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Insert a resized logo on the PCB

by: May 05,2021 181 Views 0 Comments Posted in PCB Design Tutorial

PCB Design Tutorial KiCAD PCB layout Circuit

Summary:       In a few minutes I will show you how to insert a logo in KiCAD-Pcbnew, and resize it according to your requirements.

Hello!

In this little tutorial I will show you how to import in KiCAD v5.1.9 the logo you want, and not only that, I will also show you how to insert it in Pcbnew having the dimensions you want, and then appear on the PCB you want.

First, we will create a directory, which I named it as My_Logos. We created it on the Desktop to make it easier to identify, but you can create it where you want (don't lose track of it). It is very important to know where we created this directory because later we will have to insert it in KiCAD.

Once we have created our directory, the next step is to choose a logo, and the easiest way we can do this is by searching the internet, and saving it in a known directory. Note that the file extension must be found in this list (Figure 1):

Figure 1.


I chose this image / logo with the extension * png (Figure 2):

Figure 2.


The next step is to open the ‘Bitmap to Component Converter’ utility. To do this, the easiest way is to open a project in KiCAD, and select ‘Bitmap to Component Converter’ (Figure 3) :

Figure3.


The utility should look like this (Figure 4):

Figure 4.


Select ‘Load Bitmap’ to load the desired image and press ‘Open’ (Figure 5).

Figure 5.


As you can see, the image was loaded in a nice and colorful format, but it seems too big to be printed on a PCB, in addition to that, we need another color for our logo. Select ‘Black & White Picture’(Figure 6).

Figure 6.


We need a monochrome image, that's why we selected the black and white format. The grayscale format doesn't help us too much, because we don't just have black and white, but gray levels. A grayscale image consists of grayscale levels, useful for processing images for purposes other than those of interest to us.

But what about those dimensions ??! Clearly I will not be able to insert this logo on my PCB, which by the way, it has the dimensions of only 60mm × 60mm. We will solve this further.

For now, the settings we are interested in are these (Figure 7):

Figure 7.


Usually, I put my logos on the top of the PCB, that is on the silk screen, sometimes I put it in the ground plane. This results in a file with the extension * kicad_mod.

Depending on the logo we choose, we may have to adjust the black and white threshold. However, in my case it is not necessary to do this, because of this (Figure 8):

Figure 8.


Also, the ‘Negative’ function is not required for this image, because (Figure 9):

Figure 9.


However, in some cases the ‘Negative’ function may be required.

Now comes the thing that interests us most, namely resizing the image according to our needs.

My PCB for which I want to insert a logo is this (Figure 10):

Figure 10


It has the dimensions of 60mm × 60mm. I will want to insert a 10mm × 4mm logo on the bottom left corner of the PCB (I don't want to mount PCB mounting holes, so it's not a problem for me) (Figure 11).

Figure 11


I will return to the ‘Bitmap to Component Converter’ utility. I use the following formula to calculate the dimensions I want for the logo:

(pixels×25.4)/dim =DPI

Figure 12.


What we will do is resize the image by changing the DPI values (Figure 12) (I hope that in the next versions of KiCAD we can adjust them directly in mm). The values are as follows:

- pixels, correspond to the length and width of the image as it is loaded in the utility;

- 25.4 is a constant number represented in millimeters (if you want to use inch just convert 1mm =? Inch);

- dim is the value of the desired size in mm of the image;

- the result of the calculation is written in DPI, exactly what KiCAD knows.

So, I want the chosen logo to be printed on the silk screen, and to have the following dimensions: length = 10mm, width = 4mm. The calculation shows like this ones:

-       length: (2842*25.4)/10≈7,218;

-       width: (1051*25.4)/4≈6,673.

I suggest you do not enter this data in KiCAD with Copy / Paste, the write them from the keyboard.

After entering the data, we click on ‘Export’; we save the file with what name we want in the previously created directory. Now, to introduce this logo in KiCAD, we need to tell it where it is. So, we open a KiCAD project (Figure 13):

Figure 13.


We select ‘Preferences’ and then ‘Manage Footprint Libraries’ because KiCAD recognizes our file as a footprint. The following window opens (Figure 14):

Figure 14.


I prefer that all the logos imported by me can be used for all my projects, that's why I import them in ‘Global Libraries’. We click on the icon circled as in the image to enter the library with our logos (it must first be located), and it should appear as in the rectangle surrounded by me.

The next step, we open a project in Pcbnew, and do a simple operation to add a footprint; click on ‘Add Footprint’ (Figure 15):

Figure 15.


And now we can search and insert our logo.

Figure 16.


In my case, a small logo can be seen in the lower left corner (Figure 16). If I want something bigger, then we use the same procedure presented above, and resize the logo (Figure 17):

Figure 17.


Insert the logo, right click on it and ‘Flip’; then rotate the image nicely. I suggest you ‘lock’ the logo in place after you have placed it correctly; right click on the logo and ‘Locking-> Lock’. Much bigger now. We save and visualize the 3D model of our PCB. After successfully completing this process, all we have to do is export the Gerber files, enter the PCB manufacturer's website and order the PCBs.

 

This is my little tutorial. I hope you liked it and that it is useful to you.

Thanks to the PCBWay team!


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