All posts by Per Magnusson

PCB manufacturing hitch

The PCB I mentioned in the previous post was rejected by the Chinese manufacturer I sent it to since it contained several sub-boards and they wanted (a lot of) extra money for that. This is what the board looked like:

Initial PCB design
Initial PCB design

The comment I got was:

“After checked, we found there are 10 separated sub-boards in your Gerber file, it means you should pay extra $81 for it. If you don’t want to pay extra money, you can design a big outline like below right picture, then we will manufacture your boards according to your big outline.”

This is the picture they sent:

Board outline suggested by manufacturer
Board outline suggested by manufacturer

The manufacturing of ten pieces of a 10 cm x 10 cm board costs $11.90 (plus shipment), so paying an extra $81 just because I used the space to fit several smaller boards did not seem reasonable to me. The suggestion of changing the outline to avoid this cost looked like a more attractive solution, but the square outline suggested would mean I would have a rather painful depanelization to perform, so it did not look ideal.

I checked several other Chinese PCB manufacturing sites (a reasonable list can be found at the EEVblog) but all had these odd and relatively high extra fees for placing several designs within the available area. I wonder why they all have the same rules?

So what I ended up trying was to change the panelization such that it was somewhat less obvious, but with an outline that would still help me depanelize the individual boards. I removed the internal milling and the mouse bites. Then I changed the total outline to meander around larger parts of the outline of several of the smaller boards:

Modified PCB panel
Modified PCB panel

This apparently was acceptable since I got the following response:

Yes, this Gerber file is acceptable to us. We will manufacture your boards according to your new Gerber file.
About the separated sub-boards, you can refer to below requirement.

If the milling part more than 1/3, it will be counted as the separated sub boards, because it is more difficult than normal single board.

For example, 10cm length boards:
the milling length is 3cm or less, no separated sub-board.
the milling length is 3.3cm or more, separated sub-board.

So it seems like as long as one stays away from having more narrow necks than 2/3 of the width of the  board, one will avoid the extra cost. I actually do not think I quite obeyed this rule in the modified version of the board, but apparently it was accepted, so either they are not very strict, or the rules they apply are more complicated than what they say.

Sensor node PCB

Today I finally sent a PCB I have been working on for a couple of weeks to manufacturing. It is a wireless sensor node based on a Cortex M0+ processor and an XBee ZigBee radio module. In addition to the main board with the processor and the radio, there are a couple of break-off sensor boards for measuring temperature, humidity, soil moisture, AC current etc. Here is a screenshot of the board:

Sensor node board v 1.0.
Sensor node board v 1.0.

More information will follow when I have assembled and programmed the board.

How to upgrade a secondary disk in Windows

The 1 TB D-drive on my desktop Windows 10 computer was starting to get full, so I bought a new 3 TB drive to replace it with. After some googling, it seemed like the free version of AOMEI partition assistant would be a good program to copy/clone the contents of the old disk onto the new one. I let it run overnight and in the morning it was done. I then removed the old disk and only kept the new one plugged in.

This is where my trouble began. I had intended to just change the drive letter (if necessary) so that the new disk would also have the drive letter D, just like the old disk. This can normally be done by opening Administrative tools/Computer Management/Disk management (Administrationsverktyg/Datorhantering/Diskhantering in Swedish), right clicking on a drive and selecting “Change drive letter”. After doing this, I got an entirely unhelpful error message saying “Incorrect parameter” (Felaktig parameter in Swedish).

After some googling, it seemed like it might work in safe mode (felsäkert läge), so I managed to get the computer into this mode by holding down shift while clicking restart and navigating through the various menus that ensued. This however did not help. Still I got “Incorrect parameter”.

While in safe mode, I tried another tip I read during the googling, namely to make changes to the registry. This turned out to be successful. Here is what I did:

  1. Open the registry editor by pressing Win+R and typing regedit.
  2. Click to HKEY_LOCAL_MACHINE\System\MountedDevices.
  3. Scroll down in the right pane to entries starting with \DosDevices.
  4. Select all the \DosDevices entries and save them (Archive/Export) to a .reg file on the desktop in case things get messed up and have to be restored.
  5. If there is an entry for the drive letter you want to use (\DosDevices\D: in this case), delete it. (Do not delete the entry for C:!)
  6. Change the name of the entry for the new disk so that it becomes \DosDevices\D:
  7. Reboot

After this the new drive with all the contents from the old D:\ showed up as D:\!

I am not sure it was necessary to be in safe mode while doing this, but maybe it was. I now realize that a reason changing drive letters was so complicated might be that I had the swap file pagefile.sys on the drive I wanted to change letters for. Maybe it would have also worked if I had moved the page file to C:\ before trying to change letters for the secondary disk. Or maybe this had nothing to do with the issue.

There are very many posts on the internet about upgrading the system disk C:\ (which should be harder I guess), but it was a bit more difficult to find this information about how to get the upgrade of the secondary disk to work. I hope I will remember that I wrote this the next time I need to upgrade a disk…