Lead Free Basics

7/30/2019 Lead Free Basics

1/24

LeadLead--Free BasicsFree Basics

J anuary 2005J anuary 2005

Content from this presentation is taken in part from Kestersfull-day presentation (~250 slides) Lead-Free Seminarseries presented at various sites across North America.


2/24

LeadLead--Free Solder OverviewFree Solder Overview

Legislative Update Lead-Free Solder Alloys

Kesters Position on Alloys

Kesters Recommended Lead-FreeMaterial Set


3/24

Why Do Solders Contain forWhy Do Solders Contain forElectronics Contain Lead?Electronics Contain Lead?

Lead reduces the melting point of tin

Tin 232 C

Lead 327 C

Sn63/Pb37 183 CSn62/Pb36/Ag02 179-189 C

Lead forms a solid solution with tin

Lead increases the strength of tin Lead improves the ductility of tin

Lead provides thermal cycling fatigue

resistance


4/24

HoweverHowever Lead has been targeted for elimination by

many countries due to health threatsassociated with use and disposal

Lead has already been eliminated in the

US in products such as fuel, paint, etc. Lead is listed as a hazardous material by

the US Environmental Protection Agency

The electronics assembly industry is nexton the lead elimination list.


5/24

European LegislationEuropean Legislation In 1998, called for a ban on lead in all electronics by

1/1/2004.

In 2001, the European Union released legislation calledWaste from Electrical Equipment Directive (WEEE) theoriginal legislation was dropped a new draft was issuedwith a recommendation to eliminate lead from electronics

by July 1, 2006.

Lead-free limit 0.1 % by weight.Individual (homogeneous) constituent of the finalassembly and product.

Agreed by Europe and Asia


6/24

RoHSRoHS DirectivesDirectives

A ban on hazardous materials effective

J uly 1, 2006 Banned materials include Lead, Cadmium,

Mercury, Hexavalent Chromium, PBB, PDBE

This directive makes lead-free arequirement for products on sale to

European Consumers after this date.


7/24

Asian LegislationAsian Legislation Japan: JEIDA Roadmap for Commercialization of

Lead-Free 2000: Pb-Free Components and Wave Soldering

2001: Expand Pb-Free components, Pb-Free in newproducts

2002: General use of lead-free in new products

2003: Lead-free in all new products

2006: Complete phase-put of leaded solder in all

products


8/24

Asian LegislationAsian Legislation China

Ministry of Industry is following EuropeanRoHS and WEEE guidelines in documentcalled Management Methods, published

March 2004 Also targeting elimination for J uly 1, 2006


9/24

Lead is permitted in solder forelectronics, however, American Industrywas asked by the U.S. EPA to reduce

the use of hazardous materials Lead is always on the target list

Increasing pressures to be lead-fee

occurring from offshore users. Will begreater in 2006

North American LegislationNorth American Legislation


10/24

World AgreementWorld Agreement Industry adoption of 0.1wt% as maximum

allowable Pb in lead-free products Every individual homogeneous material must be


11/24

Requirements for LeadRequirements for LeadAlternative AlloysAlternative Alloys

Low Cost Relatively non-hazardous

Capable of forming reliable joints

Relatively low temperature process compatible Corrosion resistant

Compatible with copper substrates, gold overnickel, and a variety of non-lead substrates as

well as some leaded substrates. Alloys must be available in Bar, Wire and Paste

forms


12/24

Requirements for LeadRequirements for LeadAlternative AlloysAlternative Alloys

No Potential Environmental Problems Bi


13/24

LeadLead--Free Solder AlloysFree Solder Alloys

Potential Alloys with High Percentageof Tin Silver (Ag) 0.1 to 5.0%

Bismuth (Bi) 1.0 to 5.0%

Antimony (Sb) 0.2 to 5.0%

Copper (Cu) 0.2 to 2.0%

Zinc (Zn) 0.5 to 9.0%

Indium (In) 0.5 to 20.0%

Magnesium (Mg) 0.5 to 2.0%


14/24

Common Alloys Being Used &Common Alloys Being Used &EvaluatedEvaluated

Sn96.5 Ag3.0 Cu0.5 (~217 C) IPC alloy Sn95.5 Ag3.8 Cu0.7 (~217 C)

Sn99.3 Cu0.7 (227 C)

Sn96.5 Ag3.5 (221 C) Sn95 Sb5 (232-240 C)

Sn97 Cu2.0 Sb0.8 Ag0.2 (226-228C)

Sn91.8 Ag3.4 Bi4.8 (202-215 C)

Sn42 Bi58 (138 C)


15/24

Physical Properties ofPhysical Properties ofLeadLead--Free AlloysFree Alloys

High Tin Content Alloys like Sn90+:

Typically have much higher melting points

traditional Sn63Pb37 Are stronger and less ductile than lead-

bearing alloys.

Typically exhibit poorer wetting and surfacecondition when compared to Sn63Pb37


16/24

Sn/Ag/Cu SystemSn/Ag/Cu System

Sn96.5 Ag3.0 Cu0.5 = IPC SPVC alloy MP of 217-220 C, no patent issues

Sn95.5 Ag3.9 Cu0.6 = NEMI alloy MP of 217-224 C, at least 1 patent

Other Sn / Ag / Cu variations: Sn95.6 Ag3.5 Cu 0.9 Eutectic point (MP = 217 C,

2 patents)

Sn95.5 Ag3.8 Cu 0.7 European alloy (MP = 217-

221 C, 1 patent)

MP of the SnAgCu system is ~217 C


17/24

Kesters Position onKesters Position on LeadLead--FreeFree

Kester is ready to make just about any

lead-free solder alloy, including licensedalloys that have been patented by otherorganizations.

IPC Solder Product Value Council hasnamed Sn96.5Ag3.0Cu0.5 as primarylead-free alloy for wave, SMT and

rework. Kester supports this alloy as the

industry standard.


18/24

Kesters RecommendationsKesters Recommendationsfor Leadfor Lead--Free ProcessFree Process

Surface Mount Soldering Alloys:

Sn96.5 Ag3.0 Cu0.5 (preferred)

Sn96.5 Ag3.5 Fluxes:

No-Clean EM907

Water Soluble - R520A


19/24

Kesters RecommendationsKesters Recommendationsfor Leadfor Lead--Free ProcessFree Process

Wave Soldering Operations (Nitrogen) Alloys:

Sn96.5 Ag3.0 Cu0.5

Sn99.3 Cu0.7

Fluxes

No-Clean VOC Free 979

No-Clean 959T

Water Soluble VOC Free 2220-VF

Rosin Mild Activation- 186


20/24

Product differentiation

Triangular for a

Reason


21/24

Material control

Easily identifiable

Increases awareness

Simplifies training

Avoids costly errors

Insures reliability

Solder ProductsDifferentiation

Solder ProductsSolder Products

DifferentiationDifferentiation


22/24

Kesters RecommendationsKesters Recommendationsfor Leadfor Lead--Free ProcessesFree Processes

Hand Soldering Operations

Alloys:

Sn96.5 Ag3.0 Cu0.5

Sn96.5 Ag3.5

Sn99.3 Cu0.7

Fluxes

No-Clean: 275

Water Soluble: 331

Rosin: 48


23/24

Kesters RecommendationsKesters Recommendationsfor Leadfor Lead--Free ProcessesFree Processes

Ball Attach Applications

Fluxes

No-Clean: TSF-6592

Water Soluble: TSF-6850


24/24

For a full description of KestersFor a full description of Kesters

leadlead--free offerings, please visitfree offerings, please visit

www.kester.comwww.kester.com or call Technicalor call Technical

Services at (800) 2Services at (800) 2--KESTERKESTER

Documents

Lead Free Basics