Some questions about lapping

[jeb1517]

1) After attaching the sandpaper to a flat surface, do you move it across the cpu, or does the sandpaper stay stationary and the cpu is what you move over the sandpaper?

2) Do you go in the same direction for a little while, then the opposite way while using same grit? Or like back and forth? I know you should turn the CPU after a little bit too.

3) I know you're supposed to use soap and water or some lubricant, do you just put some directly on the sandpaper? Or like the back of the sandpaper and let it seep through to the other side? Also, if you're using water, the CPU is going to get wet isn't it? I found it surprising you could use water, do you just dry the CPU with a blow dryer or something afterwards?

 

[Groveling_Wyrm]

I highly recommend that you use GOOGLE and search for answers. There are several different ways of going about it, and you are going to get several different answers on how to do it.

The best way is to research it and find out for yourself. However, you did ask the questions, and I will answer to the extent of my experiences.

1) Generally, the item being lapped is moved across the sand paper, while the sand paper remains still.

2) There are varying ways of doing this. Generally the methods used by most experienced lappers either go in a figure 8 motion, or sand in a single direction, lift the item being lapped up, and move back to starting position, sand again several times, then rotating the item 90 degrees, sand more, rotate, sand more, rotate, sand more...etc...until it is sufficiently sanded.

3) Generally, most people do simply put the lubricant on the sandpaper, on the rough side. As far as water goes, that's a matter of preference. Water is a good cleaning agent, keeping the sandpaper from filling up with metal filings, but it can also cause rust or tarnish. It is a matter of opinion on whether water is better. As to the question of getting the heatsink wet, when lapping, it will get wet with the lubricant, no matter what you use. Yes, you simply wipe the heatsink off or use alcohol or some other cleaning agent after lapping. You would want to use a cleaner that does NOT leave residue though.

Now, I have answered your questions. If you have further questions, you should research them yourself before you try lapping.

 

[little_scrapper]

You definately move the CPU over the sandpaper which should be tapped to a glass table or something very flat.

I personally did a back and fourth for 2 minutes, rotate clockwise 90 degrees, back and fourth for 2 minutes, rotate clockwise 90 degrees.....start with a 200 grit. If you start with a 400 or something it will take you twice as long to get rid of the plating on the copper.

I just put a few tbl spoons of water on the paper. The IHS is sealed so the water should not get under it. the contacts are gold and will not rust. just clean the CPU really good when your done.

 

[Mugz]

I used 200 grit to start, then 400, then 800, then burnishing compound. Finally I used alcohol to clean it (medical alcohol, not vodka). Sandpaper was stuck to a flat surface and I used a figure-8 motion.

Made a 7ºC difference with my Pentium D 805.

It's also a good idea to lap the heatsink itself too... and don't forget the thermal gel.

 

[jeb1517]

Thank you very much guys.