Designing first PCB for TA2020

[frasco]

Hi all! I'm an electronics noob getting started in the world of DIY audio. Well, that's not completely true, I built a pair of 2-way speakers around 10 years ago to which I chose the drivers and designed the crossovers for. My knowledge is however limited in the area of electronics but I'm eager to learn!

I stumbled on the T-amps and decided to build one. I've ordered parts for a TA2020 amp (schematic based on the datasheet and mods from the Lepai thread) and I thought about assembling it on stripboard first but after a few layout designs I started considering designing a PCB instead.

So, I just got started with Designspark PCB using a one-layer design and the first issue I faced was pad/hole sizes for the chip and other parts. First I made standard pads for the IC but when I tried to route the CSW caps the Design Rule Check started complaining about spacing between the pads and the traces:

Results
-------

Track to Pad Error (T-P) between (497.8 490.7) and (497.8 490.2) on Layer "Bottom Copper".
Error between Pad and Track (Net 'N0007'), Gap is 0.2 needs to be 0.6.
Track to Pad Error (T-P) between (497.8 489.7) and (497.8 490.2) on Layer "Bottom Copper".
Error between Pad and Track (Net 'N0007'), Gap is 0.2 needs to be 0.6.

So I started playing with different sizes and I found a few default alternatives:

- Large Via
- Pad
- Small Via
- SMD Pad
- Via

I noticed that by using Small Via (0.8mm pad, 0.4mm hole) and 0.4mm trace I didn't get any errors.

What I want to know now is how big the (standard?) holes should be (for the chip and other components) and how wide the power and signal traces should/can/could be.



I'll surely have a lot of other questions as I go along. Are there any recommended resources on the web for what I'm trying to learn (basic PCB design for audio amps)?

edit: And yes, I'm probably goind to use smaller decoupling caps and place them underneath the board but the questions are still valid for the other components.

[simonov]

frasco

A quick look at the TA2020's datasheet shows that each pin is 0.022" wide. The holes should be just a bit larger to allow an easy fit (say 0.027"/0.7mm). The soldering pads should be large enough to allow a 12mil trace to pas near them. If the routing software has an "auto" soldering pad diameter I'd suggest you leave it that way. The distance between this trace and the soldering pads should be no less than 12mil. This will ensure a trouble free PCB manufacturing.

Now about that PCB design for audio amps. Bare in mind that this one is no ordinary amp. This one is a digital amp so a digital routing techniques apply!

Regards,
Venci