Table 7-2. Insulation Clearance for Solder Joints

TM 750-245-4

Table 7-2. Insulation Clearance for Solder Joints

Wire

Insulation

Clearance

diameter

Minimum

maximum

32 to 24

1/32

3 x OD

22 to 12

1/32

2 x OD

10 or larger

1/32

1 x OD

degrees or more than 360 degrees. Where three or

(4) Feed-through terminals. The terminating

more terminals in a row require a continuous jumper, a

end of a wire inserted through a feed-through terminal

solid bus may be wrapped 360 degrees, and continued

shall be hooked over the lip of the terminal not less than

from terminal to terminal. The first wire on each

one-sixteenth inch. Not less than one-sixteenth inch of

terminal shall be placed parallel to the header nearest

the connection hook shall be soldered tangent to the

the terminal mounting surface. Each additional wire

terminal.

shall be placed next thereto, continuing outward from

(5) Printed circuit terminating. Components

the terminal mounting surface.

Maximum spacing

shall be installed opposite to the side to be soldered.

between wires and between wire and header is

Leads shall be bent flat to the pad and along the

recommended. There shall be no overlapping of wires.

conductor surface.

Components having pin type

Wrap may be clockwise or counter-clockwise; however,

connections shall be mounted with pins extending

on multiple connections all wraps must be in the same

straight through the printed circuit board.

When

direction, unless required by design limitations. When

component lead wire diameter, length, or composition

soldering the second joint on double ended terminals,

prevent bending, or when specified in Department of the

precaution shall be taken to prevent remelt and fracture

Army publications, the lead shall be treated as a pin

of the first joint.

type. "Double sided printed circuit boards employing

(2) Slotted or bifurcated terminals. Order of

eyelets for the interfacial circuit connections shall have

preferred terminations:

the eyelets soldered to the pad on both sides of the

(a) Side route connection. The wire

board as well as the usual mechanical bradding. Double

sided printed circuit boards employing plated through

shall enter the mounting slot at a right angle and be

holes for interfacial circuit connections shall have a

terminated with a 90-120 degree bend. A bend of 180

continuous plug of solder through the hole. The hole

degrees is permitted when design requires mechanical

pads on both sides of the board shall be completely

holding prior to soldering. In no instance shall the

wetted by the solder 360 degrees around the periphery

conductor extend beyond the outside diameter of the

of the hole."

terminal, except for the point of entry. The direction of

the 90-degree bend on each additional wire shall

alternate.

Maximum space between wires is

7-11. Rejection Criteria

recommended.

Evidence of any defects, including, but not limited to the

(b) Bottom route connection. The wire

following, shall be cause for rejection:

shall terminate with a 90-degree bend.

a. Charring, burning, or other damage to

(c) Top route connection. The wire

insulation.

shall extend the full length of the terminal forks. When

b. Splattering of fluz or solder on adjacent

the ratio of slot size to wire size is greater than 1: 1, the

connections or components.

wire should be accompanied by a tinned filler wire

c. Solder points (peaks).

during the soldering operation to help hold the wire in

d. Pits, scars, or holes.

position, or the wire can be doubled back. A large wire

which fills the slot will require only solder fillets for

e. Excessive solder which obscures the connection

retention. Multiple top route connections shall not be

configuration.

used unless specified in Department of the Army

f. Excessive wicking.

publications.

g. Loose leads or wires.

(3) Hook or perforated terminals. The wire

h. Cold solder connections.

shall be attached to the hook or perforated terminal by

i. Rosin solder connection.

forming the tinned wire to at least 90-degrees angle.

j. Fractured solder connection.

Perforated terminals to which wire sizes ACG 16 or

larger are to be attached may be connected straight

k. Cut, nicked, stretched, scraped leads, or wires.

through.

l. Unclean connection (e.g., lint, residue, flux,

solder, splash, dirt, etc.).

7-8