3 Traces between pads ?

[3v0]

I made my first board width 2 .01 inch traces between standard IC pads (.05 inches wide) using Eagle & Pulsar. It looks good but am still populating. Vias under chips is still an issue.

Is anyone doing 3 traces between standard size pads ?

 

[ikalogic]

it all depends whether you'r gonna produce you'r PCB's at home or not?

 

[3v0]

it all depends whether you'r gonna produce you'r PCB's at home or not?

I am talking about doing it at home. Pulsar is a brand of toner transfer paper.

EDIT: I am a bit of a chicken in regards to sending boards off to be made. There is this nagging fear of ending up with junk after waiting 2 weeks. When I get to the point where I need boards in quanity, and have a home brew board that works, I will have the pros produce it.

Kudos on your project site.

 

[Hero999]

Two traces between IC pads, the most I'd normally dare is 1 whatever method I'm using for artwork transfer!

The main thing that puts me of is bridging during soldering.

 

[3v0]

Since I started using a liquid flux pen I have had fewer problems with bridges. Maybe because the solder flows quicker(more easily). If get a bridge a quick swipe with the iron often clears it.

Without the flux the solder builds up in one spot instead of flowing. When it does flow there is so much solder that it spreads too far.

The solder I am using is Radio Shack lead free solder. I liked the lead/tin solder better. Is the brand name solder any better ?

 

[Nigel Goodwin]

Two traces between IC pads, the most I'd normally dare is 1 whatever method I'm using for artwork transfer!

I agree - I would consider putting even one between IC pads as poor practice, and two as bordering on criminal practice! - the thought of three makes me want hanging bringing back!

 

[3v0]

I agree - I would consider putting even one between IC pads as poor practice, and two as bordering on criminal practice! - the thought of three makes me want hanging bringing back!

Poor practice ? Why?

 

[Nigel Goodwin]

Poor practice ? Why?

It's making everything "closer to it's limits", with more chance of failures and problems - and mostly just down to poor or lazy design!. Check PCB's in commercial products, it's fairly rare to find traces between IC pads - reliability is improved by not doing it, particularly in a flow soldered situation - and I imagine lead free solder only makes matters worse?.

 

[philba]

I do toner transfer and have no problem with single track but dual is pushing it and 3 - gooood luck.

lets do some math. For commercial "low tech" boards: 8 mil trace seperation. 10 mil traces. 1 track - 26 mils, 2 track - 44 mils, 3 track - 62 mils For toner transfer, I'd use 12 mil seperation and 10 mil trace minimums. with a 50 mil budget, you are pushing it with 2.

 

[evandude]

It's making everything "closer to it's limits", with more chance of failures and problems - and mostly just down to poor or lazy design!. Check PCB's in commercial products, it's fairly rare to find traces between IC pads - reliability is improved by not doing it, particularly in a flow soldered situation - and I imagine lead free solder only makes matters worse?.

Most commercial PCB's are double-sided, but most hobbyists who make their own PCB's avoid double-sided layouts unless absolutely necessary.

I'd much rather run traces between pads in a few places than have to go to more than twice the hassle in order to make a double-sided board with only a few traces on top, or end up with an excessive number of jumper wires.

Also, I think your assessment of a single trace between pads being "bad practice" is a bit extreme, it's very common practice from what I've seen, and many boards could become WAY overcomplicated if you avoided doing so. Two or more traces does generally seem like overkill, though, I'll give you that...

 

[Nigel Goodwin]

Most commercial PCB's are double-sided, but most hobbyists who make their own PCB's avoid double-sided layouts unless absolutely necessary.

I'm talking domestic electronics, almost all PCB's are single-sided, the high cost of double-sided boards precludes their use.

 

[Hero999]

This is how I would do it but I wouldn't.

 

[3v0]

You are painting with a wide brush.

What you can do reliably depends on the process you are using. If I were not using good transfer paper I would not attempt it. With the transfer paper 1 is a non issue. If that line saves me a via of two it is a bargin esp if the vias are under a chip.

Check PCB's in commercial products

Each board is an example of what can be done with the process used to make the board. This system is not used in mass production so there are no commerical examples to examine.

I hope to start using surface mount parts. If we can not run a few lines between DIP pins then all hope is lost.

 

[justDIY]

I'm talking domestic electronics, almost all PCB's are single-sided, the high cost of double-sided boards precludes their use.

what are domestic electronics?

almost every gizmo and gadget i've opened up has a double sided pcb in it. the more complex gadgets appear to be using 4 or more layers, and the simpler ones are always double sided. just the other day I opened up a heated oil air freshner thing that plugs into the wall, sure enough, double sided PCB!

 

[Shax]

I am talking about doing it at home. Pulsar is a brand of toner transfer paper.

EDIT: I am a bit of a chicken in regards to sending boards off to be made. There is this nagging fear of ending up with junk after waiting 2 weeks. When I get to the point where I need boards in quanity, and have a home brew board that works, I will have the pros produce it.

Kudos on your project site.

I've used Futurlec several times to manufacture pcb's for me in both single and double sided.. The prices were very good, and the quality was superb.
Delivery was about 10 days from ordering.

I've tried to make decent double sided pcb's at home using transfer paper, and the results are definately not worth the effort. UV exposure box using a LED array is well under construction, and the pcb's (double sided, tracks between ic pads etc..) for the controller are going to be made by Futurlec too!!!

 

[Nigel Goodwin]

what are domestic electronics?

TV, Radio, VCR, CD player, cassette deck - almost all use single-sided boards. Double-sided are becoming more common now, mostly as the result of SM components.

A double-sided board costs a lot more than single sided, in a mass production item using single-sided makes a worthwhile difference to the price.

 

[3v0]

I've tried to make decent double sided pcb's at home using transfer paper, and the results are definately not worth the effort.!

You must be doing somthing wrong. My results are as good as they need too be.

Currently I am drilling my holes with a CNC then etching one side while the other is covered with box tape. It takes about 10 minutes to etch a side depending on the copper thickness.

I have been doing DIY PCBs off and on since we laid them out using chart pack tape. It has never been this easy.

 

[philba]

I have made numerous DS board via toner transfer. You just have to pay some care to getting proper alignment. Once you can do that, it's pretty easy. I make every boad DS these days.

One simplification is to make a DS board but use one side as a ground plane. That really simplifies your layout AND makes for a much quieter design as well. A tip - use thermals on the ground pads. It's a real PITA solder with out them.

 

[3v0]

I took another look at the Pulsar web site to see where they had run 3 lines between pads and found they had only done two. Brain fart.

**broken link removed**

The above pic is a good example of what you can do with the paper. It is typical of the results I get, I do not use the green lacquer.

You can see that with 1 you are not pushing the process. I have only done 2 once.
You have to use the right transfer paper instead of stuff you find at Staples or a page from magazine.

 

[Shax]

I have made numerous DS board via toner transfer. You just have to pay some care to getting proper alignment. Once you can do that, it's pretty easy. I make every boad DS these days.

One simplification is to make a DS board but use one side as a ground plane. That really simplifies your layout AND makes for a much quieter design as well. A tip - use thermals on the ground pads. It's a real PITA solder with out them.

Alignment aint the issue, neither is getting a decent layout... The PnP blue film seems to be extremely prone to leaving pits or missing areas on tracks. I clean the boards with wire wool, followed by a pcb cleaner block, and finally a good ole degrease with IPA and acetone (pure, not nail polish remover!!) mixed 50:50....