12-13 April 2010

This is the start of a brand new week. I started off with yet another educational visit around the assembly line, led by Miss Manggala. This time around, I was brought to a few compartments designated for research and experiment purposes. I was introduced to several experienced personnel, who greeted me with some typical questions like how long will I be having my internship, where do I live, where am I studying and so forth. All of them were undeniably jovial and gregarious as uproarious mirth filled the air. However, after I left those rooms, I could sense their taciturnity as they cut a forlorn and morose figure beneath those cheerful semblances as they returned to their respective operating position. Maybe this is what we known as Monday Blues.

Later on, Miss Manggala told me to roam around, be acquainted with the environment, and to observe the actions carried out by the assembly line staffs, be it front end, mid end or back end staffs. First off, I stumbled upon the terms batch number, index number and shift number. Basically, they refer to the output quantity. However, there are few distinctions. Batch number refers to the current die type output quantity. Index number refers to the number of dies produced, regardless of the die type, as the machine senses the number of index hole on the lead frame instead of the individual dies. Customarily, batch number is the same as index number. Next is shift number which refers to the output quantity that the current shift has produced. For your information, there are three working shifts. Apart from that, I also came across terms such as processed die, remaining die and units per minute. As I had mentioned in previous posts, each wafer may contain hundred thousand of dies. Processed die connotes the idea of how many dies that had been extracted by the die bond machine for the bonding processes; and as the name itself implies, remaining die tells us the number of available die on the wafer. Note that the processed die value is inadvertently greater than that of batch number as some dies may be substandard and duly discarded. Moving on, units per minute suggest the speed at which the machine operates. For typical die bond processes using ADAT 2 Machine, the speed is approximately 302 units per minute!

Besides that, I had also observed how the technicians carry out wafer substitution to replace exhausted wafer. Normally after replacing the wafer, they will use Propane to clean up the tip of the machine which is used to extract dies from the wafer. Moreover, these technicians will rely on the alarm triggered or visual inspection of operation light on each machine to realize erroneous processes had occurred. As usual, green light brings about the idea of normal, error-free production process, whereas red light impinges on the notion of error occurrence. Yellow light, on the other hand, indicates that the machine is in idle mode. Furthermore, I had also witnessed how welding processes were done to combines separate lead frames. Lead frames are stored in circular reels. These reels of lead frames serve as the input to almost all machines. As these reels run out of lead frames, production process at that machine will be stopped, pristine reel of lead frames will be attached to the machine, replacing the exhausted reel. The lead frames of the previous reel will now be welded together with that of the new reel, using a welding machine.

As I saunter more, I discovered more. I perceived how the indefatigable operators conduct wafer mounting processes using an expansion device. I also got to see how the dies, wire bonds look like under microscopes. The operators were obliging and helpful as they effortlessly explained coherently what variables that could culminate in imperfect dies or bonds. For instance, excessive bond force exerted by the PHICOM wire bonding machine will engender flawed bond shape.

After those horizon broadening encounters, Miss Manggala came back for me and taught me how to measure wire bond height as well as bond diameter. The microscope meant for this is not just ordinary microscope. It is a highly sophisticated microscope that can enable us to see minute object measuring few micrometers clearly. I spent few hours measuring 16 samples of lead frames. Each sample will have 15 entries of bond height as well as 15 entries of bond diameter. Indolence and nonchalance started to kick in due to the monotonicity but my forbearance prevailed. In fact, I got a little bit exhilarated as I was able to see how the dies, the bonds, the lead frames look like under the microscope.

I could not finish the measurement today as there were a lot of operators who had queued up the utilize that machine. I felt like I was an eminent singer who has long queue of ardent fans jostling for my autograph. Finally, they asked me if I could return tomorrow for the measurement and I duly obliged. I returned to my desk where I was given the third package, SOT363 to update the bonding diagrams.

By the end of 13 April 2010, I completed updating the SOT673 package bonding diagrams, which takes the amount of bonding diagrams that I had encountered so far, to approximately 300. However, the same cannot be said of the measurement of bond height and bond diameter as the device was so in demand I could only use it for short periods of time.