flexible ribbon "PCB" to regular PCB

[Winfield Hill]

gnuarm.deletethisbit@gmail.com wrote...

They make a flat cable termination that is intended for
soldering to a PCB. It has pins for through hold
mounting, very secure. I want to say the individual
pins in the body crimp to the flex, but I'm not certain
of that. It might need to be made part of the cable. Do
you not see anything like this in premade flex catalogs?

Yes, thanks, I remembered seeing something like that,
so I looked for it, but didn't find it.


--
Thanks,
- Win

 

On 1 May 2019 04:56:38 -0700, Winfield Hill <hill@rowland.harvard.edu>
wrote:

Looking for good ways to connect / solder a flexible ribbon PCB to a regular
PCB, without using a connector. We need to be able to pull hard on the link,
without the flexible ribbon coming out. Maybe using Molex Premo-Flex, etc., to
avoid having to fab the flexible ribbon? We only need four wires, for an I2C
connection.

Use "rigid-flex" board? ...basically flex FR4 laminated with rigid
FR4.

 

[Jasen Betts]

On 2019-05-01, Winfield Hill <hill@rowland.harvard.edu> wrote:

TTman wrote...

On 01/05/2019 12:56, Winfield Hill wrote:
Looking for good ways to connect / solder a flexible ribbon PCB to a
regular PCB, without using a connector. We need to be able to pull
hard on the link, without the flexible ribbon coming out. Maybe using
Molex Premo-Flex, etc., to avoid having to fab the flexible ribbon?
We only need four wires, for an I2C connection.

I've seen them soldered directly to a PCB- it was very
unreliable so don't go that route (on an LCD to PCB backlight).

OK, good advice. I can use the recommended connector, and after
mating the ribbon, seal the entrance and cover it all with epoxy.
I see 1.25mm six-wire is only 9 mm wide, but I assume it's strong.

I understand that a hot bar is used to solder flex pcb to rigid pcb.

if you're going to epoxy the joint the weakest part will be where the
flex comes out of the epoxy,

--
When I tried casting out nines I made a hash of it.

 

[Jasen Betts]

On 2019-05-01, Winfield Hill <hill@rowland.harvard.edu> wrote:

Thanks, but this time we need the super-thin aspect.
It sneaks between two "supers" = bee-hive sections.

So, open ended boxes, rebated to stack securely, or just stacked;
but softwood. Drill a 1/4" hole and put a flex with 3.5mm plug
through it. bees won't mind a 1/4" hole, if it bothers them
they'll plug it with propolis.

We only need four I2C wires, but the smallest
stocked Molex 1.25mm Premo-Flex has six.

The bees are going to glue that to both boxes with propolis, the
next time the hive is opened it'll snap depening on which side of the popolis snaps
first.

How many bee keepers are there on your team?

--
When I tried casting out nines I made a hash of it.

 

[Winfield Hill]

Jasen Betts wrote...

On 2019-05-01, Winfield Hill wrote:

Thanks, but this time we need the super-thin aspect.
It sneaks between two "supers" = bee-hive sections.

So, open ended boxes, rebated to stack securely, or just stacked;
but softwood. Drill a 1/4" hole and put a flex with 3.5mm plug
through it. bees won't mind a 1/4" hole, if it bothers them
they'll plug it with propolis.

Have you tried the Broodminder Temp+Hum sensors,
that you can locate in the center of the hive?
They have a 1x1-inch bluetooth PCB in one end of
folded clear plastic, and a strip of the plastic
sneaks out of the hive between supers. The bees
leave the plastic assembly alone, no propolis.

But we have trouble getting their data into our
hive-monitor system, prefer a wired connection,
plus I'm placing eight sensor parameters (!) at
the middle-of-the hive location. But we'd like
to keep convenient place-it-between supers, move
it up as the hive grows and gets more supers, etc.

A six-inch piece of thin flex should work fine,
using the strain-relef solutions suggested here.

> How many bee keepers are there on your team?

Hah, sadly a bit under populated at the moment,
but hey, bee hives are best left alone, right?
Some experience beekeepers have offered to help.
Then there's me for elec and PCB design, plus
an excellent math programmer, plus a 3rd-year
EE summer student to help with cables, sensors.
An informatics post-doc for database software.
Plus an Institute technician one day a week.
And the project's PI, who's doing 3D printed
housings, etc. OK, that's a pretty good team!


--
Thanks,
- Win

 

[Jasen Betts]

On 2019-05-02, Winfield Hill <hill@rowland.harvard.edu> wrote:

Jasen Betts wrote...

On 2019-05-01, Winfield Hill wrote:

Thanks, but this time we need the super-thin aspect.
It sneaks between two "supers" = bee-hive sections.

So, open ended boxes, rebated to stack securely, or just stacked;
but softwood. Drill a 1/4" hole and put a flex with 3.5mm plug
through it. bees won't mind a 1/4" hole, if it bothers them
they'll plug it with propolis.

Have you tried the Broodminder Temp+Hum sensors,
that you can locate in the center of the hive?
They have a 1x1-inch bluetooth PCB in one end of
folded clear plastic, and a strip of the plastic
sneaks out of the hive between supers. The bees
leave the plastic assembly alone, no propolis.

But we have trouble getting their data into our
hive-monitor system, prefer a wired connection,
plus I'm placing eight sensor parameters (!) at
the middle-of-the hive location. But we'd like
to keep convenient place-it-between supers, move
it up as the hive grows and gets more supers, etc.

A six-inch piece of thin flex should work fine,
using the strain-relef solutions suggested here.

so long as the bees really leave it alone, and the bee-
keeper manages to miss it when unsticking a stuck super
it now sounds like a good solution.

For strain releif zig-zagging through a PCB works
well with rubber or PVC insulated wires, but yeah
for something hard and smooth some glue will help


--
When I tried casting out nines I made a hash of it.

 

[speff]

On Wednesday, 1 May 2019 07:56:54 UTC-4, Winfield Hill wrote:

Looking for good ways to connect / solder a flexible ribbon PCB to a regular
PCB, without using a connector. We need to be able to pull hard on the link,
without the flexible ribbon coming out. Maybe using Molex Premo-Flex, etc., to
avoid having to fab the flexible ribbon? We only need four wires, for an I2C
connection.


--
Thanks,
- Win

There's the heat sealed connections (conductive heat sensitive adhesive) used in high volume. Or you could consider rigid-flex and then the board would come with the flex incorporated. But I don't think either one is all that suitable for small quantity unless cost is not a concern.

I think your connector + epoxy is probably best but I would keep the epoxy away from the connector lest it affect the reliability.

--Spehro Pefhany

This stuff is interesting- kind of a heat-sealed version of the zebra elastomeric connectors (anisotropic conductivity so you just have to line the pads up on either side) but again, probably unsuitable for small quantities:

https://www.dexerials.jp/en/products/a7/cp20000.html

 

[Winfield Hill]

speff wrote...

There's the heat sealed connections (conductive heat sensitive
adhesive) used in high volume. ...

This stuff is interesting- kind of a heat-sealed version of the
zebra elastomeric connectors (anisotropic conductivity so you
just have to line the pads up on either side) but again,
probably unsuitable for small quantities:

https://www.dexerials.jp/en/products/a7/cp20000.html

Yes, very interesting. Can you suggest other heat-sensitive
adhesives (doesn't need to be conductive if I use a socket).


--
Thanks,
- Win

 

[Hul Tytus]

Win - for thinness, you might look at Parlax's "flat cable". Digikey's
catalog shows one with a thickness of .011 inch and a current rating of
1.5 amp. There are others with a lesser rating...

Hul

Winfield Hill <hill@rowland.harvard.edu> wrote:

Hul Tytus wrote...

Win - ribbon cable, ala Belden, etc, is a "golden
oldie" for such applications. Typically, though,
a ground lead for each signal lead is required.

Thanks, but this time we need the super-thin aspect.
It sneaks between two "supers" = bee-hive sections.
We only need four I2C wires, but the smallest
stocked Molex 1.25mm Premo-Flex has six.

--
Thanks,
- Win