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USB on an 8 bit ISA Bus, it is possible!!!

I think you need to find a ruler and measure how small a .4mm ball pitch is.

.8 and 1mm BGA can be done with a home oven. However the boards are prohibitively expensive for hobbyists to order. For 1mm pitch the dog bones require 10 mil drills and 5 mil rings. That beyond most bargain PCB's DRM rules. .4mm is solidly in HDI territory which adds up to significant dollars for small runs of boards.
 
A little bit off topic but regarding BGA soldering, I agree that it is mainly a factory-level game. But it is also not absolutely impossible for a hobbyists at home. The key is a practical method to manage the temperature curve and the focus of heating. I recently fixed an ATI HD2600 video card from my 2007 Apple iMac. The GPU on this card was gone and I have to replace this one-square-inch BGA chip, which has hundreds of tiny soldering joints underneath it. I made my own "BGA rework station" with a cheap aluminum pizza case, a thermal meter, the kitchen stove and a 898D hot air gun (I will add pictures after I'm home tonight). the temperature curve that I adopted for this chip is: 110℃/120s - 200℃/120s - 265℃/30s - 100℃/120s. Long story short, I went through the curve twice for removing the damaged BGA chip and re-soldering a brand new identical BGA chip. The card seemed to work for weeks so far, although it looks quit toasted. However, the entire process that I experienced was much more complicated than what I can write here, and always with uncontrollable speculations between success and failure. Yes, it's possible but extremely difficult and speculative. Joy in pain...

Comment: do not take this as any tutorial in general. It is my true story but only for your entertainment.
 
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Well, the specialists in adapter boards Schmartboard, do market BGA adapters, but the best they've been able to do is 1.0 mm pitch. Here's their assembly instructions. I can't imagine doing an 0.4 mm BGA the same way with any measure of success. BGAs that small are definitely reflow-oven fodder, which puts them outside of the usual electronics/computer hobbyist's capabilities.
 
evildragon said:
Don't they have any BGA adapters that are spring loaded like how motherboard sockets are now these days?
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Yes, they do make sockets for the larger pitch BGA devices but they are very expensive ~$100 each.

The BGA socket would be more expensive than the rest of the board and parts combined.

BGA devices are designed to be assembled with robots and baked on in IR ovens/heat guns.

I've seen manual BGA soldering rework stations and they use a microscope like device and tiny tools.

Most of the time I can't even see what they are working on even staring right at it.

BGA is a non-starter for hobbyist projects IMO unless they are going to be pre-assembled at the factory.

In that case, be prepared for some big time prices -- as in hundreds per board in quantity.

Andrew Lynch
 
lynchaj said:
Yes, they do make sockets for the larger pitch BGA devices but they are very expensive ~$100 each.

The BGA socket would be more expensive than the rest of the board and parts combined.

BGA devices are designed to be assembled with robots and baked on in IR ovens/heat guns.

I've seen manual BGA soldering rework stations and they use a microscope like device and tiny tools.
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There's a BGA rework station just down the hall from me... I can't imagine how much it cost the company, but it wasn't cheap I'm sure. The microscope is a stereoscopic one, and on top of that also overlays a lighted template in the field of view for lining up the workpiece with the part footprint. The table is also heated and has jets underneath to heat the underside of the board, as well as the hot-air gun nozzle that heats the part up itself. The part is held to the nozzle with a vacuum and the tecnician lowers the part down directly onto the board when it the temperature is right.

It doesn't look like a complicated process, but the equipment definitely is.
 
Doesn't that sort of prove my point that BGA component work is probably beyond the skill level of most hobbyists? Look at how exotic your set up is! Could average hobbyists replicate anything like that with consistent success? I really doubt it.

I have made many PCBs and have builders almost constantly unhappy with the PCB only option. Nearly all of my hobbyist PCBs are all 0.1" PTH DIP/PLCC technology. Basically Radio Shack 25W soldering iron technology is too much for a sizeable percentage of hobbyists!

Using SMT components to a limited extent might be feasible for some with careful part selection and PCB layout. However even the "wide pitch 1mm" BGA technology is just not realistic for nearly everyone. Also it requires much more sophisticated and expensive multi-layer PCBs.

Yes, it may be possible but I don't think it is practical. You all are free to try whatever you want but all I can say is "good luck"

Andrew Lynch
 
lynchaj said:
Doesn't that sort of prove my point that BGA component work is probably beyond the skill level of most hobbyists? Look at how exotic your set up is! Could average hobbyists replicate anything like that with consistent success? I really doubt it.

I have made many PCBs and have builders almost constantly unhappy with the PCB only option. Nearly all of my hobbyist PCBs are all 0.1" PTH DIP/PLCC technology. Basically Radio Shack 25W soldering iron technology is too much for a sizeable percentage of hobbyists!

Using SMT components to a limited extent might be feasible for some with careful part selection and PCB layout. However even the "wide pitch 1mm" BGA technology is just not realistic for nearly everyone. Also it requires much more sophisticated and expensive multi-layer PCBs.

Yes, it may be possible but I don't think it is practical. You all are free to try whatever you want but all I can say is "good luck"

Andrew Lynch
Click to expand...

Agreed... in general I think the complexity of most BGA parts themselves is probably beyond the scope of most hobby applications as well. A lot of the RAM bus speeds of the microprocessors we are using now require very careful component layout and routing for DDR, well outside the capability of the hobbyist. And if you have a problem soldering that BGA? Have fun reballing it. I've been told at work that a typical processor-sized (200+ pin part) BGA can cost upwards of $400 to reball.

I do think there's a place for SMT for hobbyists, but it's limited to parts packages that have connections at the edge of the part. Fairly fine pitch QFPs can be done easily with a wide chisel tip iron and a generous amount of flux.
 
geoffm3 said:
I do think there's a place for SMT for hobbyists, but it's limited to parts packages that have connections at the edge of the part. Fairly fine pitch QFPs can be done easily with a wide chisel tip iron and a generous amount of flux.
Click to expand...

I do fine on 0.5mm QFPs with just an iron and some braid. If I can do it, anyone can.
 
lynchaj said:
Doesn't that sort of prove my point that BGA component work is probably beyond the skill level of most hobbyists? Look at how exotic your set up is! Could average hobbyists replicate anything like that with consistent success? I really doubt it.

I have made many PCBs and have builders almost constantly unhappy with the PCB only option. Nearly all of my hobbyist PCBs are all 0.1" PTH DIP/PLCC technology. Basically Radio Shack 25W soldering iron technology is too much for a sizeable percentage of hobbyists!

Using SMT components to a limited extent might be feasible for some with careful part selection and PCB layout. However even the "wide pitch 1mm" BGA technology is just not realistic for nearly everyone. Also it requires much more sophisticated and expensive multi-layer PCBs.

Yes, it may be possible but I don't think it is practical. You all are free to try whatever you want but all I can say is "good luck"

Andrew Lynch
Click to expand...

And this is the main reason hobbyists electronics died out... all about money- let the machines do everything for humans and not provide an alternative when the machines screw up. What ever happened to fixing things that were broke instead of throwing them away?!
 
cr1901 said:
And this is the main reason hobbyists electronics died out... all about money- let the machines do everything for humans and not provide an alternative when the machines screw up. What ever happened to fixing things that were broke instead of throwing them away?!
Click to expand...

I don't think it's anything so insidious. Fanout with hundreds of pins is harder without BGAs, certainly it makes for much smaller packages which makes for smaller devices. Cell phones would be much larger without them.
 
Yep, added comments in my original post @22 floor for avoiding potential misleadings.

Back to the topic, I do use USB mass-storage on most of my ISA rigs. I'll post details tomorrow...
 
Back to the topic. I'm not sure if there is a massive demand for using USB keyboard, USB sound codec or USB printer on vintage computers. But imo, using USB mass-storage does matter for the sake of convenience and cool. Actually, I have been using USB sticks on my 386DX-40 and DX4-100 for 2+ years. The product I use is a CH375 based ISA card with an USB port on its backplate (as pictured). Yes, it comes with a little (4kB) DOS driver that can be loaded by config.sys which adds a new DOS drive letter (H:\ for eg.) also visible under Windows 3.x. It allows me to use USB stick, USB card reader or USB external HD with my ISA rigs, including my 8088 XT clone (8-bit ISA), with reasonable r/w speed. It supports hot-swap and even boot from USB (if a boot ROM is installed). However, it may not be a general USB solution for ISA bus but just USB mass-storage only, and the storage has to be formatted in FAT (required by DOS). I have not yet tested it with USB hub or CD/DVD. But I do prefer its convenience over floppy disks, LL3 or FTP (command line).

So far, I'm just a user without putting any thought on what else this product can do with USB. I'm happy with its existing simplicity of use because that's all I need for my $18. Maybe it is not something truly belong to vintage computers. But it's another nice retrofit option similar to those modern LCD monitors, CF cards or FDB-based HDDs often seen in today's retro projects.

I bought it from a random online seller in China. I don't have a valid URL anymore (sorry) but full information about this product is easy to access by Googling with keywords: USB ISA CH375. That's why I didn't bother to post it here as I assume it's something known without mention.



ISA_USB_1.jpgISA_USB_2.jpgISA_USB_3.jpgISA_USB_4.jpgISA_USB_5.jpg
 
I think I have a couple of USB-serial adapters from the same maker.

If you're interested only in storage devices such as flash sticks, then it's probably okay, but it really doesn't take much to do that. But connecting to a variety of USB devices does require a USB driver stack--and that's where the software gets ugly.
 
Yeah. if I recall correctly, I was brought here by the amazing XT-IDE. But given the vast (if not infinite) categories of USB drivers, maybe the development cost will beat the power of passions in typical hobbyist measurement. As you may already noticed via Google that most of the USB ISA cards come without backplates, implying a fact that they actually target to those industrial users. So, my choices are quite limited within what're already available now.

But miracle like Raspberry PI does exist -- starting from passions but got its path to bissness eventually. Is it always duplicable then?
 
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Did a fair share of googling for this mysterious ISA USB card, but didn't come up with anything. Can you give us a manufacturer, or model number that can be added to the search? Thanks!
 
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