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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Wire to board soldering

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dougs

#42262

Wire to board soldering | 19 June, 2006

Hi All,

We have a board that's going through our process at the moment, it's 1.6mm thick and has 4 wires soldered into it, these are 10SWG multi stranded wires, i'm finding that it's difficult to get the holes filled with solder as it travels up the wire, customer expects 100% hole fill but the more solder we push in the more the wire takes, also the wire is to be flexible as the board goes into an enclosure and needs to bend pretty close to the board. Has anyone had to deal with anything like this before? Should the wires be screwed into a connector rather than soldered? What are the IPC standards for design for this type of product?

cheers

Dougs

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Thanagon

#42283

Wire to board soldering | 19 June, 2006

Try to dip that wire with flux before insert to PCB. IT's will come better .

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#42292

Wire to board soldering | 19 June, 2006

So, a 10SWG is about an 8AWG.

We can't think of a IPC standard for design of this type of product.

That the solder is running up the wire indicates something is wrong. We wonder if either: * Holes in the board might be too large for the wire. Does the wire supplier offer recommendations on hole size versus wire size? We like to see 0.4 to 0.6mm clearance between hole and lead. * Board is not being heated with the wire. This can happen when there is a large heat sink and when there is not enough contact to the board by the heat source.

So, do you bend the wire 90* prior to soldering so that it lays flat to the board? This might help fill the hole when soldered.

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FD

#42293

Wire to board soldering | 20 June, 2006

I, too, would bend it 90-degrees prior to assembly and I would also put on a little spring loaded, removable, heat sink on to the wire to stop the heat transfer up the wire. After the wire is soldered, then remove the heat sink. Try the one from Radio Shack, Model: 276-1567 Catalog #: 276-1567.

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Chunks

#42296

Wire to board soldering | 20 June, 2006

What is your process? Wave solder, hand solder, pin in paste?

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dougs

#42298

Wire to board soldering | 20 June, 2006

It's hand solder, the wires are free issued, what i'm finding is that if we keep the heat and push enough solder into the joint that the component side wets there is that much solder moved up the wire that it goes solid. this is no good as the customer has stated on their drawing that there is a space restriction which is pretty small so the wires need to be flexible. what would you guys use to inspect hole fill? Can you only really tell how full a hole is using x-ray?

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Chunks

#42303

Wire to board soldering | 20 June, 2006

I was afraid so. Hand soldering wires in general is not difficult, but with your constraint of the space restriction it does make fairly hard to do. I am assuming you have a 2 sided board and stranded copper wire. So once solder starts to flow, the flux follows the heat up the wire and the solder follows the flux. With this, timing is everything, and doing it by hand makes it very difficult. I believe you must rely on the talent of your operators.

Check the hole by looking for top side wetting. Your insulation should not touch the board according to IPC, so you can check for top side wetting. A 75% fill of the hole is the minimum for Class 1, 2, 3 with a max depression of 25%, including both secondary and primary sides permited.

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#42318

Wire to board soldering | 20 June, 2006

The minimum vertical hole fill is defined as follows: Class 1: Not specified, with a 270-degree circumferential fillet and wetting on the secondary (solder source side) of lead and barrel, and a 75% coverage of the land area on the secondary side. Class 2: 75% fill, with a 270-degree circumferential fillet and wetting on the secondary (solder source side) of lead and barrel, and a 75% coverage of the land area on the secondary side. Class 3: 75% fill,ith a 330-degree circumferential fillet and wetting on the secondary (solder source side) of lead and barrel, and a 75% coverage of the land area on the secondary side.

Consider using two soldering irons to help increase your hole fill.

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#42339

Wire to board soldering | 21 June, 2006

Agreed! More soldering irons will provide the solder joint yoiu need.

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RDR

#42348

Wire to board soldering | 21 June, 2006

You may want to pre tin wires then dip into flux before soldering

Does work!

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