Double Sided PCB

This guide covers how to make a double sided printed circuit board (PCB) with the LPKF S104 Protomat.

Starting up the machine

Make sure the machine is turned on by pressing the on switch behind the machine on the back left.

Start by opening the software called LPKF CircuitPro PM 2.7. This is the software used to operate the LPKF ProtoMat machine. The program will go through a series of  "Connection steps".

If any maintenance windows pop up, select "Not performed yet". 

Example of maintenance:

Choosing the correct template

A "New Document" window will pop up. This is where you will choose a project or a template. Head over to the "Templates" section.

For a double-sided board, the template we will be using is called the "DoubleSided_NoTHP". 

If you are interested in making a single-sided board, check out our first PCB tutorial.

Load the gerber files in this window by choosing your files. Select the Import Data button.

     The red circle shows the import button

In your unziped CAMOutputs folder, go to the GerberFiles folder and select the files that you will need to make this board. 

If you have a single sided board on the bottom, you will only need copper_top.gbr, copper_bottom.gbr and profile.gbr. The other files will not be useful to us on this machine. 

If you have through holes in your board you will need to import the drill file as well. Select the Import Data button again.

In your unziped CAMOutputs folder, go to the DrillFiles folder and select the drill_1_16.xln file. If you don't have holes, then importing a drill file will not make any changes.

Now we should have something that looks like this. The green represents the copper_bottom.gbr or Bottom Layer copper traces. The green represents the copper_top.gbr or Top Layer copper traces. The yellow is the profile.gbr or Board Outline that it will cut out to separate it from the board. The blue is the drill_1_16.xln file that represents the holes it will drill out for through hole components.

Create Fiducials

A difficult part of making double sided boards is making sure the top and bottom cuts are aligned when you flip the board. To combat that, the machine drills holes called Fiducials. After flipping, it uses the camera to find the location of those holes and uses that information to adjust for any slights angles or shifts in the board from flipping.

Select the Fiducial option from the top tool bar.

On the pop up don't select Apply. If you do, select close then undo.

Click to place 4 fiducials on the left and right sides of the board next to the corners. Then select Close on the pop up.

This must be done before generating the toolpath.

Generate toolpath

Head to the Technology Dialog menu, which is shown in the top left with the logo with the green arrow. 

At the top of this window we will change our Material Type and Copper layer thickness. Typically we will not change it from the default FR4 material that we use in the lab and we will use either 1/2oz Copper (18um) or 1oz Copper (35um). 

If you are using a scrap, double check if it is labeled. If it doesn't say, it is likely 1/2oz. 

In the Isolate tab, we will choose how much copper to remove. Since we will not be using a solder mask, we want to remove more copper to prevent use from accidentally shorting our board. 

Select Process 4/4 on left image to remove all copper.

Additionally, to save time, uncheck Micro Cutter 0.1mm and End Mill 0.8mm from the available tools unless you have a very highly detailed board.

The Contour routing tab chooses how to cut out the Board Outline. When cutting our PCB out of the stock FR4 board, we do not want to cut it out all the way because it can move around during the cutting process. Instead it leaves to hold the board in place. You can select what tab arrangement you want on the left image. Typically we use 2 tabs, or Process 3/6 or 2/6.

Typically you do not need to change anything in the Drills, Fiducials, Pockets, or Blind Vias tabs.

Once you select the Start button on the Technology Dialog box, you will get a popup that says Computation Results. You can ignore any warning for Pockets.

Once you have generated the toolpath, you should see many different colors on your board representing the different paths that our tools will take. 

If everything looks good, change to the Machining View tab near the top of the window. 

For Carduino only - in the toolpath tab, under the drills dropdown Delete the 1,7mm drill toolpath. Then return to the Processing tab.

Placement 

Place your FR4 board on the bed of the machine. Make sure it is aligned with the front left corner and tape down the corners of the board.

If there are already holes in the board, cover them up with tape. The machine uses a vacuum table to keep the board down and too many holes will reduce the suction.

On the computer, right click the image of your board and select Placement.

With the Placement window, you can move or rotate your design. 

For Carduino - rotate it 90 deg and place it somewhere along the top half of the board. If there is only space in the bottom half of the board, flip it so that the space is on the top. 

To check the location of your design on the physical board, use the Mouse cursor tool.

Then click outside the corner of your board to move the head of the machine to that location.

Unfortunately, it is difficult to tell where exactly the head is above on the board. It's location is represented approximately by the blue dot. 

You can approximate the location of the head to ensure it is avoiding any holes by looking directly in front of it and to the side. 

From the front view, the center of the head is aligned with the small notch. On the side view it is aligned with the dot. 

Processing

Once you find a suitable place for the board, double check all the previous settings to make sure that everything is correct. Head over to the operate window and select the green arrow selecting "Process All" for the drop down menu. If you don't see "Process All" select it from the drop down before starting. 

If the Processing Phase: MountMaterial window pops up, click OK.

If any warnings come up, or tool maintenance information, select ignore or complete later. 

A Material settings window will pop up. Most settings you can leave as is, however please input the Material thickness you measured with calipers.

A placement window will pop up. Confirm rotation and center. Select continue. 

Once you have gone through all of the popup windows your job will start. If it the first job of the day, there will be an automatic spindle warmup. 

The first process that will be completed is hole drilling which will involve several tool changes. 

Flip Material

After the board completes the bottom side, a pop up will appear letting you know to flip material.

Flip it over the red axis indicated by the red dotted line. For example, if it was in the top left corner, it will now be in the bottom left corner after flipped. Make sure to align the board with that front left corner and retape! Don't put tape on top of where it will cut.

It will go from here

To here

Carduino Optional: To save time

If you don't have any wires on the top side (100% w/ autorouter on the bottom), then at the FlipMaterial pop up select Cancel. 

After you flip the material and select Ok, the machine will take some time to focus. If the image in the camera view is clear and not blurry, select Yes. 

The camera will then search for the fiducial holes we made earlier. If the yellow circle lines up with the hole in the image and you see Fiducial acceptance, select Ok. This process will repeat for all four holes. If it doesn't find it see below.

If the camera was not able to find the fiducial but it is in the camera view, select the Find and Center option. 

If the camera view looks blurry and it is having trouble, select the Autofocus button in the Head actions section before selecting Find and Center.

If the yellow circle lines up with the hole, then select Accept Current Position. 

If it is unable to find the fiducials automatically, you may have to use the arrows in the X/Y position section to manually move the camera over the fiducial. You can also change the movement step size from 10mm to something smaller.

When you line it up, select Accept Current Position.

After it finds all the fiducials, it will finish the rest of the board.

When finished, you can twist your PCB out of the large FR4 board with the two tabs.