MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

routing a PCB is hard!
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Author routing a PCB is hard!
akrylik
After 3 days of solid work, I just finally finished routing my first decent sized (15cm x 20cm, 2 layers) board which has 256 components (about 1200 pins total). My tools were Kicad's PCBNew and FreeRoute.net.

I'm not sure I want to do that again...that was hard. Dead Banana

I'm curious why I don't hear more complaining about the whole process. What are your secrets?
andrewF
It is quite a mental exercise, but once I get started on a design it is totally addictive. Recently one layout took me 3 months to complete Dead Banana just couldn't stop fussing over it, but it all worked when i built it so nanners

Usually I place chips and route power rails and ground 1st.
Once first draft is finished, I spend at least a few sessions refining the design, moving components to better positions, thickening up traces wherever appropriate.

When I think I am done i print out the schematic and check the PCB against it and mark off the schematic with a red pen to ensure every connection is correct. Then check all the pos, neg and ground connections are done and all route back to the power pins.
Tombola
I use eagle autoroute for 90% of the traces (sometimes lay some power lines by hand first) and have stopped reading all the web forums telling me it's evil.
The last PCB I did, I did put in a lot of work thinking about part placement, doing pin swaps to make traces shorter, and ended up with a pretty neat-looking layout, still mainly auto routed. It's still with itead, so don't know if it will work!
I spent ages trying to route the Turing Machine board until I decided I probably didn't need a ground plane, then it was fine.
I think a lot of the negativity about auto routers is looking at the high end - if you're doing super fast mixed signal circuits, I'm sure it's a real issue.
I figure if something works on breadboard, won't it work on any kind of PCB so long as the connections are right?
CJ Miller
I started by doing my designs on perfboard. Doing this without thinking about my layout was the hard way (stupid). So I started sketching out layout ideas on graph paper. This poses the same challenge, in many ways, as doing the layout in Kicad. A puzzle which involves finding optimal positions for many components. Specific challenges can be the desired size of the board, and the inter-connections of different kinds of parts. So, I go through a few iterations to decide where I want everything to be. It has to happen sooner or later for the project to be realized.

I have found that the layout ideas come more readily over time, one gets better at it. The tools of a decent layout and routing program make the job easier than keeping track of on paper or in my head.
L-1
hahaha. how about to route this?

I'm still thinking possible it or no..

SlayerBadger!

Chopper28
What recommendations do people have for free/cheap pcb drafting software for the casual/occasional user? Oh, and for Mac OSX. I've played with Fritzing but its very flaky on my Mac Mini.
Graham Hinton
Chopper28 wrote:
What recommendations do people have for free/cheap pcb drafting software for the casual/occasional user? Oh, and for Mac OSX. I've played with Fritzing but its very flaky on my Mac Mini.


Osmond PCB

Free up to 700 pins, $79 after that and worth every penny. Written by a rocket scientist, literally.
I wish I could recommend a Mac schematic app to go with it. DesignWorks is still available, but is so deeply rooted in System 7 and 9" screens [sic.] that I hesitate even though I still use it after 20 years. It's really the investment in creating libraries and drawings that makes it difficult to change, even if there was something to change to.
negativspace
I'm a graphic designer by trade, not an engineer, so I consider the routing process to be the "easy" part. Making the circuit itself work is where most of my time goes.
Spandex
Tombola wrote:
I use eagle autoroute for 90% of the traces (sometimes lay some power lines by hand first) and have stopped reading all the web forums telling me it's evil.

[snip]

I think a lot of the negativity about auto routers is looking at the high end - if you're doing super fast mixed signal circuits, I'm sure it's a real issue.
I figure if something works on breadboard, won't it work on any kind of PCB so long as the connections are right?


Ditto. I've only done two boards in my life - and all the mistakes on them were entirely my own work and I won't let eagle's autorouter take credit for them 8_)

I let it route everything and then just moved a few vias where I felt there might be a chance of a bridge. I figure that, by the time it becomes an issue for me, I'll understand why and care enough to fix it. Until then, it works, so I'm happy.
daverj
I gave up on autorouters. They work OK if the boards aren't packed too tight, but I tend to pack my parts in quite tight and I can almost manually route the board faster than the autorouter can get 75% done and then quits.

I spend almost as much time moving parts around, imagining how they are connected as I do actually routing the board. Parts placement is critical to a good layout. Both electrically and for routing.
daverj
L-1 wrote:
hahaha. how about to route this?

I'm still thinking possible it or no..

SlayerBadger!



Why use smt caps and resistors but through hole chips? SMT chips are much smaller and would give you more room for the other parts. Plus, since they don't have through holes you can also fit some of the smt parts on the back of the board if you need to (though that costs more to have assembled)

Or just go to two boards stacked. One for panel parts and one for the circuit.
L-1
I've already routed but didn't optimized yet. This image without groundplanes shown.

It means Quad VCA will be 14HP on one board !!! SlayerBadger! SlayerBadger! SlayerBadger!

Quote:
Why use smt caps and resistors but through hole chips?


I make 1206 SMD resistors and ceramic caps, other parts through-holes. Because I sell boards for DIYers. 1206 can be soldered with thin tip iron. SMD chips are too small for iron soldering.


negativspace
Also the THAT218x VCAs are SIP-package-only so no choice there.

Personally I don't mind soldering 0805 and SOIC by hand, but I know there's still a lot of resistance to that from DIYers.
daverj
Yeah, I would think 0805 and SOIC would be no problem for DIYers who have been soldering for a while. Maybe not good for somebody just starting out though. I do 0603 and fine pitch chips by hand, but those chips would be beyond even many experienced DIYers.
L-1
I see a sense in 0805 or 0603 only if IC's are SMD too.
I think I found good compromise how to avoid wiring and save hand soldering.
I know, many people can solder anything with hand iron. But it is for easy comfortable soldering.
akrylik
negativspace wrote:
I'm a graphic designer by trade, not an engineer, so I consider the routing process to be the "easy" part. Making the circuit itself work is where most of my time goes.


Ha! Maybe next time I have a huge routing job, I think I will put up a flyer in the local art school.

"Wanted! Someone who loves drawing thousands of lines on a computer screen.

Pay = [($0.02) x (# of traces) - ($0.01)x(# of vias)] x (0 if DRC fails, 1 otherwise)"

twisted
akrylik
So far, I consider the autorouter to be godsend. For example, I had a bunch of repeated elements with lots of traces like this:



which the autorouter did with no trouble (once I set down power and ground). But no matter what I did the autorouter would barf on this pvqfn-n48 package:



So ended up having to manually fix a lot of its decisions here. Probably should have manually routed that whole chip by hand. I'm not sure.

I would be very interested in an autorouter that was more designed to work with a human operator, a kind of semi-autorouter. For example, it would have been nice to be able to specify a subsection of the entire circuit to autoroute at a time. I also think it would help the autorouter to be able to prioritize what nets or pins it should trace first. It must be an interesting thing, building an autorouter... hmmm.....
Chopper28
Quote:

Chopper28 wrote:
What recommendations do people have for free/cheap pcb drafting software for the casual/occasional user? Oh, and for Mac OSX. I've played with Fritzing but its very flaky on my Mac Mini.



Quote:

Graham Hinton wrote:
http://osmondpcb.com/


Ok, have had a little play and I really like this. Suspect that it will do just what I want, so thanks Graham.

Cheers. Malcolm
NV
Chopper28 wrote:

What recommendations do people have for free/cheap pcb drafting software for the casual/occasional user? Oh, and for Mac OSX. I've played with Fritzing but its very flaky on my Mac Mini.


There's also KiCAD, which is open source and has no restrictions. All the PCB packages are a little fiddly in one way or another and take some time to learn the quirks but I've personally found KiCAD to be more suited to my tastes than Eagle and others, particularly since it's devoid of size restrictions (important for front panel PCBs). That being said I've never used Osmond before.

From what I understand there's a Mac version of KiCAD that's still "experimental" but basically works fine.
J3RK
I actually really enjoy laying out boards. It can infuriate me at times, but overall, it's a puzzle that needs to be solved. I will generally autoroute something once, and see if it can be salvaged with a bit of tweaking. If not, I'll route by hand. I slip into a state of calm, (unless something sets me off) very frustrating and just route away until the wee hours of the morning. Kind of losing track of the things around me. It's interesting.

I use Labcenter Proteus (which includes both schematic and board layout tools.) It makes things really easy. You get the schematic set up, click a button, and your netlist, parts, and packages are all brought into a blank board file. So, if the simulation runs ok, and the schematic is good, you can't really route a bad board. It just takes time to run the traces, and place components well.

I've barely started to use certain SMT parts now, but they've actually been simplifying some things for me. I can squeeze them into an otherwise tricky spot where a through-hole part is tricky. I try not to do it too much on through-hole oriented boards, but they've saved me a couple of times now.
paults


Latest Euro route (100% by hand), ground and power planes not shown (4-layer board).

0805 resistors, 0603 caprs, TSSOP and a MSOP. Bought a nice stereo zoom microscope and soldering was not that bad.
galingong
I'm bumping this, because I didn't want to start a new one.

Is there a way in Eagle to tell the Auto-router to use only top or only bottom layer for a specific component? I'm designing two-layer PCBs and since I etch them myself, I won't be able to solder top layer on some components (pin headers, electrolytic caps, etc.) And please don't go autorouter-police on me, I don't really like it either but I'm a bit short on time with this project.
synthdude
If you put a component on the back side, the auto router will route on that side until it needs to switch to the top side by using a, "Via". You have to use, "Mirror" to get a component to go onto the other side. You can also tell the auto router not to route anything on a specific layer. I love the auto router, you just can't rely on it 100%. You will always have to route by hand to some point. The key is to place your components correctly, and that experience comes with time.

By the way I have tried many times to make my own DIY 2 sided pcbs and its an excersize in frustration. I gave up on that and just have them made since its dirt cheap now.
SOFTWIRE
Routing boards is the best part of the design process in my opinion. I hand route everything since I've never had any luck with the auto router. I find that I like to stick to traces that are running up and down are on one side of the board and traces running left and right are on the opposite side of the board. That way you dont get yourself to a point where you cant run a trace through a particular section of the board.





This board is all 0805 res/cap parts and uses TSSOP for the most part but some of the chips are only available in SOIC. I used to put parts on both sides of the board also but i now only put components on the top side so I only have to use one solder paste stencil.
galingong
synthdude wrote:
If you put a component on the back side, the auto router will route on that side until it needs to switch to the top side by using a, "Via". You have to use, "Mirror" to get a component to go onto the other side. You can also tell the auto router not to route anything on a specific layer. I love the auto router, you just can't rely on it 100%. You will always have to route by hand to some point. The key is to place your components correctly, and that experience comes with time.

By the way I have tried many times to make my own DIY 2 sided pcbs and its an excersize in frustration. I gave up on that and just have them made since its dirt cheap now.


Thanks! That's what I've overlooked - I wasn't aware that mirroring does that. Cool, problem solved smile
By the way in the past I've managed to etch double sided PCBs (MFOS ones namely). You have to cut the raw PCB and your paper really precisely. For me they usually fall together in a +/-0.1mm margin, which is fine since my pad diameters are most likely 1.6mm.

SOFTWIRE wrote:
Routing boards is the best part of the design process in my opinion. I hand route everything since I've never had any luck with the auto router. I find that I like to stick to traces that are running up and down are on one side of the board and traces running left and right are on the opposite side of the board. That way you dont get yourself to a point where you cant run a trace through a particular section of the board.


I agree, as I mentioned I too prefer manual routing, it's fun if you have time and reiterate, try different layouts, etc. Not fun if you want to route 15 modules in a week in your free time smile
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Page 1 of 2
Powered by phpBB © phpBB Group