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Date: Wed, 11 Oct 2006 20:40:56 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: solder vs. crimp; was: Re: Latest EC2 updates,
 Installation n...
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WRJJRS@aol.com wrote:

> In a message dated 10/10/2006 7:41:10 PM Pacific Standard Time, 
> ceengland@bellsouth.net writes:
>
>
>     I must respectfully offer a somewhat modified view.
>
>     In general, crimped connectors are only reliable if done with very
>     high
>     quality crimpers, costing many 10's to hundreds of dollars. In a
>     production environment, big bucks for a crimper means any klutz
>     who can
>     squeeze can be very productive.
>
>     Soldered joints are prone to corrosion only if corrosive flux is
>     used.
>     Improperly crimped pins can have corrosion within the joint, just
>     like a
>     riveted or bolted structural joint. Crystallizing is a product of
>     improper technique, not the soldering process itself. Breakage from
>     vibration is an issue with either technique; the stress riser on a
>     crimped joint is much sharper than a soldered joint. Proper
>     support just
>     outside the joint is the remedy, whichever process is chosen.
>
>     Milled pins are certainly better than the rolled sheet metal pins,
>     but
>     with proper technique, they can be soldered with relatively
>     inexpensive
>     equipment.
>
>     FWIW,
>
>     Charlie
>
> Charlie
> This is one of those where people must agree to disagree. Get the 
> proper crimpers, you need only buy them once. Far to many failures 
> occur due to incidentals and ancillary systems. The milled pins or 
> even the better rolled pins work with the crimper to form the best 
> possible connection. The conductor is crimped in the pin and the 
> insulator is captured by the "tails" of the pin forming a sort of 
> strain relief. This isn't possible with the soldered pins 
> regardless of how good your technique is. Even a perfect solder joint 
> is more likely to break. We need solder joints on circuit boards but 
> crimps are better for everything else. The US Navy now uses crimp 
> connectors on everything. They can "afford" it of course at our 
> expense. If you live in Florida or California's coastal area corrosion 
> could be a factor. Any coastal area for that matter.
> Bill Jepson

Having spent a lot of years repairing crimped connectors (built in a 
production environment in high dollar commercial products) with 
corrosion or stress riser broken wires, I can say with confidence that 
crimped connectors aren't immune to the problems attributed to soldered 
connections. I've repaired my share of 'cold' solder joints, too.

I'm just saying that neither is inherently superior to the other & 
neither is inherently more prone to failure from stress risers. The 
built-in strain relief in crimp connectors exists only in some specific 
brands & models of connectors. Without high quality connectors, tooling 
& training, crimped connections are failure prone due to both corrosion 
& stress risers.

Just a cautionary note that crimp isn't automatically 'quality'.

Charlie