MCG Employee Solder Training Course. Session I Agenda Coarse Objectives Terms and Definitions Soldering Tools and Materials Lead Preparation Soldering

MCG Employee

Solder Training Course点焊培训课程

Session I Agenda

Coarse Objectives主要目的Terms and Definitions学习和定义Soldering Tools and Materials点焊工具和材料Lead Preparation准备Soldering Methods点焊方法Soldering Connections点焊连接Soldering Defects点焊缺陷Quiz测试

Session I Agenda

Coarse ObjectivesTerms and DefinitionsSoldering Tools and MaterialsLead PreparationSoldering MethodsSoldering ConnectionsSoldering DefectsQuiz

Course Objectives课程目标

•Allow operators to identify unacceptable workmanship at the point it occurs.

•允许作业员问题发生时能识别好坏•To improve the operator’s soldering knowledge and proficiency.

•提高作业远点焊技术和熟练程度

Session I Agenda


Three Classes of Assemblies3个等级生产

• Class 1: General electronic products• 级别 1：普通电子产品• Class 2: Dedicated service electronic products• 级别 2：专业电子产品• Class 3: High performance electronic products• 级别 3：高性能的电子产品

• Customer determines class to which assembly is evaluated.

•客户决定装配等级要求

Class 1General Electronic Products

级别 1普通电子产品

• Includes products suitable for applications where the major requirement is function of the completed assembly.

• 包括适合应用

Class 2Dedicated ServiceElectronics Parts级别 2 专业电子产品

• Includes products where continued performance and extended life are required, and for which uninterrupted service is desired, but not critical. Typically the end-use environment would not cause failures.

• 包括持续性能和寿命要求，

Class 3High Performance

Electronics Products级别 3 高性能电子产品

• Includes products where continued high performance or performance-on-demand is critical, equipment downtime cannot be tolerated, end-use environment may be uncommonly harsh, and the equipment must function when required, such as life support or other critical systems.

What Class Does MCG Use?MCG使用等级

• Typically MCG uses Classes 2 and 3.• Based on IPC-A-610 Acceptability of Electronic

Assemblies.• The customer ultimately determines the class to which

the assembly is evaluated.• MCG主要运用 2 和 3等级• 基于 IPC-A-610电子装配• 客户最终决定产品等级

Terms To Know学习须知

• Solder Source点焊课程• Solder Destination点焊目标

• Primary Side主要边• Secondary Side次要边• Through Hole通孔• Target Condition目标条件• Acceptable Condition接受条件

• Defect Condition缺陷条件

• Solder Pad焊点• Heat Bridge电桥• Wetting湿• Solder Fillet焊带• Cold Solder 冷

焊 Connection

Session I Agenda


Solder Irons烙铁

• Fixed Temperature• Temperature

Controlled我们使用的两种类型：• 恒温电烙铁• 温控电烙铁

Two types we use:

Soldering点焊

• The tip determines how much heat will be transferred to the solder joint.

• There are many different types of tips for different applications.

• 铁芯决定热量从烙铁到焊接部位的传递

• 不同运用情况下的各种类型铁芯

The Soldering Iron Tip电烙铁铁芯

• A properly “Tinned” tip provides rapid heat transfer.

The Conical Tip锥形铁芯

• Used for small pads with a small amount of solder.

• Directs the heat into a small area.

• Minimal contact = minimal heat transfer.

• 适用于小的键合点和少量的焊料

• 直接加热至小的地方• 小的接触 =小的热量传递

The Chisel Tip凿形铁芯

• Evenly distributes the heat between the pad and the lead.

• Used to solder multilayer boards which require a faster transfer of heat to a large surface area.

• Larger contact = larger heat transfer.

Changing Soldering Tips换铁芯

• Tips may be replaced for different applications.

• Tips should be kept clean and tinned at all times.

• 铁芯更换的不同运用• 铁芯必须清洁，表面要镀锡

Solder Wire焊锡丝• Different diameters of solder.• There are different ratios of

Tin, and Lead, compounds.• MCG recently began using

Lead-Free solder to comply with RoHS.

• There are different types of flux cores for different applications.

• 不同直径的焊料• 不同比率的锡，和复合成分• MCG最近开始使用符合

ROHS的无铅焊料• 不同运用条件下的不同焊料

Solder Alloys合金焊料

• Solder may include metals such as tin, silver, copper, bismuth, indium, zinc & lead.

• The ratio of each element determines melting point.• The solder should have a lower melting point than the

metals that are being joined.• 焊料材料包括：锡，银，铜，铋，铟，锌和主成• 不同元素的比例决定熔点• 焊料应该有个低的熔点，材料才能被连接

Solder at MCGMCG焊料

• To comply with RoHS directives, MCG now uses lead free solder containing 96.5% tin (Sn), 3% silver (Ag), and .5% copper (Cu).

• 为了符合 ROHS标准，MCG目前用无铅焊料包括 96.5%的锡， 3%的银和 5%的铜

Percentage of eachelement in the alloy元素比例

Different Solder Diameters不同焊料直径

• Common sizes are .5, 1.0, and 1.5MM.• The size of the solder used depends on the application.• At MCG we range from .40mm (.015”) to 1.50mm (.062”).• 一般尺寸在 .5, 1.0, 和 1.5MM• 焊料尺寸决定其应用• MCG的

Solder wire diameter焊料直径

or .020in

or .040in

or .062in

Standard Wire Diameters

Solder Melting Points• MCG’s lead free solder has a

melting point of 219°C (426°F), which is 36°C (nearly 100°F) higher than the former solder used.

MCG无铅焊料的熔点是219°C (426°F), 比普通焊料高 36°C (几乎 100°F)

• Plastic stage is important because this is the range that solder joint should not be disturbed while solidifying.

• 塑性很重要因为这是焊接过程中不容易被破坏。

Solder Fluxes助焊剂

• Most hand soldering type solders contain flux in the solder core.

• 多数的手工焊料都含有助焊剂。• May also be a liquid that is applied to

the connection before soldering.

• Used to reduce the oxides on the metals before the joints are soldered.

• Also aids in forming the “heat bridge”.• May leave behind residue that should

be cleaned away.

Classification of Solder Fluxes

• L= Low or no flux/flux residue activity• M = Moderate flux/flux residue activity• H = High flux/flux residue activity

• R = Rosin flux• RMA = Rosin Mildly Active• RA = Rosin Active

Fluxes may be classified as one of the following:

Traditionally classified rosin based fluxes:

The “No Clean” Fluxes

• “No Clean” flux is actually a low residue flux.

• May, or may not, need to be cleaned away after use.

• Leaves behind very little residue.

Type R Flux

• Pure water/white pine rosin flux.

• Mild and non-corrosive.

• Designated by the letter “R”.

RMA Type Fluxes

• “RMA” – Mildly Active Flux

• Has more cleaning power than “R” type flux

• The more active the flux, the more corrosive it will be.

RA Type Fluxes

• “RA” – Rosin Active Flux

• Very high cleaning power.

• Residue is easily visible and corrosive.

• Must be cleaned away after soldering.

Types of Fluxes at MCG

• We currently use RA1544, RMA 197 and 961 no-clean flux.

• Consider 959T (RoHS ready) in place of the 961.

• RMA186 (RoHS ready) flux would be an option of we need something more active (replace RMA197).

• RMA197 flux is currently used for Defense-Aerospace applications.

• The flux-core solder we use contains the 275 no-clean flux.

Flux-Core Sizes

#58 core with 275no-clean flux core.

MCG Recommended FluxesNo-Clean Flux Rosin Based Liquid Fluxes

Session I Agenda


Lead Prep – Tinning• The wire should be “tinned”

before soldering it to the terminal

• Tin the wire using a soldering iron & solder.

• An alternate and sometimes preferred method would be to use an RA flux and dip in a solder pot.

Lead Prep – Tinning (cont)

• Stranded wire is uniformly coated with a thin coat of solder with the individual strands of the wire easily visible.

• Un-tinned length of strands from end of insulation is not greater than one wire diameter.

• The solder wets the tinned portion of the wire and penetrates to the inner strands of stranded wire.

Tinning


• Some solder wicking as long as the solder does not extend to a portion of the wire that is required to remain flexible.

• Strands are not discernible but excess solder does not affect form, fit or function.

• Solder does not penetrate to the inner strands of the wire.

Acceptable


• Pinholes, voids or nonwetting exceeds 5% of the area required to be tinned.

• Length of untinned strands from end of insulation is greater than one wire diameter.

• Solder does not wet the tinned portion of the wire.• Stranded wire is not tinned prior to attachment to terminals or forming

splices.

Acceptable – Class 1Process Indicator – Class 2Defect – Class 3

Defect – Class 2, 3


• Solder wicking extends into the portion of wire that is required to remain flexible after soldering.

• Solder build-up or icicles within tinned wire area that affect subsequent assembly steps.

Defect – Class 1, 2, 3

Bending the Wire

• Use round nose pliers that do not have serrated jaws.

• Bend the wire to the proper radius.

Wire Preparation for a Solder Cup

• Wire runs the entire depth of the solder cup.• No wire strands misplaced.

Solder Cups (cont)

• Solder cups should have the wire(s) inserted straight in and contact the back wall for the full depth of the cup.

Solder Cups (cont)

• Here multiple wires are inserted the full depth of the cup.

• Each wire must contact the back of the solder cup.

Splicing Connections

• Butt joint lengths should be at least three time their width.

• Wires should be tinned prior to splicing.

• Add flux to connection prior to fusing.

• Do not disturb wire position while joint is solidifying.

• A preferred method is to form a good mechanical connection prior to soldering.

Magnet Wire Connection

• Wire is stripped per the specified process.

• Wrap the magnet wire around the tinned lead wire a minimum of three full revolutions.

Insulation Damage

• Insulation has been trimmed neatly with no signs of pinching, pulling, fraying, discoloration, charring or burning.

• A slight uniform impression in the insulation from the gripping of mechanical strippers.

• Chemical solutions, paste, and creams used to strip solid wires do not cause degradation to the wire.

• Slight discoloration of insulation resulting from thermal processing is permissible, providing it is not charred, cracked or split.

Target – Class 1, 2, 3

Acceptable – Class 1, 2, 3

Insulation Damage

• Any cuts, breaks, cracks or splits in insulation (not shown).

• Insulation is melted into the wire strands (not shown).

• Insulation thickness is reduced by more than 20%.

• Uneven or ragged pieces of insulation greater than 50% of the insulation outside diameter or 1mm, whichever is more.

• Insulation is charred.


Session I Agenda


Solder Pad

• Provides a conductive area for the lead of a component.

• Specifications determine how close they can be to other pads or traces.

• May also be called a “land”.

Soldering Components• Soldering is performed on

the solder side of the board.• By working on the solder

side, the components are less likely to be damaged.

• The opposite side of the PCB is referred to as the component side.

Soldering

• A quality solder joint provides an electrical connection that is physically strong.

Soldering

• The solder heat bridge transfers heat rapidly from the tip to the connection.

• Molten solder forms a bridge or “avenue” to the connection to rapidly transfer heat.

The “Wetting” Process

• Metals are coated with “oxides” from the air and must be removed before the metals can be joined properly.

• The flux chemically reduces or removes these oxides to promote “wetting”.

• The solder flows after the flux and joins the two metals.

The Soldering Process

2)Form the solder heat bridge.

1)The tip is placed between the pad and the lead.

The Soldering Process (cont)

3)Solder is moved to the opposite side of the lead.

4)The fillet is formed.

The Soldering Process (cont)

6)Then the tip is removed.

5)Solder wire is removed first.

The Intermetallic Bond

• If the soldered joint has been properly wetted, an “intermetallic bond” is created.

• An “intermetallic bond” is the joining of two metals.

The Solder “Fillet”

• A properly wetted solder joint produces a “fillet”.

• The fillet should normally be concave, feathering out to a thin edge.

Soldering the Solder Cup

• Minimum insulation gap may contact the solder, but shall not be covered by solder.

• Do not move wire until solder has solidified.

• No solder splash or overflow onto the outside of the cup terminal.

Soldered Connections

• Use an RMA or RA flux depending on wetting results.

• Solder pot dip or hand solder connection.

Session I Agenda


Solder Wetting Angle

• Solder angle not to exceed 90°.

• Can vary with different types of solder.

Solder Wetting Examples

SnAgCu Solder

Solder Wetting Examples

SnPb, no clean solder

SnAgCu, no clean solder

Inspecting Solder Cups

• Solder wets the entire inside of the cup.• Solder fill is 100%.


Inspecting Solder Cups (cont)


• Thin film of solder on the outside of the cup.

• Solder fill 75% or more.

• Solder buildup on the outside of the cup, as long as it does not affect form, fit, or function.

Inspecting Solder Cups (cont)• Maximum insulation gap should be less than 2

times the wire diameter, or 1.5mm, whichever is larger. Target clearance is 1 wire diameter.

Example• A 30 Ga. teflon insulated wire has

a diameter over the insulation of .029”. This would abide by the 1.5mm (.059”) limit or less.

• A 16 Ga. teflon insulated wire has a diameter over the insulation of .075”. The 2x guideline would be used so the max allowable insulation clearance would be .150” or less.

Inspecting Solder Cups (cont)

• Solder vertical fill less than 75%.

• Solder buildup on outside of the cup negatively affects form, fit or function.


Insulation Clearance

• The insulation clearance (C) is two wire diameters or less including insulation or 1.5 mm [0.059 in] (whichever is greater).

• Insulation clearance (C) does not permit violation of minimum electrical clearance to adjacent conductors.

• The insulation is in contact with the solder but does not interfere with formation of an acceptable connection.


Through Hole Connections

• There is 100% fill.

• Minimum 75% fill. A maximum of 25% total depression, including both secondary and primary sides is permitted.



Vertical Fill – Supported Holes

Through Hole Connections

• The plated through hole (PTH) is connected to thermal or conductor planes that act as a thermal heat sinks.

• The component lead is discernable in the Side B solder connection.

• The solder fillet on Side B has wetted 360° of the PTH barrel wall and 360° of the lead.

Defect Class 3,Acceptable Class 2 if:

Session I Agenda


Common Rejectable Solder Joints

1. The Cold Solder Joint

2. Non-wetting

3. Overheated Solder Joint

4. Disturbed Joint

5. Blowhole

6. Solder Bridge

7. Solder Icicle

8. Lifted Pad

9. Miscellaneous

The Cold Solder Joint

• In the cold solder joint, the solder was melted by the iron, but did not bond to the parts to be soldered.

• The joint did not exhibit proper wetting.

• This is an unacceptable solder joint.

Non-Wetting

• A properly wetted solder joint produces a fillet.

• If the oxides are not reduced, a quality solder joint cannot be produced.

• Insufficient heat can also cause poor wetting.This is a rejected

solder joint.

Non-Wetting (cont)

• Lack of or poor solder wetting can cause defective solder connections.

The Overheated Solder Joint

• The overheated solder joint has a chalky, dull, or pitted finish.

• Caused by excessive dwell time (leaving the iron in contact too long), or excessive heating cycles.

• This is an Unacceptable Solder Joint.

The Disturbed Joint

• In the disturbed joint, the board or the part was moved while the solder was solidifying.


Disturbed Joint

The Disturbed Joint (cont)

• Disturbed solder joint characterized by stress lines from movement in the connection.

• Fractured or cracked solder.

Defects

The Blowhole

• In a blowhole defect, gas has escaped through the solder while hardening.

• This can be caused by moisture or solvent on the board.• This is an unacceptable solder joint.• Blow holes are acceptable if they do not reduce solder

connections below minimum requirements.

The Solder Bridge

• The solder bridge is caused by using too much solder on the connection.

• The solder has “bridged” or connected to another joint causing a short.

• This is and unacceptable solder joint.

Solder Bridge

Solder Bridge (cont)

• Solder bridging across non-common conductors.

• Solder splashes or webbing.

Defects

Soldering Anomalies (cont)

• Solder balls violate minimum electrical clearance.

• Solder balls can migrate because they are not entrapped in conformal coating.

The Solder Icicle or Projection

• The solder icicle is usually caused by improper removal of the iron or excessive “dwell time”.

• Also can be caused by insufficient flux.


Solder Icicle

Solder Projections (cont)

• Solder projections can violated assembly maximum height requirements, or minimum electrical clearance.

The Lifted Pad

• A lifted pad can be caused by applying too much pressure with the iron while heating.

• Too much heat was transferred to the pad.

• This is and unacceptable solder joint.Lifted Pad

Exposed Base Metal

• Exposed base metal on vertical conductor edges.

• Exposed metal on cut ends of component leads or wires.

Acceptable - Class 1, 2, 3

Birdcaging

Acceptable – Class 1Process Indicator – Class 2Defect – Class 3• Wire strands have separation

exceeding one strand diameter but do not extend beyond wire insulation outside diameter.

Defect – Class 2, 3• Wire strands are birdcaged

beyond wire insulation outside diameter.

Soldering Anomalies (cont)

Acceptable - Class 1, 2, 3For connections made with lead-free

alloys:• The bottom of the tear is visible.• The tear or shrink hole does not

contact the lead, land or barrel wall.

Defect – Class 1, 2, 3Shrink holes or hot tear in connections

made with SnPb solder alloys:• The bottom of the shrink hole or hot

tear is not visible.• The tear or shrink hole contacts the

lead or land.

Session I Agenda

Coarse ObjectivesTerms and DefinitionsSoldering Tools and MaterialsLead PreparationSoldering MethodsSoldering ConnectionsSoldering Defects

Quiz

Quiz Questions1. Which element was removed from solder alloys under RoHS?

a) Copperb) Mercuryc) Tind) Lead

2. Solder wire comes in several different diameters. (T or F)

3. Solder joints with a wetting angle greater than 90° are ok if removed with a side cutter. (T or F)

4. After the insulation is remove from lead wire, what should be done to the strands prior to further processing?

a) Check for obvious damage to the insulation caused by the stripping operation.b) Tin the lead wire using the specified process.c) Check for obvious damage to the wire strands caused by the stripping operation.d) All of the above.

5. A “heat bridge” is used to?a) Test the flux for melting point.b) Rapidly transfer heat to a connection during soldering.c) Prevent dangerous driving conditions in freezing weather.

Quiz Questions

6. When completing a solder joint which is removed first?a) The solder iron tipb) The solder wirec) The component lead

7. Which solder joint generally has a shiny finish?a) A solder joint soldered with solder containing lead.b) A solder joint that had heat applied too long.c) A solder joint solder with lead-free solder.

8. If a stray wire strand is outside a through hole or solder cup, this is:a) A defect because it may violate minimum electrical clearance.b) A defect because the connection integrity is compromised.c) OK, because that is what side cutters are for.d) a) and b) above.

9. Which flux is the least reactive and likely to leave less residue?a) Type “R”b) Type “RA”c) Type “RMA”

10. Which solder tip generally transfers heat faster, a conical or chisel tip?

Quiz Anxiety

How do you think it went?

Quiz Answers1. Which element was removed from solder alloys under RoHS?














True



2. Solder wire comes in several different diameters. (T or F) True





False




3. Solder joints with a wetting angle greater than 90° are ok if removed with a side cutter. (T or F) False







3. Solder joints with a wetting angle greater than 90° are ok if removed with a side cutter. (T or F) False




Quiz Answers6. When completing a solder joint which is removed first?

a) The solder iron tipb) The solder wirec) The component lead





























The Chisel Tip

Documents

MCG Employee Solder Training Course. Session I Agenda Coarse Objectives Terms and Definitions Soldering Tools and Materials Lead Preparation Soldering