Process: Explore Aluminum etching starting 2013-06-05 ending 2013-06-05

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Outputs

Scheduled:

Method - luminum etching 1.00 Idea due June 5, 2013

a new method developed in-house for microfabrication - etching of aluminum using sodium hydroxide.

Completed: produces 1.00 Idea July 23, 2014
  Resource: Method - luminum etching: Aluminum etching method 1.00 Idea

Work

Planned Work: (Requirements are ordered by due date)

Work - R&D chemistry: 1.00 Time - Hours due June 5, 2013

JUNE 05, 2013
I needed a metal stamp to make Y connectors for 125um diameter PMMA fiber out of PCL (plastic that melts at 60C). I tried to make some molds from clay, but the material turned out to be to bridle. I brainstormed with Jonathan and was about to use the technique to make electronic boards, by etching copper using acid. Francois had told me a few weeks before that I could use sodium hydroxide to etch aluminum. So because I could not find an adequate copper plate I decided to play with aluminum.
I polished a small piece of aluminum and tried different techniques to apply a mark and to etch it. I used a thin kapton tape for the mask. The problem is that it detaches in places, and lets the solution go under it, producing nonuniform features. I also tried a few glues, 2 parts silicon cured with temperature and crazy glue, as a mask, and I could get under mm features, but very nonuniform, due to the fact that even these glues could detach themselves.
Need to document with pictures!!!
Another problem is the gain of the aluminum used. We need to find fine grain metal. Probably we should continue on the copper lead, since this is used in electronics to achieve fine traces. But etching aluminum seems to easy, that it is also worth exploring more.

JUNE 07, 2013
Tried other methods for etching aluminum. It turns out that we can etch aluminum using the feric chloride acid solution that is normally used for etching copper circuit boards. The reaction with the normal concentration sold for electronics is very fast, makes a lot of bobbles, is very turbulent, and doesn't produce a smooth surface.

Etching aluminum foil - I used a permanent marker to pattern the surface of an aluminum foil and plunged it into a diluted acid solution. The aluminum foil needs to be painted with the market on both sides. It worked, but the edges of the pattern aren't smooth enough. Moreover, the marker leaves microscopic holes and the acid goes in and makes the aluminum foil very porous. We need to find another way to protect the aluminum that we don't want to expose to etching and have higher resolution of the edge of the mask pattern. Applications are masks for UV or X-ray micromachining of polymer.

I went back to the idea of etching a positive pattern onto a piece of solid aluminum. I used kapton take to create a first mask, area to be etched. I used car paint to fill the pattern not to be etched. I used a heat plate to fast cure the paint. I removed the tape to leave only the painted area. I used a diluted feric chloride acid solution on a hot plate with a magnet to violently mix the solution. The mixing is needed in order to remove the bobbles that form on the surface. These bobbles increase the roughness of the surface. I also noticed that even if I mix fast there is still formation of a soft layer on top of the surface which will slow down the reaction and increase surface roughness. One idea around this is to insert silica powder into the solution and sonicate it, or use pipettes to pump high velocity fluid over the surface. I already identified a source for silica powder http://www.aliexpress.com/item/spherical-silica-powder/871186615.html

I also did some documentation and propagated the findings.
https://docs.google.com/document/d/1DfR_uwR0vUlF_UVJX1xeyFTCit2NBERz7g0-PvpMS1E/pub
I was also shopping for high power UV LED on Aliexpress, and identified a few candidates.
We'll make an order this weekend.
I created a webpage for microfabrication
http://www.sensorica.co/home/working-space/activity-clusters/manufacturing/sensorica-howtos/microfabrication-1

Taken by Tibi
Work events:
June 8, 2013 0.03 Time - Hours Done by Tibi

JUNE 05, 2013
I needed a metal stamp to make Y connectors for 125um diameter PMMA fiber out of PCL (plastic that melts at 60C). I tried to make some molds from clay, but the material turned out to be to bridle. I brainstormed with Jonathan and was about to use the technique to make electronic boards, by etching copper using acid. Francois had told me a few weeks before that I could use sodium hydroxide to etch aluminum. So because I could not find an adequate copper plate I decided to play with aluminum.
I polished a small piece of aluminum and tried different techniques to apply a mark and to etch it. I used a thin kapton tape for the mask. The problem is that it detaches in places, and lets the solution go under it, producing nonuniform features. I also tried a few glues, 2 parts silicon cured with temperature and crazy glue, as a mask, and I could get under mm features, but very nonuniform, due to the fact that even these glues could detach themselves.
Need to document with pictures!!!
Another problem is the gain of the aluminum used. We need to find fine grain metal. Probably we should continue on the copper lead, since this is used in electronics to achieve fine traces. But etching aluminum seems to easy, that it is also worth exploring more.

JUNE 07, 2013
Tried other methods for etching aluminum. It turns out that we can etch aluminum using the feric chloride acid solution that is normally used for etching copper circuit boards. The reaction with the normal concentration sold for electronics is very fast, makes a lot of bobbles, is very turbulent, and doesn't produce a smooth surface.

Etching aluminum foil - I used a permanent marker to pattern the surface of an aluminum foil and plunged it into a diluted acid solution. The aluminum foil needs to be painted with the market on both sides. It worked, but the edges of the pattern aren't smooth enough. Moreover, the marker leaves microscopic holes and the acid goes in and makes the aluminum foil very porous. We need to find another way to protect the aluminum that we don't want to expose to etching and have higher resolution of the edge of the mask pattern. Applications are masks for UV or X-ray micromachining of polymer.

I went back to the idea of etching a positive pattern onto a piece of solid aluminum. I used kapton take to create a first mask, area to be etched. I used car paint to fill the pattern not to be etched. I used a heat plate to fast cure the paint. I removed the tape to leave only the painted area. I used a diluted feric chloride acid solution on a hot plate with a magnet to violently mix the solution. The mixing is needed in order to remove the bobbles that form on the surface. These bobbles increase the roughness of the surface. I also noticed that even if I mix fast there is still formation of a soft layer on top of the surface which will slow down the reaction and increase surface roughness. One idea around this is to insert silica powder into the solution and sonicate it, or use pipettes to pump high velocity fluid over the surface. I already identified a source for silica powder http://www.aliexpress.com/item/spherical-silica-powder/871186615.html

I also did some documentation and propagated the findings.
https://docs.google.com/document/d/1DfR_uwR0vUlF_UVJX1xeyFTCit2NBERz7g0-PvpMS1E/pub
I was also shopping for high power UV LED on Aliexpress, and identified a few candidates.
We'll make an order this weekend.
I created a webpage for microfabrication
http://www.sensorica.co/home/working-space/activity-clusters/manufacturing/sensorica-howtos/microfabrication-1

June 7, 2013 6.55 Time - Hours Done by Tibi

JUNE 05, 2013
I needed a metal stamp to make Y connectors for 125um diameter PMMA fiber out of PCL (plastic that melts at 60C). I tried to make some molds from clay, but the material turned out to be to bridle. I brainstormed with Jonathan and was about to use the technique to make electronic boards, by etching cooper using acid. Francois had told me a few weeks before that I could use sodium hydroxide to etch aluminum. So because I could not find an adequate cooper plate I decided to play with aluminum.
I polished a small piece of aluminum and tried different techniques to apply a mark and to etch it. I used a thin kapton tape for the mask. The problem is that it detaches in places, and lets the solution go under it, producing nonuniform features. I also tried a few glues, 2 parts silicon cured with temperature and crazy glue, as a mask, and I could get under mm features, but very nonuniform, due to the fact that even these glues could detach themselves.
Need to document with pictures!!!
Another problem is the gain of the aluminum used. We need to find fine grain metal. Probably we should continue on the cooper lead, since this is used in electronics to achieve fine traces. But etching aluminum seems to easy, that it is also worth exploring more.

JUNE 07, 2013
Tried other methods for etching aluminum. It turns out that we can etch aluminum using the feric chloride acid solution that is normally used for etching cooper circuit boards. The reaction with the normal concentration sold for electronics is very fast, makes a lot of bobbles, is very turbulent, and doesn't produce a smooth surface.

Etching aluminum foil - I used a permanent marker to pattern the surface of an aluminum foil and plunged it into a diluted acid solution. The aluminum foil needs to be painted with the market on both sides. It worked, but the edges of the pattern aren't smooth enough. Moreover, the marker leaves microscopic holes and the acid goes in and makes the aluminum foil very porous. We need to find another way to protect the aluminum that we don't want to expose to etching and have higher resolution of the edge of the mask pattern. Applications are masks for UV or X-ray micromachining of polymer.

I went back to the idea of etching a positive pattern onto a piece of solid aluminum. I used kapton take to create a first mask, area to be etched. I used car paint to fill the pattern not to be etched. I used a heat plate to fast cure the paint. I removed the tape to leave only the painted area. I used a diluted feric chloride acid solution on a hot plate with a magnet to violently mix the solution. The mixing is needed in order to remove the bobbles that form on the surface. These bobbles increase the roughness of the surface. I also noticed that even if I mix fast there is still formation of a soft layer on top of the surface which will slow down the reaction and increase surface roughness. One idea around this is to insert silica powder into the solution and sonicate it, or use pipettes to pump high velocity fluid over the surface. I already identified a source for silica powder http://www.aliexpress.com/item/spherical-silica-powder/871186615.html

I also did some documentation and propagated the findings.
https://docs.google.com/document/d/1DfR_uwR0vUlF_UVJX1xeyFTCit2NBERz7g0-PvpMS1E/pub
I was also shopping for high power UV LED on Aliexpress, and identified a few candidates.
We'll make an order this weekend.

June 5, 2013 7.00 Time - Hours Done by Tibi

JUNE 05
I needed a metal stamp to make Y connectors for 125um diameter PMMA fiber out of PCL (plastic that melts at 60C). I tried to make some molds from clay, but the material turned out to be to bridle. I brainstormed with Jonathan and was about to use the technique to make electronic boards, by etching cooper using acid. Francois had told me a few weeks before that I could use sodium hydroxide to etch aluminum. So because I could not find an adequate cooper plate I decided to play with aluminum.
I polished a small piece of aluminum and tried different techniques to apply a mark and to etch it. I used a thin kapton tape for the mask. The problem is that it detaches in places, and lets the solution go under it, producing nonuniform features. I also tried a few glues, 2 parts silicon cured with temperature and crazy glue, as a mask, and I could get under mm features, but very nonuniform, due to the fact that even these glues could detach themselves.
Need to document with pictures!!!
Another problem is the gain of the aluminum used. We need to find fine grain metal. Probably we should continue on the cooper lead, since this is used in electronics to achieve fine traces. But etching aluminum seems to easy, that it is also worth exploring more.

Process context:

Pattern: Generic R&D
Context: Tape Sensor
Order: Work order 120 due: 2013-06-05

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Process notes:

Explore different inhouse and low cost etching techniques.