Best Soldering Helping Hands

[Rob Flinn]

How were you holding the connector during the process ? As in - didn't it get too hot ?

In my hand. It doesn't get too hot if one is quick enough, & I also have asbestos fingers now.

 

[sahib]

How were you holding the connector during the process ? As in - didn't it get too hot ?

Part of my business used to be in modelmaking. So, I have a wide range of vices, clamps and all sort of contraptions that I make use of if my fingers can not deal with it. But I also have fingers like Rob's.

However, I have been soldering for over 45 years now, and I have never ever needed to use helping hands for soldering PCBs.

One technique I use for soldering through hole, particularly resistors and diodes is that I have rectangular kitchen sponges that I very lightly wet (not to drip). After inserting the resistors/diodes, I sandwich them with the sponge, lay the board over the desk and solder. This not only keeps the components in place but also dissipates the heat.

Some people my disagree, but the worst thing one can do is to bend component leads to keep them in place to solder. I have recently fixed a customer's build which was plagued with shorts due to this.

 

[scott2000]

but the worst thing one can do is to bend component leads to keep them in place to solder

Can you elaborate on this?

 

[abbey road d enfer]

However, I have been soldering for over 45 years now, and I have never ever needed to use helping hands for soldering PCBs.

Well, quite often I feel teh need for a third hand to bring solder to a part that I hold in my left hand, while the right one is busy holding the iron.
I have a combined iron/dispenser for that task.
https://www.amazon.com/Toolour-Automatic-Detachable-Desoldering-Anti-static/dp/B07JZ4JV1F

Some people my disagree, but the worst thing one can do is to bend component leads to keep them in place to solder. I have recently fixed a customer's build which was plagued with shorts due to this.

+1! Shorts and improper wetting.

 

[sahib]

Can you elaborate on this?

See the sketch. Bending the leads outwards or inwards to keep the components in position.

Bending outwards will interfere with the adjacent component leads and even when you trim there is still a substantial risk of a short. As Abbey also rightly commented you may not get a good solder node either. You may not be able to see it with naked eye, but trust me, you will have it sooner or later.

The argument can be made to bend it inwards so that it would be safe. This still is a very bad practice. In the case of troubleshooting you will be applying the soldering iron longer and also to straighten the lead. Big risk of damaging the pad and tracks. Although statistically very low, there can nevertheless be hairline shorts between the tracks, particularly around the solder pads due to imperfect etching. Or even microscopic area where the solder mask receded and solder bridge formed. Bending the lead will cover it over and you'll be pulling your hair out to find where the short is.

The other thing I'd like to mention is not to trim the leads before soldering as they help dissipate heat. Say, you are soldering a diode. Do not solder one lead, trim it and then solder the other lead. Solder them both first and then trim.

Always keep the leads straight.

 

[moamps]

Bending component leads is very often used in consoles (I know about Soundcraft, Audient, ...) and almost always in industrial and military control panels that I repaired (industrial computers, telephone exchanges, etc.). This technique is problematic when a component needs to be removed, but it certainly contributes to mechanical strength, improves contact, and probably contributes to better heat transfer. I would recommend bending but no more than 45deg.

 

[abbey road d enfer]

Bending component leads is very often used in consoles (I know about Soundcraft, Audient, ...) and almost always in industrial and military control panels that I repaired (industrial computers, telephone exchanges, etc.).

I'm not sure there's a good justification for that. I've never seen a resistor falling off a PCB it is was properly soldered. I have seen resistors with bent leads but no solder and the circuit worked for a long time till the day it ceases working because dirt and corrosion have done their work.
I reckon it's a sequel of the old military wiring techniques that required three turns around a lug before applying solder. As you know, military does not necessarily mean better. Two examples: military music and military justice.
I don't think the insertion machines at Soundcraft did bend the leads. It was after wave soldering, the leads were cut with some kind of mechanical scythe, which left the remains bent all in the same direction.

 

[moamps]

I don't think the insertion machines at Soundcraft did bend the leads. It was after wave soldering, the leads were cut with some kind of mechanical scythe, which left the remains bent all in the same direction.

I don't believe so. The leads are cut and bent before soldering for sure.

 

[moamps]

I'm not sure there's a good justification for that. I've never seen a resistor falling off a PCB it is was properly soldered.

I have seen a lot of high power resistors (especially in SMPSs) that have lost contact due to heating and unbent contact. The bent lead has better mechanical and electrical contact.

I have seen resistors with bent leads but no solder and the circuit worked for a long time till the day it ceases working because dirt and corrosion have done their work.

If it hadn't been bent, that resistor wouldn't have worked at all.

 

[Carlsoti]

Build one out of CNC machine coolant lines. Various sizes available, as long and as many arms as you wish. Just don't get duped by buying a similar looking thing at rock bottom prices. Good ones are molded well enough that coolant leakage is minimal, making them more secure once you've set them into position. Cheap ones won't hold position as well.

 

[sahib]

I have seen a lot of high power resistors (especially in SMPSs) that have lost contact due to heating and unbent contact. The bent lead has better mechanical and electrical contact.

If the solder is subjected to a sufficiently high temperature then the bond with the resistor lead will be lost in all surface areas of the resistor lead. So, this argument does not hold.

So, from excessive heat point of view the bent lead also does not present a better mechanical contact if the bond with the solder is lost.

From mechanical stress point of view ( say vibration ) as Abbey commented the component's weight comparing to the strength of the solder bond does not even enter the realm of significance.

The only reason the leads are bent because of speed of assembly.

Edit: However, in the case of the example you have given with the image, one can tolerate a modest degree of bending as there is sufficient spacing around the pads to prevent shorts. But in densely populated boards it will be an extremely bad practice.

 

[industrialarts]

The Stanley vise is a lot like a Panavise (here at Digikey). I acquired one a few years ago, probably my most useful soldering aid.

There is also this sort of device that has been on my wish list for a while. I currently have one of those old Radio Shack two clip things that drives me mad with it's unreliability but until I throw it hard enough against the shop while, it'll do for now.

 

[Disco Volante]

I guess it depends on the population density... Most of the amps I've worked on in the past 40-odd years have had bent leads. It may not be good practice, but it seems to have economical significance on the assembly line. I find that bending just a tad helps get the work done, without compromising contact safety.

 

[moamps]

If the solder is subjected to a sufficiently high temperature then the bond with the resistor lead will be lost in all surface areas of the resistor lead. So, this argument does not hold.
So, from excessive heat point of view the bent lead also does not present a better mechanical contact if the bond with the solder is lost.
From mechanical stress point of view ( say vibration ) as Abbey commented the component's weight comparing to the strength of the solder bond does not even enter the realm of significance.

I'm sorry, but I think you're wrong.

My arguments are based on considerable experience and knowledge I have gained over many years dealing with electronic devices for various purposes.

First, a joint with a bent lead will have lower electrical resistance and thus lower thermal resistance. It should not be forgotten that the tin-lead solder has about 10-20 times higher electrical and thermal resistance than copper, which means that the joint will heat up much more if the lead is not bent and at the same time a significant current flows through the joint. So it is actually the best joint when the lead is completely bent by 90deg. because the two structures (component lead and PCB track) are closest to each other and the path of current through the solder is the shortest.
Second, the bent lead gives better mechanical contact especially with parts that have more weight such as power resistors, capacitors, etc. regardless of the condition of the solder. That is why such parts are harder to remove from the PCB.


http://www.industrial-electronics.com/et-4e_14.html

"
FIG. 10 Two methods of assembling axial lead components to printed circuit boards: (a) fully clinched leads: (b) leads with service bends.
......
Finally, the leads must be properly bent after passing through the insulating material. One of two types of bending procedures may be adopted; these are the fully clinched lead arrangement, as shown in FIG. 10a, and a service bend, shown in FIG. 10b. The fully clinched lead is used when maximum rigidity of the component is desired. This technique also requires less solder to complete the electrical connection. Service bends, as the name implies, are adopted if components may have to be removed later on. This lead arrangement is made by bending the component lead to within approximately 30 degrees of the terminal pad. This technique makes it less difficult to remove a component after it has been soldered than one with fully clinched leads."

What about Neve?

 

[abbey road d enfer]

I don't believe so. The leads are cut and bent before soldering for sure.

Correct, they are cut AND bent in one go.

 

[abbey road d enfer]

The Stanley vise is a lot like a Panavise (here at Digikey). I acquired one a few years ago, probably my most useful soldering aid.

There is also this sort of device that has been on my wish list for a while. I currently have one of those old Radio Shack two clip things that drives me mad with it's unreliability but until I throw it hard enough against the shop while, it'll do for now.

It seems like this 4-clip thing is twice unreliable than a 2-clip.

 

[abbey road d enfer]

My arguments are based on considerable experience and knowledge I have gained over many years dealing with electronic devices for various purposes.

I don't doubt it, but it seems to me like rehashing the Bible would make it unquestionable, just because so many people live by it.

First, a joint with a bent lead will have lower electrical resistance and thus lower thermal resistance. It should not be forgotten that the tin-lead solder has about 10-20 times higher electrical and thermal resistance than copper, which means that the joint will heat up much more if the lead is not bent and at the same time a significant current flows through the joint. So it is actually the best joint when the lead is completely bent by 90deg. because the two structures (component lead and PCB track) are closest to each other and the path of current through the solder is the shortest.

Moot argument when put in perspective of a 10k resistor of less than 1W.

Second, the bent lead gives better mechanical contact especially with parts that have more weight such as power resistors, capacitors, etc. regardless of the condition of the solder. That is why such parts are harder to remove from the PCB.

Agreed, heavy components need special attention regarding mounting. This was a big subject for the late Bernardt Weingartner (founder and CTO of Neutrik). All his creations were designed to offer extra mechanical support via diverse aids such as screws, dedicated solder pins and plastic protrusions.

http://www.industrial-electronics.com/et-4e_14.html
View attachment 95084
"
FIG. 10 Two methods of assembling axial lead components to printed circuit boards: (a) fully clinched leads: (b) leads with service bends.
......
Finally, the leads must be properly bent after passing through the insulating material. One of two types of bending procedures may be adopted; these are the fully clinched lead arrangement, as shown in FIG. 10a, and a service bend, shown in FIG. 10b. The fully clinched lead is used when maximum rigidity of the component is desired. This technique also requires less solder to complete the electrical connection. Service bends, as the name implies, are adopted if components may have to be removed later on. This lead arrangement is made by bending the component lead to within approximately 30 degrees of the terminal pad. This technique makes it less difficult to remove a component after it has been soldered than one with fully clinched leads."

For me, it's typical of perpetuation of an archaic arrangement. The way it's formulated, "thou shalt not", does not leave much place for reflection and possible betterment. It's an inheritance of old point-to-point techniques. I'm not saying it's 100% wrong, I just say it's not justified for most resistors, small caps, low-power transistors. It just makes servicing unduly tiresome.
It may be justified if there is no other way of retaining components in place when the PCB is turned over, which seems amateurish to me.
Most DIYers (should) have a foam gizmo for preventing components to fall off.

 

[abbey road d enfer]

If it hadn't been bent, that resistor wouldn't have worked at all.

Yes, but if it hadn't been bent, it would have fallen off the PCB and the problem would have been detected at the factory, not years later in the field.

 

[sahib]

I'm sorry, but I think you're wrong.

I may well be.

My arguments are based on considerable experience and knowledge I have gained over many years dealing with electronic devices for various purposes.

This assumes that mine is not..

First, a joint with a bent lead will have lower electrical resistance and thus lower thermal resistance. It should not be forgotten that the tin-lead solder has about 10-20 times higher electrical and thermal resistance than copper, which means that the joint will heat up much more if the lead is not bent and at the same time a significant current flows through the joint. So it is actually the best joint when the lead is completely bent by 90deg. because the two structures (component lead and PCB track) are closest to each other and the path of current through the solder is the shortest.

This clearly claims a considerable performance difference between the straight and bent. I'd like to see the comparative data.

Second, the bent lead gives better mechanical contact especially with parts that have more weight such as power resistors, capacitors, etc. regardless of the condition of the solder. That is why such parts are harder to remove from the PCB.

No it does not. As I mentioned before in general the weight of the component in comparison to the bonding strength of a given solder node is insignificant.

In the case of heavy-power components, relying on bent component leads for component stability is a bad practice to start with. The stability should be provided by the use of mechanical fixing or adhesive, whichever is appropriate for a given component.

For the article you posted I disagree with the phrase "must". I have a considerable size of my own technical library but I do not take the things I read as the word of lord. I question.

In the case of Neve?

Is that why the old Neve cards sound better?

 

[moamps]

.... I'm not saying it's 100% wrong, I just say it's not justified for most resistors, small caps, low-power transistors. It just makes servicing unduly tiresome..

One of the aspects that you may not have thought about is the mechanical stress in the form of bending and torsion of PCBs and thus the components on them, where bending leads can help. Especially when it comes to large PCBs of channel strips or unsuported 500 type modules.

Ok, I think I have fulfilled my wish to give a second opinion that the correct bending of the leads can not be bad and that it can only improve the quality of joints and that it is still used by many manufacturers. To finish the discussion, I think we could come to a conclusion similar to what you said.