Connecting to the real world

[John Devereux]

Hi,

I have a PCB with 0.1 inch dual row headers, inside a sealed metal
box. I need to connect the Real World to it. We usually avoid using
external connectors, but in this case we need to make the whole box
"unpluggable" and do not want the end user going inside the box.

Does anybody know of any "waterproof" (IP67) connectors suitable for
terminating ribbon cables (4-12 ways)?

Ideally I would like to use insulation displacement style terminations
at the bulkhead connectors, but I can't seem to find any.

We have tried various circular connectors with "solder bucket" pins;
they are very fiddly and time consuming to wire up. Also the ribbon
cable wires tend to drop off since they are very thin! Then the others
drop off while you are fixing the first one etc...

What do people use for this?

Thanks,

 

[PeteS]

As you have found, most IP67 connectors are not IDC. Two big names I
can suggest you look at are Bulgin and Binder. They have a wide variety
of IP67 rated connectors with varying styles.

If IP67 is a must, you are probably not going to get an IDC style
connector, simply because to get that rating, there has to be a
compression seal all the way around the connector, and IDC connectors
only have fit compression at the ends, not all the way around.

You can get IDC (for D style connectors, for instance) if you can live
with IP44 or thereabouts, but I don't recall seeing anything above
that.

I (occasionally) design IP67 stuff, and connectors are always my single
biggest concern (to say nothing of cost).

Cheers
PeteS

 

[Greg Neff]

Hi,

I have a PCB with 0.1 inch dual row headers, inside a sealed metal
box. I need to connect the Real World to it. We usually avoid using
external connectors, but in this case we need to make the whole box
"unpluggable" and do not want the end user going inside the box.

Does anybody know of any "waterproof" (IP67) connectors suitable for
terminating ribbon cables (4-12 ways)?

Ideally I would like to use insulation displacement style terminations
at the bulkhead connectors, but I can't seem to find any.

We have tried various circular connectors with "solder bucket" pins;
they are very fiddly and time consuming to wire up. Also the ribbon
cable wires tend to drop off since they are very thin! Then the others
drop off while you are fixing the first one etc...

What do people use for this?

Thanks,

Not ribbon cables. If you want to use a standard ribbon cable style
header on your board, then try Tyco AMP 102387 (MOD IV) series
housings. These accept wires with crimp socket contacts. The other
ends of the wires can then be crimped to any contact suitable for your
waterproof connector.

================================

Greg Neff
VP Engineering
*Microsym* Computers Inc.
[email protected]

 

[Alan Turner]

Hi,

I have a PCB with 0.1 inch dual row headers, inside a sealed metal
box. I need to connect the Real World to it. We usually avoid using
external connectors, but in this case we need to make the whole box
"unpluggable" and do not want the end user going inside the box. Hi,


Does anybody know of any "waterproof" (IP67) connectors suitable for
terminating ribbon cables (4-12 ways)?

Ideally I would like to use insulation displacement style terminations
at the bulkhead connectors, but I can't seem to find any.

We have tried various circular connectors with "solder bucket" pins;
they are very fiddly and time consuming to wire up. Also the ribbon
cable wires tend to drop off since they are very thin! Then the others
drop off while you are fixing the first one etc...

Perhaps you could use a microcontroller to multiplex the signal(s) onto a
serial link with fewer leads to connect. I suppose an optical coupling
would be ideal if you want to make it waterproof.

Regards,
Alan

 

[John Devereux]

Perhaps you could use a microcontroller to multiplex the signal(s) onto a
serial link with fewer leads to connect. I suppose an optical coupling
would be ideal if you want to make it waterproof.

Thanks, but we are already using a serial link. But we also need to
provide other signals for power, and for customers that cannot use the
serial link.

 

[Mark Jones]

Hi,

I have a PCB with 0.1 inch dual row headers, inside a sealed metal
box. I need to connect the Real World to it. We usually avoid using
external connectors, but in this case we need to make the whole box
"unpluggable" and do not want the end user going inside the box.

Does anybody know of any "waterproof" (IP67) connectors suitable for
terminating ribbon cables (4-12 ways)?

Ideally I would like to use insulation displacement style terminations
at the bulkhead connectors, but I can't seem to find any.

We have tried various circular connectors with "solder bucket" pins;
they are very fiddly and time consuming to wire up. Also the ribbon
cable wires tend to drop off since they are very thin! Then the others
drop off while you are fixing the first one etc...

What do people use for this?

Thanks,

Try Permatex blue RTV engine sealant from your local car parts store. This
stuff will withstand almost anything. Use a wide bead area if user disassembly
is a concern.

 

[Tony Williams]

I have a PCB with 0.1 inch dual row headers, inside a sealed
metal box. I need to connect the Real World to it. We usually
avoid using external connectors, but in this case we need to make
the whole box "unpluggable" and do not want the end user going
inside the box.

Does anybody know of any "waterproof" (IP67) connectors suitable
for terminating ribbon cables (4-12 ways)?

Use an ITT Cannon - TNM IP67 circular connector.
The QM range of pcb-mount pins will fit the TNM.
So have a small pcb at the rear of the connector,
converting the round pin layout into a 0.1" IDC
header. 1:1 IDC cable from there to the main pcb.

In the RS cat: 265-9705 chassis plug, and 349-8854
gold-plated pcb TNM contacts.

 

[John Devereux]

Use an ITT Cannon - TNM IP67 circular connector.
The QM range of pcb-mount pins will fit the TNM.
So have a small pcb at the rear of the connector,
converting the round pin layout into a 0.1" IDC
header. 1:1 IDC cable from there to the main pcb.

Thanks Tony!

Actually I had already considered something like that with the
connectors we tried... glad idea not completely barmy.

In the RS cat: 265-9705 chassis plug, and 349-8854
gold-plated pcb TNM contacts.

I just got the new catalogue the other day. The contacts appear to be
discontinued! Possibly I can get elsewhere though.


Thanks,

 

[Rich Grise]

Thanks, but we are already using a serial link. But we also need to
provide other signals for power, and for customers that cannot use the
serial link.

Look at automotive connectors. They can get hefty, but they're quite
water- and dirt-resistant.

Good Luck!
Rich

 

[Tony Williams]

Actually I had already considered something like that with the
connectors we tried... glad idea not completely barmy.

Getting the pins lined up exactly right before
soldering is liable to be the bum-biter though.

I suspect it will need slightly oversize holes
in the pcb, assemble the plug, plug it into a
socket, *then* solder the pcb on.

 

[Frithiof Andreas Jensen]

We have tried various circular connectors with "solder bucket" pins;
they are very fiddly and time consuming to wire up. Also the ribbon
cable wires tend to drop off since they are very thin! Then the others
drop off while you are fixing the first one etc...

Ahhh... Practice, Practice - you also need heat-shrink on all the wires ....


The semi-mil circular connectors are the only ones that will last with dirt
and moisture around - you *can* get types with crimp-pins but splitting
ribbon-cable and crimping the ends is IMO at best a Hobby-Thing (in larger
series, I would consider it Cowboy ;-).

One solution, i have seen, was to use a flexible mylar "pcb" with a layout
matching the connector, solder the connector into that and connect the other
end via some kind of header. But that costs..

Maybe your best option is simply to have someone specializing in wire
harnesses produce a quality connector assembly for you. With a little
flexibility in connecting the other end - i.e. you might need to loose the
ribbon - it is probably not expensive either compared to endless D.I.Y
efforts.

 

[John Devereux]

"Frithiof Andreas Jensen"

Ahhh... Practice, Practice - you also need heat-shrink on all the
wires ....

Yes, doing that too... of course that takes even more time, and makes
it harder to inspect / fault find.

The semi-mil circular connectors are the only ones that will last
with dirt and moisture around - you *can* get types with crimp-pins
but splitting ribbon-cable and crimping the ends is IMO at best a
Hobby-Thing (in larger series, I would consider it Cowboy ;-).

Agreed . (Actually we are just supplying the PCB, it is my customer
that is "packaging" it).

One solution, i have seen, was to use a flexible mylar "pcb" with a
layout matching the connector, solder the connector into that and
connect the other end via some kind of header. But that costs..

Maybe your best option is simply to have someone specializing in
wire harnesses produce a quality connector assembly for you. With a
little flexibility in connecting the other end - i.e. you might need
to loose the ribbon - it is probably not expensive either compared
to endless D.I.Y efforts.

Yes. It looks like the easiest option is to accept losing the
convenience of the ribbon cable (as suggested) and just use individual
wires. You can get crimp housings that go onto the PCBs dual row 0.1
inch headers, instead of the IDC ribbon. The thicker wires that these
will accept should solve most of the problems. Still surprised you
can't get an IDC "military" style circular connector though.

 

[Frithiof Andreas Jensen]

Yes. It looks like the easiest option is to accept losing the
convenience of the ribbon cable (as suggested) and just use individual
wires. You can get crimp housings that go onto the PCBs dual row 0.1
inch headers, instead of the IDC ribbon.

Of Course - I have forgotten that; Those are very widely used - so the
tools/people who can do them are available.

The thicker wires that these
will accept should solve most of the problems. Still surprised you
can't get an IDC "military" style circular connector though.

That's the Millitary for ya: "If it was good enuff for General McArthur then
it's damn fine stuff, son" ;-) ....

And it takes many approvals from many V.I.P's to get different components
authorized - maybe the manufacturers do not see the point in trying to push
a new standard, after all: Soldering this stuff up is routinely billed at
"cost + x%" in millitary contracts, so it is only a lead-time problem for
everybody (except for the Tax-payer, but maybe he/she works at Raytheon
anyway).