Photoresist PCB Etching

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Boards from have been tested and work with the method described below


Rub the developed board to remove the exposed portions of the plastic.


UV Exposure Box[edit]

UV Exposure Box


This wooden box contains eight ultraviolet UV-C germicidal lamps (type M6T5).

Health and Safety[edit]

UV-C light is dangerous! The radiation due to these lamps is harmful to the eyes and skin. You should not look at these lamps while they are on.


For this particular box the ideal exposure time is 4 minutes.

Product Information[edit]

Chemsavers Ferric Chloride Hexahydrate[edit]

Chemsavers Ferric Chloride Hexahydrate



CAS 10025-77-1

MF FeCl3.6H2O

MW 270.30


97.4% Purified

Health and Safety[edit]

"Causes eye, skin, respiratory, and digestive tract burns. Maybe harmful swallowed. May cause central nervous system effects, cardiac disturbances, liver and kidney damage. For laboratory use only. Not for drug, household or human consumption.

Mixing and Usage[edit]

Mix 200 g of ferric chloride into each 1000 ml of hot water.

Place your exposed board into the developer solution for two minutes. Move the container back and forth to keep a regular flow of solution across the surface of the board. Photoresist_PCB_Etching_Testing

It seems to take approximately 15 minutes of immersion in the etchant solution. This figure was determined while agitation the solution. More time is likely necessary if the board was just sitting still in the solution. The solution was tested at room tempreature. A shorter immersion time would be likely if the solution were at a higher temperature.

Seno 4007 Developer Powder[edit]

Seno 4007 Developer Powder

Original instructions

Mega Part number Mass Yield Volume
600-007 500 g 10 liter
600-008 50 g 1 liter
600-009 5 g 0.5 liter


A powder for making liquid developer for the processing of Mega's Fotoboard, FPC-16 and other alkaline-developed positive photoresists. Supplied as a powder to make 0.5 to 10 liters of developer solution.


4007 Seno developer is very stable and contains no "Caustic Soda" (sodium hydroxide NaOH). The developer has a high safety margin against over development. A board can be left immersed for up to 25 times longer than the normal, 30 seconds developing time without any risk of over developing or thinning a board's resist layer. The developer has a long life when used in a PCB processing tank, or when stored in an air-tight container.

Health and Safety[edit]

Full health and safety details. A report by an occupational hygienist concluded that, under the test conditions, NO LOCAL EXHAUST VENTILATION IS REQUIRED using this developer in Mega's PCB processing tanks. Copies of the report are available upon request from Mega Electronics Ltd..

Mixing and Usage[edit]

Fotoboard (1) and FPC 16 (1)[edit]

Mix 1 part developer with 9 parts cold tap water (500 ml with 4.5 ml to make 5 ml). WIth this mix and using our fotoboard image will appear in 20 to 30 seconds. Board should be fully developed in 1 to 2 minutes depending on temperature. Should be 18 to 24 degrees C. If not developing properly or takes a long time add 100 to 200 ml conc. to your working solution. Repeat as necessary.

Fotoboard (2) and FPC 16 (2)[edit]

If the above concentrations are used with Fotoboard (2) resist the image will develop within 15 seconds when it should be rinsed immediately. For greater safety margin against over-development, use at half strength (250 ml developer concentrate to makeliters of working solution) Please note that reducing developer strength may result in the solution having a shorter working life.