Hi, I'm new to electronics and circuit design so I'm looking for a bit of information and advice.
I'm designing a little "widget" which has just three components in a circuit, a coin cell battery holder, a sliding micro switch and a LED light, the idea is to have them hand solder together using 0.5mm insulated wire. The problem is with the micro switch, it seems impossible to find a 2 pin switch ( I've search Alibaba for weeks) all the switches are two way with the common pin in the center, the space between the common pin and the other pins is only 2.5mm and the soldering company says they are too close together for soldering.

Is there any other way to connect a 0.5mm wire to the pins, why would they make a micro switch if it is to small to use solder?
Any advise would be much appreciated.

 

Welcome to AAC.

First, just a detail but "microswitch" refers to a snap action switch of the sort used as a limit or sensitive detection switch. What you have there is an SPDT (Single Pole Double Throw) slide switch. It could be called "sub-miniature" but not "micro".

2.5(4)mm is the standard spacing for PCB mounting. It's 1/10" which is why it became the standard. It is very easy solder in place.

I don't understand how you want to solder them together, could you draw a picture? And, I don't know what your "soldering company" refers to, could you clarify?

You are not going to find a two pin slide switch, it would make no sense to manufacture since mechanically the space on each side of the center needs to be the same and adding the contact provide both switching flexibility and mechanical strength.

 

I regularly solder pins that are 0.6mm apart, so 2.5 mm is not a problem.

Bb

 

That switch is intended for PCB mounting. If you intend to use wires, get a panel mount switch, these are made to have wires soldered to them.

Bob

 

This can be done.

 

Welcome to AAC.

First, just a detail but "microswitch" refers to a snap action switch of the sort used as a limit or sensitive detection switch. What you have there is an SPDT (Single Pole Double Throw) slide switch. It could be called "sub-miniature" but not "micro".

2.5(4)mm is the standard spacing for PCB mounting. It's 1/10" which is why it became the standard. It is very easy solder in place.

I don't understand how you want to solder them together, could you draw a picture? And, I don't know what your "soldering company" refers to, could you clarify?

You are not going to find a two pin slide switch, it would make no sense to manufacture since mechanically the space on each side of the center needs to be the same and adding the contact provide both switching flexibility and mechanical strength.

Yaakov hi thanks for your reply, yes you are correct it is a Single Pole Double Throw switch. I just have a very simple circuit but it has to go into a very narrow space. Here is a picture of the components ( not to scale )Initially just soldered them myself but as I needed a lot doing I sent a sample to a hand solder company who said they could not make solder joints at C and D because the contact pins were too close together. They said they would need to mount the switch on a PCB which needs to be 1.mm thick and the solder would be around 1.5mm thick, (the wire is 0.5mm). The data sheet diagram shows the switch to be 2.45mm + 1.05mm high excluding the sliding knob. Using these figures that would make the height from the base of the switch to the top of the solder 6mm, this would be too high for the space available so is there another way to do this? Any alternate ideas welcome.

 

I would say design a small PCB and have it fabricated. They are cheap and it would improve the reliability a lot.

What is this, exactly? What housing will it be in?

 

I should add you can get PCBs as thin as .2mm and you would route the switch to the edge and solder there, not on the terminals. The pads for soldering would be further apart than the switch terminals.

 

I sent a sample to a hand solder company who said they could not make solder joints at C and D because the contact pins were too close together. They said they would need to mount the switch on a PCB which needs to be 1.mm thick and the solder would be around 1.5mm thick, (the wire is 0.5mm).

IF they said they "Could Not Make" solder joints what they probably mean is that they 'WOULDN'T'. Likely their solder tech's are not so skilled as to do what is called "Dead Bug" solder work. Personally I wouldn't want to do business with them. HOWEVER, it's likely many if not most solder houses would refuse to do this sort of build.

As Yaakov suggests, having a PCB fabricated would greatly increase reliability and durability of your circuit. All that is needed is to know the layout and space available for such components. Shouldn't be a big expense, minor is more likely.

 

I suspect that they refused to do this because of its fragility. They don’t want to be blamed when it shorts or breaks off during installation.

Bob

 

I should add you can get PCBs as thin as .2mm and you would route the switch to the edge and solder there, not on the terminals. The pads for soldering would be further apart than the switch terminals.

Thanks again for your help, the parts have to go into a case about the size of a chunky square watch will I be able to get a PCB fabricated which is small enough. I know nothing about designing PCBs would the company who fabricates them be able to design it if I send them the data sheet for the switch?

 

IF they said they "Could Not Make" solder joints what they probably mean is that they 'WOULDN'T'. Likely their solder tech's are not so skilled as to do what is called "Dead Bug" solder work. Personally I wouldn't want to do business with them. HOWEVER, it's likely many if not most solder houses would refuse to do this sort of build.

As Yaakov suggests, having a PCB fabricated would greatly increase reliability and durability of your circuit. All that is needed is to know the layout and space available for such components. Shouldn't be a big expense, minor is more likely.

Thanks, the battery holder and LED are not a problem, it's just the switch due to the height of the case which it has to go in which can't be altered.

 

Are you using a white LED perchance?

 

Get a switch like this and bend the two leads apart by 45° to give yourself some extra working area (or buy a finer tip and/or finer solder to avoid issues. I regularly solder 1mm parts with solder that is 0.2mm diameter.
https://www.digikey.com/en/products/detail/c-k/TS02CQE/3755397

 

Get a switch like this and bend the two leads apart by 45° to give yourself some extra working area (or buy a finer tip and/or finer solder to avoid issues. I regularly solder 1mm parts with solder that is 0.2mm diameter.
https://www.digikey.com/en/products/detail/c-k/TS02CQE/3755397

Thanks but that switch is around 30 x more expensive than the ones I want to use so they're just not a viable option.

 

Are you using a white LED perchance?

Yes but I don't see the why that makes any difference

 

That has to do with the battery voltage vs LED current. You are unlikely to need a resistor in series with a white LED, but if it were a red LED, for example, would have to be careful limiting the current.

Just looking out for you.

 

That has to do with the battery voltage vs LED current. You are unlikely to need a resistor in series with a white LED, but if it were a red LED, for example, would have to be careful limiting the current.

Just looking out for you.

Ah, that's way over my head but thanks, I learn something new every day.

 

I should add you can get PCBs as thin as .2mm and you would route the switch to the edge and solder there, not on the terminals. The pads for soldering would be further apart than the switch terminals.

I don't understand how mounting the switch on a PCB would help, I'm a complete novice but surely the switch terminals are still the same distance apart so how does it make them easier to solder??

 

I told you why they won’t solder them. It has nothing to do with the dustance beween the pins. The were using a polite excuse instead of telling you it was a bad design. I just finished soldering 4 boards with an IC with pins 0.65 mm apart. And that is not the smallest. You pins are 2.54 mm or 4 times as far apart as the ones I just soldered. It id soldering them to wires unsupported that the object to, and for good reason.

If you could find a switch that is designed for panel mount, which is what you are doing, it would be solderable. They use stiffer pins with an eye like a needle that you thread the wire through.

Bob