Re: headers and sockets for pcbs?

From: Thomas P. Gootee (tomg_at_fullnet.com)
Date: 08/02/04 

Date: 2 Aug 2004 11:00:21 -0700

"Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message news:<o%nPc.207$Uk3.87@newsfe6-gui.ntli.net>...
> "Thomas P. Gootee" <tomg@fullnet.com> wrote in message
> news:11915d6.0408012108.59369103@posting.google.com...
> > "Ryan Wheeler" <mojo@nospam_netscape.com> wrote in message
> news:<f27Pc.5216$zXz1.4031@news04.bloor.is.net.cable.rogers.com>...
> > > Thomas P. Gootee wrote:
> > >
> > > > I am re-designing some pcbs, to make the equipment they're in easier
> > > > to manufacture, and service or upgrade.
> > > >
> > > > The pcbs currently have quite a few wires that are soldered directly
> > > > to them, that go to front-panel controls (and to other pcbs).
> > > >
> > > > The wires to all of the front-panel controls are also soldered
> > > > directly to the solder lugs of the controls (switches, pots, etc).
> > > >
> > > > To make manufacturing and service/maintenance/upgrading faster and
> > > > easier, I think that ALL of the wire connections to the pcbs should
> > > > use removable connectors, such as pin headers on the boards and
> crimp
> > > > sockets on the wires. Also, where desirable and logical, I think
> that
> > > > sets of multiple individual wires should be replaced with ribbon
> > > > cables, with appropriate headers and sockets.
> > > >
> > > > To make this possible, I think that I will have to re-design the
> front
> > > > panel controls, to use a pcb behind the front panel, changing all of
> > > > the controls from solder-lug types to pcb-mount types. That way, I
> can
> > > > use headers, sockets, ribbon cables, etc, to connect the existing
> pcbs
> > > > to the front panel controls (via headers on the new
> > > > front-panel-interface pcb).
> > > >
> > > > Here's where I would like some help:
> > > >
> > > > I am not very familiar with the vast majority of the myriad
> different
> > > > types of wire-to-board (and board-to-board) connector systems that
> are
> > > > available. There seem to be zillions of different ones. And the
> > > > catalogs, and even the manufacturers' websites, seem to assume that
> I
> > > > already know how they're assembled and installed, etc. But THAT'S
> what
> > > > I'm trying to find out, so I can decide which ones would be
> convenient
> > > > and cost-effective to put into the design.
> > > >
> > > > So: Does anybody have any "favorite" makes and models of
> wire-to-board
> > > > (or board-to-board) connectors? (They need to be able to handle at
> > > > least 1.5 Amps and up to at least 15 V DC. And they need to be easy
> > > > and cheap to assemble.) Or any least favorites?
> > > >
> > > > What I was also HOPING to find was someplace that sells ready-made
> > > > ribbon-cable types of assemblies, in short lengths (4 to 6 inches),
> > > > with versions having 2, 4, and 6 conductors, with connectors already
> > > > installed on both ends. I have looked long and hard and can only
> find
> > > > standard computer-type cables that are ready-made (i.e. either way
> too
> > > > many conductors, or way too long).
> > > >
> > > > Anybody?
> > > >
> > > > Regards,
> > > >
> > > > Tom Gootee
> > > >
> > > > http://www.fullnet.com/u/tomg
> > > >
> > > > -----------------------------
> > >
> > > look at MOLEX or AMP
> >
> > Gee... THANKS!!!
> >
> > I *HAVE* been looking at them, for quite some time. Too long of a
> > time.
> >
> > I realize that beggars can't be choosers. But I was hoping for
> > something just a LITTLE more-specific than THAT.
> >
> > But thanks for at least replying.
> >
> > Regards,
> >
> > Tom Gootee
> It really does depend massively on the 'nature' of your front panel. You
> are doing a balancing act between tooling cost on the front panel, and
> assembly costs, and the changeover point, will depend on the quantities
> involved, and the actual parts used on the front panel. As an example, I
> had a panel, which had a keypad, LCD, some seperate buttons, and a single
> pot. For genuinely 'mass' production, it was cheaper to get rid of the pot
> completely, change the main electronics to use a computer controlled pot,
> then have a flexible PCB made for the front panel, with direct connection
> to the LCD, and the key matrix all built onto one board, with a couple of
> new buttons to adjust the digital pot. The connection then became a matter
> of using a single strip connector, that goes directly to such flexible
> boards. Manufacturers like Molex, and AMP, provide most connector families
> you ae likely to need. You need to work out the best way of laying out the
> front panel, and the number of connections you need. Then the design you
> have chosen here, will 'set' the nature of the plugs you need. The reason
> for no specific replies, is that you have not presented enough data to
> make anything 'better' really possible...
>
> Best Wishes

Roger,

Thanks for responding!

I am planning to probably just have a ribbon cable or multi-wire
socket or header on each pcb, to connect them each to the front
panel's new pcb (i.e. to another socket or header, there), and then
route traces from the sockets or headers to the appropriate control
and i/o connectors.

In this case, while it MAY eventually be truly mass-produced by
another company, right now it will be produced in relatively small
quantities (just in the hundreds per year, probably). BUT, it will
ALSO still be made available as a KIT version. So I "have" to try to
keep it simple and easy to construct, especially since one of the kit
options that I would LIKE to continue to offer (but don't care too
much if I can't) is an even-lower-cost version of the kit that
includes do-it-yourself PCBs (i.e. blank boards, iron-on patterns,
etchant, etc).

So, in this case, I will be using a plain single-sided standard PCB,
which will be almost the size of the front panel, and will be parallel
to and just behind the panel. The front-panel controls include only
rotary switches, pots, mini-toggle switches, and an LED, all of which
also come in versions with PCB-pin connectors instead of solder lugs.

On the front panel, there are two 2P6T rotary switches, a 1P12T
rotary, two 4P3T rotaries, 2 pots, and 6 SPDT toggle switches, plus an
LED, and i/o connectors, including 5 BNC, three banana jacks, and an
8-pin transistor socket. But there are three different PCBs that
everything connects to (only certain things connect to each pcb). I
also want to use plug and socket connectors for the power and ground
distribution, from the power supply board to the two other boards, and
to power-supply outputs (banana), on the rear panel.

I am planning to probably just have ribbon cable or multi-wire
socket(s) or header(s) on each pcb, to connect them each to the front
panel's new pcb's sockets or headers, and then route traces to the
appropriate control or i/o connectors.

It looks like the Molex KK line, or something similar, might work
well, for this, using a separate wire for each pin. But their
flex-cable (ribbon-like) jumpers, or something like them, look
attractive, too, if appropriate connectors are installed on both ends.

BUT, what I had **HOPED** to find available was ribbon-cable-type, or
similar but multi-discrete-wire-type, **ASSEMBLIES**, that already had
the connectors installed on both ends. I guess that that was too much
to hope for.

One other option that I can think of is card-edge ribbon-cable
connections, since it would be pretty easy for me to put in traces to
match them, and cut slots for the connectors to fit into the edges of
all of the boards. But, again, the fewer steps that are involved in
the production process, the better. However, if I could find
pre-assembled card-edge-connector ribbon cables with a reasonable
number of conductors and enough current-carrying capacity, that might
not be a bad way to go.

Tom

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