Comments on my first PCB layout please

[Matador]

It's the resistor/cap pads that look incredibly small to me. I worry about lifting a pad when there's that little amount of copper to absorb the heat while soldering.

Just get plated through holes and this isn't an issue.

[quote author=ej_whyte]
I'm assuming the standard eagle resistors and capacitors will be fine, or do you recommend increasing their pad/hole sizes as well?
[/quote]

The library author cannot know which actual components you will use.  Get each component's datasheet and check the sizes against what is on your layout.  There's no other way to make sure.  Your PCB software should be able to make you a drill legend so you can print it and check each and every hole one by one.

 

[BradAvenson]

The neutrik pads look pretty small...have you printed your layout out on paper using a scale factor of 1 to see how it will really look?

The bottom jack pins are larger than the top jack pins.  I used 0.045" holes on the top jack and 0.065" on the bottom when I built some board with this part.  It isn't listed on the pinout, but you can see it in the drawing:
http://www.neutrik.com/us/en/industry/210_2146034064/NSJ12HF-1_detail.aspx

 

[ej_whyte]

Ok right changes made to the latest revision:

1. Resistor and capacitor pad sizes increased to 1.6mm
2. Transformer pad sizes increased.
3. Bigger holes for the bottom jack.

I increased the bottom jack pad sizes as you suggested, but now they seem rather close together to me? The holes were all 0.063", and now the bottom holes have been increased to 0.078", as that was the next available size above 0.063".

Thanks

 

[ej_whyte]

Anyone have any thoughts on the proximity of the increased pad sizes of the jack?

Also, wanted to clear something up. As this board only has tracks on one layer, i could order it single sided, but would it have plated through holes if i ordered it single sided or does that only come with double layer (or more) boards?

Cheers

 

[Matador]

Anyone have any thoughts on the proximity of the increased pad sizes of the jack?

Also, wanted to clear something up. As this board only has tracks on one layer, i could order it single sided, but would it have plated through holes if i ordered it single sided or does that only come with double layer (or more) boards?

Cheers

Does it still pass your DRC check?  If it does proximity shouldn't be an issue.

Your need to get a double sided board if you want a plated through hole.  Single sided will only have a pad/landing on the track side of the board.  The other side will be vanilla FR4 (or whatever material is being used).  Double sided will etch an annular ring (e.g. a pad top and bottom) on both sides, then deposit material in the holes to connect them.

 

[ej_whyte]

Well i originally put the clearance up to 0.8mm because i wanted it  nice and clear, now that i've changed the pad sizes it doesn't make the 0.8 clearance, but makes 0.7mm, so i'm guessing it'll still be ok seeing as i had already increased it from the standard eagle value?

Thats what i thought about the single/double sided thing, and most places i've checked seem to have double sided as standard with single not usually being any cheaper.

Cheers

 

[Matador]

0.7 is HUGE so if it's passing you won't have any problems.

I routinely use 10 mil trace/clearance and that is usually very conservative against what most board houses can do (that's only 0.254mm).

 

[ej_whyte]

Yeh I think the standard eagle value was 10mil when I started the board, I wasn't sure if there was a larger convention specifically for audio though. Well all seems good to me now, so I will probably order a couple on weds.

Thanks for the help

 

[ej_whyte]

Seeing as i plan on ordering double-sided, as its the same price and i would prefer plated through holes, is there any advantage to making the top layer into large ground polygon aswel?

 

[ej_whyte]

Anyone? Im meaning have the exiting bottom layer polygon, but add one covering all of the top layer aswel, seeing as at the mo it only has pads & vias.

Cheers

 

[Ptownkid]

You can...but there's little point

 

[Matador]

You can...but there's little point

Agreed.  If you were doing home etch it would save time as it would minimize the amount of copper that needs to be etched away.

But since you are ordering from a fab house it really doesn't matter.

 

[ej_whyte]

Thanks for the help everyone

 

[dustbro]

congrats!

 

[ej_whyte]

Cheers, i just got a delivery from mouser today and all the components fit well, just waiting on the transformers now and then i'll give it a test.

 

[Ptownkid]

Feels good don't it?

 

[ej_whyte]

Ha well i don't know if it works yet....

 

[Ptownkid]

Pfffft, works...you should be proud to have gotten this far!

 

[kestep]

So how did it turn out? Send some pics of where you are with this currently. Very interested to see!

 

[ej_whyte]

Well.....it works......almost as expected......  :

I got the transformers in from Whistlerock (thanks Mike, no thanks to canada post though!) on monday. I've only fitted one for the while to test it and cos i've just started a new placement/job (really interesting, working at technical earth repairing stuff, learning lots, also a good deal cos i get to use all there really good equipment like the Weller irons and Prism dScope  ))

All signal flows as it should, i haven't tested that all the levels match all the theoretical values but i'll do that sometime this week. The only problem is that i messed up the transformer pinouts. I took them from this page: http://cinemag.biz/mic_input/cm-75101APC-machine_drawings.html but i messed it up and got them mirrored. The pic shows the transformer viewed from the bottom, but i just assumed it was a view from the top of board side as usual. But hey, its the first pcb i've designed so oh well, lesson learned.

So the board all works at the minute, i just have to mount the transformers on the bottom of the pcb (good job i went for double sided in the end). The only real disadvantage at the moment is that i will have to mount the input jacks higher up on the back panel and it won't fit in a 1U case now, but with the other boards and all the front panel controls of this project it wouldn't have fit anyway. If i have time this week im gona make a small adaptor out of protoboard so that i can mount them on top anyway. Ill post a pic in a couple of days.

Cheers