Screaming Circuits: September 2007


Plugged Micro via in pad

One of the options we recommend for vias in BGA pads is to have them filled and plated over. You can Copper_filled_via_flat_2have this done at the your board house for full vias or microvias. If done properly, it effectively takes the via out of consideration. It doesn't matter any more.

However, sometimes the processing isn't nailed down and you can get either a indent Copper_filled_via_bulge or small bump over the filled via. The indent is probably most common when resin is used to fill the via. In either case, the bump or dip can lead to a less reliable assembly, especially with fine pitch BGAs and chip scale packages.

There's always just one more thing. Isn't there.

So, if you are going to put vias in your BGA pads, our first recommendation is to have them filled andCopper_filled_via_droop  plated over at the board house. If you do that, make sure you discuss it with them and see what their standards are for creating a planar surface.

You can probably tell, but I simulated the bump and dip in these images. I don't have good real examples, but this is pretty much what it would look like.

Duane Benson
Bad wolf

Good PCB CAD Software

Here's a scenario we run across reasonably frequently. It happens to a lot of different types of folks. First, there's the small company engineer. He or she has to design a board and get it out the door with pretty much no budget. Then, you might have a seasoned EE at a large company suddenly tasked with more than just the phase locked loop design. Now the project also requires designing the rest of the board, the layout and the prototyping. Oh, and by the way, there isn't a budget for buying another seat on the big CAD system.

Enter PCB123. You might know them as Sunstone Circuits. If not that, then you might have used them as PCBexpress. All the same company. Probably half or more of our customers buy their pc boards from Sunstone. They always give us (and more importantly, our customers) great service. They're just up the road from us so we can get things back and forth quickly too.

Back to the subject at hand - PCB123 is a free to download and easy to use but powerful schematic Linktopcb123 capture and PCB layout package. It also automates the process of board quoting and ordering. Yes, it does require that you purchase the finished boards from them, but we'd recommend you do that anyway. If you get your boards from PCB123 and your assembly from us, all you have to do is tell them in the special instructions to send the boards to us.

They are a different company than we are so you do have to quote the assembly with us separately, but it's really easy to do. Give the PCB123 folks your screaming circuits order number and tell us the boards are coming from them. Ship us your parts kit (or have us order them for you as a turn-key) and you don't have to worry about the boards. When they are all fabbed up, PCB123 will send the boards and necessary files directly to us and we'll ship you the completed assemblies. Cool.

Duane Benson
Software is fun

On Time Delivery at Screaming Circuits

While most of the posts in this blog are more related to pcb design, assembly and the environment engineers live in, I wanted to mention something about the culture we have here at Screaming Circuits.  We just finished August, traditionally a month of vacations (at least in Europe), when things tend to be a little slower at work.

We had an above average month, our volume of orders was slightly better than expected.  It was not a record month for us, but was within 10% of our best and we were busy.  Last month was particularly nice for us because we had 99.5% on time delivery.  Just to put that differently, that is 1 order late in 200 orders.  We are very proud of our on time delivery, and show the importance of that to our customers with our delivery policy, where we refund 50% of your order if we are 1 day late, and 100% if we are 2 days late with shipment.

Great job to the team here at Screaming Circuits and we hope that you customers will continue to reward us for performing with more work!

Thank you,

Jered

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