Typically dies are moved around with tweezers.

Metal tweezers

Do not use metal tweezers to handle dies. It is very easy to apply too much pressure and chip dies.

Carbon fiber tweezers

Preferred method used by cleanrooms. These are unfortunately the most expensive as well. on eBay you can pick up a pair for $15. Typically they have a metal body and a (screwed on) carbon fiber tip.

WARNING: these are epoxy / resin filled. Do not expect them to be resistant to acids and be wary of acetone. (as I realized the hard way…)

Trim brand Carbon Tip Pointed Tweezers are an inexpensive brand intended for hair removal. They don't have a sharp tip but work well enough for general handling. I got them when they were cheap on eBay but still can be found around (example)

Advantages

  • Very gentle on die
  • Durable

Disadvantages:

  • Expensive
  • Less chemical resistant than some plastic tweezers

Plastic tweezers

These tend to be the best compromise between price and performance. They do vary though as to their chemical resistance and cleanliness.

“Antistatic type” tend to have better chemical resistance

Advantages

  • Low cost
  • Moderate chemical resistance (depends on brand)

Disadvantages

  • Vary considerably
  • Brittle: easy to snap tip off, difficult to use after that. I have also had problems with some coming compressed and trying to splay them to make them springy has resulted in them snapping in half.

Brand notes

9330X

These are very common on eBay. They come in a few different sizes and sell for something around 2 / 2$. They have a large mixed particle content (glass and ?) which makes them somewhat resistant to acetone. Here is a pair that was in acetone for a short period of time:

It will leave black streaks when wiped after exposure. Additionally it will flake off particulates which is bad for keeping dies clean.

Example models:

  • 93307
  • 93302: the tip is longer than the 93307 but otherwise identical (other than the number)

93307 tip top, 93302 tip bottom:

ProsKit

I got these as a Jameco antistatic tweezer set.

This seems to have good resistance against acetone. Here is a well used tweezer:

Although its dirty its still in very good shape. Getting it wet with acetone and wiping it doesn't leave a black streak.

Advantages:

  • Good chemical resistance
  • Soft against dies

Disadvantages:

  • More expensive than other brands

Tweezers

Tweezers are often useful for several purposes including picking dies out of chemical solutions (acid, acetone), plucking bond wires, and general handling. Each has its own issues that make different kinds of tweezers useful.

General handling

Plastic tweezers are preferred as they tend to cause less damage.

Plucking

Hold the die with those described in “general handling.” If you are plucking by knocking wires off, definitely go with plastic. If you are coordinated, metal tweezers are preferred for normal plucking. Otherwise, go with plastic if you think you might slip and hit the die. It won't grip as well and will probably degrade much faster, but will be safer for the die.

Acetone

Useful for pulling dies out of rinse solutions. Some tweezers are resistant, others aren't. Wet a paper towel with acetone and try rubbing the upper area of the tweezers. If plastic comes off, its no go. TODO: get a list of some known acetone resistant tweezers.

Nitric acid

Plastic aluminium, or stainless tweezers. Unknown if any plastics react with nitric? If you need to pull it out of hot acid, definitely go with aluminium. Stainless is also pretty resistant to nitric acid.

Sulphuric acid

Plastic (or maybe stainless?) tweezers.

 
equipment/handling.txt · Last modified: 2013/11/10 18:10 by mcmaster
 
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution 4.0 International
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki