Homebrew PCBs

Hi

I have an HP 1102W laser printer. There are numerous references that indicate it is good for toner transfer. As far as I can see so far, it isn't going to work  on my mac.

I get a couple of problems. One is that, from Eagle V5.8, I find the pads print too large and start to blend in to one another when trying to use a 0.5mm pitch LQFP64 package. There are not many settings to choose, no combination seems to improve things.

There is also some evidence that the underlying resolution is poor. So, for example, with the  same 0.5mm LQFP64, some pads come to closer together than others as if there was some rounding going on.

I am reasonably sure all this happens somewhere in the printer driver. If I print to a PDF, I get good scalable, vector-based artwork. But I still cannot print it out worth a damn.

Also, there is a fair bit of toner spicily on anything but plain printer paper.

Regardless of toner transfer, this is not even going to be any good for photo-etch.

Anyone got any useful suggestions? Assuming I am not going to go back to a Windows PC that is.


Peter Harrison

Keep in mind, the average laser printer (including yours) is 600 DPI -
that's 1.33 mils PER PIXEL.  An 0.5mm pitch part has pads on the order
of only six pixels, so "off by one" is a 16% difference.

Som postscript printers "fill" a region by drawing both the outline and
the fill. That tends to produce features that are one pixel larger than
you expect.  gEDA's PCB has a setting to compensate for this if needed,
or you can use some other program to convert the output to a 600 DPI
bitmap, preview it, adjust if needed, and print the bitmap.

The bitmap idea sounds like a good possibility.

As far as I know, the mac print engine is CUPS and I would guess that everything gets fed through an intermediate rendering stage - probably postscript and only then will the driver talk to the printer. Pure conjecture for now.


The printer claims to be able to do 1200 dpi and I know it will be pushing the limits of what might be possible. Yet I recall others claiming to have managed it so I will persist for a while.


Peter Harrison

On 24 Dec 2011, at 06:23, DJ Delorie wrote:

> 
> Keep in mind, the average laser printer (including yours) is 600 DPI -
> that's 1.33 mils PER PIXEL.  An 0.5mm pitch part has pads on the order
> of only six pixels, so "off by one" is a 16% difference.
> 
> Som postscript printers "fill" a region by drawing both the outline and
> the fill. That tends to produce features that are one pixel larger than
> you expect.  gEDA's PCB has a setting to compensate for this if needed,
> or you can use some other program to convert the output to a 600 DPI
> bitmap, preview it, adjust if needed, and print the bitmap.
> 
> 
> ------------------------------------
> 
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> 
> 
>

On 24/12/2011, at 7:34 PM, Peter Harrison wrote:

> The bitmap idea sounds like a good possibility.
> 
> As far as I know, the mac print engine is CUPS and I would guess that everything gets fed through an intermediate rendering stage - probably postscript and only then will the driver talk to the printer. Pure conjecture for now.

It is cups, but "rendering" to postscript does not involve turning it into pixels ("rasterising") - postscript is a vector language and your pcb would be described as such. The printer does the actual rasterising

> The printer claims to be able to do 1200 dpi and I know it will be pushing the limits of what might be possible. Yet I recall others claiming to have managed it so I will persist for a while.

For the 5MP I can specify the dpi under "Color/Quality options" in the print dialogue.

PG

I had that problem, until I found a setting for the graphics output. Unfortunately I don't recall where that setting was, but it was under Linux, so maybe something similar on your Mac. 

--- In Homebrew_PCBs@yahoogroups.com, Peter Harrison <peter.harrison@...> wrote:

>
> Hi
> 
> I have an HP 1102W laser printer. There are numerous references that indicate it is good for toner transfer. As far as I can see so far, it isn't going to work  on my mac.
> 
> I get a couple of problems. One is that, from Eagle V5.8, I find the pads print too large and start to blend in to one another when trying to use a 0.5mm pitch LQFP64 package. There are not many settings to choose, no combination seems to improve things.
> 
> There is also some evidence that the underlying resolution is poor. So, for example, with the  same 0.5mm LQFP64, some pads come to closer together than others as if there was some rounding going on.
> 
> I am reasonably sure all this happens somewhere in the printer driver. If I print to a PDF, I get good scalable, vector-based artwork. But I still cannot print it out worth a damn.
> 
> Also, there is a fair bit of toner spicily on anything but plain printer paper.
> 
> Regardless of toner transfer, this is not even going to be any good for photo-etch.
> 
> Anyone got any useful suggestions? Assuming I am not going to go back to a Windows PC that is.
> 
> 
> Peter Harrison
>