Enclosure toner transfer failures - What could be wrong?

[Kearns892]

So I finally have a consistent method for etching my own PCBs using the toner transfer method. Found a great paper that's cheap and gives me nearly 100% transfer every time. However, my methods do not carry over for enclosures  

I tried 3 transfers on this 125A size enclosure. Sanded with 220 grit sandpaper between steps then cleaned with alcohol and wiped dry.

I figured this would take longer than a board and followed Slade's tutorial and did about 8.5 minutes - thin transfer with no coverage in some open areas

Second try I used less time checked after 4-5 minutes and hardly any transfer had occurred at all

Final try (so far) heated for 20 minutes   checking a corner in 4 minute intervals. The transfer seemed to get slightly better each time, but still was lacking.

Here are pictures so you can see what I'm talking about:

(20 minute transfer about what the 8.5 minute transfer looked like)


The transfer paper has a lot of toner still on it.

Suggestions?

[Govmnt_Lacky]

Did you only iron the first 7 1/2 minutes on your right foot? 

Did you sing the first verse of "American Woman" in Spanish backwards? 

Personally, I think that enclosure etching is a mystical beast. There are tutorials however, I am also one of the people who have followed them to the letter with bad results.

I think you have to spend countless hours going through countless amounts of materials to find " the perfect combination." Some have found it (Slade, deadastronaut, etc.) and have TRIED to convey it but I believe it is only something that can be perfected with hours of self deprivation and a lot of money spent on printers, toner, transfer media, etc.

I wish you nothing but luck in your endeavour. 

[Kearns892]

Exactly the same conclusion I have come up with. With so many variables (toner, iron, paper, metal etc.) there is definitely no one size fits all method for this.

I went through the process of fine tuning my set up for PCBs with dollar store brand photopaper and was hoping not much would change between PCBs and enclosures.

I guess I was wondering if any of the pros have any tips as to whether this looks like over-heating or under-heating, or if good PCB transfer paper does not always equal good Enclosure transfer paper.

Also, most of the threads I have used when fine tuning my PCB transfer method (and what I have been using while preparing for enclosure transfer) have been yours Govmnt Lacky - so thanks for posting your trials because they have been a huge help to me!

[tiges_ tendres]

Has anyone had any luck after sanding, putting the enclosure in an oven to get it heated up?  They you'd have to carefully place the pnp on the enclosure before ironing.

[defaced]

I've never etched an enclosure, but I'm a welding engineer and keeping metal clean is part of specialty; this jumped out at me.  

I tried 3 transfers on this 125A size enclosure. Sanded with 220 grit sandpaper between steps then cleaned with alcohol and wiped dry.

Alcohol only removes water.  First wipe with Acetone (removes oils), then Alcohol, then DON'T EFFING TOUCH IT!  Any oils will prohibit anything from bonding to metal.  

Also consider that a big chunk of aluminum (like an enclosure) is not going to get nearly as hot as a thin foil of copper.  I'm willing to bet that the heat sink created by the enclosure is part of your problem.  

[Kearns892]

I'm willing to bet that the heat sink created by the enclosure is part of your problem. 

Something I definitely noticed. I don't know a lot about clothes irons, but I'm using the cheapest one I could find at Wal-Mart, maybe I'm not getting enough heat...

I'll reclean it (I don't have any acetone, will soap work well enough?) and pop it in my toaster oven for 15 and then try the toner transfer.

[defaced]

Nothing replaces acetone.  You can find it at hardware stores in the paint/solvent section.  And no, finger nail polish removed doesn't count.  There is stuff added to that to keep nails from drying out, which you can't be sure evaporate when the acetone does. 

Crank the heat on the iron, and if you have to, add a supplemental heat source (cooking grittle, pan, etc).  Yes, this is getting kinda absurd, but if that truly is the problem, preheat, higher temperatures, or more heat sources are going to be needed.  

[frequencycentral]

Are you doing 3 -4 minutes on low heat before whacking it up to maximum?

[Kearns892]

I did low heat on the first for about 2.5 minutes and low heat on the second for about 2. Should I be doing longer? About to try pre heating with toaster oven...

[frequencycentral]

I do 4 or 5 on low depending on the enclosure size. Then 7 - 10 on high.

[boogietone]

Has anyone had any luck after sanding, putting the enclosure in an oven to get it heated up?  They you'd have to carefully place the pnp on the enclosure before ironing.

Bought a toaster oven from Goodwill for 6 bucks for other purposes and tried just what you describe and it did seem to help.

Though the thermal conductivity of aluminum may be lower than copper (and I can't be sure of the purity of either the Al or Cu), you are dealing with a different total mass and insulation configuration comparing Cu clad boards to an Al box. Very little Cu needs to be heated and it is insulated by plastic or fiberglass. Preheating the Al box should allow the iron to be more effective.

Not sure that soapy water would help and it probably will hurt if you don't get all of the soap off. Tap water will also leave a residue of salts on the surface. The deal with acetone is that being a liquid it will help pick up particulates onto your rag/paper towel, it is an excellent solvent for leftover toner and finger oils and water for that matter, and it evaporates quickly for a dry surface. Acetone is a very common solvent in chemistry labs for all the above reasons. Where water and soap is used the final rinse water is very highly purified.

[.Mike]

I'm curious about the sanding you are doing.

Are you using a piece of 220 grit, and your hand? Or are you using a proper block, taking your time, and ensuring the surface is as flat as can be?

It can take quite a while to get some boxes flat. They tend to be concave in the middle, and high around the edges. If this is not corrected before transferring, you will not get a good transfer. I think this is a larger issue with enclosures than with PCBs because PCB material has a little give to it, while enclosures are pretty rigid.

A warped iron could also cause poor contact. I could see that being a bigger problem for enclosures than for PCBs.

Mike

[Beo]

Heat gun can help get the enclosure up to speed as well. I blast the sides of the enclosure up close, and I'll even blow the hot air from above onto the transfer paper, being careful not to overcook or warp the paper. Use the tip and edge of the iron in a scraping motion, again being careful not to tear through your paper. This especially helps around corners and edges. I don't preheat, as it's next to impossible to get the paper lined up on first touch.

[Kearns892]

Well here is attempt 4. Marginally better than attempt 3. This try I sanded 100, 150, 220 cleaned with water then alcohol, dried, toaster oven at 450 F for 15 followed by 12 minutes on highest heat settings with the iron.



I knew acetone was a better solvent than water, but I didn't know it was that huge. I'll run to Lowe's and grab some acetone before they close and test into the night...

@ Mike - For sanding I am using a sanding block 100, 150, 220. This looks very flat and good to me, but admittedly I am no expert.

@ Boogietone and Defaced - will use acetone on next trial

@ Frequencycentral - What setting does "low" translate to on your iron?

Suggestions for next trial? Does this look like not enough heat still or a clean issue?

[Tony Forestiere]

   As a side note, it may or may not be your cleanliness or preparation, but the toner being used.
  There are two major types of toner development processes used in copiers/laser printers. All copiers and laser printers use the same photo-conductive process for charging and creating the "Electrostatic Latent Image" on the surface of the drum. The biggest difference in technologies is how the toner image is developed on the drum.  The original method used by Xerox, Ricoh, Savin and many others is a "Dual Component" system. The pigment (toner) is mixed at a specific ratio with a "carrier" (normally iron filings) to create a "brush" on the surface of the developing cylinder to be applied to develop the latent image. This method gives a very thick, black coverage on the output media. It also (as the carrier became worn through rotational friction) created the need for periodic "Developer Changes" as the carrier can no longer hold the correct amount of toner on the brush, and the copies/prints became washed out and grayed-out. Canon developed the "Toner Projection" system in the early '80s, using what is also called a "Mono-Component" toner (licensed to HP and other copier/printer companies). This method combined the carrier portion (magnetite) with the pigment portion into each individual toner particle, avoiding the need for developer changes, and reducing the cost of labor for the servicing dealer. The difference is the lack of "strong" blacks, and therefore the image on the output media is not as thick or "rich".
  You might want to try creating your toner transfer with another machine that uses a dual-component system. Test on regular paper and compare the look of the outputs. I am sure you will see a vast difference.  
  My $.0  

  P.S. Added: Most color copiers and laser printers (to include Canons and their licensees) use the dual component system for the richness of the colors. Try testing one in black or full color. The color toner also melts at a much lower temperature than their B/W counterparts (165C as opposed to 192C).  

[Kearns892]

Got the acetone and cleaned the box (100, 150, 220 all on a sanding block again) wiped down with acetone and then alcohol. Hopefully this will at least rule out the possibility of not clean enough.



Does anyone with experience doing transfers on both PCBs and enclosures know if certain papers that work well with PCBs come up short when using enclosures? Or are the requirements on the transfer page about the same?

[Kearns892]

Tony - Both of my printers are HP black only lasers. I can run a piece of my photo paper to Office Depot tomorrow and ask if they will print on it. Still I am not sure this is the problem. It doesn't seem like the toner is coming off the paper at all, but then again the different toner composition may melt at a lower temp...

Thanks for the input, I will try that tomorrow.

[Tony Forestiere]

   I have not etched an enclosure, but I could never get a good PCB transfer from my HP LJ4000. They looked good on the media, but were always were very weak and blotchy on the ironed PCB from all of the media I tried. I started printing on magazine paper with a Xerox m20 b/w MFD at work and get great results with the iron transfer.
  Bring a print from your HP on regular paper with you to compare with a print from your service bureau (again on regular paper first). Hold them up to a light source and compare the densities.
Good luck, and let us know.

[Beo]

I was never able to get good toner transfer using my B/W brother printer, or from the Fedex copier, but I could from a new Canon B/W laser printer I bought. The brand/toner can make a big difference.

Also, you know to do the sanding in descending order right? 220-150-100...

[.Mike]

Also, you know to do the sanding in descending order right? 220-150-100...

Ermm... you want it the other way around. I do 100 grit with a random orbital sander to mostly flatten the surface, and then wet sand my way up with a block, depending on the finish: 220, 400, 800, 1200.

To me, the box in the last photo just doesn't look flat. Maybe they're fingerprints or smudges, but I see shadows that might indicate low spots in the top right, the bottom right, and the bottom left. Also, possibly in the bottom center. I would expect the brushed look to be even and consistent.

Mike