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Old 30th Jun 2017, 5:58 pm   #1
David G4EBT
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Default UV Dry Film PCB technique - experiences to date.

In a thread now closed, some months ago I mentioned that this technique - which was new to me at the time - seemed to hold much promise, and seemed maybe a little too good to be true! Up to that point, for many years I'd used self-spray positive resist UV lacquer, which can be difficult to apply in terms of excluding dust and pollen floating around, indoors or outdoors. Generally, I held a plastic container above the board to exclude dust while spraying, then lowered the container over the board while it dried, then put it in a desk drawer overnight to harden off. It has to be on a perfectly level surface when spraying, or it runs to one end and leaves an uneven layer of lacquer. (I haven't used pre-sensitised boards for many years as I always ended up with useless offcuts, and with self-sprayed boards, if they're under-exposed, you can always wipe off the lacquer and re-spray the board).

Last Autumn I learned of the negative UV dry film technique and from youtube videos it seemed to hold much promise. The film is cheap and sells in large quantities on e-bay, both with suppliers in the UK and from China. Typical ebay prices are UK suppliers £7.99 post free for 30cm x 5M roll, China, 15cms x 2 M £3.00, 30cms x 1M £2.50 post free.

Initially I tried a 15cms x 2M roll, but it had been squashed flat on it's way to me, so the film was creased and wrinkled and even when the backing film is stripped off, the wrinkles remain. OK for very small boards - say 25mm x 50mm, but no use for anything larger. I then bought a 2M x 30cms roll which came on a still cardboard roll, but nevertheless, it has a few wrinkles as it comes off the roll, and I've found it next to impossible to exclude every single tiny air bubble when applying the film. When passed through the laminator, these air bubbles become more prominent and when the board is developed, it leaves a few blemishes which - if etched - would eat into the tracks.

I recently designed a PCB for the AM/FM converter which featured in Summer 2017 BVWS Bulletin, the original of which built on strip-board, which I dislike with a passion. I've had two attempts today and applying the film and exposing and developing the board. Not happy with the first attempt, so cleaned off the exposed and developed UV lacquer with acetone and had a second go. The second one was more successful. Firstly, though most videos show several passes of the board through the laminator to attach the film to the PCB, only one pass is necessary and any more seems to wrinkle the film and make matters worse. This second attempt left just a few blemishes, which I'll use rub-down transfers to correct prior to etching.

The board is a simple one and only 10.5cms x 4.5cms, but it seems to me that the larger and more complex the board the less the chances are of a successful outcome. However, the upside is that the layer of resist left on the board is quite thick and can be felt by running a finger over the tracks. Exposure time seems uncritical - I used 1 minute in a 2 x 8W box. The sodium carbonate ('soda ash') used as the developer is cheap - typically £5.50 a Kilogram post free on e-bay. Only 5 gms (one level teaspoon) per 100ml of water is needed, so 2 level teaspoons is 200ml of water is ample. I used an empty margarine container and ran a piece of kitchen roll over the board to wipe off the dissolved lacquer, then rinsed in clear water.

I've attached a pic of the board showing the blemishes.

The artwork for the mask has to be a negative but it only takes seconds to change a positive to a negative using MS 'PAINT. You open the file in ‘PAINT’ then use the ‘Select’ option and with the mouse, select the image. Then right click on the image and a drop-down menu will appear. The bottom option on that menu is ‘invert colour’. Select that option and left click, when it will invert the colour to create the negative. Click on ‘save as’ and rename the image ‘PCB negative’ or whatever. I then reverse the image, so that when printed, the ink will be on the side of film next to the PCB in the exposure box to prevent 'undercutting' the tracks when exposed. By adding some lettering to the design, that obviates and confusion as to which way round the artwork needs to be when placed in the box. If you can read the lettering, it's the right way round.

I use 'micro-porous film' and an ink jet printer for the UV mask - totally opaque - far superior to OHP film, and far better than a laser printer. (Most youtube videos using masks printed on laser printers use two or even three layers of film taped to each other to get sufficient opacity). I print a sheet of two positive and two negative layouts to keep my options open. Attached below is the track layout I've devised. Though I've carefully checked it against the circuit, until the converter has been built and tested, I've added it just for interest. The terminations on the little FM module - 'U2' are non-standard, in that unlike DIL ICs, they're not on a 2.5mm grid. I've correctly spaced them to enable the module to be soldered in using veropins.

I know that homebrew PCBs are a minority interest on the forum and my prime reason for this thread isn't to open a discussion about the merits of various PCB techniques or other options - it's simply about the dry film UV technique. I'd be interested to learn of anyone else's experience if they've used the dry film process as a hobbyist, and if they've found a successful way of fixing the film without blemishes. ('Big Clive' who has quite a following on youtube applied his film by wetting the board with water, apparently with success, but I've not tried that).

Has anyone given it a go please?

Previous thread:

http://www.vintage-radio.net/forum/s...=132065&page=2
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Old 30th Jun 2017, 7:20 pm   #2
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Default Re: UV Dry Film PCB technique - experiences to daet.

I worked at a place with a PCB shop. Dry film resist was used. The area working with it had yellow lights and filtered windows from the adjacent areas with plain fluorescent lights.

Air was clean-room filtered and the film was applied with a very high pressure on the roller.

Artwork was photo-reduced from 2:1 tapemasters onto very high density monochrome emulsion film.

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Old 30th Jun 2017, 7:34 pm   #3
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Default Re: UV Dry Film PCB technique - experiences to daet.

Thanks for reading David, and for your interesting comments.

Ooops - seemingly I can spell 'experiences' and can spell 'daet' but not 'date'.

How embarrassing.

As Captain Mainwaring would have said: 'Stupid boy'.
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Old 4th Jul 2017, 8:08 pm   #4
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Default Re: UV Dry Film PCB technique - experiences to date.

Reading/watching with interest, David, as I'm in the final stages of my light box. Problem I'm finding is getting small quantities of negative developer so I can play. Positive is easily obtainable in small quantities, but price of board is high, and I've still got a quantity of reject board from one of my work places. ( board that failed QA was dumped, but if you knew the blokes in that area, a trade was possible). I've never had any success with spray photo resist.
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Old 4th Jul 2017, 9:47 pm   #5
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Default Re: UV Dry Film PCB technique - experiences to date.

Quote:
Originally Posted by Oldcodger View Post
Reading/watching with interest, David, as I'm in the final stages of my light box. Problem I'm finding is getting small quantities of negative developer so I can play.
The negative film developer is sodium carbonate, commonly known as 'soda ash' used extensively in water softeners.

It's widely available in small quantities on ebay (from 100g upwards). You need a solution of 100 ml of water to 1 – 2 grams of Sodium Carbonate, so 1 Litre of water requires 10 – 20 grams of sodium carbonate. 1 gram is 1 level teaspoon, (which is 5ml). I usually make 250ml of developer, stirring 5 grams of crystals into 250ml of lukewarm water. I've developed a board today - it only takes about 30 secs - I keep taking it out of the developer and gently rubbing it with kitchen roll, which is slightly abrasive, till it's all dissolved, then rinse it in clear water. The dissolved UV film turns a sort of 'soapy' grey colour and texture. Being negative film, it's the unexposed areas that dissolve, and the exposed areas remain on the board as the PCB tracks - the opposite of positive resist.

Really, 100grams is all you need to start you off - that would make up to ten Litres of developer. That would only set you back £1.79, post free from a UK supplier. EG, this one will supply 100G upwards (100g £1.79, 1kG £5.99) post free:

http://www.ebay.co.uk/itm/Sodium-car...r=440395731468

250grams here for £2.80 post free:

http://www.ebay.co.uk/itm/250g-Sodiu...gAAOSwyQtVlYtf

It's much cheaper than positive resist developer - lab grade sodium metasilicate pentahydrate is typically £12.99 per kG post free from a reputable UK supplier.
Or the same quantity can be had from Maplin at £33.28. (I won't mention MEGA).

Hope that helps a bit - good luck in your endeavours..
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Old 5th Jul 2017, 8:07 pm   #6
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Default Re: UV Dry Film PCB technique - experiences to date.

Many thanks, David- I've ordered some. Box finished, and I've managed to get a start up setting of just over 30s , and with a lin pot of 470 k, and a graduated knob, that will give me a max time of over six minutes - plenty of scope for playing , as I've "guestimated" a few measurements on tube spacing and height to PCB.
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Old 5th Jul 2017, 9:22 pm   #7
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Default Re: UV Dry Film PCB technique - experiences to date.

Well done on the progress to date. I don't think anything is critical. Provided you've got a totally opaque PCB mask which allows no light through when held up to a light, you can't really 'over expose' a board, but of course you can under expose it. In days gone by, when I used to rely on acetate photocopier copies and tape two or three together to try to maximise opacity of the tracks, exposure time was certainly critical and hit and miss. I either ended up with lacquer still on the board with no sign of any tracks, or lacquer totally dissolved from the board, (with no sign of any track), or if I was lucky, a usable board.

One definition of insanity is doing the same thing over and over again and expecting a different outcome.

Now that I use micro-porous film, providing a totally opaque mask, I find that 60 seconds exposure is fine for dry film negative resist, and four minutes for positive lacquer. I always warm up the tubes for five minutes before I use the box. No idea whether the need to do that is just an 'urban myth' or whether it does make a difference - people say the same thing about warming a teapot with hot water before making a pot of tea!

Have fun.
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Old 7th Jul 2017, 12:56 am   #8
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Default Re: UV Dry Film PCB technique - experiences to date.

Quote:
Originally Posted by David G4EBT View Post
I always warm up the tubes for five minutes before I use the box. No idea whether the need to do that is just an 'urban myth' or whether it does make a difference
I've always warmed my lightbox tubes too (although for 15 mins) and did find that if they weren't warmed, the exposure results were variable at times.

One place I worked at had theirs permanently on during the day (it had shutters that opened and closed to admit the light to the pcb material).

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Old 8th Jul 2017, 7:28 pm   #9
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Default Re: UV Dry Film PCB technique - experiences to date.

Looking back at #1 ,where David said he used Paint to invert the colour. I use Express PCB for the PCB layout and found a Prntscr copy to Paint always gave produced a larger than life result- dimensions were odd percentages larger than the original and it was almost impossible to get the correct size of board . Then I remembered my Adobe Photo Shop Elements.
on Express PCB, I removed the screen print component values and then did a Print Screen copy to Adobe Photo shop Elements . Copy the image to a new page,and then use the Enhance /colour control to remove colour and change to greyscale. On the image/adjustments menu choose invert. On the enhance menu- set level of black /white/contrast to suite. Finally on the print preview, you can set the size of the printed image to within .01 " .
Than there's Microsoft Photodraw 2000. Similar process, but with this program, there's no dimension distortion , so all that's needed is to remove the colour , turn the result to grey scale and invert. Similar process with the balance of brightness and contrast.

David- I've found this place -http://www.ebay.co.uk/itm/A4-Laser-Printer-PCB-Artwork-Film-Transparant-Clear-Transparency-Per-Sheet-/301211204299?epid=757755423&hash=item4621963acb:g: 81QAAOxyEqNTlvT5
amongst the cheapest for artwork. However, I've just thought of baking greaseproof paper ,not unlike tracing paper . Might need a few extra minutes in the light box, but it's cheap.


NB- if using a PCB program with a visible grid to aid setting components- BEFORE doing a copy/printscreen, remove the grid ( Express PCB has a tick box to remove grid) , as it will show up on any copy .

Last edited by Oldcodger; 8th Jul 2017 at 7:53 pm.
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Old 13th Jul 2017, 8:07 pm   #10
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Default Re: UV Dry Film PCB technique - experiences to date.

Since last post, I've been playing with various programs to try and solve the size change program and my results --
1 - I design the PCB layout in PCB Express ,which lets me keep the maximum amount of copper by inserting a ground plane.
2 - copy ( Prntscr) to Adobe Photoshop Elements and remove colour, then Invert and auto adjust brightness/contrast to get best black/white contrast .
3 -Paste into Photodraw 2000 and use the resize facility to reset the board size to that in design, and also lets you reset the size of the paper you will be printing on, independent of the PCB size.
4 print from photodraw ,which lets you modify the size of sheet to print onto .
David -can you advise on how well the attached will come out ?
OH-BTW- I did try greaseproof paper .On it's own in my printer, it wouldn't feed in as it's too thin, and with a sheet of A5 ,it's too shiny, so that's another idea up the swanny.
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Old 14th Jul 2017, 11:25 am   #11
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Default Re: UV Dry Film PCB technique - experiences to date.

Quote:
Originally Posted by Oldcodger View Post
David -can you advise on how well the attached will come out ?
Firstly, well done on getting to grips with Express PCB and for creating your layout.

As I've said before I'm not a fan of Express PCB because basically, like similar PCB programs, its intention is for the DIY creation of a PCB design but for that design to be commercially produced. I'd reiterate that to my mind, the tracks are usually too thin and the pads far too small for DIY etching and drilling. This risks the tracks being undercut during etching, leaving even less copper on the board, the holes being miss-drilled and the copper lifting due to heat when soldered. No reason at all that you can't create the design in Express PCB and use that as a basis to refine the layout in Photoshop, PAINT or whatever.

In your design, the track widths looks fine, but in my experience, the pads are too small to survive etching, drilling and soldering. Not a big job to 'beef them up' but for DIL I.C. pads, about 1.8mm is about as large as you can go. Whenever there's space, I try to make the pad size no less than 3mm diam. As an example, I've clipped a portion of the bottom RH corner of your design, and using MS PAINT have increased the size of the pads to show what I mean. I also note that there seems to be a grid of feint holes on the tracks, which I've highlighted. If they're intended to be etched, they'll weaken the track so would need to have pads created around the holes. Otherwise, if not to be etched they'd need to be blacked out.

Personally, without wishing to drone on about it, whenever I can, I try to have as thick a track width or as large a pad size as is possible, and as much clearance between tracks. Also, the more copper that can be left on the board, the quicker the etching time. If I see a design which I'd like to use, which has thin tracks and small pads, (often showing the hallmarks of being an Express PCB design), I use that as a basis to retain the same basic layout, but to increase clearance between tracks and a groundplane if there is one, and to increase the track thickness and pad size. As an example, pic 2 shows the track layout of the 'mini-mod' kindly provided by Ian, the designer, and pic 3 the pattern that I created from that, which retains exactly the same holes and component placement, but for me at any rate, maximised the chance of successful DIY etching & drilling. (A PCB production company would of course have no difficulty in making PCBs from the original design, and maybe some home-brewers too).

The fourth pic is of a small PCB for a sawtooth generator which I didn't design, but modified the artwork to leave more copper on the board.
That last pic shows the PCB that I etched and drilled from that artwork.

Not in any way intended to be critical of your efforts - just a kindred spirit who's trodden this well-worn path on a 'voyage of discovery' in the black arts of home PCB production, trying to give constructive tips and advice in helping to avoid pitfalls. Every good wish in your efforts - you've already invested much time to get to this stage and I'm sure it won't be long before your first PCB project will be up and running! The overall aim is to maximise the chance of success at every stage - artwork, exposure, developing, etching, drilling and building, so as to achieve consistent rather than hit & miss results.

Hope that helps.
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Old 15th Jul 2017, 7:10 pm   #12
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Many thanks, David- all comments are welcome. Looking at the IC pads, I think I'll have to make my own DIL sets. I had wondered about the pads, as in the past, I've always used transfers for these .
The "holes " in the tracks - I must admit that they are there in the printed copy ,but not as pronounced. Looking at the design with no grid on ( I at first thought that these were grid markings), I can see them as lighter colour dots on the tracks , where they join. I can only think that this is the track showing where it ends, and joins another ( in a bend) , and there must be some way to get rid of them ,that I haven't found out. Thanks for pointing them out.
I notice that you also use an inkjet for printing the mask. Haven't tried yet, but have you found any optimum settings for the printer wrt paper settings. I'm tempted to try the glossy photo setting .

I've just printed out a B &W copy of the positive and no holes appear,so I'm now convinced that the holes are line end markers ( which the corner tool should cover up, but I can't get it to do ) , so if all else fails, then it looks like print/ scan and use the scan to make a negative mask.

I've just realised that my inversion didn't work out as it should, and have now found how to invert in Adobe. But those dreaded end of line holes are still there. Might be time to ask Express help for help on how to use the corner tool to eliminate them .
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Old 15th Jul 2017, 8:53 pm   #13
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Default Re: UV Dry Film PCB technique - experiences to date.

Quote:
Originally Posted by Oldcodger View Post
I notice that you also use an inkjet for printing the mask. Haven't tried yet, but have you found any optimum settings for the printer wrt paper settings. I'm tempted to try the glossy photo setting.
I mentioned in another post (which I'm blowed if I can find), the settings that I use for my Epson Stylus SX535 ink-jet printer. I tried all the paper selection and print quality options, none of which enabled a satisfactory print onto OHP acetate. I also tried several brands of acetates and that too made no difference. This printer was a replacement for an HP 'Photosmart' which had a 'transparency' setting and for years until that printer died on me to print fine onto OHP sheet. The acetate film I used back then was this, and it was excellent with my HP printer:

https://www.amazon.co.uk/INKJET-CLEA.../dp/B000KJO7BO

You'll see that a 50 sheet pack is just over £13.00 - 27p a sheet so excellent value for money. You'll also see that the film attracts mostly five star reviews. However, all of the critical reviews relate to the film producing poor results on Epson printers, but the criticism should be directed at Epson - not the acetates.

As to creating a mask, everyone has their own ideas and all makes and models of printers are different in how they behave. Some use lasers, which I've had no success with, including commercial laser printers. After much experimentation, the only way I've been able to get the Epson Stylus SX535 inkjet that I use to print totally opaque black is to create a specific setting in the 'printer options' which I've saved and named 'PCB'. If anyone else has an Epson printer, I learnt how to adjust the settings from a 'Big Clive' video which Joe 'The Pillenwerfer' on the forum, kindly pointed me to.

Here are the steps I used to creating the settings, but won't be of help to those who don't use an Epson inkjet, in which case this might as well be filed under 'burn before reading'.

Open 'Printer Management'.
'Adjust Print Option'
Colour/B&W?' Select 'colour'. Even though you want to print black, to get full density black you need to make the following adjustments to the printer colour settings:
Paper: Select Epson Matte
Colour Correction: Select 'Custom'.
Click on Advanced' tab.
Colour Management: Select Colour Controls'
Colour Mode: Select Epson Vivid.

Colour Adjustment method - circle/slide bar? Select 'Slide Bar'.

There are six sliders:
Brightness.
Contrast.
Saturation.
Cyan.
Magenta.
Yellow.

Set all sliders to maximum.

When all the above settings have been selected, click OK save the settings and exit 'Print Options'.

Quite a rigmarole, but it only needs to be once, and saved as say 'PCB' and I use that setting in 'Print Options' whenever I print PCB artwork.

To print onto the film, I remove all plain paper from the tray and put in one sheet of film in the tray with the correct side down. I open the artwork in Photoshop, but don't yet press ''PRINT' as it won't print top quality, for reasons that elude me. Under the 'File' menu, I select 'Print Multiple Pictures' which the printer seems to need to print photographs onto acetate. Though I select 'Print Multiple Pictures' it will only print the one that you have open.

Then I print onto microporous acetate film (not OHP acetate), the printer makes many passes to create the image(s), which are excellent.

As I say, much depends on each printer and what settings are or aren't built into the software as to acetates, but it seems to me that ever since Powerpoint and digital projectors took over from OHP projectors, that most modern printers don't have 'transparency' settings as they were once called. Certainly no Epson printers do and Epson so called 'Technical Support' have confirmed this to me.

Obviously the best thing to do is to experiment with your own printer - what works with one make or model may not work with another. Same thing with acetated. As I said above, those standard OHP acetates produced excellent totally opaque artwork on my HP printer, albeit I had to be careful not to smudge the ink while it was drying, but if I try those OHP acetates in any normal built-in paper and quality settings on my standard printer options, the results are just dire.

First thing I'd suggest with any printer is to search the settings to see if it has one for acetates, and if not, just try different photo and paper settings and be resigned to wasting a few acetates in the process.

Hope that helps a bit, but probably not!
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Old 15th Jul 2017, 9:36 pm   #14
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Default Re: UV Dry Film PCB technique - experiences to date.

Epson have tended to prefer pigment based inks. Canon, HP have mostly used dye based inks. This might explain what you've found.

The pigment inks are highly rated for life expectancy of photographic prints, but they can be devils for print-head blockages.

Many of the HP printers used to have the print head integrated with the ink reservoir, so you fitted a new head with every refill. Today, they're more mainstream.

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Old 15th Jul 2017, 10:25 pm   #15
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Default Re: UV Dry Film PCB technique - experiences to date.

RW- I’ve found a solution, and it's not ink based . Delving further into Express PCB, I’ve found that it's possible to set colours for things like corners etc. I've now made the colour for corners the same as for corners,top layer the same as for top layer tracks, and the holes have gone. It's even possible to set up a colour scheme to invert the layout on screen, but I've yet to find out if it will print this inverted scheme. Express say no ( and early experiments bear this out), but I wonder then if playing with the colour scheme in Express to give a negative design and then copying the design to something like PhotoDraw 2000 might give a printable design without any re sizing - one of the drawbacks I find with the likes of Paint, where resizing is done as a percentage of the larger size.
David- many thanks for the printer info- I'm using a Epson WF2010 ,which hasn't got an acetate setting, but has settings for glossy photo- I'll try those first. But the sheet is one designed to be used in an Inkjet .
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Old 15th Jul 2017, 11:30 pm   #16
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Been playing and it's taken more than 30 mins, which forum software does not like.
Found that by playing with set colours, it's possible to invert in Express PCB. DESIGN- then on main menu- select VIEW, OPTIONS/COLOURS. Set tracks & corners ( top layer) to white, and ignore all others. Use colour show options to get rid of green and yellow , and you're left with an inverted design. Copy ( PRTSysRq) to Photodraw, paste, check size ( resize) and paste to the size of print medium you're using. It's possible in the print options to change this/size of printed sheet.
The board is for a 12v SMPSU /4W drive at +/- 1V from car supply. Betsy is being dragged into the 20th century, but as she's got a chipped key system, and Swimbo loves to loose keys, I've decided to change over to a remote system for Swimbo to open doors/boot etc, BEFORE Swimbo locks us out by either loosing my key or locking keys in car. (AGAIN).
Simple idea- car 12v nominal is sent to a 7805 to drop 12v nominal to 5v, then sent to a 5-12v mini SWPSU to get back to 12v . System is set to operate ONLY when ignition is off, as power is sensed by a relay and supply to
remote unit shut off when ignition is on. In truth- I've had a prototype of this running on a bit of vero board, but I've noticed a lot of green on the board, and as I've decided to put it on PCB, with some form of moisture protection, I decided to put in the only on when ignition off option, to protect against any in motion voltage spikes.
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Old 16th Jul 2017, 9:16 am   #17
David G4EBT
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Default Re: UV Dry Film PCB technique - experiences to date.

That looks a much better bet, with beefed up tracks and pads.

Good luck with 'test driving' your new UV exposure box, and with the dry film technique!

You've certainly put in a lot of effort to get to this stage.
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Old 16th Jul 2017, 7:31 pm   #18
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Default Re: UV Dry Film PCB technique - experiences to date.

Stepped back and wondered if I really needed to use another program to invert, seeing as how I could show the design as a negative on Express. So I tried a test print and it's as Express say- you can't print an invert design straight from Express , not even showing background as black with tracks white and using the print in colour option . So it looks like designing in Express with black tracks and corners , copying into Photodraw ,and inverting /correcting size and printing negative .
Many thanks for the assistance, David - been a while since I did any PCB design, so I'm a bit rusty and it's hit my confidence. As well as ,it's amazing how things get forgotten if you don't do them regularly. Once upon a day many years ago ,i'd have gotten out transfers/ felt tip marker and bodged up a PCB in an hour or two.

Last edited by Oldcodger; 16th Jul 2017 at 7:41 pm.
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Old 17th Jul 2017, 10:40 pm   #19
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Default Re: UV Dry Film PCB technique - experiences to date.

David - feedback - it might seem laborious, but I've got the transition from Express to photodraw down to an art now.
I looked at the jetstar sheets I got and couldn't any difference in which side to print on, so guessed- yep - I got it wrong, but fortunately on the non porous side, the ink just sponged off. Latest print on to the other side is brilliant .
I've split the A4 sheets into two A5 ones and printed a test piece ( to determine optimum exposure time ), with the two PCB i intend to make.
I notice the "warming up " time for the tubes- so I think I'll just set my timer to max ( min is approx 36 secs , so max should be 11 times that using a 470k pot on a 555 timer circuit) ,for a warm up time, then I've got a test mask of 4x periods, so I'll start with 30 (nominal ) seconds and work up. Like Doctors & Legal Guys, I'll just practice- and as one jovial solicitor said- "one day we''ll get it right".
Far cry from ye olde days . I remember making kids a XYLAPHONE from a PE/PW design. Keyboard was printed in the mag( which some one has posted to me - another project in the future for grandson) . I simply photo copied the
keyboard layout, traced it onto a PCB ,then bribed SWIMBO a new bottle of nail varnish for giving my board a coat or two of her least favourite clear/nearly clear stuff. I then cut out the keys with a sharp nail, added the electronic circuit with a Dalo( or felt tip pen -I can't remember which), and etched.
For history, years ago, some one came out with a nail varnish pen, along the lines of a fine felt tip pen. Swimbo pointed it out to me ,as it might be great for making PCB, but alas ,we never found one on sale.
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Old 18th Jul 2017, 7:00 am   #20
Nickthedentist
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Default Re: UV Dry Film PCB technique - experiences to date.

Quote:
Originally Posted by David G4EBT View Post
I mentioned in another post (which I'm blowed if I can find), the settings that I use for my Epson Stylus SX535 ink-jet printer.
Golborne, maybe, David? http://golbornevintageradio.co.uk/fo...d.php?tid=1921
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