The Copper Connection layout software has the ability to include images on your PCBs. The images can be logos, symbols, instructional, or even fancy shaped pads and traces. You can use the images for tracing, sizing, etching onto a board at home, or converting to polygons to appear on a manufactured board.
This article describes how to use images in Copper Connection, as well as best practices for the finest results.
There are two methods of getting images into Copper Connection:
In either case, the image usually appears to be very large on the board. This is because the board is usually magnified. If you change the zoom to 100%, you'll notice the image is the same size as it appears in other applications.
You can resize the image by entering a new width and height in the respective fields in the Size and Position section of the main ribbon. Alternatively, you can drag the corners of the image to resize it. If desired, hold down the Ctrl key while dragging to keep the same proportion (width to height ratio) as the original image.
Blank image? If the image has a transparent background and black content, it may appear to be an empty image due to the black background of the editor window. Right-click on the image and choose Color Image to Layer to make it appear.
One major reason for including an image is to manually reproduce a circuit from a photo of a board or from another layout source (like a screenshot, a book, or a magazine). With the image in the background, you can draw the appropriate elements on top of it.
The other major purpose for an image on the PCB is to include artwork, logos, and symbols on etched or manufactured boards. Unlike temporary tracing, the images used for this purpose need to be carefully selected and adjusted to produce acceptable output.
If you zoom in on an image in a painting program, you'll notice that it contains speckles of millions of colors and various amounts of transparency. From a normal viewing distance, these pixels blend together such that we perceive a specific shape. Without the variety of colors, this trick would not be possible.
Shapes in photographs are complex visual illusions
That brings us to the issue of reproducing a symbol or logo on a printed circuit board. Regardless of whether the image is placed on the copper layer or silkscreen layer, there are only two colors to choose from (copper/silkscreen color or board color), not millions.
Black and white newspapers use tiny individual dots of varying size (halftone) to generate complex photographs and illustrations. That trick is also not available on PCBs. Circuit board manufacturing is not conducive to thin lines and single dots – they tend to etch away, smear, or flake off the board.
Therefore, for reliable results, you must choose artwork that consists of bold, single color, solid areas. Think of geometric shapes, silhouettes, and pictograms, rather than photos. This is not a limitation of software; this is a limitation of the output medium.
Image choices for printed circuit boards
Above Left: A photo is not reproducible on a PCB, because a PCB layer is one color only (spot color). Even a grayscale image of a photo is unacceptable, because the light intensity varies.
Above Middle: A line or dot based drawing, even in strict black and white, is unacceptable. The issue isn't the number of colors, but the ability to reproduce tiny disconnected details.
Above Right: Large, thick, continuous single-color blobs are excellent.
PCB manufacturing equipment does not accept common bitmap images (JPG, BMP, TIFF, PNG, GIF), but a computer printer does. So, you may be able to get away with a little bit more if you're etching your board at home. If you can print it, you can etch it. Well, you can try to etch it.
Ordinary images will not appear on manufactured boards! If you etch a beautiful PNG at home and expect it to appear on the production board, you're going to be disappointed.
As discussed earlier, PCB manufacturing equipment simply does not accept these picture formats. Instead, these industrial machines require an exact mathematical description of each line, point, and shape. This is called vector graphics. Your image needs to be converted into mathematical polygons to be reproducible on a manufactured board (which will also work for etching at home).
Each shape is solid, so holes (like in the letter 'o') will not be reproduced. To create open interiors, cut thin lines into those areas in the original image and then cover up the cuts after conversion. Alternatively, split the image into pieces. Nudge them next to each other after conversion.
For example, below is the shape of a hexagonal nut. A thin white line has been drawn vertically from the bottom to the center, so that the tracing routine can get inside. After conversion, a small polygon patch should be placed over the slit, and grouped together. This is the correct method.
Successfully closed gap by grouping with a small polygon patch
Everyone will try to close the gap by nudging the points on top of each other. But, a polygon is not allowed by industry rules to overlap itself. Don't do it -- it will just end up creating additional gaps due to inversion. See below.
Failed attempt to close gap by dragging points
Thin lines (one solid pixel in wide) and standalone dots will not be converted to polygons, because the shapes need to comply with the minimum thickness and size rules like any other element on the PCB.
After conversion, you'll need to edit the various points to tweak the shapes:
Does the original image have a border? Crop it or erase the border in a painting program.
Was the image pasted? Instead, click the Image tool, click on the board, and then open the image file from the window that appears. Because the PCB editor has a black background, it is difficult to tell if image transparency was lost in the paste.