Is single layer PCB really worse reliability than double layer

trying to do a design on 1 layer PCB

ower reliability due to the soldering giving up. Clinching of pins, and glu ing can mitigate this somewhat

To answer your question, no, I've not studied it. But I've never heard any one claim 1 layer PCBs were inherently unreliable. Back in the day I've se en many low cost products with single layer PCBs and never saw a problem fr om that.

Do you really mean the soldering joint cracked? Or do you mean the traces come off the board? A properly soldered pin should not come loose from the pad. But if someone is cutting such corners that they use single sided bo ards, they may not be too particular with the soldering as well.

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No idea.. but I could imagine that the plated through holes are going to be worse with only one side... with bigger copper area you are probably OK.... I've seen single layer pcb's. :^)

George H.

In our field (arcade games/coin operated amusements) Single Sided PCBs (SS PCBs) are a serious pain! These boards are all old school (1970s through 1990s) with through hole parts, not SMD so take the following with a grain of salt.

When you have parts mounted on the non-copper side and using the leads to hold said parts in place then the part in question must be FIRMLY mounted down to the PCB or you will get cracks developing in the solder connections over time due to vibration or other stresses. The old Molex

0.100 or 0.125 pin connections on single sided boards often developed cracks over time leading to all sorts of intermittents. So experienced techs in the game field always touch up solder joints on SS-PCBs when they run into them.

If your board components are all SMD and the connections are soldered just to one side and are properly anchored I see no reason not to go with SS-PCB, but if you are using and holes to mount connectors or leads through then you will have trouble down stream.

John :-#)#

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John Robertson wrote in news: snipped-for-privacy@giganews.com:

Any game you can name (other than most of the clones) has likely been emulated.

Here are photos of all the PCB assemblies used on many of the arcade games we played.

Not really but think about it. When plated through holes, if say the both top and bottom were exactly the same, that would be extreme reliability. But nobody is going to do that.

With anything FR-4 or better you don't have to worry much about delineation. With cheap boards environmental condition could cause the substance to expand, absorbing something because it is porous and when it expands it breaks the vias.

I still am into the K I S S theory.

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

Old TVs were pushed through the wave solder machines so fast that they had huge solder joint failure issues. If your TV went south many times the problem was a broken via, but usually a fractured solder joint.

However, HAND Soldered with good old 63/37 with proper active flux makes a solder joint that will not be fracturing. An unset part could rip a trace free from the board though on single sided pcbs.

BTW, you must be talking about old juke box, pinball, and arcade games, because most arcade games and pinballs are multi-layer.(not you, the OP) Except for the really old jobs.

Yes, solder joints are much thinner (a little web, not a full barrel), so they fatigue from much less stress or strain.

Studied, no, I'd be a little surprised if there was ever enough money in the subject to "study" it. Maybe Sony has some locked away, they made 1-layer power supplies and consumer goods in the hundreds of millions. Good luck asking them though. :o)

But, to be fair, most of that is shown in IPC-2221, at least in terms of recommended process, if not with studies.

Tim

--
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Electrical Engineering Consultation and Design 
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I am looking at only copper on a single layer, with no plated holes. From what I can tell, the big cost difference is in them not needing to plate the holes, but anyway, since you brought it up, I will try to quote "single layer, with plated holes" :-)

Regards

Klaus

As others have noted the problem is not so much the number of layers as the absence of a plated hole. Without the strength of the plated hole you become reliant on the weak adhesive glueing the copper to the substrate. So make the pads around holes as large as possible. Staking and clinching also help. IME it is better to use right angle connectors instead of vertical pin headers. With careful design and build quality single sided reliability is good.

piglet

That's the same I was told, that temperature cycles will create small cracks

It can be mitigated somewhat by clinching the pins

Yes, I am talking about problems with THT components, SMD should be same reliability as 2 layer PCB

From 4 to 2 layer PCB, there is a gain in reliability, since delamination occurs on layer 2 and 3, and it difficult to inspect. That problem is gone in 2 layer PCB

Cheers

Klaus

+1 Plating holes adds a great number of demanding process steps.

piglet

Regarding total system cost and EMC issues:

Single sided boards can quite easily have EMC issues, requiring a metallic enclosure. OTOH, a double sided board with a ground plane on the other side is much better in EMC sense, so you might be able to use a plastic enclosure.

Am 11.05.19 um 08:37 schrieb snipped-for-privacy@gmail.com:

We once did a pipeline pig system, i.e. a torpedo-shaped device, usually more than one torpedo in a gang that pull an ultrasonics array behind them. That is used to check the pipeline from inside for cracks and corrosion. Our ultrasonics array had 1024 channels, each with transmitter, analog receiver and digitizer/FPGA/PowerPC/network for each group of 16. Enough stuff for a bad failure statistic.

The pig is pumped through the pipeline together with the oil. They reduce the flow rate somewhat but it is still 5 or 10 meters per second, so hard shock and vibration are to be expected. And hydrocarbons.

Hydrocarbons are soaked up by FR4 and the vias etc may crack open from that. So it was decided that something better than FR-4 had to be used. We decided to go with Kapton / Polyimide.

It turned out that we got delamination in unheard-of severity, right after vapor phase soldering.

The Kapton prepregs have a _very_ short shelf life and the board producers are constantly tempted to stretch that for a week and not to throw it away. Also temperature for baking is higher than for fr-4.

There are not many companies who do that at all. Our production department had lots of fun with this.

regards, Gerhard

In my case, it's a RFI filter, so there is no need for a ground plane, in fact a ground plane just makes matters worse (shorting the CM coil function)

Cheers

Klaus

It happend on transformers and other large components too. Large solder blobs holding heavy components often develop circular cracks at about half the diameter of the whole blob. This was the last bit of solder to solidify and the cracks were probably initiated by vibration on the production conveyor causing movement as the joint set.

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The reliability of the single-layer non-plated-thru PCBs of e.g. synthesizer manufacturers like Roland and Oberheim products from the

1980s is not good. Well I mean it's probably OK until you actually want to repair something else on the board. they're brittle and fragile and the pads want to drop and lift at the slightest amount of heat from an iron

2 layer boards have much more mechanical strength of solder joints than single layer, where the soldering penetrates, so of course single layer is more vibration vulnerable.

Zero layer is even worse :)

NT

MAME, PinMAME...

Like sex and most everything else, it just ain't the same as the real thing!

You haven't been in my shop's storage area - I have a thousand or so vintage PCBs...

John :-#)#

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(Please post followups or tech inquiries to the USENET newsgroup) 
                      John's Jukes Ltd. 
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 
          (604)872-5757 (Pinballs, Jukes, Video Games) 
                      www.flippers.com 
        "Old pinballers never die, they just flip out."

Plenty of hi-rel aerospace stuff in the 1950s and 1960s used single sided before plated holes became mainstream.

You are right about the adhesive being the weak link. You see that nowadays with smd rework too.

piglet