Bridging Those L1's With DeFogger Paint

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Having spent the last few weeks surfing the net in search of such information and spent some many hours now developing a technique, I decided that the information might be beneficial to other newbies like myself.

The biggest problem facing anyone attempting this task is the absolute opposite. To say that these bridges are small is an understatement.

I am not going to produce a picture of the processor. If you haven’t seen one, then there are numbers of them all over the place. Suffice to say that the L1 bridges are clearly marked and, when looking at the processor the right way up so that the L1 is in its correct readable position, it is the top left row. The points of each bridge are approximately 1mm apart.

So what do you need to do the job? I recommend the following;

  1. A piece of sponge to sit the processor on to stop it being damaged and, more importantly, to stop it slipping around while you trying to do micro-surgery on it;
  2. A fairly powerful magnifying glass (unless you have incredible eye sight). I recommend the type that is mounted on a stand. The one I have cost a couple of Pounds Sterling and has clips for holding things – it makes for easy focus. I found that to do the job you need both hands, but that I’ll explain later;
  3. A jeweller’s or optician’s screw driver. They are common, coming in sets. The one I recommend is the smallest with a blade of about 1mm. The one I used has a 0.9mm blade;
  4. A good desk lamp with tilting head;
  5. A bottle of acetone – this is essential – available from your pharmacy. Make sure that there are no naked flames around this stuff – it is highly flammable!;

  6. Tissue type cloth that is used in good computer cleaning kits. It must not shed fibres – you don’t want to get those on the processor.

So let’s do it!

Place the processor on the sponge so that the L1 bridge is in fact upside down i.e., it is closest to you and in the bottom right hand corner. Get the magnifying glass and focus it so that you have about a 45 degree angle to the edge of the processor i.e., you can see the side and the top at the same time.

Clean the bridges with pure alcohol e.g. Iso-propyl alcohol or some of the acetone. I used a cotton ear bud for this. The area will dry quickly under the lamp.

The following is intended for right handers but if you are left handed, for left read right.

Give your paint a really good shake as per manufacturer’s instructions. Take the brush out and, while holding the brush in the left hand, take the blade of the screwdriver in the right hand. Starting about 80% of the way down, run the blade along the bristles so that a drop of paint about the size of a pinhead accumulates on the tip of the blade. See picture below:

Brush

Make sure that you keep the screwdriver in the same position i.e. don’t rotate it.

Put your right hand in your left so that the left hand steadies the right and, while looking through the magnifying glass, lower the screwdriver slowly so that it will come into contact with the surface – about 0.5mm to the left of the left-most bridge i.e. closest to the centre. The blade should be at about 60 degrees to the horizontal. See picture below:

Fuel Pump

The drop of paint should make contact with the bridge and trickle onto it to form a blob. If the drop on the blade was too big, you will see that the spread will be too big to do the next one and you must clean it off with some acetone, wiping outward toward the edge of the chip.

Clean the blade with acetone and you’re ready to do the next one to the right

Remember to ensure that each drop does not make contact with its neighbour!

When you have finished, be satisfied! The temptation to just add a little more to that bridge could be the straw that broke the camel’s back.

Leave it alone and go and have a cup of coffee or something stronger – you’re probably going to need it when it comes to firing that baby up. Good luck!

Remember though, it’s your chip and your work – I take no responsibility for what happens.

Rob Oats – UK


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