Acid Etching Documentation
The following with discuss all parts of the acid etching process. This includes the equipment and chemicals needed, along with the procedure and safety requirements for performing this experiment.
Equipment and Chemicals
Personal Protective Equipment
- Lab Coat
- Lab Apron
- Heavy Rubber Gloves (Preferrably Elbow Length)
- Face Shield (8-inch)
- Chemical Splash Goggles
- If performing work in fume hood, respirator not required
- Standard lab attire (ie. pants, close toed shoes, etc.)
- Evaporating dish (150 ml)
- Ceramic Dish (as large as you want, usually around 35-150 ml)
- Acetone (Any Grade will do)
- Red Fuming Nitric Acid (RFNA)
- Note that Nitric Acid used should be higher than 90% grade
Users should take note, RFNA is federally regulated and requires certain training to utilize. Extreme caution should be taken when using RFNA as improper handling of chemical can be deadly. Users should refer to the Fuming Nitric Acid MSDS before handling.
This procedure is fairly straight forward once you obtain the equipment and chemicals. All work should be done under a fume hood unless noted otherwise. This procedure contains two main areas: CNC Pocket Milling, and Acid Etching.
CNC Pocket Milling
In order to contain where the acid dissolves the packaging of the chip, a small "pocket" must first be milled into the top of the chip. To do this, we must first come up with a 3D model of the chip in a CAD software that is compatable with the CNC machine we are going to use (we used SolidWorks for this). Once we have modeled the chip in the CAD program, we drew up a 10x10x0.25 mm pocket that we cut out of the chip (The depth of 0.25 mm can vary, the absolute deepest you should go to avoid damage to the die is 0.25 mm). An example of what the 3D model should look like can be found here: INSERT IMAGE HERE
Once this 3D model is complete, take the chip to a CNC machine (the mechanical engineering department has CNC labs and techs that can do this work for you) to have the pocket milled out from the chip.
RFNA is extremely toxic and any unnecessary contact should be limited. At room temperature, RFNA gives off highly toxic vapors which can be deadly if inhaled. Below are listed specific health effects and first aid measures.
Potential Health Effects
- May be fatal if inhaled. Material is extremely destructive to the tissue of the mucous membranes and upper respiratory tract. Causes respiratory tract irritation.
- Skin Contact
- May be fatal if absorbed through skin. Causes skin burns. Causes skin irritation.
- Eye Contact
- Causes eye burns. Causes severe eye burns. Causes eye irritation.
- May be harmful if swallowed.
First Aid Measures
- In case of Inhalation
- If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician.
- In case of Skin Contact
- Take off contaminated clothing and shoes immediately. Wash off with soap and plenty of water. Take victim immediately to hospital. Consult a physician.
- In case of Eye Contact
- Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.Continue rinsing eyes during transport to hospital.
- In case of Ingestion
- Do NOT induce vomiting. Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.