Identify this stencil please

[dicky96]

Hi guys
Does anyone know what this stencil is called?

I've attached some pics

The chip is off a Soundblaster Xfi

CA20K1-PAG LF

I can find chips on Alibaba but not stencils, but while I have been playing around on scrap boards I have found this type of stencil shape (a square block in the centre then a gap) seems very common

It's 0.6mm P1.0

Is there a common name for stencils of this layout/shape?

See pics. I noticed that my microscope camera needs setting to the correct aspect ratio!

[dicky96]

Re: Identify this stencil please

Here is the cleaned PCB

With a combination of....

my new KSGER T12 with BC3 tip set to 330C
Amtech NC-559 Flux
Chemtronics Size #4 Solderwick
Advice from several kind folks here
and a fair amount of practice

I am now able to clean up the PCB after BGA removal without losing any pads! I honestly thought at several points this was all a big mistake but I seem to be finally getting somewhere

I'm not sure exactly which factor finally got me there, I think it was the T12 compared to my old Maplin ZD-916

[Spider1211]

Re: Identify this stencil please

Hi, the solder ball array looks very similar to this chip: SONY CXD9209GB.

http://www.chipsetsupplier.com/htm/5...ll%200.6mm.htm

[Spider1211]

Re: Identify this stencil please

Alternatively, you could use a 0.6mm P=1.0mm universal stencil and just mask off the areas you don't want with kapton tape.

That's what I usually do for simple pattern BGA chips.

[diif]

Re: Identify this stencil please

With a simple pattern like that, I do as Spider1211 does. One of my universal stencils and some kapton tape. I use 50mm wide, so it covers all of the holes and then I trim with a scalpel.

[dicky96]

Re: Identify this stencil please

Yeah I know the Kapton tape trick, in fact it was yourself who taught me that.

I was just thinking as some stencils seem fairly common I would grab those as I come across them and gradually build up a decent collection.

That grey brown dust you can see in the pics when I removed the BGA - that stuff gets into absolutely everything here and I think it may be the cause of many an electronics failure.

[Spider1211]

Re: Identify this stencil please

Dust for the most part act as an insulator thus preventing proper heat dissipation. Running electronics at higher temperature reduced their lifespan. High humidity could also be a problem, especially if the quality of solder used isn't great.

You can get different type/size of universal stencils with different pitch distance and ball size. Most common are 0.35, 0.45 and 0.6mm. Its a good idea to also keep solderballs at hand, they are fairly cheap. That, and solder paste (for those "Urgent" reballs and you don't have the appropriate solder balls :P

[diif]

Re: Identify this stencil please

Yes, I totally agree about building up a set of the most common stencils but I don't think you'll see to many of these and at £15-£20 for a working card, it doesn't make sense to me commercially.

Whilst annoying, I'd take that dust over UK weather and it's obviously provides regular work.

[dicky96]

Re: Identify this stencil please

You are completely correct diif - though as you know I am not doing these repairs BGA for commercial purposes at the moment.

Having said that, this Sound Blaster Xfi Extreme Gamer will find a useful place in one of my retro gaming rigs if I get it working

That dust comes from the Calima weather (when the wind blows from the south east and carries dust from the Sahara) We can get them any time of year and they usually increase the temperature by up to an extra 10C as well as bringing dust for a few days. We had one this week and are forecast another for next week - hence we are getting around 26C-28C compared to the normal 21C for January. Sometimes the Calima gets as far as the UK and gets deposited all over your cars!
I think it has quite a high salt content though I don't know if it is actually conductive with some moisture. It's hard to prove as we don't get a lot of moisture, only 88mm rain a year here. It hasn't rained yet this year.

I'm originally from northwest England (Stoke-on-Trent actually.... somewhere near you diif?) so yes I know all about UK weather!

Hi Spider1211, not seen you on the forum before. I see you come from Mauritius, it's somewhere I always wanted to visit. There are some similarities between our islands, though yours looks much much wetter and greener. Do you get that desert dust there?

Back on topic - I am debating with myself whether to buy something like this
https://www.aliexpress.com/item/3302...49cf2e0eVQKtRw

Or this
https://www.aliexpress.com/item/3295...49cf2e0eVQKtRw

Then add more if/when I need them.

I'll just go stand in the corner and vacillate for a while...

At least now I know I CAN remove and clean up a BGA. I am in no doubt I will trash more stuff yet... but knowing I am capable of doing it is a big relief.

[Spider1211]

Re: Identify this stencil please

I am very new to this forum and only recently started posting. No desert dust Mauritius is a tropical Island (a dot on the world map ), humidity varies but overall its very nice. Area near the seaside usually has higher air salt content and unprotected metal will rust very easily. Amazing beaches, mountain ranges, great food and cultural diversity among others. Definitely worth a visit!

Back to BGA, I think for starter you might want to stick with the 184pcs. You might not even ever use some of those to be honest.

One thing to keep in mind though is that the link you provided are jig mounted stencils. You clamp them in a jig like this:
https://www.aliexpress.com/item/1869...chweb201603_55

The jig version is much easier and less hassle to use but are more expensive. There is also the direct heat version but those are prone to warping if you don't hold them properly + require quite a bit of setup and getting used to.

Direct-heat version:
https://www.aliexpress.com/item/3239...chweb201603_55

As with anything, practice makes perfect! What initially seem difficult eventually becomes second nature

[dicky96]

Re: Identify this stencil please

Welcome to the forum Spider and I hope you enjoy it

This Island (Gran Canaria) is similar to yours, dot on the map, very warm and sunny, stunningly beautiful, amazing beaches, mountains (up to 2000m), great food, cheap beer and...... etc. We are at similar latitude but different hemisphere... You are very near to the tropic of Capricorn and we are very near to the tropic of Cancer, and there is the Africa continent between us.

But I would still love to visit yours sometime! why not put a local pic in your avatar as I did. The avatar of mine I can see from my balcony though not quite from that angle :-)

I have one of those jigs already (thanks to diif recommendation)

I'm very old to electroncis repair and very new to BGA rework but learning as fast as I can.

IMHO a lot of practice + good advice + good equipment is the necessary combination to make BGA work anywhere near perfect. Not practice alone. With all my previous experience i was having no success until I got some better kit.

Rich

[diif]

Re: Identify this stencil please

Yes, I live a 5 minute walk from the worlds largest crisp factory and we won some footy thing a couple of years ago. I used to take my daughter to Waterworld when she was younger.
I thought you had some stencils, hence suggesting the tape method, so you can carry on and get it reballed rather than waiting. There's only 376 balls required. At 5 seconds a ball that's half an hour, at 3 seconds it's under 20 minutes. Any practice is good practice and it's about getting the balls on the pads, a stencil is just a useful aid.
Back to your question, I'd get the smaller of the two stencil packs and add to it.

[Spider1211]

Re: Identify this stencil please

Thank you! And yes, I am most certainly enjoying this forum. You are very welcome to come visit. I'd suggest coming during summer season though, it's much more enjoyable.

Great! It gets much more interesting (and frustrating) when you start dealing with underfill BGA chips . You might consider getting one of those: https://www.aliexpress.com/item/3296...chweb201603_55

Do share your experience with us when you try underfill.

[dicky96]

Re: Identify this stencil please

I do have some 90mm stencils, just 10 of the common size/pitch in a large square grid. I was thinking of expanding my collection.

The Kapton tape method did work though it was a bit fiddly and I probably need some decent scalpels rather than my Stanley knife

I did also think overnight of just manually dropping balls into the required holes with a fine pair of tweezers. I will try that.

I've been to your fair city numerous times - I used to buy a lot of satellite kit from a company who were very near there. You do have considerably better weather than Stoke though :-)

[dicky96]

Re: Identify this stencil please

Hmm all this is a bit of a moot point as I have managed to damage the BGA in the process somehow

It looks like the green part (is that called substrate?) has warped, cracked or bubbled on one edge and, coincidentally, this is exactly at the place where I got my screwdriver between the topside of the BGA and heatsink and twisted it to pop the heat sink off. That did take a fair amount of force.

When I was looking to see what had happened there, one of the pads fell off. But I think the BGA was already damaged anyway

See pics

[Spider1211]

Re: Identify this stencil please

This looks like a ripped pad. Usually ripped pad happens on the motherboard, very rarely on the chip itself. Are you using a BGA reflow station to work with BGA chips? What size screwdriver did you use?

[dicky96]

Re: Identify this stencil please

When I first removed the BGA all the pads were still attached

See the photo in post #1

This came off after I had cleaned the BGA and there is definitely some bubbling and what looks like a crack in the 'substrate?' at that point. I can see it clearly under the microscope but it may not come out well on the photo

I used a flat blade screwdriver 5mm wide. The heat sink was very difficult to remove - here is the thread about it
https://www.badcaps.net/forum/showthread.php?t=81998

I am using one of these BGA machines

https://es.aliexpress.com/item/32868...B&gclsrc=aw.ds

I bought it on singles day 11.11 so got some discount on the price. It arrived around mid December. As I am only learning to use it at the moment, I have to fit my spare time around real work. So some days I don't have time to play with it.

[Spider1211]

Re: Identify this stencil please

It could have been the screwdriver, details not very visible in the picture (from the picture it looks like fiber weave you would see on PCBs on close ups). When removing stuck heatsink , it might be a good idea to use a thin but rigid piece of metal/material as a shim such that when you twist the screwdriver the force is spread on a larger surface area rather than concentrated on a single spot (where the side edge/bevel of the screwdriver contact the PCB).

Traces near BGA chips are very thin and can easily be damaged/cracked as well as the possibility of damaging internal layer traces if too much force is exerted.

Sweet BGA machine by the way! Would love to get my hands on one of these

[Spider1211]

Re: Identify this stencil please

Could also have been damaged during wicking.

[dicky96]

Re: Identify this stencil please

Yes probably. I noticed it was missing when i cleaned all the flux off with IPA and a brush.

I'm still convinced there is some damage to the green plastic part of the BGA in the same area the pad came off