Hello,
New to soldering, and I think I have been pretty diligent and had good results from Arduino/adafruit parts I've soldered. Then I bought a super cheap 7-segment display off of Ebay and could not get the solder to flow or stick. Worked it so hard I actually melted the PCB without getting the solder to flow. Do cheap electronics cut corners with solder-repelling parts? Or was it just me?
Hi, can you post pictures of the damage? Usually, if the solder doesnt flow/stick is a lack/too little flux involved or dirty soldering iron tip. Are you using solder wire with flux core? Post a pic of your equipment used if you can
PCBs do not melt, they burn. Is this what you mean? What type of solder and flux are you using?
Paul
Are you are using lead free solder? That stuff is harder to use than lead/tin solder. I still, and always will, use lead/tin solder.
Also do you have a flux pen? Sometimes a bit of extra flux helps a lot.
Do you use liquid flux ? (typically used with a dispenser).
If you are not using any flux then have not learned that it is necessary for good solder connections.
It does however , require you to clean it off with IPA and a brush after you have finished soldering.
Don't believe anyone who tries to discourage you from using it until you have at least tried it for yourself
and then make your decision based on personal first hand experience and not hearsay. I have been working
as an electronics technician for 40 years and all my soldering problems disappeared immediately after I
started using the liquid flux. I once soldered a 46 guage magnet wire to a 0201 SMD resistor. I could not
have done it without liquid flux"
SMD resistor sizes
Code Length (l) Width (w) Height (h) Height (h) Imperial Metric inch mm inch 0201 0603 0.024 0.6 0.012 0402 1005 0.04 1.0 0.02
I once lost a 0402 SMD resistor and later found it under my thumbnail so you can imagine how small a 0201
is.
As you can see a 0402 is 1mm LONG X 0.5mm WIDE
Or was it just me?
Yes
I would guess the parts were old and the leads had some oxidation on the surface.
Two options that I am aware of:
-
"clean" the leads with scotchbrite (maybe difficult) or some fine sandpaper (1200 and up). Re-tin the leads with solder before attempting to solder them into a board.
-
use a liquid flux (as mentioned above) it usually comes in a dispenser like a felt tip marker. Often it is sold for "rework" applications. If you go this route I suggest you "tin" the leads with solder and clean off the flux with alcohol. They should solder to the board relatively easy.
Do cheap electronics cut corners with solder-repelling parts? Or was it just me?
You have to look at the big picture. From the time a part is manufactured, if it is exposed to open air, it can oxidize. Contamination and oxidation on a part exposed to the air for extended periods of time reduces the solder bonding process. Some parts have to be cleaned with IPA before you can even solder them. The flux cleans the contamination off and allows the solder to bond. "Cheap parts" may simply have been exposed to open air longer or exposed to contaminated environments which speed up the oxidation process. I have encountered CPU chips that did not bond well during the flow solder process. I personally identified at least 20 CPU boards with pins that had no solder bonded to them after removing them from the board. I attribute this to extended exposure to a
contaminated environment. Maybe they were loaded in the part placing machine and then left overnight until the morning shift arrived. In any case it was obvious under a microscope that some of the pins were pristine after after removing from the PCB and had no solder on them. (the bds worked if you resoldered the cpu chips)
So 'cheap parts' may well mean 'dirty parts'.
I suspect your parts have been under water for some period of time.
I had a customer who insisted on buying their own parts. Their purchaser always went for the cheapest she could find. then the customer complained when parts popped off the circuit board!
Paul
esquirish:
Hi, can you post pictures of the damage?
After royally messing it up, I threw it on the ground, smashed it to bits with a 2X4 and left it there for like a month. Now I know to use flux. Thanks all!
After royally messing it up, I threw it on the ground, smashed it to bits with a 2X4 and left it there for like a month. Now I know to use flux
That sounds like something my brother would do. He used to come very close to smashing his PC before calling
me to help.
When I worked in a CPU test/repair department of a hospital equipment mfg, there was a young tech who would
get frustrated and start giving his UUT the middle finger vigorously until I told him one day "Mark, we are professionals. We are supposed to remain calm... (I'll leave you to imagine the look he gave me)
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