Blob Grid Array Technique Mounts Board-To-Board

[Howard Matthews] mills his own PCBs, and man, does he hate drilling through-holes. Manually changing the bits between engraving and drilling after isolation routing? What is this? The stone age? [Howard] decided to rethink his DIY PCB manufacturing process, and came to one essential conclusion: Only a fraction of these drills are actually necessary. Many of our cheap and beloved components, such as the NRF24L01+ and ESP-01 wireless modules come with unnecessarily bulky pin headers. To get away without drilling, [Howard] figured, that all he needs to do is leave out the pin headers and mount these modules board-to-board, using what could be best described as a BGA (blob grid array). To mount an NRF24L01+ module, [Howard] first removes the pin headers from the module and cleans the pads. He then tins the eight corresponding pads on his milled PCB and adds two index blobs. Kapton tape surrounding the joint helps with the isolation. The module’s plated holes are then first soldered to these index blobs before the other holes are filled with solder to make a connection. The result is pretty slick, since board-to-board mounting saves a lot of space, although the pin-header-removal step undermines the productivity aspect of the trick. Modules with castellated mounting holes are still slightly more expensive and not always available, so this might be a nice technique to keep in mind. Got some even better pro-tips on DIY PCB manufacturing? Put them right below in the comments!