One of more advanced PCB manufacturing methods is exposing laminate copper boards covered by photo resistive layer through mask. Using UV light in manufacturing PCBa‚¬ s has many benefits according to other methods: you can get thin tracks like 0. 2mm. You couldna‚¬ t do this by using other home techniques like laser printers or hand artwork; oth
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er advantage is that this method gives clean image a‚¬ smooth edges of PCB tracks. Little bit effort and you can compare results to commercial products. And pf course third benefit is speed and multiple replications of your boards by using the same mask. In this article is described the manufacturing of an automatic ultraviolet light source exposure box. POWER switch is used to turn on/off power of the UV box. Green LED indicates the ON. MANUAL/AUTOMATIC switch is used to power l the UV lamps manually or automatically. Switches UPSIDE and UNDERSIDE are used to enable upper and lower lamps separately a‚¬ in case you are using single or double sided boards. When automatic mode is selected, then by pressing buttons MIN UP, MIN DOWN, SEC UP, SEC DOWN exposure time is selected. START starts timer counter and powers the lamps through relays. STOP/CLEAR is not implemented yet. LCD displays the Time of exposure, and after start is pressed it shows remaining time of UV exposure. Control circuit is very simple. Buttons are connected directly to I/O pins through internal Pull-Up resistors. When button is pressed a‚¬ the a‚¬ 0a‚¬ level in port input is generated, which triggers an action. UV lamps are connected in series of 2 and then ballasts are connected. Starter is connected to lamps in parallel. Upper and lower covers of box can be controlled separately by using switch. In this circuit you can also see power control for...
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