PCB component placing - Page 1
Forum section: electronics / general

author: Christopher
author_rank: Frequent Contributor
timestamp: October 16, 2012, 02:34:26 pm
content: Any tips?Only designing small circuits (Atmega 328p tqfp) but I'm finding it hard to keep it all single-sided with the ISP and TTL headers... Any tips for component placing?ATM i'm placing/routing the different modular blocks off the board and moving them into the right space, and placing headers and other things like sockets first...Component placing (before routing) always gives me a bit of a head ache...

author: miceuz
author_rank: Frequent Contributor
timestamp: October 16, 2012, 05:22:26 pm
content: Image might help to get some more answersalso, is it a two layer board produced at pcb fabhouse, is it two layer board that you will etch yourself or is it a one layer board that you will etch yourself?

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 16, 2012, 05:36:23 pm
content: Quote from: Christopher on October 16, 2012, 02:34:26 pmQuote from: Christopher on October 16, 2012, 02:34:26 pmuse double sided layer.Quote from: Christopher on October 16, 2012, 02:34:26 pmthats normal.do you need tips for high speed and signal itegrity circuit? read jim williams appnote, or other more expert can give you some tips, i'm still learning. its like asking advice on how to run faster, well... you run!i guess.edit: oh i forgot our admin wrote a whole book on it...http://alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdfhave fun!

author: JoannaK
author_rank: Frequent Contributor
timestamp: October 16, 2012, 07:08:36 pm
content: Good component placing needs both visual skills to estimate routing space needed and also knowldge of the parts for part specific detals. Placement of filtering caps, crystal quartz and similar parts can be quite critical to good reliability. Also a lot depends on number of pcb-layers, component types and placement restrictions, so there is simply no easy way to give any hard rules for placement.And sometimes it's just necessary to tweak placement during the routing, there may be too tight areas, way too long signals and sometimes weak power/ground connections that need to be taken account. And unfortunately not, there are no obvious rules of the maximums, mostly just rules of thumb and real word experience.A picture/screen capture might help ... Or if the design files are available and you are willing to share them it would be a lot easier to comment.

author: Neilm
author_rank: Super Contributor
timestamp: October 17, 2012, 06:50:44 pm
content: Quote from: Mechatrommer on October 16, 2012, 05:36:23 pmIf you need more information on layout I would suggest reading the free articles athttp://www.compliance-club.com/The series on layout by Keith Armstrong is very informative. It most concentrates on meeting EMC compliance regulations but the techniques work for SI as well.Neil

author: Christopher
author_rank: Frequent Contributor
timestamp: October 17, 2012, 09:07:23 pm
content: Thing is, I'm making the boards at home (for now) so the traces have to be 16 thou minimum really, SMD and single sided (some jumpers).I've read daves tutorial a few times, it doesn't really go into component placement in detail, any screencasts out there of someone doing simple boards?What I'm making is simply a breakout board for a TQFP USB AVR with USB connector, crystal, 0805 resistors and caps, and headers for the pins. Looking to get it about 500mmx500mm (2x2")I'll have another go tomorrow at it, I like to just try out as many different ways of routing as possible, power lines and crystal first. Schematic is just a simple AVR on a board.Cheers.

author: jakeypoo
author_rank: Regular Contributor
timestamp: October 24, 2012, 01:49:37 pm
content: I would stick to DIP packages and thru components if you are etching your own pcbs. Use jumpers where you have to.