Why PCB pads come off easily? - Page 1
Forum section: electronics / beginners

author: Dhanushka
author_rank: Regular Contributor
timestamp: September 27, 2019, 06:55:04 am
content: I made a PCB with no heat based toner transfer using paint thinner. I used cheap copper clad board available.This guy use nail polish remover (acetone based). Both chemicals works to toner transfer. Then, I etched the PCB and start soldering. But, when I was soldering, the pads came off easily when I keep the solder to the pads or slight movement of component after soldering. I used a cheap adjustable 60 W ebay soldering iron at 200 Celsius setting. Can anyone tell me why this happens as your experience?Thanks.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 27, 2019, 07:28:22 am
content: You can't solder at 200 degC solder iron setting. If youcan, the actual temperature is far from 200, and hence, can be anything. For example, if it is 450, pad lifting happens easily.Another probable cause is poor quality copper clad PCB material.Likely the combination of the two.

author: sleemanj
author_rank: Super Contributor
timestamp: September 27, 2019, 07:55:22 am
content: Phenolic resin ("bakelite" as called in china) type pcb does have a tendency to lose pads easier than FR4 (fiberglass) in my experience, but it shouldn't be so easy to do that it's a problem outside of reworking pads.Check your iron, check your technique, check you are using extra flux especially for home brewed pcbs, the bare copper will get a tarnish layer very very quickly, you must clean the pcb right before you start, and use extra flux or you will have a bad time.

author: tautech
author_rank: Super Contributor
timestamp: September 27, 2019, 08:05:14 am
content: What sleemanj says plus iron dwell time on the pad is too long.Clean pads and components and good Pb solder just 2s is long enough to make a perfect joint.Another common mistake for newbies doing their own TH PCB's is the pads are too small. Keep them 100 mil/thou round/square and these issues vanish.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 27, 2019, 12:05:31 pm
content: Way too hot. Guessing that's one of those open-loop irons? The dial is just a dimmer in front of the heating element, actual tip temperature is not otherwise regulated? So the dial setting bears only coincidence with the real tip temperature.And since the tip is too hot, it may be burned and dry? Maybe you set it much higher than you remember, or it's so uncontrolled that it simply runs that hot regardless? (Or the dimmer is broken and it always runs at 100%!) And with a burned tip, you're trying desperately to get any heat into the pad and pressing way too hard, peeling up the pad?The tip should be clean and shiny and solder readily flows onto it, not dull, and not solder-phobic. The rosin (if this is leaded solder you're using) should smoke on the tip about like smoke from a cigarette; it should not erupt in a cloud all at once.Hold the iron to the pad, don't press or rub at it. If the pad or pin isn't getting hot, dab a little solder between the tip and pad/pin. Try to wet the work. Then continue flowing solder into the joint until you have a nice fillet.Tim

author: Dhanushka
author_rank: Regular Contributor
timestamp: October 01, 2019, 06:27:57 am
content: Thanks for the comments from all of youI found the reason that was a problem of iron tip. It was flat due to red hot slightly. So, when I moved to new keen tip it worked. Also, the PCB is low quality one. After adding two layers of solder mask, the solder pads could not come off easily due to most of the heat is absorbed by the solder mask. The holes was about 1.2 mm. I used a 0.8 mm drill bit for the new PCB. The pads was not broken when moving the components.