TIP OR APEX
Kinds of Terminal Configurations that Can Be Wrapped.
MAX. ‘~..AP?A.BLE	MN. WRAPPABLE
TERMINAL LENGTH	TERMINAL LENflTfl
	(3 LEVELS)	(3 LEVELS,
24
WIRE
GAUGE

‘?S<oa” j 30 ga.

Preferred Materials for Terminals.
Common materials used are beryllium copper, phosphor bronze, half-hard brass, copper-nickel, and nickel-silver alloys. Usually the configuration of the end opposite the wrap portion of the terminal dictates the type of material required. As an example, terminals that have a direct entry, such as the ‘‘tuning fork” concept, are usually phosphor bronze due to the spring requirement of the ‘‘tuning fork” portion of the terminal.

Plating Unnecessary.
There is no evidence that indicates that the connection is better as a result of tinning or plating of either the wire or terminal with the exception that certain combinations of plating materials have increased the rate of solid state diffusion of metals which is part of the solderless wrapping process.

Finishes Commonly Applied to Terminals.
Commonly used finishes are gold (TYPE I per Mil-G-45204), tin, tin-lead alloys and nickel. Gold plating is used for increased contact reliability where the opposite end of the terminal is a plug-in type contact.

Certain finishes, particularly hard gold plate, tend to lower the strip force (force required to move the connection on the terminal) of the connection. Special care should be used when using gold finish on one piece design terminals. Usually this type of terminal is heat treated to give it the necessary spring characteristic at the contact end. This, of course, also hardens the portion of the terminal that will be wrapped. The use of gold on this type terminal sometimes makes it difficult to meet even the minimum strip force requirements.

Length of Terminals for Wire Wrapping.
It is advisable to specify a terminal that has an adequate “wrappable terminal length” to allow for three connections even though the circuitry is designed to have no more than two connections per terminal. This permits the addition of wires on the third position (Z level 3) of the terminal in the event of engineering changes or field modification. The following table gives the recommended wrappable terminal lengths for three connections per terminal:
Defining the Term “Wrappable Terminal Length.”
“Wrappable Terminal Length” is the portion of the terminal which is suitable for making connections. In other words, the wrap cannot extend on the tip or apex of the terminal or the base of the terminal which does not meet the terminal requirements. See examples below:
2.	A rectangular cross section, pattern results in the possibili wrapped to project beyond if This condition is referred to likely to occur with the circu square cross-section. See ex~
-tERMINAL
BASE
Defining the Term “Z Level.”
The term “Z Level’’ refers to the position of the connection on the terminal with respect to the surface of the panel. The Z- I Level is the connections closest to the surface of the panel. Z-2 is directly above the Z-l position and Z-3 is directly above the Z-2 position. Reference to following illustration:
Any terminal which has two or more contacting edges crosswise to the axis of the wrapped wire is satisfactory for a wrap. Types of terminals in everyday use include square, rectangular, embossed, serrated, V-type, U-type, diamond and split terminals. Examples of these configurations are as follows:

m
0	m

Ph
		if
SQUARE	RECTANGULAR	SPLII
TERMINAL	TERMINAL	TERMINAL
01 AM 0 N C TERMINAL
	II
TERMINAL	TERMINAL
Preferred Terminal Configurations.
3.	A square cross-section has a modulus in all directions. Th positioning the terminal relati also tends to make the termu wrapping operation.

4.	The square terminal has far I it’s axis than does the rectan:

5.	The square terminal lends its tip for lead-in to the wrappin

6.	The strip force values obtaini usually more consistent than rectangular terminals or simi]

“Rule of Thumb” for Deternv
Terminals must be of sufficient torsion of wrapping the wire. N thickness should not be less thai the terminal width should not bt terminal thickness. The list belo used squaw and rectangular tern

SQUARE TERMINALS
.045	Sq.
.025	Sq. (.0340 ± .0015
RECTANGULAR TERMINi
.035	x .050
.031	x .062
.023	x .050
.020	x .030 (.0340 .001
It should also be kept in mind th~ size that is unique to the industr wrapping bits for the wrapping. time items which may affect yoi

Other Requirements that a Te
There are requirements for term:
tip configurations, terminal retei replaceability.

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the position of the connection o the surface of the panel. The closest to the surface of the he Z- I position and Z-3 is
n.	Reference to following

Z 3 —

ations that Can Be Wrapped.
w more contacting edges
apped wire is satisfactory for a veryday use include square, ~d, V-type, U-type, diamond of these configurations are as
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TER~~lNAL
3.	A square cross-section has a more uniform section modulus in all directions. This is useful in initially positioning the terminal relative to its “true position” and also tends to make the terminal more rigid during the wrapping operation.

4.	The square terminal has far less tendency to twist about it’s axis than does the rectangular cross-section.

5.	The square terminal lends itself to a symmetrically pointed tip for lead-in to the wrapping bits.

6.	The strip force values obtained on square terminals is usually more consistent than those obtained from rectangular terminals or similar cross-section.

“Rule of Thumb” for Determining the Terminal Size.
Termin&s must be of sufficient strength to withstand the torsion of wrapping the wire. As a generM rule, the terminal thickness should not be less than one conductor diameter and the terminal width should not be more than double the terminal thickness. The list below gives the most commordy used square and rectangular terminal sizes:

SQUARE TERMINALS
.045	Sq.
.025	Sq. (.0340 ± .0015 diagonal)

RECTANGULAR TERMINALS
.035	x .050
.031	x .062
023 x .050
.020	x .030 (.0340 .0015 diagonal)

It should also be kept in mind that the selection of a terminal size that is unique to the industry may require special wrapping bits for the wrapping. Special bits are long lead time items which may affect your production schedule.
p

TEflMINAL
rations.
Ldvantages over other types. rot always significant when Lions with hand tools, they with the use of semi-automatic ines. Some of these advantages

on of a wire on a square ttem. A rectangular ticularly one with a large suIts in an elliptical wrap with
Other Requirements that a Terminal Should Meet.
There are requirements for terminal corners, terminal edges, tip configurations, terminal retention and terminal replaceability.

Terminzd Corners
The corner radii of the terminal should not exceed .003”.
Maximum edge burrs should not exceed .002’’.

Terminal Edges
The TenninM Edges must be parallel within .005” per inch
A taper or lead-in should be provided on the terminal tip. The purpose of this taper is to assist in getting the terminal into the terminal hole of the wrapping bit. The maximum tip flat for terminals used in machine wrapping 26 gauge and larger wire is .015” x .015’’. For 30 gauge machine wrapping, the tip flat must not exceed .010’’ x .010’’.

Common tip configurations are shown below:
PYRAMID
~/“

CONICAL
RADIUS	SEMI-RADIUS
Terminal Retention
When the wire wrapping operation is performed by an
automatic wrapping machine, it is essential that the terminals meet minimum retention force. The wrapping tools are placed over the pins automatically and if a pin is not straight (within the location tolerances for automatic wrapping), the force of the tool coming down on the pin (even though it’s minimal) may unseat it. The following rules apply to all automatic
machine wrapped terminals:

Terminals for 26 ga. wrapping and larger should be capabk of withstanding an axial force of 15 pounds. Terminals for 30 ga. wrapping should be capable of withstanding an axial force of 7 pounds.

Terminal Replacement
Occasionally a terminal may be broken off prior to or during the wrapping process, during a wiring change, during systems test or field repair modifications- Therefore, it is advisable to select a tenninal that is individually replaceable. This eliminates the need to replace an entire connector which could have as many as a hundred wires on it which would have to be removed and replaced making the replacement a costly and time consuming operation.