I suppose so. If you make longer exposures. My 500W has phosphor inside coating, to convert UV in visible "daylight" light. Maybe yours not.... Just make a test! ----- Original Message ----- From: Luis Moreira To: Sent: Monday, November 24, 2003 8:12 AM Subject: Re: [EE]:PCB etching: gravity method works > Hi Rafael > would it be possible to use an 80W bulb insted ? Is just for the fact that I > already have the complete thing. > thanks > Luis > > -----Original Message----- > From: Rafael Fraga [mailto:rfraga@SY-NAPSIS.COM] > Sent: 22 November 2003 15:07 > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [EE]:PCB etching: gravity method works > > > To get the best exposure time, do a test: > Use a strip of sensitized board, cover almost all of it with something > non-transparent *to UV* light, and do an exposure longer than expected. As > the time goes, say each minute, uncover a little part of the board. At the > end, develop and process as usual. This way, you will get under and over > exposures in the same board, so if you took notes of the times, you will get > the optimum exposure. > I use a 500W mercury vapor lamp (standard lightning lamp), getting around 18 > minutes at a distance of 20cm. > I use the gravity method, with saturated ferric chloride solution. As the > specific gravity of the solution is higher than the board, it floats easily. > Sadly, this is not so easy with ammonium perchlorate. > Photoresist: Kontakt Chemie Positiv 20, positive action, spray applied and > oven cured. > Anyway, craftsmanship and luck are essential > > Rafael Fraga > > > ----- Original Message ----- > From: Luis Moreira > To: > Sent: Saturday, November 22, 2003 10:09 AM > Subject: Re: [EE]:PCB etching: gravity method works > > > > Hi Rick > > because I whant to try to do some PCB's for 44 pin PQFP to 208 pin PQFP,I > am > > not sure about exposure time and etching times, how would you solve this? > > Luis > > > > -----Original Message----- > > From: Rick C. [mailto:rixy@VVALLEY.COM] > > Sent: 22 November 2003 12:41 > > To: PICLIST@MITVMA.MIT.EDU > > Subject: Re: [EE]:PCB etching: gravity method works > > > > > > P.S. If you use a casserole dish, the bottom is not flat, but slightly > > rounded. Thus, the resist does not make contact with the glass. Only the > > very corners of the board touch the glass and leave enough etch solution > > to work on the board. Providing heat will circulate the etchant > > sufficiently. Occasionally, lifting the board and exposing it to air > > will also speed up the etching. > > Rick C. > > > > "Rick C." wrote: > > > > > You can etch and make lines as small as you can lay out the board. > > > Etching with copper side down will speed up your process as noted in > > > paragraph 6 on my website http://www.pic101.com/pcb > > > > > > Negative photoresist method I find is very successful with quality > > > results. However, my supplier of sensitized boards, Kepro, is out of > > > business so I'm back to sensitizing my own boards now. > > > Rick C. > > > > > > Luis Moreira wrote: > > > > > > > Jinx > > > > did you ever use the photoresist method ? > > > > > > > > Luis > > > > > > > > ----- > > > > -- > > http://www.piclist.com hint: To leave the PICList > > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > > > -- > > http://www.piclist.com hint: To leave the PICList > > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > > > > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics