This is my first post here, big Hello to the community
I’m in need for advice. Currently I’m doing hobby project in KiCad
for which I’ve set a bit high criteria, i.e. I would like to cramp a lot of
functionality in small space. Probably going for the 4 layer PCB and smaller
package versions of ICs. Plan is to use hot air soldering or homemade reflow oven
to assemble board (I have no special equipment for the inspection of joints
made).
I was looking into the CSP (STmicroelectronics WLCSP) package for the main uC,
0.4mm pitch and 49 pins. Does anybody have experience with current China PCB fab
manufacturers which do small quantity PCBs for hobbyists and could support design
with such a component (Ball pad size, Fanout clearance, via size, …)?
Or perhaps, if somebody had done some BGA design in KiCad and
had it produced for relatively small price <60-80$ for 5-10 pieces?
From my personal experience we have been working
with technotronix.us from last 15 years and they have been good in terms of
turn around and over all build quality of my products, we did start with them
from prototype and also they have BGA equipments so I am assuming they might be
doing BGA CSP design.
You might want to try Seeedstudio’s service. They successfully made 10 prototype 0.5mm BGA boards for me for less than 10 bucks (shipping was extra). The quality wasn’t the best, but it worked. In particular, the silk screen was offset about 1mm, and solder masks were a bit too large.
You need to specify tolerances for you board before you can have any meaningful answer. What is your smallest trace width? What is your smallest spacing, smallest plated or non-plated hole? That aside, I often use 4pcb.com (Advanced Circuits). They have specials for 2 and 4 layer boards. For four layer board it is $66 per board and you need to order 4 min. It doesn’t sound very good, but if you have a board that is relatively small you can create an array of boards and then cut them yourself. They will charge you an extra $50 for multiple parts but even so, if you can fit around 10 boards per array it puts you at ~$7 per board which is ok.
Here are the specs for that special:
Min. Qty 4 Boards, Lead Time 5 Days, 4-Layers, FR-4, 0.062" 1 oz. cu plate, Lead FREE Solder Finish, Min. 0.006" line/space, Min. 0.015" hole size, Plated or Non-plated holes (if no specifications provided, holes will be plated), Maximum 35 drilled holes per sq. inch, White Legend (1 or 2 sides), 1 Part Number per Order (extra $50 charge for multiple parts or step & repeat), Max. Size 30 sq. inches, No Slots (or overlapping drill hits), No Internal Routing (cutouts), No Scoring, tab rout, or drilled hole board separations, Routed to overall dimensions, Green LPI Mask
If you can get away with a two layer board you can cut the price roughly by half.
If you tolerances are tighter than those stated above, check out pcbcart.com I had a decent experience with them.
I had to get some BGA parts replaced at a motherboard fab I used to work for. The new part had to be aligned using microscope a contraption that did x, y, and rotate. They could not use airflow because it would jiggle the part. They used an infrared heater. That was many years ago and it may be easier these days.
In Malaysia many of the more IT related malls have shops repairing cell phones. They have equipment for soldering BGA packages and could do the BGA assembly for a small fee. Hand placing BGA is not easy.
Is 4 layer realistic?
Hand-placing BGA and reflowing can be easier than you think. I made a video showing how I do it with nothing more than flux, some magnifying glasses and a hot air gun:
My technique is obviously not for a production environment, but it works when you have to get a BGA onto the board in a lab setting. I’ve done 1mm and 0.8mm BGAs with 256 balls. (Obviously, smaller stuff like those Kinetis microcontrollers that fit inside a golf ball dimple would just blow away.)
The original post was about 0.4mm, which is a different ball game
I have done commercial boards with 0.8mm and still needed X-ray inspection as we had cracking problems (a tip, don’t put V-cuts anywhere near a BGA device)
At least not in sub 100$ range.