basic wave soldering

SOLDER FOR WAVE SOLDER FOR WAVE SOLDERINGSOLDERING

The Standard Alloy: 63% Tin/37% LeadThe Standard Alloy: 63% Tin/37% Lead

Pure Metals Melt (go from a solid to a liquid or from a Pure Metals Melt (go from a solid to a liquid or from a liquid to a solid) at One Temperatureliquid to a solid) at One Temperature

Mixtures of Metals (alloys) Usually Melt Over A Range Mixtures of Metals (alloys) Usually Melt Over A Range of Temperatures (solid and liquid exist over a range of of Temperatures (solid and liquid exist over a range of temperatures - this is called a mushy zone or a pasty temperatures - this is called a mushy zone or a pasty range)range)

SOLDER FOR WAVE SOLDER FOR WAVE SOLDERINGSOLDERING

A A EUTECTICEUTECTIC is a special alloy composition is a special alloy composition where melting occurs at a single temperature.where melting occurs at a single temperature.

63% Tin and 37% Lead is the eutectic 63% Tin and 37% Lead is the eutectic composition for the Tin-Lead System of composition for the Tin-Lead System of AlloysAlloys

Melting Temperatures = 183Melting Temperatures = 183ooC or 361C or 361ooFF

GRADES OF SOLDERGRADES OF SOLDER Level of Metallic Impurities - Level of Metallic Impurities -

Metallic Impurities Can:Metallic Impurities Can:– Cause severe bridging defects (particularly when iron exceeds Cause severe bridging defects (particularly when iron exceeds

0.005%)0.005%)– Weaken solder joint strengthWeaken solder joint strength– Increase Dross RateIncrease Dross Rate– Cause dull or grainy solder jointsCause dull or grainy solder joints– Reduce the wetability (particularly sulfur)Reduce the wetability (particularly sulfur)

Compare Supplier's SpecificationsCompare Supplier's Specifications

GRADES OF SOLDERGRADES OF SOLDER Level of Non-Metallic Impurities or Included Level of Non-Metallic Impurities or Included

OxidesOxides– Included oxides wet very well to molten solder and do Included oxides wet very well to molten solder and do

not easily separate from the solder into the drossnot easily separate from the solder into the dross– Included oxides increase the viscosity of molten Included oxides increase the viscosity of molten

solder, which makes the solder more sluggish, causing solder, which makes the solder more sluggish, causing bridging and iciclesbridging and icicles

– Included oxides can be measured via the Dross Included oxides can be measured via the Dross Inclusion TestInclusion Test

PURPOSE OF FLUXPURPOSE OF FLUX Reduces oxides on all surfaces involved in the solder Reduces oxides on all surfaces involved in the solder

connectionconnection

Reduces surface tension of molten solderReduces surface tension of molten solder

Helps prevent reoxidation of surfaces during reflowHelps prevent reoxidation of surfaces during reflow

Assists in transfer of heat to solderable surfacesAssists in transfer of heat to solderable surfaces

TYPES OF ASSEMBLY TYPES OF ASSEMBLY FLUXESFLUXES

RR - ROSIN (no halides/no organic acids)- ROSIN (no halides/no organic acids)– Suitable for no-clean or solvent/saponifier cleaningSuitable for no-clean or solvent/saponifier cleaning

RMARMA - ROSIN, MIDLY ACTIVATED (limited - ROSIN, MIDLY ACTIVATED (limited halides/limited weak organic acids)halides/limited weak organic acids)– Suitable for no-clean or solvent/saponifier cleaningSuitable for no-clean or solvent/saponifier cleaning

TYPES OF ASSEMBLY FLUXESTYPES OF ASSEMBLY FLUXES

RARA - ROSIN, FULLY ACTIVATED (halides/- ROSIN, FULLY ACTIVATED (halides/weak organic acids)weak organic acids)– Used by some for no-clean; usually cleaned with Used by some for no-clean; usually cleaned with

solvent/saponifiersolvent/saponifier

RSARSA - ROSIN, SUPER ACTIVATED (high level of - ROSIN, SUPER ACTIVATED (high level of halides and weak organic acids)halides and weak organic acids)– Clean with solvent/saponifierClean with solvent/saponifier

TYPES OF ASSEMBLY FLUXESTYPES OF ASSEMBLY FLUXES OAOA - ORGANIC ACTIVATED (high halides, high level of strong - ORGANIC ACTIVATED (high halides, high level of strong

organic acids)organic acids)– Must clean with water or saponifierMust clean with water or saponifier

NO-CLEAN - NO-CLEAN - Uncleaned residues do not degrade Surface Insulation Uncleaned residues do not degrade Surface Insulation ResistanceResistance– ROSIN-BASED - Rosin/Resin with weak organic acids and halidesROSIN-BASED - Rosin/Resin with weak organic acids and halides– ROSIN/RESIN-BASED - Weak organic acidsROSIN/RESIN-BASED - Weak organic acids– VOC-FREE - Usually rosin/resin-free; weak organic acids. Alcohol is replaced VOC-FREE - Usually rosin/resin-free; weak organic acids. Alcohol is replaced

by water.by water.– ROSIN/RESIN-BASED - Weak organic acids only (no halides)ROSIN/RESIN-BASED - Weak organic acids only (no halides)

FLUX COMPONENTSFLUX COMPONENTS

Weak Organic AcidsWeak Organic Acids– RMA, RA, RSA, RMA, RA, RSA,

No-CleanNo-Clean

Strong Organic AcidsStrong Organic Acids– OAOA

AminesAmines– RMA, RA, RSA, OA, No-RMA, RA, RSA, OA, No-

CleanClean

Rosin/ResinRosin/Resin– R, RMA, RA, RSA, No-R, RMA, RA, RSA, No-

CleanClean

HalidesHalides– RMA, RA, RSA, OA, RMA, RA, RSA, OA,

Rosin-Based Rosin-Based No-CleansNo-Cleans

ACTIVATORSACTIVATORS

FLUX COMPONENTSFLUX COMPONENTS

VEHICLESVEHICLES

GlycolsGlycols– OAOA

PolyglycolsPolyglycols– RA, OARA, OA

SurfactantsSurfactants– OA, No-CleansOA, No-Cleans

SOLVENTSSOLVENTS

AlcoholsAlcohols Glycol EthersGlycol Ethers PetroleumPetroleum WaterWater Various High Boiling Various High Boiling

SolventsSolvents

What are the Top 10 variables What are the Top 10 variables Influencing Solderability?Influencing Solderability?

1.1. Solderability Of Boards (Pads/Holes) Solderability Of Boards (Pads/Holes) and Components and Components

2.2. Spray Fluxer CapabilitiesSpray Fluxer Capabilities- penetration of flux into holes- penetration of flux into holes- uniformity of flux deposition- uniformity of flux deposition- day-to-day consistency- day-to-day consistency

3.3. Flux SelectionFlux Selection

4.4. Amount Of Flux AppliedAmount Of Flux Applied5.5. Board OrientationBoard Orientation6.6. Conveyor SpeedConveyor Speed7.7. Preheat TemperaturePreheat Temperature8.8. Use Of Chip WaveUse Of Chip Wave9.9. Solder Pot TemperatureSolder Pot Temperature10.10. Inert Gas Wave SolderingInert Gas Wave Soldering

What are the Top 10 variables What are the Top 10 variables Influencing Solderability (cont.)?Influencing Solderability (cont.)?

PROCESS OPTIMIZATIONPROCESS OPTIMIZATION

In the Wave Soldering Process, it seems In the Wave Soldering Process, it seems like there are many variables which can like there are many variables which can affect soldering performance, how can I affect soldering performance, how can I quickly and efficiently identify the optimal quickly and efficiently identify the optimal process settings?process settings?

Answer: Designed ExperimentsAnswer: Designed Experiments

PROCESS OPTIMIZATIONPROCESS OPTIMIZATIONFractional Factorial - Four VariablesFractional Factorial - Four Variables

Two Levels - Twenty ReplicatesTwo Levels - Twenty ReplicatesNumber

OfBoards

TopsidePreheat

Temperature

ConveyorSpeed

Amt. OfFlux

Applied

BoardOrientation

DEFECTSBridges

DEFECTSOther

20 Each 200 4.5 30 STD

20 Each 200 4.5 45 180

20 Each 200 5.5 45 STD

20 Each 200 5.5 30 180

20 Each 230 4.5 45 STD

20 Each 230 4.5 30 180

20 Each 230 5.5 30 STD

20 Each 230 5.5 45 180

PROCESS OPTIMIZATIONPROCESS OPTIMIZATIONFractional Factorial - Four VariablesFractional Factorial - Four Variables

Two Levels - Twenty ReplicatesTwo Levels - Twenty ReplicatesNumber

OfBoards

TopsidePreheat

Temperature(F)

ConveyorSpeed

Amt. OfFlux

Applied

BoardOrientation

DEFECTSBridges

DEFECTSOther

20 Each 220 4.5 30 STD

20 Each 220 4.5 40 180

20 Each 220 5.5 40 STD

20 Each 220 5.5 30 180

20 Each 245 4.5 40 STD

20 Each 245 4.5 30 180

20 Each 245 5.5 30 STD

20 Each 245 5.5 40 180

Flux Application MethodsFlux Application Methods

ApplicationApplication FoamFoam Wave Wave Spray Spray

(sealed flux reservoir)(sealed flux reservoir)

ControlControl Specific GravitySpecific Gravity TitrationTitration NoneNone

Foam / Wave FluxingFoam / Wave Fluxing

AdvantagesAdvantages Low Capital CostLow Capital Cost Copper BoardsCopper Boards

DisadvantagesDisadvantages Flux VolumeFlux Volume SG ControlSG Control

Spray Fluxing Spray Fluxing

AdvantagesAdvantages Even DepositionEven Deposition Volume ControlVolume Control Sealed SupplySealed Supply Minimum Flux Minimum Flux

WasteWaste

DisadvantagesDisadvantages High Capital CostHigh Capital Cost Hole-Fill with Bare Hole-Fill with Bare

Copper Boards & Copper Boards & OSPOSP 뭩뭩

SPRAY FLUXERSSPRAY FLUXERSWHAT SHOULD THEY BE ABLE TO DO?WHAT SHOULD THEY BE ABLE TO DO?

Hold Flux in A Sealed ContainerHold Flux in A Sealed Container– Why? No exposure of flux to air, therefore, no evaporative losses. Why? No exposure of flux to air, therefore, no evaporative losses.

No need to monitor the solids content of the flux. No need to add No need to monitor the solids content of the flux. No need to add thinners.thinners.

Provide Ability to Adjust the Flux Deposition PreciselyProvide Ability to Adjust the Flux Deposition Precisely– Why? Amount of flux applied is an important variable to control Why? Amount of flux applied is an important variable to control

to reduce defects. The precise control of the amount of flux to reduce defects. The precise control of the amount of flux applied will allow optimization of the process.applied will allow optimization of the process.


Provide Uniform Flux Deposition Across the Provide Uniform Flux Deposition Across the Width and Along the Length of the BoardWidth and Along the Length of the Board– Why? Process control for defect minimization.Why? Process control for defect minimization.– Is there a simple method that can tell me if my spray Is there a simple method that can tell me if my spray

fluxer is applying a uniform coating of flux? A piece of fluxer is applying a uniform coating of flux? A piece of cardboard!!! It is not high technology, but it will cardboard!!! It is not high technology, but it will quickly tell you if you have a uniform spray pattern.quickly tell you if you have a uniform spray pattern.

Easy to operate, maintain, and does not clog easily.Easy to operate, maintain, and does not clog easily.


Good Hole Penetration for Topside Hole-FillGood Hole Penetration for Topside Hole-Fill– I heard that by heating a VOC-Free flux before spraying I heard that by heating a VOC-Free flux before spraying

it, you can achieve much better capillary action of flux it, you can achieve much better capillary action of flux up the holes and achieve better hole-fill. Is this true?up the holes and achieve better hole-fill. Is this true?

– No. When a fine mist of flux is sprayed, the air cools the No. When a fine mist of flux is sprayed, the air cools the flux almost immediately (even after heating to 185flux almost immediately (even after heating to 185ooF), F), providing no added benefit to hole-fill.providing no added benefit to hole-fill.


I know that it is important to apply the same I know that it is important to apply the same amount of flux to every board, every day, but amount of flux to every board, every day, but how can I tell if the spray fluxer is delivering the how can I tell if the spray fluxer is delivering the same amount of flux consistently?same amount of flux consistently?

– THE IONOGRAPH!THE IONOGRAPH!

Solder Balls In Wave SolderingSolder Balls In Wave Soldering

밪밪 plash-Back?Solder Balls From Fully-Inerted plash-Back?Solder Balls From Fully-Inerted And TunnelsAnd Tunnels

Random (Random ( 밪밪 pattering-Type?pattering-Type?

Non-Random (found behind the protruding leads Non-Random (found behind the protruding leads on the bottomside)on the bottomside)

3 Types:3 Types:

Random Solder BallsRandom Solder Balls

Check Preheat Profile (max. ramp rate to desired Check Preheat Profile (max. ramp rate to desired topside preheat and hold)topside preheat and hold)

Forced Air Convection PreheatForced Air Convection Preheat

밮밮 ented?Pallets Or Pallets With Finger-Like ented?Pallets Or Pallets With Finger-Like Bottom Edge DesignBottom Edge Design

Found randomly on topside or bottomside of Found randomly on topside or bottomside of board.board.Listen for associated Listen for associated 밪밪 IZZLE?at wave. IZZLE?at wave. Common when using VOC-Free fluxes.Common when using VOC-Free fluxes.

Non-Random Solder BallsNon-Random Solder Balls

Primary Factors Primary Factors (60-90% reduction)(60-90% reduction)

Mask Selection - Surface Morphology (matte much Mask Selection - Surface Morphology (matte much lower solderballs than glossy)lower solderballs than glossy)

Mask Selection - Chemistry Of MaskMask Selection - Chemistry Of Mask Flux Selection (Alcohol-Based: Flux Selection (Alcohol-Based:

Lonco 65 Series; VOC-Free: NR310 Series)Lonco 65 Series; VOC-Free: NR310 Series)

Found on the bottomside of board and observed at Found on the bottomside of board and observed at the same locations (board-after-board), usually at the same locations (board-after-board), usually at the trailing side of a protruding lead. Related to the trailing side of a protruding lead. Related to the surface tension between the solder mask and the surface tension between the solder mask and the solder.the solder.

Non-Random Solder BallsNon-Random Solder Balls

Secondary Factors Secondary Factors (20-50% reduction)(20-50% reduction) Amount Of Flux At Exit Of WaveAmount Of Flux At Exit Of Wave

- Amt of Flux Applied - Amt of Flux Applied (more reduces solderballs)(more reduces solderballs)- Conveyor Speed - Conveyor Speed (faster reduces solderballs)(faster reduces solderballs)- Chip Wave - Chip Wave (off reduces solderballs)(off reduces solderballs)

Tertiary Factor (5-10% reduction)Tertiary Factor (5-10% reduction) Solder Pot Temperature Solder Pot Temperature (lower reduces solderballs)(lower reduces solderballs)

Found on the bottomside of board and observed Found on the bottomside of board and observed at the same locations (board-after-board), usually at the same locations (board-after-board), usually at the trailing side of a protruding lead. Related at the trailing side of a protruding lead. Related to the surface tension between the solder mask to the surface tension between the solder mask and the solder.and the solder.

TROUBLESHOOTING TROUBLESHOOTING SOLDER BRIDGES/SHORTSSOLDER BRIDGES/SHORTS

Non-Uniform Flux Non-Uniform Flux ApplicationApplication

Solder Pot Temperature Too Solder Pot Temperature Too LowLow

Conveyor speed too slow and Conveyor speed too slow and flux is prematurely flux is prematurely volatilizing due to excessive volatilizing due to excessive time in the wavetime in the wave

Check spray pattern with Check spray pattern with cardboard and fix spray fluxer, cardboard and fix spray fluxer, if necessaryif necessary

If possible, increase solder pot If possible, increase solder pot temperature to 500temperature to 500ooF.F.

Increase Conveyor Speed by Increase Conveyor Speed by 0.5 - 1 Foot per minute0.5 - 1 Foot per minute

Possible CausePossible Cause Corrective ActionCorrective Action


Solder contamination with high Solder contamination with high levels of metallic impurities levels of metallic impurities (particularly Iron > 0.005%) or (particularly Iron > 0.005%) or high levels of included oxideshigh levels of included oxides

Solder Wave Not Set-Up Solder Wave Not Set-Up ProperlyProperly

Analyze composition of solder Analyze composition of solder and perform dross inclusion and perform dross inclusion testtest

Make sure that the solder Make sure that the solder wave height reaches half wave height reaches half thickness of the board and that thickness of the board and that other wave adjustments are set other wave adjustments are set correctlycorrectly



Flux Chemistry is not Flux Chemistry is not optimizedoptimized

Rough Solder WaveRough Solder Wave

Check the acid number of the Check the acid number of the flux to ensure that the flux is flux to ensure that the flux is at the proper solids content at the proper solids content and ask flux supplier for and ask flux supplier for improved formulation to improved formulation to reduce bridging (Lonco 65 or reduce bridging (Lonco 65 or NR310)NR310)

Clear Wave Nozzles and Clear Wave Nozzles and Screen, Remove DrossScreen, Remove Dross



Chip Wave Being UsedChip Wave Being Used

Preheat temperature not set Preheat temperature not set correctlycorrectly

Possible CausePossible Cause If you don't need to use chip If you don't need to use chip

wave for soldering bottomside wave for soldering bottomside SMD's, do not use it.SMD's, do not use it.

High preheat temp can High preheat temp can prematurely volatilize the flux prematurely volatilize the flux activators. Low preheat activators. Low preheat temperatures may not temperatures may not sufficiently activate the flux sufficiently activate the flux activators, then higher preheat activators, then higher preheat temperatures may be required.temperatures may be required.

Corrective ActionCorrective Action


Board Not Meeting Wave Board Not Meeting Wave ParallelParallel

Leads Too LongLeads Too Long

Bridge only across last two Bridge only across last two leads of a row of leads (SOIC)leads of a row of leads (SOIC)

Check for bent Check for bent fingers/fixtures, non-level fingers/fixtures, non-level conveyor rails, conveyor rails, wave/nozzles not level, wave/nozzles not level, conveyor width too tightconveyor width too tight

Cut the leads to shorten Cut the leads to shorten themthem

Add "Solder Thieves" into Add "Solder Thieves" into the design of the boardthe design of the board



Bridge only across last two Bridge only across last two leads (QFP)leads (QFP)

Improper Board OrientationImproper Board Orientation

Possible CausePossible Cause Turn part 45Turn part 45oo and add and add

"Solder Thief""Solder Thief"

If possible, process boards in If possible, process boards in parallel direction with rows of parallel direction with rows of leads. Run experiment to leads. Run experiment to determine optimal direction. If determine optimal direction. If possible, change design of the possible, change design of the board so that board can be run board so that board can be run parallel with the connectors.parallel with the connectors.

Corrective ActionCorrective Action

SOLDER SKIPSSOLDER SKIPS Flux not properly applied to pad surfaceFlux not properly applied to pad surface

Solder did not adequately contact pad surfaceSolder did not adequately contact pad surface

Flux does not posses sufficient wetting force or Flux does not posses sufficient wetting force or wetting speed for specific surfacewetting speed for specific surface

SOLDER SKIPSSOLDER SKIPS

Check spray pattern with glass plate or Check spray pattern with glass plate or cardboardcardboard

Experiment with varying levels of flux Experiment with varying levels of flux applicationapplication

Was Flux Properly Applied?Was Flux Properly Applied?


Is the board contacting the wave uniformly and level?Is the board contacting the wave uniformly and level?– Conveyor rails level?Conveyor rails level?– Conveyor fingers bent?Conveyor fingers bent?– Pallets/Fixtures bent or damaged?Pallets/Fixtures bent or damaged?– Boards warped?Boards warped?– Solder pot level?Solder pot level?– Conveyor width too narrow?Conveyor width too narrow?

Did the Solder Adequately Contact the Pad?Did the Solder Adequately Contact the Pad?


Is there solder mask on the pads?Is there solder mask on the pads? Is there SMD adhesive on the pads?Is there SMD adhesive on the pads? Is the turbulent wave turned on? Is the turbulent wave turned on? Is the turbulent wave nozzle clogged?Is the turbulent wave nozzle clogged? Is the turbulent wave set too low?Is the turbulent wave set too low? Is the solder wave set high enough? (It should be ?up Is the solder wave set high enough? (It should be ?up

board thickness)board thickness)



Can changing the orientation of the circuit board Can changing the orientation of the circuit board help (try 90help (try 90oo, 180, 180oo and 270 and 270oo))

Pads too small or pads too far under partPads too small or pads too far under part


SOLDER SKIPSSOLDER SKIPS Is there sufficient contact time in the wave (try reducing the Is there sufficient contact time in the wave (try reducing the

conveyor speed)?conveyor speed)?

Are the pads and leads solderable?Are the pads and leads solderable?

Does the flux have sufficient wetting force/speed?Does the flux have sufficient wetting force/speed?– Make sure the acid number of the flux is correctMake sure the acid number of the flux is correct– Ask flux supplier for an alternative flux (NR310H and Lonco 65H).Ask flux supplier for an alternative flux (NR310H and Lonco 65H).

Flux Does Not Possess Sufficient Wetting Flux Does Not Possess Sufficient Wetting For Surfaces?For Surfaces?

basic wave soldering

Documents