connecting traces on opposite sides of a double sided board - Page 1
Forum section: electronics / beginners

author: Simon
author_rank: Unknown
timestamp: December 09, 2010, 08:01:27 pm
content: So supposing I did manage to produce a double sided board, how do I connect the traces on the two sides, literally run a wire through the board and solder both ends ?

author: cfrolander
author_rank: Newbie
timestamp: December 09, 2010, 08:33:31 pm
content: Connect the traces with a through hole via!http://en.wikipedia.org/wiki/Via_(electronics)

author: Simon
author_rank: Unknown
timestamp: December 09, 2010, 08:38:39 pm
content: right so how do I produce a via at home ?

author: djsb
author_rank: Super Contributor
timestamp: December 09, 2010, 08:39:42 pm
content: That's what I do. Also you can use the component lead itself as a via, it just takes a bit of practice. That's all you can do unless you are able to make plated through holes.

author: Simon
author_rank: Unknown
timestamp: December 09, 2010, 08:42:24 pm
content: right so there is no semi mechanised method for small productions just plain old soldering

author: djsb
author_rank: Super Contributor
timestamp: December 09, 2010, 08:53:46 pm
content: LPKF do kits.http://www.lpkf.com/products/rapid-pcb-prototyping/through-hole-plating/manual/index.htmNot tried this yet, but may be a practical solution.

author: Bored@Work
author_rank: Super Contributor
timestamp: December 09, 2010, 09:07:39 pm
content: http://bungard.de/index.php?option=com_content&view=article&id=48&Itemid=65&lang=english

author: TheDirty
author_rank: Frequent Contributor
timestamp: December 09, 2010, 09:24:31 pm
content: Never tried it, but you can try this:http://www.colinmackenzie.net/electronics/14-pcb/25-thru-hole-plating-diy-printed-circuit-boardsThe method that I use, which is kinda semi-production line requires a hot air station. The steps are.Drill the via holes and place the board on a piece of wood.With a bare piece a wire and wire cutters I step through each via. Put the bare wire in the hole and cut the wire flush. Step through all the holes.At this point there should be a tiny bit of loose wire in each hole.Place a bit of solder paste on top of each via then hit it with the hot air station.Flip the board and put it in clips/clamps/whatever gets it in the air. Put solder paste other side and hit it with hot air.It can be pretty quick.

author: tyblu
author_rank: Frequent Contributor
timestamp: December 09, 2010, 09:26:29 pm
content: can use tiny rivets (1mm), but I usually just solder a short wire.

author: Zero999
author_rank: Super Contributor
timestamp: December 09, 2010, 09:28:50 pm
content: I've never made a double sided board before but I'd go for soldering pieces of wire.

author: johnmx
author_rank: Frequent Contributor
timestamp: December 09, 2010, 09:47:00 pm
content: You can try these track pins:http://pt.farnell.com/harwin/t1559f46/track-pin-0-84mm-pk500/dp/1143874?Ntt=1143874

author: Unknown
author_rank: Unknown
timestamp: December 09, 2010, 10:01:08 pm
content: Hi Simon,If you have got to a point where you start using two or more layers and vias, then you should consider outsourcing the PCB manufacturing.iTead Studio has a PCB prototyping service (I assume outsourced). They can do 10-off generic, 5x5 cm, 2 layer boards for $12. They are based in China, so you should also check postage costs. I cannot comment on their manufacturing quality yet.Here is a link to their PCB service:http://iteadstudio.com/store/index.php?main_page=index&cPath=19_20I checked the price of via kits two years ago they were too expensive for what they do. Therefore I would also recommend using small pieces of wire, or component leads where applicable. Just remember not to place the vias under flat packages (e.g. TQFP, SOIC).To use johnmx's pins you will also need this instertion tool:http://pt.farnell.com/harwin/z1002-00/insertion-tool-track-pin/dp/145248?Ntt=z1002-00Some sizes and shapes of via rivets can be applied using a mechanical pencil instead of the expensive tool that comes with the kit.Hope this helps.Alex

author: Time
author_rank: Frequent Contributor
timestamp: December 09, 2010, 10:11:11 pm
content: i always just use pieces of clipped leads from resistors or capacitors etc.

author: johnmx
author_rank: Frequent Contributor
timestamp: December 09, 2010, 11:43:12 pm
content: Quote from: Alex on December 09, 2010, 10:01:08 pmActually you can insert them without that tool and it’s very easy. I have these pins. For me, the main disadvantage is the size (big in diameter).Quote from: Alex on December 09, 2010, 10:01:08 pmIt gives more work but it’s possible and I usually do it for my first prototype boards. After soldering the via (made by wrapping wire) I polish it carefully with a sandpaper to reduce the height.

author: Balaur
author_rank: Unknown
timestamp: December 10, 2010, 12:07:49 am
content: Hello,Do you know this method:http://www.youritronics.com/double-layer-pcb-home-made-vias/Quick and easy.Cheers

author: Unknown
author_rank: Unknown
timestamp: December 10, 2010, 12:53:54 am
content: Hi Balaur,Thanks for the link, that's the method a few have proposed.Johnmx,I would feel that I am buying overpriced pre-cut pieces of wire.The standoff of SOIC packages can be as low as 0.1mm and for TQFP 0.05mm. I imagine it will be of the same order for large SMT chip components too. It is not possible to maintain a reliable electical connection between the tracks on the two layers if you sand off the solder joint to this length; it will crack before that by sanding alone. Therefore it is better to place the via next to the low-standoff component rather than under it.Alex

author: Simon
author_rank: Unknown
timestamp: December 10, 2010, 06:53:28 am
content: Quote from: Time on December 09, 2010, 10:11:11 pmthat sounds like the best thing at least for prototyping, as someone else said if I were to make loads of the same thing outsourcing would be best

author: GeoffS
author_rank: Unknown
timestamp: December 10, 2010, 07:40:32 am
content: I got a bit sidetracked reading this thread and went looking for DIY solutions to through hole plating. What can I say? I'm bored.Thinktink.comhas a conductive paste/electroplating solution that looks doable at home but the basic materials are not cheap.LPKFhave the answer if one off turnaround time is more important than money! The paste/bake solution looks neat, check out the video. I'll have one of the CNC millsAt the sort of prices charged by the above, it would be cheaper just to get 10 boards run off at somewhere like itead or seeed and throw away the ones you don't need.

author: Simon
author_rank: Unknown
timestamp: December 10, 2010, 07:54:35 am
content: ok next dumb questionnow I'm going ever more surface mount and considering double sided (I'm going to start by glueing two boards together)What is the largest/easiest SMD size to work with for my passives (resistor / capacitors) ?

author: joelby
author_rank: Frequent Contributor
timestamp: December 10, 2010, 08:05:35 am
content: 0805 are cheap, ubiquitous and relatively easy to deal with. You can buy grab-bags of thousands of 0805 resistors and capacitors on eBay for a few dollars.0603 isn't too bad either, though you'll probably want a good magnifying glass or stereo microscope and lighting, at least to check your work.0402 is getting a bit silly but are not too difficult. It can occasionally be good to use a couple if you don't have trouble with larger sizes and need to decouple power pins very close to larger chips and have limited space.

author: Psi
author_rank: Super Contributor
timestamp: December 10, 2010, 09:02:10 am
content: For connecting top layer tracks to the bottom layer with home made boards i add dedicated holes for that purpose and solder a wire in.You can sometimes get away with using the holes for top/bottom joins AND components, ie, if you had a resistor laying flat on the pcb you can solder both sides easy and the resistor leg itself joins your tracks.However you have to carefully watch what you're doing if you go down that road, lots of components cover up the holes, relays etc. so you can't solder both sides. You dont want to find that out after youve made the pcb.So yeah, i just have dedicated holes for joining the top/bottom. It gets around the whole issue of keeping track of which holes can and cant be soldered on both sides.But i do agree with what other people have said, making two layers boards at home is pushing it.It's so much nicer to have them made professionally.Ya really dont understand how nice it is until you actually have some pcbs made professionally.The day they arrive and you have your board design in your hands with mask and silkscreen is a pretty nice feeling. And wow is it nice to assemble them when the holes are correctly aligned and you have a solder mask

author: Simon
author_rank: Unknown
timestamp: December 10, 2010, 10:12:35 am
content: Quote from: Psi on December 10, 2010, 09:02:10 amoh I do, but for as long as it is a prototype, homemade is cheapest

author: TheDirty
author_rank: Frequent Contributor
timestamp: December 10, 2010, 01:43:44 pm
content: All my resistors are 0805. They are small enough and you can still pass a trace through one on a homemade board if it's needed. Then I can just drop resistors into my schematic and they are all 0805 and I don't need to worry about thinking about package size. I only get a different size if it's really needed.Capacitors are tough to standardize on, because obviously they change in size based on value. I try to keep 0603 for 1uf and smaller for decoupling caps. It's good to have small decoupling caps because putting the caps close to pins can be tough to squeeze things in. I use metal canister caps now but without reflowing they are tough to solder with an iron.

author: GeoffS
author_rank: Unknown
timestamp: December 11, 2010, 03:59:03 am
content: Still on the subject of plated through holes for home made PCBs.I came across this video on Youtube [www.youtube.com/watch?v=koT4tUit6aU&feature=related]about a simple process for doing through hole plating. Problem is that it's in Chinese.Received an answer back from the local distributor as follows:The process is being used by trial customers in China at this time.Kinsten are not ready to release it to a wider market yet. I requesteda release date from the factory, but I have not been given one.The development is on hold until next year due to work on the drilling machine.As soon as the process is released for full sale I will be supplying it.No detail son the process though, at least not in English.

author: tyblu
author_rank: Frequent Contributor
timestamp: December 11, 2010, 04:31:02 am
content: Quote from: GeoffS on December 11, 2010, 03:59:03 amVery interesting -- that's many more steps than I've seen typical DIY kits use, and the results look good, though it looks like you have to drill twice (once beforehand, once with the cured paste).

author: GeoffS
author_rank: Unknown
timestamp: December 11, 2010, 06:17:04 am
content: Quote from: tyblu on December 11, 2010, 04:31:02 amI didn't pick that up on the first time through. Could be a real pain for a complex board.

author: tyblu
author_rank: Frequent Contributor
timestamp: December 11, 2010, 06:36:05 am
content: I only assume that because otherwise you wouldn't be able to see the pads well enough to drill accurately with the cured paste, and his example board looks like it has small features. You could restrict it to vias, too, skipping TO pkg and mounting holes (though may want them for strength).

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 11, 2010, 04:45:15 pm
content: Quote from: johnmx on December 09, 2010, 09:47:00 pmThes track pins are definitely the way to go - very quick - just insert & snap off in each hole, go round then soldering both sides. Solder the top (wide) end first, while pushing down with the iron quite hard - this helps wedge them in, so the pin doesn't pop out when soldering on the underside.For small holes down to 0.6mm OD, Mega dothese rivets, which are quite useable without the press tooling - just use fine-point tweezers to drop them in the hole solder then solder the underside.

author: Unknown
author_rank: Unknown
timestamp: December 13, 2010, 10:30:48 am
content: Quote from: mikeselectricstuff on December 11, 2010, 04:45:15 pmDoing so will damage the tip's iron plating accelerrating its destruction. It is best to do any mechanical work before soldering surfaces together.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 13, 2010, 01:44:41 pm
content: Quote from: Alex on December 13, 2010, 10:30:48 amUse a big tip. It's easiest to do it with the iron so it softens the PCB material as it goes in - the heat means you don't need anywhere near as much pressure as if doing it cold - not enough to cause damage - the pins are softer than the tip plating.

author: scrat
author_rank: Frequent Contributor
timestamp: December 13, 2010, 04:52:49 pm
content: About vias, I've used the LPKF polymer paste, works well, it's quite simple.As drawback, it is not very resistant (don't heat up it too much, like while soldering and desoldering many times), and it can cause shorts if you don't work precisely and...it costs! I think a single packet (3-4 small boards) costs about 5euro.I confirm 0805 passives (and SOIC ICs, too) are handy, better than TH, IMHO.EDIT: ...SMT is easy to work with...provided that you have desoldering tweezers or at least two soldering irons.

author: osmosis321
author_rank: Regular Contributor
timestamp: December 14, 2010, 04:33:14 am
content: Quote from: Balaur on December 10, 2010, 12:07:49 amI don't know if he did, but I didn't, and it was beautiful. Thanks for that.