Haywires are used to facilitate minor circuit modifications to printed
wiring assemblies (PWA), rather than redesign and manufacture a new board.
While their use is an accepted industry practice, the customer must grant
approval prior to their use and installation. A good technician can make a
modification look like it was planned to be an original part of the board
design, a sloppy tech can make the mod look like a completely disorganized
mess (haywired).
Haywires are usually solid, insulated copper conductor with tin/lead plating
(i.e.: wire wrap wire), although wires less than 25mm (0.984 in.) may be
uninsulated, provided the wire is not liable to short between lands or
component leads.
The cross-sectional diameter of the haywire should not exceed 66% of the
original trace width. For critical applications (military / spaceflight) the
wire should be TFE-insulated (Type EE / E), solid or stranded, silver-plated
copper. For common commercial applications, the wire used is typically
Kynar-insulated, solid, silver-plated copper (wirewrap wire). Insulation
color seems to be more of an aesthetic choice, with green, black, and blue
common colors if the engineer wants to camouflage the modification, and
white, red, and orange for easy identification and verification by quality
assurance (QA).
"Jumpers" are short lengths of uninsulated wire used in place of a switch or
shorting post to hardwire a circuit routing selection on a board. Jumpers
allow the engineer to design a single circuit board capable of multiple
uses. They are designed into the board during layout, and are considered to
be components / parts.
Really demanding applications rely on use of zero-ohm resistors as jumpers
rather than discrete wires, and pick-and-place systems will almost
exclusively require zero-ohms or specially designed "formed wires".
Bob
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Friday, July 09, 2004 3:50 AM
To: [log in to unmask]
Subject: Re: [TN] Haywire vs. jumper wries
As it's Friday, let's look at what haywire means according to the
Shorter Oxford Dictionary:
haywire, noun & adjective.
E20.
[from HAY noun1 + WIRE noun.]
A. noun. Wire for binding bales of hay, straw, etc. E20.
B. adjective.
1. Poorly or roughly contrived (with ref. to the practice of using
wire for baling hay to effect makeshift repairs). E20.
Quote from the Listener: A haywire, unpredictable, one-man business.
2. Of a person: in an emotional state, distracted, crazy. Of
circumstances: tangled, in disorder, confused. colloq. (orig. US). M20.
go haywire go wrong, become confused or crazy.
Quotes from J. O'Hara: A married man..and absolutely haywire on the
subject of another woman. E. C. R. Lorac: The time element's all
haywire.
:-D
Brian
Marita Zavala wrote:
> Hello,
>
> Can anyone provide a comprehensible or can differentiate
> haywire vs. jumper wire?
>
> IPC 610C states: Haywire is used to modify the basic
> conductor pattern and jumper wire is part of the original
> design
> And is used to bridge portions of the basic conductor
> pattern. Thank you.
>
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