Logos and Artwork in PCBs

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.

Unusual shapes for hole pads and silkscreen images
Cutting line on PCB marked by scissor artwork

This article describes how to use images in Copper Connection, as well as best practices for the finest results.

Getting Images onto the Board

There are two methods of getting images into Copper Connection:

  1. You can paste images from other programs. This is simplest approach, but has a few limitations. First, the Microsoft clipboard does not handle transparency. Second, the image may take up more disk space in the PCB file.
  2. You can choose the Image tool, click on the board, and open the image file from the window that appears. This preserves transparency and image size, and therefore is the recommend method. It just means you need to save the image from the original source to the disk in order to open it in 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.

Tracing

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.

  1. After adding the image to the board, click on the image to select it.
  2. In the Shape section of the ribbon, choose a layer:
    1. Board Background layer places the image behind all other layers and...
      1. Will Print (except for Etching)
      2. Will Turn Over with the board
    2. Workspace layer places the image behind all other layers and...
      1. Will not Print
      2. Will not Turn Over with the board
  3. Uncheck Background Images Selectable in the Grid menu. You can now draw and select elements on top of the image without affecting the image.
  4. When you are done, check Background Images Selectable, select the image, and delete it (with the delete key).

Output to Physical Board

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

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

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.

Images for Etching

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.

  1. After adding the image to the board, click on the image if it isn't already selected.
  2. In the Shape section of the ribbon, choose a layer. Usually, you'll choose Top Copper or Bottom Copper, depending on which side of the board you want the image to appear.
  3. For editing convenience, you can move the image above or behind other elements on the same layer by choosing Bring to Front or Send to Back in the Arrange menu.
  4. Right-click on the image and choose Color Image To Layer. The light areas in the image are made transparent and the other areas are set to the current layer color. If you are dissatisfied with the results, alter the image in a painting program and then try these steps again.
  5. When printed for etching, the image automatically appears as black and white.

Manufactured Boards

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).

  1. After adding the image to the board, click on the image if it isn't already selected.
  2. Right-click on the image and choose Convert Image to Polygon. The image will be replaced by one or more filled polygons in the color of the image's current layer.

    What's cool about these polygons is that they are just like polygons you can make by hand. So, they can be edited, printed, duplicated, moved, resized, and moved to layers just like any other element. Most importantly, because the shape is made of polygons, it will now appear on manufactured PCBs.
  3. If you are dissatisfied with the results, alter the image in a painting program and then try these steps again. To get a hint as to what Copper Connection is doing, right-click on the image and choose Color Image To Layer. Copper Connection traces around the edges of each shape and turns them solid.

Holes

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

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

Failed attempt to close gap by dragging points

Dots and Lines

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.

Post Conversion Improvements

After conversion, you'll need to edit the various points to tweak the shapes:

  1. If there are multiple shapes, right-click and choose Ungroup.
  2. Click on the particular shape you want to edit to select it.
  3. Zoom in and click on the point (represented by a small square) that you want to edit.

    Editing points to clean up vector art
  4. Press the delete key to remove the point, or press the arrow keys to move the point slightly, or drag the point with the mouse for a more aggressive change. You may need to turn off Snap in the Grid menu to avoid the point jumping around if you are moving it with the mouse.
  5. When all of the shapes look acceptable, select them and choose Group from the Edit menu. (If there is more than one shape).
  6. You can now drag the group to the desired location.
  7. To resize, type a new width or height in the corresponding field in the Size and Position section of the main ribbon. Use math in those fields to keep the width and height at the same proportion as the original. For example, if the shape group was originally 1.0521 in x 0.9938 in, simply type "/2" at the end of the width and hit enter. Do the same for the height. The image is now half the size.

    Resizing polygon by typing new width

Rules for Successful Polygon Conversion

  1. Use a large image. Small images have fewer pixels, resulting in blockier edges with small spikes and divots. After the conversion, the larger image can be shrunk mathematically in Copper Connection, producing an even smoother appearance.

    That being said, too many points can slow application performance. So, either make sure the image is not too large or edit the polygon enough to reduce unnecessary points.
  2. Use an image with crisp edges. Soft edges are often composed of mixed color pixels and transparency, which it difficult to trace precisely.
  3. Images from PNG files are usually the best choice, as they are high quality, reasonably small, and allow transparent areas. JPGs tend to have a lot of fuzz and distortion that isn't obvious until you zoom in with a painting program. These artifacts result in inaccuracies.
  4. Avoid pasting the image. The Windows clipboard is designed for image interoperability, not quality. Instead, click the Image tool, click on the board, and then open the image file from the window that appears.
  5. If the conversion isn't working well, preprocess the image in a painting program to clean it up. Even inexpensive paint applications include a huge variety of filters and tools specifically designed for processing images. Sharpen, increase contrast, remove hairlines, remove JPG artifacts, crop, and so on. A few minutes in a paint program can save you time and frustration, as well as increase the final quality.
  6. After converting to polygons, plan on putting a little bit of work to delete extraneous points, add points to curves, and nudge a few points for better shapes. You'll likely reuse the resulting shapes, particularly if it is a logo or symbol. So, the quality improvements of a human touch are worthwhile investments.
    Shield icon on PCB silkscreen

Troubleshooting

Conversion to polygon results in a single solid rectangle the size of the image

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.