TM4C129 "ZAD" (BGA212) package orientation question

Thank you Amit!

Best Regards,

Dave

@Dave,

We note similar "ambiguity" has visited another M4 provider.  (and in that case "multiple" embossed circles sometimes appeared - how delightful that!)

At least for your first few shipments - suggest that (you) visually verify via that "missing" ball - at least for a small sampling - to insure conformance.  Vagueness w/in data manual - for so important an issue - is hard to fathom...

SourceTwo said:

As a result, I'm going to be using a BGA for the first time, and I have a rather basic question:

 Hi Source two, I try discourage you if this is your first experience with BGA, try another large package before to use this fine pitch, PCB cost a fortune and it is not simple to prepare correct land pattern.

 I am not the first time using a BGA, this one at end discouraged me due to cost and too fine line to escape pattern.

 Few chip QFP are available from EBV, if you check Digikey and Mouser I bet they get soon, the part are you seeking is in stock available from digikey:

http://www.digikey.com/product-search/en/integrated-circuits-ics/embedded-microcontrollers/2556109?k=tm4c129

Hello CB1 and Roberto,

Thank you for your kind advice and support!  I can provide a bit of background on my thought process:

This project is to design a drop-in replacement for the Luminary IDM-L35 display module, which we long ago integrated into a successful laboratory instrument.  The flash is wiped clean and replaced with considerable amount of code for machine control and GUI.  The GUI uses GrLib (which is destined only for Luminary/TI devices).

If the TM4C123 family had sufficient RAM, I would eagerly use it in an LQFP100 package and be on to the next project.  However, to match the RAM provided by the original LM3S1958 (64K) and comply with the GrLib terms of use, I intend to use the TM4C129 in the redesign.

As you have both noted in this forum, TI seems to be rolling out the ZAD package initially - much to the chagrin of many!  Ironically, this project is the first one in a long time where I have lots of PCB area to work with, so the large LQFP100 would be no problem!  Just since my post yesterday, DigiKey shows a 5th TM4C129 in stock - also a ZAD.  They have just 22 pieces of one single part number using the PDT package...

I have been very impressed and appreciative of the Application Report "System Design Guidelines for the TM4C129x Family of Tiva™ C Series Microcontrollers" provided by TI.  It details the BGA's escape routing, land pattern, and suggested decoupling placements.  To my inexperienced eyes, this BGA package looks well thought out and relatively simple to apply - the one exception being the native 0.5mm pitch.  I used the pad array generator in my layout tool (OrCAD 16.0) to make the full 19x19 array, then deleted the missing pads and triple checked it.  So, I am gaining some comfort in proceeding with the ZAD package.

We need to build 100+ of these assemblies, so I am taking this path to avoid the unknown risk in sourcing enough PDT parts for the production run.  I acknowledge that the BGA is increasing risk on the fabrication side though.  Our fabricator charges about $1.00 per placement for X-RAY inspection, so that's OK, and the board will be 4-layer either way.

As others (perhaps yourselves) have pointed out, it would be helpful if TI could be more forthcoming - it seems as though they're deeply roadmap-adverse.

I'll provide an update when the solder cools.  Thanks again for the concern and advise!

Best Regards,

Dave

Hi Dave,

Yours is a complete, well detailed (and justified) report. 

May I offer some further suggestions - gleaned from our recent (non-expert) BGA experience?

a) Show your Gerber files to your board fabricator - insure that they, "bless" your treatment of pad features & the proper escape of MCU signals

b) Insure that the fabricator has past experience w/that exact BGA package/style.  And - beyond that - has sufficient track-record w/BGA fab in general.  (I'd not be shy about seeking, & confirming, BGA references)

c) It would not be unusual (to my mind) to experience some MCU and/or board "loss" as the fabricator, "fine tunes" his process to your unique board/BGA IC.  Some find it useful to load just the MCU during the first few BGA assemblies. 

Bon chance, mon ami.

SourceTwo said:

We need to build 100+ of these assemblies, so I am taking this path to avoid the unknown risk in sourcing enough PDT parts for the production run.  I acknowledge that the BGA is increasing risk on the fabrication side though.  Our fabricator charges about $1.00 per placement for X-RAY inspection, so that's OK, and the board will be 4-layer either way.

 Try also as suggested by CB1 ask how much it cost board fabrication with 4 mils track and microvia technology. Also remember .5mm BGA can be a nightmare. 4 Layer are feasible but you have to take a long time to arrange all around it.

 Another idea can be to use internal LCD controller to have better performance and less component.

 You can evaluate mikroelectronika board to see how it work before to make:

http://www.mikroe.com/mikromedia/5/tiva/

 it use a TIVA and controllerless LCD TFT, you can develop your code on this board and also show it to your manufacturer to ask what it think about.