Removal of selected portions of protective coatings from substrates

1. A method for selectively applying a moisture-resistant protective coating to an electronic device subassembly, comprising:

applying a moisture-resistant protective coating comprising poly(p-xylylene) to one or more electronic components of the electronic device subassembly; and

dispensing a removal medium comprising particulate solid carbon dioxide on at least one selected portion of the moisture-resistant protective coating on the one or more electronic components of the electronic device subassembly to selectively remove the at least one selected portion of the moisture resistant protective coating to expose at least one selected component or feature through the moisture-resistant protective coating.

2. The method of claim 1 , wherein the electronic device subassembly is configured to be installed inside an electronic device.

3. The method of claim 1 , wherein dispensing the removal medium comprises exposing an entirety of the at least one selected portion of the moisture-resistant protective coating to the removal medium.

4. The method of claim 1 , wherein dispensing the removal medium comprises exposing a periphery of the moisture-resistant protective coating to the removal medium.

5. The method of claim 1 , further comprising:

aligning and positioning a template over the protective coating with the at least one selected portion of the protective coating exposed through an aperture in the template before dispensing the removal medium on the at least one selected portion of the protective coating.

6. A method for selectively applying a moisture-resistant protective coating to an electronic device subassembly, comprising:

applying a moisture-resistant protective coating comprising poly(p-xylylene) to one or more electronic components of the electronic device subassembly; and

positioning a removal tool or the electronic device subassembly relative to each other such that the removal tool is at a given position relative to at least one selected portion of the moisture-resistant protective coating and using the removal tool to direct a removal medium comprising particulate solid carbon dioxide onto the at least one selected portion of the moisture-resistant protective coating to selectively remove the at least one selected portion of the moisture-resistant protective coating and expose at least one selected component or feature through a remainder of the moisture-resistant protective coating.

7. The method of claim 6 , wherein positioning the removal tool or the electronic device subassembly relative to each other comprises manually positioning the removal tool or the electronic device subassembly.

8. The method of claim 6 , further comprising:

aligning and positioning a template over the protective coating with the at least one selected portion of the protective coating exposed through an aperture in the template.

9. The method of claim 6 , wherein positioning the removal tool or the electronic device subassembly relative to each other comprises automatically moving the removal tool or the electronic device subassembly while using the removal tool to direct the removal medium onto the at least one selected portion of the protective coating.

10. A method for selectively applying a moisture-resistant protective coating to an electronic device subassembly, comprising:

applying a moisture-resistant protective coating to a plurality of components and features of the subassembly configured to be installed inside an electronic device; and

automatedly moving a removal tool or the electronic device subassembly relative to each other to position the removal tool over at least one selected portion of the protective coating while using the removal tool to direct an abrasive removal medium comprising particulate solid carbon dioxide onto the at least one selected portion of the protective coating to selectively remove the at least one selected portion of the protective coating from at least one selected component or feature of the plurality of components and features of the subassembly and to expose the at least one selected component or feature through a remainder of the protective coating.

11. The method of claim 10 , wherein using the removal tool to direct the abrasive removal medium onto the at least one selected portion of the protective coating comprises using the removal tool to direct a focused stream of the particulate solid carbon dioxide onto the at least one selected portion of the protective coating.

12. The method of claim 10 , wherein applying the protective coating comprises applying a moisture-resistant coating to the plurality of components and features of the subassembly.

13. The method of claim 12 , wherein applying the protective coating comprises applying a poly(p-xylylene) coating to the plurality of components and features of the subassembly.

14. The method of claim 1 , wherein dispensing a removal medium comprises dispensing the particulate solid carbon dioxide at a feed rate of about 1 pound per minute.

15. The method of claim 1 , wherein dispensing a removal medium comprises dispensing the particulate solid carbon dioxide at pressure of about 40 psi.

16. The method of claim 1 , wherein dispensing a removal medium comprises dispensing the particulate solid carbon dioxide with a diffuser nozzle.

17. The method of claim 1 , wherein dispensing a removal medium comprises dispensing the removal medium through a nozzle having a diameter of about 0.018 mm to about 8 mm.

18. The method of claim 1 , wherein applying a moisture-resistant protective coating comprises applying a moisture-resistant protective coating to one or more electronic components positioned on a printed circuit board of the electronic device subassembly, and wherein dispensing a removal medium comprises dispensing the removal material on the one or more electronic components positioned on the printed circuit board.

19. The method of claim 1 , wherein the removal medium is dispensed from a removal element, and wherein the method further comprises automatically moving the removal element or the electronic device subassembly relative to one another while dispensing the removal material.

20. The method of claim 19 , automatically moving the removal element or the electronic device subassembly relative to one another comprises moving the removal element or the electronic device subassembly in a scanning motion relative to one another.

21. The method of claim 1 , wherein dispensing the removal medium comprises dispensing a focused stream of the particulate solid carbon dioxide.

22. The method of claim 1 , wherein the one or more electronic components of the electronic device subassembly comprise one or more completed functionable electronic components.

23. The method of claim 22 , wherein the one or more completed functionable electronic components comprise a processor, a microcontroller, or a memory device.

24. The method of claim 6 , wherein using the removal tool to direct a removal medium comprises dispensing the particulate solid carbon dioxide from the removal tool at a feed rate of about 1 pound per minute.

25. The method of claim 6 , wherein using the removal tool to direct a removal medium comprises dispensing the particulate solid carbon dioxide at pressure of about 40 psi.

26. The method of claim 6 , wherein using the removal tool to direct a removal medium comprises dispensing the particulate solid carbon dioxide through a diffuser nozzle.

27. The method of claim 6 , wherein the one or more electronic components of the electronic device subassembly comprise one or more completed functionable electronic components.

28. The method of claim 27 , wherein the one or more completed functionable electronic components comprise a processor, a microcontroller, or a memory device.