They require a continuous gate source voltage in order to keep them in the on state. The switching is around 100 nano seconds which depends on a gate resistor.

IGBT stands for Insulated Gate Bioploar transistor, this is also an IC. IGBT are fast switches with high voltage and current capabilities. Commonly used in most of high power converters when fast switching is required. Off and ON process similar to MOSFET with high gate impedance which requires a small amount of energy to switch the device. Turn on speed of IGBT can be controlled by a gate resistor. IGBTs have turn on and off times in the order of microseconds. If an IGBT stucture Contains a parasitic thyristor, it should not be turned on or else the gate will lose the ability to turn off the device.

After this, I was given a set of papers to look at and see what they were doing. There is a lot of potential relevant stuff.

The next aims I have got is:

  1. Add more information to RDA1 form
  2. Do a literature review and write it up
  3. After attending Power electronics workshop, write up a summary of what I have leant and if any of it is relevant