TECHNICAL DATA SHEET 1/4 POSITIV 20 Ref. : 20820 1. GENERAL DESCRIPTION Liquid photo-positive resist based on o-naphto-chinon-diazide and Novolack, used in the production of printed circuit boards. 2. FEATURES POSITIV 20 is a classic liquid photo-resist that transfers patterns directly onto working materials for processing by etching. The lacquer resists strong acidic etching products however can be easily be removed by solvents (ester, ketone) or aqueous alkalines. The lacquer is at its most photo-sensitive at close utlra-violet range (UVA). The lacquer should therefore be applied in yellow light or darkened daylight. 3. APPLICATIONS The main application for POSITIV 20 is the production of printed circuits boards. The transparent positive-pattern from the circuit diagram is accurately transferred. Surfaces impervious to light e.g. the electrical circuits, do remain present after etching. Other application include photo-lithographics on metal or glass. 4. DIRECTIONS Directions in producing printed circuits 4.a. Surface preparation Surfaces must be free of grease and oxide. A water-based cleaning process is available. When preparing metal surfaces manually, household scouring powders are ideal. Solvents are only used when dirty, oily stains have to be removed. The last step in the cleaning process should be rinsing with demineralized water. At this stage the cleaned surface should be fully wetable and hence no water repellant areas should be left. The cleaned board should be left drying in a dust-free environment. 4.b. Coating Following the cleaning stage, the horizontally positioned copper plate is coated by spraying (aerosol) from a distance of 20 cm. Best result in getting a uniform coating is obtained by continuously spraying in a zigzag pattern. A typical coat thickness is 6-8m and has a bluish colour. To overcome discontinuities while spraying, the aerosol can should not be held too tilted. Manufactured by : CRC Industries Europe NV Touwslagerstraat 1 9240 Zele Belgium Tel (32) (0) 52/45.60.11 Fax (32) (0) 52/45.00.34 www.crcind.com TECHNICAL DATA SHEET 2/4 POSITIV 20 Ref. : 20820 The lacquer is sensitive to UV-light and hence exposure to direct sunlight or bright day light should be avoided. Coated materials can be stored in the dark at 25C for up to 4 weeks. 4.c. Drying After application of the film, boards must be dried immediately in the dark. The drying temperature should be increased slowly to 70C and kept at that temperature for approximately 15 minutes. Infrared or forced air drying is possible. When air drying at ambient temperature is used (24 hrs minimum), the quality of the film will only allow very simple work. The adhesion is poor and the danger for dust entrapment and pinholes is high. 4.d. Exposure The transparent circuit diagram must be placed flat and error free on the copper plate. Paper based diagrams can be made transparent using Kontakt Chemie TRANSPARENT 21. The spectral sensitivity for the photo resist POSITIVE 20 lacquer lies in the wave length range 340 to 420 nm, so one can use UV-lamps to expose the film/copper plate. At an exposure strength of 100 mJ/cm the exposure time will be approximately 10 seconds for a film thickness of 8m. In practice the exposure time is between 60 and 120 seconds when lamps are used from a distance of 25-30 cm. It is recommended to allow the lamps to warm-up for approximately 3 minutes. 4.e. Developing The exposed plate is being developed by immersion in a sodium hydroxide bath (10 g/l sodium hydroxide in water) at ambient temperature for approximately 60 seconds. The exposed lacquer dissolves. The developing process can be assisted by minor bath agitations. After developing, the plates are rinsed thoroughly with water. 4.f. Etching Etching of copper and brass plates is best done with an iron-3-chloride solution (400 g/l water). The required time is between 30 and 60 minutes. Warming-up the solution to 40C plus minor bath movements will assist the etching. At the end of the etching process, plates should be rinsed excessively under running water. Manufactured by : CRC Industries Europe NV Touwslagerstraat 1 9240 Zele Belgium Tel (32) (0) 52/45.60.11 Fax (32) (0) 52/45.00.34 www.crcind.com