BGA and home assembly - Page 1
Forum section: electronics / general

author: TomS_
author_rank: Frequent Contributor
timestamp: April 12, 2020, 11:23:26 pm
content: Hi everyone. Im working on a project that will likely see me use a BGA or two, specifically for some CPLDs (MAX V).The CPLDs come in a variety of BGA flavours, some FBGA with 1mm ball spacing, and others like MGBA with 0.5mm ball spacing. The FBGA is mostly available for the biggest LE variants, while the MBGAs are mostly on the lower count LEs.Im getting the feeling that the FBGA packages will be easy enough to manufacture boards for and also assemble at home, I can get away with mostly 5-6mil spacings between traces, pads etc.But the MBGA package looks unachievable, even for someone like PCBWay that have pretty decent capabilities (down to 4mil). Playing around with some layout Im also struggling to fit traces through without going down to 2-3mil dimensions meaning board manufacturing is going to need to step up a notch or two, and thats probably beyond the expense I would like to incur.The other alternative I have for the smaller LEs are some TQFP packages. Unfortuntely they take up more board space, but at least I would be able to manufacture them with most of the cheaper Chinese houses and solder them myself.How do others handle such fine pitches in their projects?

author: kizmit99
author_rank: Regular Contributor
timestamp: April 13, 2020, 04:22:35 pm
content: This is simply a data-point for you to consider, but I had success with a 256ball, .8mm pitch BGA (it was a cyclone 10) using JLCPCB's standard (cheap) 4-layer PCB rules.Based on what I had to do for that one, I would suspect that .5mm pitch would require tolerances beyond their standards...I had success soldering the BGAs on those boards with a home-made reflow oven (Controleo 3 based).Best of luck with your project.

author: cgroen
author_rank: Unknown
timestamp: April 13, 2020, 05:35:44 pm
content: Somewhat related:https://www.eevblog.com/forum/microcontrollers/pcb-for-a-bga-microcontroller/msg3013184/#msg3013184

author: asmi
author_rank: Super Contributor
timestamp: April 15, 2020, 01:13:53 am
content: Quote from: kizmit99 on April 13, 2020, 04:22:35 pmThe project in my signature (Spartan board) has 2 BGAs (1 mm pitch for FPGA, 0.8 mm pitch for DDR2). It was specifically designed for JLCPCB's 4 layer process, it actually works (I've assembled the board to verify that), and it's fully open source (as the idea is for that project to be a basis for custom boards with some other peripherals). I assembled it at home, as well as many other boards with BGAs with zero reflow failures on BGA parts so far.

author: asmi
author_rank: Super Contributor
timestamp: April 15, 2020, 01:15:11 am
content: Quote from: TomS_ on April 12, 2020, 11:23:26 pmBGA typically require multilayer PCBs, and in many cases with controlled impedance, so I doubt you would be able to make them at home

author: TomS_
author_rank: Frequent Contributor
timestamp: April 15, 2020, 09:13:18 am
content: Quote from: asmi on April 15, 2020, 01:15:11 amI won't be manufacturing boards at home. I need 4 layers minimum.And I doubt I'm going to be doing anything needing controlled impedance. No diff pairs, nothing high speed, just a CPLD to integrate a whole bunch of stuff that will be clocked by an SPI clock, so maybe low single digit MHz.