# Solder joints in automotive and high tech industries

#### Autobike

Joined Feb 23, 2018
91
hello. this is something i've noticed for a long time. in my motorcycle the solder joints are not shiny silver color ones. they are black in color. i could see solder joints in a few places. specially inside the handle bar switch assemblies and at the bottom of the ignition barrel. those parts are OEM parts. i checked some google photos of different Honda motorcycles and they have the same black color solder joints. if you check the below picture you can clearly see it.

i have two questions

1) is that a paint/protective coating ? or is that a special solder itself ?

2) i got to know that solder joints + vibration is not a good combination. wouldn't it be a problem in high tech machines like fighter jets? saw some videos of Lockheed Martin company. they use thousands of wires and circuits. i couldn't see any alternative to soldering. i just asked since the stress/vibration applied to the parts is enormous in those machines. it's obvious that there's no room for any error.

thank you

#### CROSSBOLT

Joined Dec 9, 2008
21
Black solder is probably because of "lead free" push which uses silver content. Silver oxide is black. Lead free solder has serious structural weaknesses.

#### AlbertHall

Joined Jun 4, 2014
11,600
i got to know that solder joints + vibration is not a good combination. wouldn't it be a problem in high tech machines like fighter jets?
You can use crimp connectors where the crimp also grips the insulation to take the strain off the electrical connection.

#### Autobike

Joined Feb 23, 2018
91
Black solder is probably because of "lead free" push which uses silver content. Silver oxide is black. Lead free solder has serious structural weaknesses.
i have some experience with the lead free solder and honestly i can't solder well with them. the lead solder flows without a problem. lead free solder joints didn't give me a black finish. it was still in silver color but not glossy. kind of a matte finish. thx a lot

You can use crimp connectors where the crimp also grips the insulation to take the strain off the electrical connection.
you are correct i had to replace a wiring terminal in my bike and it was my first attempt doing that kind of DIY. so i thought soldering a wire to the terminal is the best option. but i had a quick search on the internet and realized that crimping is the best method. i'm not sure but most of the articles mentioned that soldering wouldn't work ( long term ) in these cases due to vibration. so manufacturers use crimping method. thank you

#### shortbus

Joined Sep 30, 2009
8,959
i'm not sure but most of the articles mentioned that soldering wouldn't work ( long term ) in these cases due to vibration. so manufacturers use crimping method.
Many times automotive terminals are both soldered and crimped. Having worked where they made vehicle wiring harnesses the on some wires first add solder using a solder pot, then crimp on the terminal and then melt the solder in the crimp. Some were even laser welded after crimping.

#### nsaspook

Joined Aug 27, 2009
8,904
Many times automotive terminals are both soldered and crimped. Having worked where they made vehicle wiring harnesses the on some wires first add solder using a solder pot, then crimp on the terminal and then melt the solder in the crimp. Some were even laser welded after crimping.
I know it's done but I REALLY don't like solder and crimp. The solder layer will only degrade a good crimp connection. It might electrically test better for the INITIAL joint but the long term reliability has been proven to be poorer in comparison to a properly crimped connection under most temperature and vibration conditions expected in mobile use.

#### Autobike

Joined Feb 23, 2018
91
Many times automotive terminals are both soldered and crimped. Having worked where they made vehicle wiring harnesses the on some wires first add solder using a solder pot, then crimp on the terminal and then melt the solder in the crimp. Some were even laser welded after crimping.
thx a lot for sharing your experience it seems that different manufacturers/companies use different methods. my OEM harness has no solder around terminals. just the crimp connections.

I know it's done but I REALLY don't like solder and crimp. The solder layer will only degrade a good crimp connection. It might electrically test better for the INITIAL joint but the long term reliability has been proven to be poorer in comparison to a properly crimped connection under most temperature and vibration conditions expected in mobile use.
yea. as they/you say it's not the initial joint it's the long term reliability. the terminal i removed from the harness was prefectly crimped. well it was like welded. you just can't damage/wiggle or give any kind of strain to that connection. it was that much a perfect connection. may be they do them by machines. i got mine crimped by a guy who used a crimping pliers and it was good too. i didn't do it myself since i didn't know how to choose a correct crimping pliers. in my bike there are three different terminals. i think they are standard sizes. may be i have to do a search and find a relevant pliers. thank you

#### nsaspook

Joined Aug 27, 2009
8,904
thx a lot for sharing your experience it seems that different manufacturers/companies use different methods. my OEM harness has no solder around terminals. just the crimp connections.

yea. as they/you say it's not the initial joint it's the long term reliability. the terminal i removed from the harness was prefectly crimped. well it was like welded. you just can't damage/wiggle or give any kind of strain to that connection. it was that much a perfect connection. may be they do them by machines. i got mine crimped by a guy who used a crimping pliers and it was good too. i didn't do it myself since i didn't know how to choose a correct crimping pliers. in my bike there are three different terminals. i think they are standard sizes. may be i have to do a search and find a relevant pliers. thank you
Be sure to read actual usage reviews on each low-cost crimper. Some (Chinese brands) are a lot better than others.
I can tell you that certified crimpers are expensive. I've got a LOCKED tool box with the needed models for several equipment lines with extra die sets for some types. The replacement cost would be well over $10K to replace everything. Examples. AMP Micro MATE-N-LOK 24-20AWG Contacts http://www.farnell.com/datasheets/2...MIrpy7ueL55gIVA8NkCh21QgdFEAQYByABEgIIYfD_BwE ITT Cannon Trident Series Machined Contacts http://www.farnell.com/datasheets/2...MIrpy7ueL55gIVA8NkCh21QgdFEAQYByABEgIIYfD_BwE Thread Starter #### Autobike Joined Feb 23, 2018 91 Be sure to read actual usage reviews on each low-cost crimper. Some (Chinese brands) are a lot better than others. I can tell you that certified crimpers are expensive. I've got a LOCKED tool box with the needed models for several equipment lines with extra die sets for some types. The replacement cost would be well over$10K to replace everything.

Examples.
AMP Micro MATE-N-LOK 24-20AWG Contacts http://www.farnell.com/datasheets/2...MIrpy7ueL55gIVA8NkCh21QgdFEAQYByABEgIIYfD_BwE
ITT Cannon Trident Series Machined Contacts http://www.farnell.com/datasheets/2...MIrpy7ueL55gIVA8NkCh21QgdFEAQYByABEgIIYfD_BwE
thx a lot for your information. have to consider about the reviews as you said. it seems that some pliers are very expensive.
i wasn't aware of the specific name of those terminals i'm having in my bike but later got to know that they are called "spade terminals". common terminal type i think. guess they are in standard/universal sizes.