Looking for cheap pcb manufacturer service for 1mm pitch BGA prototyping - Page 1
Forum section: electronics / general

author: luisr
author_rank: Contributor
timestamp: June 19, 2013, 06:12:37 pm
content: Hi I'm working on a board that have a 1mm Pitch LBGA uC... I've been reading some good info about BGA scape routing and doing some test with Diptrace and so far it's seens that I will need a pcb manufacturer that is able to go down to 6/6mil with 12mil via hole/6mil annular ringSo far I was able to find OSHPark (www.oshpark.com) but they only are able to do 13mil via holes with 7mil annular ring... with this specs the outer diameter of the via will be 27mil (7+13+7) which will give DRC errors (and be out of manufacturers specs) when placing vias between the BGA pads (See image attached via.png)Now... I got the idea of putting the via next to its corresponding bga pad but I've concerns about doing this since it can affect the BGA soldering process... example: due to the shape of the pad being modified it can prevent(affect the bga self-alignment while reflowing the board. (See via2.png)I was wondering if somebody knows a pcb manufacturer that offers cheap service for small prototypes (les't say 2 boards) with good enough capabilities to develop a board with the scape routing needed for this type og BGA (1mm pitch)Also, comments on using the method displayed in via2.png will be apprecitedThanks in advanceP.S The idea displayed on via2.png is not mine... I might seen this on one of the countless articles I've read about BGA scape routing

author: gxti
author_rank: Frequent Contributor
timestamp: June 20, 2013, 12:19:07 am
content: Unfortunately it's not posted on the website yet, but the current specs for the OSHPark 4 layer order are actually much better now. 5/5 trace and space, 4 mil annular ring, and 10 mil drill.It's also FR408 (better impedance characteristics than FR4), the stackup is listed here:http://blog.oshpark.com/kb/4-layer-stackup/

author: luisr
author_rank: Contributor
timestamp: June 20, 2013, 01:26:31 am
content: Quote from: gxti on June 20, 2013, 12:19:07 amMan thanks for pointing that out... I was getting crazy looking for such service...BTW The info is actually in their site... found it while looking for info about how to migrate an account from BatchPCB to OSHPark... go figure... they must be so busy that don't have time to update the website properlyAnyway...I really appreciate your help... thanksP.S: the info about new specs are herehttp://batchpcb.oshpark.com/

author: Falcon69
author_rank: Super Contributor
timestamp: June 21, 2013, 01:48:30 am
content: I've been using Sitopway off of eBay. Kevin is a pretty nice guy, and Trustworthy. I've been getting my boards within 10 days after ordering. The boards have been pretty decent so far.

author: marshallh
author_rank: Unknown
timestamp: June 21, 2013, 03:13:04 am
content: Solution: Fudge things until you fit in spec... for prototypingIn your case make sure your bga lands are the right size. Take the nominal ball size, and multiply by 0.6, that is your actual pad size.Also you can shave some off the annular ring.I've done many bga boards through oshpark and had success.You could probably do the itead/seeed services and cram in 1mm bga without a problem.Keep in mind Laen rotates through fabs for the 4layer order. He changed things up a month ago andthe drill registration is not 100% spot on like it used to be. Hopefully that's worked through, but only a problem if you were doing 0.8mm bgaAn old board done with the old fab (the new ones do better LPI silkscreen and tighter specs)

author: cwz
author_rank: Newbie
timestamp: June 22, 2013, 05:01:43 am
content: What you show in via1 is basically called a dogbone -- your vias are enormous, and you might have trouble because of that, but it's a fairly standard method for doing fanout. You might have better luck with large vias if your fab will tent them with soldermask.As you mention, what you show in via2 may have problems because the pad shape is poorly defined. It depends on how many of these you plan on making. If it's just a one off, you might get away with it, but you are almost certainly going to have problems in any larger qtys.Not sure what you're doing, but unless it's a fairly small BGA in terms of pin count, I can't imagine that fanout is going to be a lot of fun on 2 signal layers (assuming you're using a layer ea for power and gnd).

author: luisr
author_rank: Contributor
timestamp: June 24, 2013, 01:30:00 am
content: Thanks to all for the Helpmarshallh: Until now 1mm BGAs are the smallest BGA pitch I'm planning to use.cwz: Those vias are 13mil Hole with 7mil annular ring, I was doing test with those specs because so far I was unable to find a pcb service that could do better than that for cheap.The device I'm planning to use is a NXP LPC1857FET256 which comes in a BGA256 package (full 16x16 matrix), which I'm hoping to be able to route it on a 4 layer pcb with some decoupling caps, a couple of supporting ICs and some connectors... Nothing complex since I only have the Non-profit 500pin license for Diptrace (until I buy the Non-profit 1000pin license or go with Cadsoft Eagle)

author: will9twl
author_rank: Contributor
timestamp: November 23, 2015, 08:16:21 am
content: This might be a bit late.You could try smart-prototyping.comThey can do 3*3mils track width and clearance, as well as 0.2/0.25/0.3mm vias.I'm planning another new design with them and the BGA pad sizes are 0.22-0.25mm in size.