Main Site Documentation

Sticky Pandas


#1

I just got my panda’s in and the PCB is sticky on all of them. Did manufacturing do something wrong with the chemical bath thing after soldering?

It feels like someone spilled soda on them (that type of sticky feeling.) All four feel like this.

Can someone suggest how to clean them?


#2

I am sure that these boards went through washing in production. If you are concerned, you can use a soft brush and IPA to clean them.


#3

Maybe you’re feeling flux or something? Is the entire board sticky?


#4

Yeah mine are a little sticky. probably some remaining cleaner on them. I haven’t tried to clean them yet.


#5

Yeah, the entire front and back of all the boards are sticky. If I angle the boards and look at them in the light, you can see a film of gunk on them. My Cobra board definitely came out cleaner than these. Can I use rubbing alcohol to clean the boards?

The boards also have some slightly funky smell to them too. Not like the normal PCB smell.


#6

i would guess its flux cleaner residue since they are white pcbs. what ot clean with depends on how the silk screen was done. Rubbing alc should be ok but at your own risk.


#7

It’s probably residue from a no-clean type of flux, nothing to worry about.


#8

Maybe this board has passed the washing stage by error. You can try cleaning it if you like or send back for an exchange


#9

This might be stupid note. But just in case:

Washing electronics board process is completely different from “the regular washing”. No water! No dishwasher please! :smiley:


#10

[quote]No water! No dishwasher please!
[/quote]

You would be surprised. If your using a water clean flux and have components that are wash safe many small companies will use a dishwasher as it works great and costs very little. For cleaning off water clean flux at home I use an old toothbrush dipped in water to lightly scrub the board (I avoid dunking boards). If it is a not a water clean flux then dipping the toothbrush dipped in some denatured alcohol (NOT rubbing alcohol) works great.


#11

Water doesn’t necessarily kill electronics. Just ask my flash drive that went through the washing machine. ::slight_smile:

Put your keyboard in the dishwasher on “LOW” if you don’t believe me. Just make sure to let it dry for a very long time. If you can, displace the water with alcohol after the wash. :smiley:


#12

As an anecdote to backup water not necessarily killing electronics, I had a mobile phone accidently left in the wash bay of a high pressure water deburrer and come out fine. It was flooded with 80°C water flowing at about 2500lt/min with jets of 5000psi water all around it. The phone was found in the swarf trap in the wash bay, dried out for a few days and turned on. Worked perfectly, LCD and all!


#13

As an anecdote to backup water not necessarily killing electronics, I had a mobile phone accidently left in the wash bay of a high pressure water deburrer and come out fine. It was flooded with 80°C water flowing at about 2500lt/min with jets of 5000psi water all around it. The phone was found in the swarf trap in the wash bay, dried out for a few days and turned on. Worked perfectly, LCD and all!


#14

I might start dish washing my electronics. :wink:


#15

Electronics and water mix just fine, just not electricity and water. As long as you dont power up wet electronics all should be fine :slight_smile:

As far as cleaning the pcb’s - it sounds like their wash tank was way too dirty and so spread a film of dirty flux over the boards instead of removing it. I’ve mentioned a few times my perceived lack of quality from your manufacturer (HASL pcb’s, FR4 and silk darkened from over cooking, flux left on pins, etc.)

Was your PCB with ISO Propanol (Isopropyl alcohol) or denatured alcohol (methanol and ethanol) that is 99%+ pure. If you use something like “Methylated spirits” they usually have 5%+ impurities like bitterising agents and such which will leave a white haze on your pcb and electronics and is less than desirable. Pure alcohol/iso alcohol is best. You can use a soft toothbrush however i’d recommend a lint free cloth or microfibre cloth (no paper based product - they will tear on the electronics and pins leaving behind fibres).


#16

Alright, I got all four (4) Panda boards clean! They don’t have that sticky film on them and they don’t smell weird anymore :slight_smile:

Seriously, you guys should get on your manufacturer’s case. The job they did was just plain sloppy and inexcusable. As someone else commented, I did notice globs of flux left on some solder joints.

One last thing I am concerned about is most of the solder joints are a dull grey. They don’t look like shiny silver solder joints. Was this due to sub-standard manufacturing or bad solder? Honestly, my Cobra and Domino I have look like pro’s built them, but the Panda’s I have look like the quality of an amateur. Something I didn’t expect…


#17

RE: Weird looking solder:

That may be a result of the RoHS compliant solder they use.


#18

Is the dull looking solder on surface mounted components or through hole?

If it’s on through hole, it’s likely they were hand soldered so the dullness could be resin (cheap solders use resin, rather than more expensive fluxes in the core). If the board is clean of resin, it could be from soldering at the wrong temperature which will create a thin oxide film or sections of oxide on the surface. It won’t affect the quality of the join if it doesn’t penetrate too deep.

Chris: RoHS solder comes up much shinier than lead/tin because it doesn’t oxidise as quickly. Good quality lead free is tin, copper, silver - sometimes other metals. Cheap lead free is basically just tin which can oxidise quickly - it’s actually pretty hard to find solder that bad though (check dealextreme for some).


#19

I think you mean ‘rosin’ which is a type of flux made from pine pitch. It works very well and has been used for decades. Nothing cheap about it. Like any other type of tool rosin my not be the correct flux for every job though.

Actually you have it backwards Mark. One of the biggest issues when lead free solders came on the market was that they did not provide a nice shiny joint when soldered properly. With a lead/tin solder a dull looking joint is a sign of an improper soldering job. With lead free a visual inspection can be very tough.

Lead free solders melt at a much higher temperature than lead/tin solders do. Consequently they tend to oxidize much easier. Fluxes deigned for lead free soldering must have a higher working temperature to avoid the flux from flashing off before the solder is properly re-flowed.


#20

yes i did mean rosin sorry - typo :slight_smile: I’ve always found that in cheap fluxes and found it to leave a sticky brown residue behind.

Hmm ok, i guess it’s been a difference in manufacturers then - I’ve always found my lead free to come up looking better than lead in mass production. I guess the company using lead was even more crappy than i though (They were pretty bad which is why i stopped using them.)