12焊接

CCAR-66部基本技能培训教材

Soldering（焊接） 编号：02-MULT-12

1. Introduction……………………………………………………………1 2. Procedure………………………………………………………………1

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CCAR-66部基本技能培训教材

1. Introduction

The data in this subject comes from SOPM 20-12-01.For soldering of surface mounted devices refer to SOPM 20-11-07. 1.1 Materials & tools 1) Solder alloys per QQ-S-571

(1) Tin/lead wire form with rosin flux -- SN60WRP2 or 3, SN63WRP2 or 3 (2) Tin/lead wire form with mildly activated flux -- SN60WRMAP2or 3, SN63WRMAP2 or 3

(3) Tin/silver wire form with mildly activated flux -- SN96WRMAP2 or 3

2) Flux, Rosin Base

(1) Non activated -- MIL-F-14256, Type R, Kester 135, V14597

(2) Mildly activated -- MIL-F-14256, Type RMA, Kester 197, Vl4597, or Almit RF-35-RMA

3) Soldering iron

2. Procedure:

2.1 Preparation

1) Soldering iron:

 For soldering iron, keep the soldering tip tight in the heating element. Keep the tip

clean and coated with a continuous layer of solder. A small amount of solder can be applied to the tip as necessary.

 Soldering Iron Temperature Control - Usually, if the soldering iron is operated at

the specified voltage, temperature control is not necessary. But if the iron is kept on at full heat a long time and not kept clean, oxides could occur on the tip and cause

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CCAR-66部基本技能培训教材

contamination and corrosion. This problem could be decreased if the temperature is decreased while the iron is not used, but you must make sure the is back at full heat before you start to solder.

2) Conductors or terminals

 Remove a sufficient length of insulation from the wire to permit an inspection gap

between the end of the insulation and the end of the solder on the bare conductor after the connection is soldered. As a minimum, the insulation must not be included in the solder. As a maximum, the gap must be the larger of 0.060 inch or 2 wire diameters (insulation included), but not that long that a short circuit with adjacent conductors could occur.

 Some scraped wire strands are permitted if there is no bare metal. Bare metal is

permitted on the cut ends of the wires. Broken strands are permitted, within the limits specified in BAC5044, unless the wire will be used at 6,000 volts or more.

 The insulation must not be burnt, frayed, split, punctured or crushed, when examined

visually without magnification.

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 Clean the wires, part leads and terminals (but not flatpacks) as necessary, to be sure

the solder will make a good bond. Remove oxides, tarnish, and other contamination with rubber erasers, fiberglass rods, tinned copper shield braid, or abrasive material. Hold the part leads tightly between the body and the surface to be cleaned. Be careful not to bend or put stress on the joint between the wire and the body of the part. Then clean the surfaces with isopropyl alcohol.

 When you attach part leads to lugs or terminals or parts bonded to a circuit board,

make a stress-relief bend in each lead. Only one of the two leads must be bent if the part will not be bonded, or not to be given a conformal coating. Hold the lead between the part body and the bend to prevent stress in the wire joint the body. Start the bend no nearer than 0.03-inch from the part body.

2.2 Soldering 2.2.1 General

 Bend, install, or hold conductors and part leads to not let them move while the hot

solder cools and becomes solid.

 If the component is identified as heat-sensitive, be sure to install a heat shunt between

the body of the part and the location to be touched by the soldering iron tip (Fig. 1). Heat shunts can also be used to give protection to insulation when you solder stranded conductors.

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CCAR-66部基本技能培训教材

 Apply the soldering iron tip to the connection area to supply a maximum of heat to

the metal surfaces to be soldered. But also make sure you give maximum protection to the parts that could be damaged by the heat.

 Wait until the metal surfaces get to the melting temperature of the solder. Then apply

solder to the metal surfaces and let it flow into the joint. If possible, do not let the solder wire touch the soldering iron tip.

 On printed circuit boards, keep to a minimum the time and pressure of the soldering

iron to prevent damage to the boards, adjacent components, insulation and parts. Do not apply the iron longer than 3 seconds.

 If a soldered joint must be heated again, let it cool approximately 30 seconds before

you apply the heat again.

 CAUTION: DO NOT VAPOR DEGREASE, PUT INTO SOLVENT, OR CLEAN

WITH WATER UNSEALED COMPONENTS, ENCAPSULATED OR POTTED ASSEMBLIES OR UNSEALED ELECTROLYTIC CAPACITORS.

Clean off the flux from the soldered areas and adjacent areas. For rosin flux (Type R) use isopropyl alcohol (BAC5225 Type 1, Class 1, 2, or 6). For activated flux (Type RMA), use isopropyl alcohol (BAC5225 Type 1, Class 1, 2, or 6) and then the Axarel 32/ECD batch washing system (BAC5225 Type 4, Class 1). Start to clean the areas within 1 hour, and complete the cleaning in 8 hours, after the solder is cool and solid.

2.2.2. Hand Tinning Procedure

(1) You can use a soldering iron or resistance soldering electrodes to apply heat. (2) Heat shunts are necessary on all but connectors, wire, terminals, pins or contacts. Keep the jaw faces of the shunts clean of contamination and corrosion. Do not set the iron temperature higher then 700F.

(3) Heat the area to be tinned. Then apply flux-cored solder to make a smooth, continuous shiny surface. Do not let the iron stay on the surface more than a total of 5 seconds during the operation.

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(4) If necessary, you can do step (3) again, but not more than two more times. (5) Remove flux residues per par. 4.A. above.

2.2.3. Soldering to Terminals and Lugs

(1) Refer to SOPM 20-11-01 for instructions about how to bend and install the wires and component leads.

(2) Wrap the wires around the terminals a minimum of 180-degrees unless these are forked terminals or one wire goes through a series of terminals. Do not overlap wraps or wires.

(3) One continuous wire can be used to connect a series of connectors. At the first and last terminal, attach the wire to the terminal as if this was the only terminal. For the terminals in between, send the wire straight through, and make sure you solder the wire to a minimum of two surfaces of each of these terminals.

(4) For stress relief, make a bend in the leads of parts attached to or between terminals, as shown in SOPM 20-11 -01. When you make the bend, be sure to hold the lead at a point between the part body and the location of the bend.

(5) If the distance between two terminals is 0.75-inch or less, you can use solid wire of the same size, as an alternative to stranded wire, but only if the specified wire size is 22-gage or thinner ,

(6) If the terminal or connection will have more than one conductor attached, it is best to solder all of the conductors at the same time.

2.2.4 Soldering to Solder Cups (Fig. 2)

- NOTE: Resistance heating is preferred, but you can use a soldering iron with or without resistance heating equipment.

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Use the soldering iron, to apply heat to the outside of the solder cup.

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CCAR-66部基本技能培训教材

 When the cup becomes as hot as the melting point of the solder, melt a sufficient

quantity of flux-cored solder in the cup to make a satisfactory fillet after the wires are installed, within the limits shown.

 Strip and cut the wire to let it fit into the cup to the bottom, as shown. Install the wire

as shown. Make sure the melted solder fills the inspection hole, wets the complete circumference of the bottom of the cup interior, and does not overflow the hole. A thin layer on the outside surface of the cup is permitted.  Remove the soldering iron.

 Remove flux as necessary per par, 4.A.

2.2.5 IN-PROCESS CORRECTION

A. Solder joints can be touched up or soldered again as necessary. This includes such conditions as too much solder, not sufficient solder, peaks, points (icicles), bridges, spatter, pits, scars, holes and voids.

B. Solder connections can be touched up again and again if the results agree with the quality controls of BAC5242. But keep to a minimum the number of times you do this to joints on circuit boards, to prevent damage.

C. Heat the soldered area and correct the problem as quickly as possible after the solder melts.Add more solder or flux as necessary.

D. Unwanted solder can be soaked up with wicking material or a tool that melts the solder and removes it with vacuum.

E. To use wicking material, use shield braid from coaxial cable, a vendor product such as Soder Wick (V34605) or a stranded wire with the insulation removed.

 Apply liquid flux to the shield braid or the stranded conductor. Soder Wick comes

with flux in it.

 Put the wicking material or stranded conductor on the soldered connection and apply

the hot tip of a soldering iron on top.

 Let the heated wick soak up the solder as necessary. Then remove the wick and the

iron from the joint.

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CCAR-66部基本技能培训教材

F. To use a vacuum solder removal tool, apply the heat source to the area, operate the tool to remove the solder as necessary, then remove the tool and the heat source.

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