Reflow soldering processes : SMT, BGA, CSP and flip chip technologies

273 Pages·2002·12.647 MB·English

by  Ning-Cheng Lee

To my mother, Shu-shuen Chang, for her care and encouragement
To my wife, Shen-chwen Lee, for her understandingand full support
Reflow Soldering
Processes and
Troubleshooting:
SMT, BGA, CSP
and Flip Chip
Technologies
Ning-Cheng Lee
BOSTON OXFORD AUCKLAND JOHANNESBURG
MELBOURNE NEWDELHI
Copyright2002byNewnes,animprintofButterworth-Heinemann
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.............................................................................................................P. reface
1 Introduc.t.i.o...n.. .t.o.. .S...u..r.f.a..c..e.. .M...o...u..n..t. .T..e..c..h..nology
..............................................1....1.. .S..u..r.f.a..c..e.. .m...o..u..n..t. .t.e..c.hnology
....................................................................1....1....1.. .H...i.s..t.o..r.y. .a..n..d. benefits
...........................................1....1....2.. .S...u..r.f.a..c..e.. .m...o..u..n..t. .c.o..m. ponents
1.1.3 Typ..e..s. .o..f. .s..u..r.f.a..c..e.. .m...o..u..n..t. .a..s..s..e..m...b..l.y. .t.e..chnology
..........................1....1....4.. .S...u..r.f.a..c..e.. .m...o..u..n..t. .s.o..l.d..e..r.i.n..g. process
1.1.5 Advan..t.a..g..e..s. .o..f. .s..o..l.d..e..r. .p..a..s..t.e.. .t.e..c..h..n..o..l.o..g.y in SMT
........................1....2.. .S..u..r.f.a..c..e.. .m...o..u..n..t. .t.e..c..h..n..o..l.o..g.y trends
.....................................................1....2....1.. .T..e..c..h..n..o..l.o..g..y. .d..r..iv.ing force
.................................................................1....2....2.. .A..r.e..a.. .a..r.r..a..y. .p.ackages
..............................................................................................1....3.. .C...o.nclusion
2 Fu.n..d..a..m....e..n..t.a..l.s.. .o..f. .S...o..l.d..e..r..s.. .a..n..d.. .S..o..ldering
.............................................................................2....1.. .S...o..ld..e..r..in..g theory
...................................................................................................2....1....1.. .S.preading
.....................................................................................................2....1....2.. .Fluid flow
...................................................2....1....3.. .D..i.s..s..o..lu..t.i.o..n.. .o..f. .b..a.se metal
.........................................................................................2....1....4.. .I.n..t.e..rmetallics
2.2 .E...f.f.e..c.t. .o..f. .e..l.e..m...e..n..t.a..l. .c..o..n..s..t.it.u..e..n..t.s.. .o..n. wetting
....................................2....3.. .P..h..a..s..e.. .d..i.a..g..r.a..m... .a..n..d.. .s.oldering
.......................................2....4.. .M...i.c..r.o..s..t.r.u..c..t.u..r.e.. .a..n..d.. .s.oldering
..................................................2....4....1.. .D...e..f.o..r.m...a..t.i.o..n.. .m...e..chanisms
2.4.2 D..e..s..i.r.a..b..l.e.. .s..o..l.d..e..r.s.. .a..n..d.. .t.h..e.. .s.o..l.d..e..r.i.n..g. process
...............................2....4....3.. .E..f.f.e..c..t. .o..f. .i.m...p..u..r.i.t.i.e..s. .o..n.. .soldering
.............................................................................................2....5.. .C..o..n.clusion
Appendix 2.1 Effect of flux surface tension on the spread o.f. .m...o..l.t.e.n solder
...........................................3.. .S...o..l.d..e..r.. .P..a..s..t.e.. .T..e..c..h..nology
...........................................................................3....1.. .F..l.u..x..i.n..g.. .r.eactions
....................................................................3....1....1.. .A..c..i.d..(cid:133) .b..a..s.e.. .reactions
.....................................3....1....2.. .O...x..i.d..a..t.io..n..(cid:133) .r..e..d..u..c.t.i.o..n.. .reactions
...............................................3....1....3.. .F..l.u..x..e..s. .f.o..r.. .r.e..f.l.o..w.. .soldering
...................................................................................3....2.. .F..l.u..x.. .c..hemistry
.............................................................................................................3....2...1 Resins
....................................................................................................3....2....2.. .A.ctivators
........................................................................................................3....2....3.. Solvents
...............................................................3....2....4.. .R..h..e..o..l.o..g..i.c..a..l. additives
...................................................................................3....3.. .S...o..ld..e..r. powder
..............................................................................................3....3....1.. .A...t.omization
.........................................................3....3....2.. .P..a..r.t.i.c..l.e.. .s..iz..e.. .a..nd shape
3.4 Solde..r.. .p..a..s.t.e.. .c..o..m...p..o..s..i.t.i.o..n.. .a..n..d.. .m...a..n..u..facturing
............................................................3....5.. .S..o..l.d..e..r. .p..a..s..t.e.. .rheology
..............................................................................3....5....1.. .R...h..e..o..l.o..gy basics
................3....5....2.. .S..o..l.d..e..r. .p..a..s..t.e.. .v..i.s..c.o..s..i.t.y.. .m...e..a..surement
...................3....6.. .S...o..ld..e..r.. .p..a..s.t.e.. .r..h..e..o..lo..g..y.. .r.e..q..u.irement
.........................3....6....1.. .E..f.f.e..c..t. .o..f. .c..o..m...p..o..s..i.t.io..n.. .o..n.. rheology
..............................................................................................3....7.. .C..o..nclusion
......4.. .S..u..r..f.a..c..e.. .M...o..u..n..t.. .A..s..s..e..m...b...l.y.. .P..r.o..cesses
..........................................................4....1.. .S..o..l.d..e..r. .p..a..s..t.e.. .m. aterials
............................................4....1....1.. .P..a..s..t.e.. .h..a..n..d..l.i.n..g.. .a..n..d storage
..............................................................................4....1....2.. .P...a..s..t.e.. .d.eposition
...............................................4....2.. .P..r..in..t.e..r.. .le..v..e..l. .c..o..n..s..ideration
..............................................................................................................4....2...1 Stencil
..................................................................................................4....2....2.. .S..queegee
...............................4....2....3.. .P..r.i.n..t.i.n..g.. .a..n..d.. .i.n..s..p..e..c.t.i.o..n. process
..................................................................................4....3.. .P..i.c..k.-..a..nd-place
............................................................................................................4....4 Reflow
.....................................................................................4....4....1.. .I.n..f.r.a..r.ed reflow
.....................................................................4....4....2.. .V..a..p..o..r.. .p..h..a.se reflow
...................................................4....4....3.. .F..o..r.c..e..d.. .c..o..n..v..e..c..t.ion reflow
.....................................................4....4....4.. .I.n..-.l.i.n..e..-.c..o..n..d..u..c..t.ion reflow
......................................................................................4....4....5.. .H...o..t.-.b.ar reflow
............................................................................................4....4....6.. .L..a..s.er reflow
.4....5.. .E...f.f.e..c.t. .o..f. .r..e..f.lo..w... .a..t.m...o..s..p..h..e..r.e.. .o..n.. .s.oldering
..........................4....6.. .S..p..e..c..i.a..l. .s..o..ld..e..r..in..g.. .c..o..n..s..i.d.erations
.....................................................................................4....6....1.. .S..t.e..p.. .soldering
..................................................................................4....6....2.. .R...e..f.l.o..w.-alloying
.........................................................................................4....6....3.. .P..a..s..te-in-hole
...........................................................4....7.. .S...o..l.d..e..r. .j.o..in..t. .i.n..spection
.....................................................................................................4....8.. .C. leaning
...............................................................................4....9.. .I.n..-.c..i.r.c..u..it-testing
4.10 Princ..i.p..l.e.. .o..f. .t.r.o..u..b..l.e..s.h..o..o..t.i.n..g.. .r.e..f.l.o..w... .s.oldering
.........................................................................................4....1..1.. .C..o..n.clusion
..........................5.. .S..M...T.. .P...r.o..b...l.e..m...s.. .P..r..i.o..r. .t.o... Reflow
................................................................................5....1.. .F..l.u..x.. .s.e..paration
.......................................................................................................5....2.. .Crusting
.............................................................................5....3.. .P...a..s.t.e.. .h..a.rdening
.................................................................................5....4.. .P..o..o..r.. .s.t.encil life
...................5....5.. .P...o..o..r. .p..a..s..t.e.. .r.e..l.e..a..s.e.. .f.r..o..m... .s.q.ueegee
..................................................................5....6.. .P..o..o..r.. .p..r.i.n..t. .t.hickness
............................................................................................................5....7 Smear
..........................................................................................5....8.. .I.n..s.u..fficiency
..............................................................................5....9.. .N..e..e..d..l.e.. .clogging
.........................................................................................................5....1..0 Slump
.................................................................................................5....1..1.. .L.ow tack
............................................................................5....1..2.. .S...h..o..r.t. .t.a.ck time
..........................................................................................5....1..3.. .C..o..nclusion
............................6.. .S...M...T.. .P..r..o..b..l.e..m...s.. .D...u..r.i.n...g.. Reflow
................................................................................................6....1.. .C..o.ld joints
..............................................................................................6....2.. .N..o..nwetting
..................................................................................................6....3.. .D..ewetting
....................................................................................................6....4.. .L.eaching
.......................................................................................6....5.. .I.n..t.e..r.m. etallics
..........................................................................................................6....5....1. General
....................................................................................................................6...5.2 Gold
........................................................................................6....6.. .T..o..m...bstoning
......................................................................................................6....7.. .Skewing
........................................................................................................6....8.. Wicking
.......................................................................................................6....9.. .Bridging
......................................................................................................6....1..0. Voiding
..................................................................................................6....1..1.. .Opening
...................................................................................................6....1..1....1.. Pillowing
..............................................................................6....1..1....2.. .O...t.h..e..r. .openings
.............................................................................................6....1..1....3.. .F..illet lifting
...........................................................................6....1..1....4.. .P..r.o..j.e..c..t.ed solder
..................................................................................6....1..2.. .S..o..l.d..e.r balling
.............................................................................6....1..3.. .S...o..l.d..e..r. beading
.............................................................................................6....1..4.. .S...pattering
..........................................................................................6....1..5.. .C..o..nclusion
7 SMT... .P..r.o...b..l.e..m...s.. .A...t. .t.h..e.. .P...o..s..t.-. .r..e..f.l.o..w. Stage
.....................................................................................7....1.. .W....h..i.t.e. residue
..............................................................................7....2.. .C..h..a..r.r..e..d. residue
...............................................................7....3.. .P...o..o..r. .p..r.o..b..i.n..g. contact
...................................................................7....3....1.. .F..l.u..x. .r..e..s.i.d..u..e content
..................................................................7....3....2.. .T...o..p..-.s..id..e.. .f.l.u.x spread
........................................................7....3....3.. .B..o..t.t.o..m...-..s.i.d..e.. .f.l.u.x spread
.........................................................................7....3....4.. .R..e..s..i.d..u..e.. .hardness
.....................................................................7....3....5.. .R...e..f.lo..w... .a..t.m. osphere
........................................................................................7....3....6.. .M...e..t.a.l content
...............................7....3....7.. .S..o..f.t.-.r.e..s..i.d..u..e.. .v..e..r.s..u..s.. .lo..w. -residue
..........................7....3....8.. .S..o..f.t.-..r.e..s..id..u..e.. .v..e..r.s..u..s.. .R...M...A residue
..........................7....3....9.. .M...u..l.t.i.p..l.e.. .c..y.c..l.e..s.. .p..r.o..b..i.n..g.. .testability
7.4 Surface insulation resistance or electrochem.ic..a..l. .m...i.g..r.a..t.i.o.n failure
....................7....4....1.. .S...u..r.f.a..c..e.. .i.n..s.u..l.a..t.i.o..n.. .r.e..s..i.s..t.a..nce (SIR)
...............................7....4....2.. .E..l.e..c..t.r.o..c..h..e..m...i.c..a..l .m...i.g..r.a..tion (EM)
.................7....4....3.. .E..f.f.e..c..t. .o..f. .f.l.u..x.. .c.h..e..m...i.s..t.r.y.. .o..n.. .IR values
.................................7....4....4.. .E..f.f.e..c..t. .o..f. .s..o..l.d..e..r.i.n..g.. .t.e..m.perature
...........7....4....5.. .E..f.f.e..c..t. .o..f. .c..le..a..n..l.i.n..e..s..s.. .o..f. .in..c..o..m..ing parts
7....4....6.. .E...f.f.e..c.t. .o..f. .c..o..n..f.o..r.m...a..l. .c..o..a..t.i.n..g../.e..n..c..a.psulation
7.4.7 Effect of inte..r.a..c..t.io..n.. .b..e..t.w...e..e..n.. .f.l.u..x.. .a..n..d.. .s.o..l.der mask
7.4.8 Effect of interaction between solder paste flux res..i.d..u..e.. .a..n..d.. .wave flux
7.5 Delamination/voiding/non-curing of conformal coatin..g../. .e..n..c..a..psulants
...........................................................................................................7....5....1 Voiding
.........................................................................................7....5....2.. .D...e..la.mination
..........................................................................7....5....3.. .I.n..c..o..m...p..l.e.te curing
..............................................................................................7....6.. .C..o..nclusion
8 Solde.r. .B...u..m...p..i.n...g.. .f.o..r.. .A..r..e..a.. .A..r..r.a..y.. .P..a..ckages
.....................................................................................8....1.. .S...o..ld..e..r criteria
8.1.1 Alloys used in flip. .c..h..i.p.. .s.o..l.d..e..r. .b..u..m...p..i.n..g.. .a..n..d.. .soldering
8.1.2 Alloys used in BGA and CSP s.o..ld..e..r.. .b..u..m...p..in..g.. .a..n..d.. .soldering
...........................................................................8....1....3.. .L..e..a..d..-.f.r.e..e solders
.............................8....2.. .S...o..ld..e..r.. .b..u..m...p..in..g.. .a..n..d.. .c..h..allenges
..............................................................................8....2....1.. .B...u..il.d..-.u..p. process
.....................................8....2....2.. .L..i.q..u..id.. .s..o..l.d..e..r. .t.r.a..n..s..f.e..r process
.................................8....2....3.. .S..o..l.i.d.. .s.o..l.d..e..r. .t.r..a..n..s.f.e..r.. .p.rocesses
.............................................................8....2....4.. .S..o..l.d..e..r. .p..a..s..t.e.. bumping
..............................................................................................8....3.. .C...o.nclusion
...9.. .B...G...A.. .a..n...d.. .C..S...P.. .A...s..s..e..m...b..l.y.. .a..n..d... .Rework
.......................................................................9....1.. .A...s..s.e..m...b..l.y.. process
.............................9....1....1.. .G...e..n..e..r.a..l. .s..t.e..n..c.i.l. .d..e..s..i.g..n.. guideline
................................................................9....1....2.. .B...G...A../.C...S..P.. .p..lacement
.............................................................................................................9....1...3 Reflow
...................................................................................................9....1....4.. .I.nspection
.........................................................................................................9....2.. Rework
..........................................................................................9....2....1... .P..r.o..cess flow
.................................................................................................9....2....2.. .P..re-baking
...................................................................9....2....3.. .C..o..m...p..o..n..e..n..t removal
..........................................................................9....2....4.. .R...e..f.lo..w... .e..quipment
.................................................................................9....2....5.. .S..i.t.e.. .p..r.eparation
...............................................................9....2....6.. .S..o..l.d..e..r. .r.e..p..l.e..nishment
....................................................9....2....7.. .P...la..c..e..m...e..n..t. .o..f. .c..o.mponent
.....................................................9....2....8.. .R...e..f.lo..w... .o..f. .B..G...A... and CSP
9.3 C.h..a..l.le..n..g..e..s.. .a..t. .a..s..s..e..m...b..l.y. .a..n..d.. .r.e..w...o..r.k stages
......................................................................9....3....1.. .S...t.a..r.v..e..d.. .s.o.lder joint
.....................................................................9....3....2.. .P..o..o..r.. .s.e..l.f.-.a.lignment
...........................................................................................9....3....3.. .P..o..o.r wetting
...........................................................................................................9....3....4 Voiding
.........................................................................................................9....3....5. Bridging
..................................................................................................................9....3.6 Open
......................................................................9....3....7.. .U...n..e..v..e..n.. .jo..int height
..................................................................................9....3....8.. .S..o..l.d..e..r. webbing
........................................................................................9....3....9.. .S...o..ld..er balling
............................................9....3....1..0.. .P..o..p..c..o..r.n.. .a..n..d.. .d..e..l.a.mination
..............................................................................................9....4.. .C...o.nclusion
............................1..0.. .F..l.i.p.. .C...h..i.p.. .R...e..f.l.o..w... .A..t..t.a..chment
.............................................................1..0....1.. .F...li.p.. .c..h..i.p.. .a..t.t.achment
.....................1..0....1....1.. .C..o..n..v..e..n..t.i.o..n..a..l. .f.l.ip.. .c..h..i.p.. .a..t.tachment
..............................................................................................1..0....1....2.. .S..nap cure
..............................................................................................1..0....1....3.. .E..poxy flux
......................................................................................................1..0....1....4. No-flow
................................................................................................................1..0...1.5 SMT
.....................................................................1..0....1....6.. .F..l.u..x..l.e..s.s.. .s.oldering
10.1.7 Wafer-applied underfill 10.1.8 Wafer level compres.s..i.v.e..-..f.lo..w... underfill
.....................................................................................................................(..WLCFU)
10.2 Prob..l.e..m...s.. .d..u..r.i.n..g.. .f.li.p.. .c..h..i.p.. .r.e..f.l.o..w.. .a..t.t.a..chment
...................................................................................1..0....2....1.. .M...i.s..a..lignment
.......................................................................................1..0....2....2.. .P..o..o.r wetting
..................................................................................1..0....2....3.. .S..o..l.d..e.r voiding
............................................................................1..0....2....4.. .U...n..d..e..r.f.ill voiding
....................................................................................................1..0....2....5.. Bridging
..............................................................................................................1..0....2.6 Open
..................................................................................1..0....2....7.. .U..n..d..e..rfill crack
.....................................................................................1..0....2....8.. .D..e..l.a.mination
........................................................................1..0....2....9.. .F..i.l.l.e..r. .s..e..gregation
....................................................1..0....2....1..0.. .I.n..s..u..f.f.i.c..ie..n..t. .u..n.derfilling
.........................................................................................1..0....3.. .C...o..nclusion
11 Optimizing a Reflow Profile Via Defect Mechan..i.s..m....s.. .A..nalysis
....................................................................................1..1....1.. .F..l.u..x.. reaction
11.1.1 Time/temperature req..u..i.r.e..m...e..n..t. .f.o..r.. .t.h..e.. .f.lu..x..i.n..g. reaction
11.1.2 Fluxing contrib.u..t.io..n.. .b..e..l.o..w... .t.h..e.. .m...e..l.t.in..g.. .t.e..m..perature
....................................................................1..1....2.. .P...e..a..k. .t.e..m...perature
..........................................1..1....2....1.. .C...o..l.d.. .j.o..in..t. .a..n..d.. .p..o..o.r wetting
11.2....2.. .C..h..a..r.r..in..g..,. .d..e..l.a..m...i.n..a..t.i.o..n..,. .a..n..d.. .i.n..t.e..rmetallics
..................................................................................................1..1....2....3.. .Leaching
..................................................................................1..1....3.. .C..o..o..l.i.ng stage
.....................................................................................1..1....3....1.. .I.n..t.e..rmetallics
...............................................................................................1..1....3....2.. .G.rain size
...............1..1....3....3.. .I.n..t.e..r.n..a..l. .s..t.r.e..s..s.-..c.o..m...p..o..n..e..n..t. cracking
.............................................................1..1....3....4.. .D...e..f.o..r.m...a..t.io..n. of joints
1.1....3....5.. .I.n..t.e..r.n..a..l. .s.t.r..e..s.s.. .s..o..l.d..e..r. .o..r. .p..a..d.. .d..e..tachment
.................................................................................1..1....4.. .H...e..a..t.i.ng stage
........................................................1..1....4....1.. .S..l.u..m...p..i.n..g.. .a..n..d. bridging
...............................................................................1..1....4....2.. .S..o..l.d..e..r beading
......................................................................................................1..1....4....3. Wicking
............................................1..1....4....4.. .T..o..m...b..s..t.o..n..i.n..g.. .a..n..d. skewing
....................................................................................1..1....4....5.. .S..o..l.d..er balling
.......................................................................................1..1....4....6.. .P..o..o.r wetting
.......................................................................................................1..1....4....7 Voiding
..........................................................................................................1..1....4...8 Opens
.......................................................1..1....5.. .T...im...i.n..g.. .c..o..n..s..i.d.erations
..............................................................................1..1....5....1.. .R...a..m...p..-up stage
....................................................................................1..1....5....2.. .S..o..a..k.ing zone
.......................1..1....5....3.. .O...n..s.e..t. .t.e..m...p..e..r..a..t.u..r.e.. .o..f. .s..pike zone
........................................................1..1....6.. .O..p..t.i.m...i.z..a..t.i.o..n.. .of profile
.................1..1....6....1.. .S..u..m...m...a..r.y.. .o..f. .d..e..s..i.r.e..d.. .p..r.o..f.i.le feature
.......................1..1....6....2.. .E..n..g..i.n..e..e..r.i.n..g.. .t.h..e.. .o..p..t.i.m...iz..ed profile
....1..1....7.. .C...o..m...p..a..r.i.s.o..n.. .w...i.t.h.. .c..o..n..v.e..n..t.i.o..n..a..l profiles
............................................................1..1....7....1.. .C...o..n..v..e..n..t.i.o..n..al profiles
.............1..1....7....2.. .B..a..c..k..g..r.o..u..n..d.. .o..f. .c..o..n..v..e..n..t.i.o..n..al profiles
.....................1..1....7....3.. .A..p..p..r.o..a..c..h.. .o..f. .c..o..n..v..e..n..t.i.o..n..al profiles
...........1..1....7....4.. .C..o..m...p..r.o..m...i.s..e.. .o..f. .c..o..n..v..e..n..t.io..n..a.l profiles
........................1..1....7....5.. .E...a..r.l.ie..r.. .m...a..s.s.. .r.e..f.l.o..w... .t.e..c..hnologies
1..1....7....6.. .F...o..r.c..e..d.. .a..ir.. .c.o..n..v..e..c..t.i.o..n.. .r.e..f.l.o..w.. .t.e..chnology
11.7.7 Defect potential ass.o..c..i.a..t.e..d.. .w..i.t.h.. .c..o..n..v..e..n..t.i.o..n..al profiles
...........................................................................................1..1....8.. .D...is.cussion
11.8....1.. .P..r.o..f.i.l.e..s.. .f.o..r. .l.o..w.. .t.e..m...p..e..r.a..t.u..r..e.. .s.o..l.d..er pastes
11.8.2.. .P...r.o..f.i.le..s.. .f.o..r. .h..i.g..h.. .t.e..m...p..e..r.a..t.u..r.e.. .s..o..l.d..er pastes
..........................................1..1....8....3.. .L..i.m...i.t.e..d.. .o..x..id..a..t.i.o..n.. .tolerance
11.8.4 Unevenly d..is..t.r.i.b..u..t.e..d.. .h..i.g..h.. .t.h..e..r.m...a..l. .m...a..s..s. systems
.......................................1..1....8....5.. .N..i.t.r.o..g..e..n.. .r..e..f.lo..w... .a..t.m. osphere
.........................................................................................1..1....8....6.. .A...ir. flow rate
....................................1..1....8....7.. .A...d..j.u..s.t.m...e..n..t. .o..f. .o..p..t.i.m..al profile
............1..1....9.. .I.m...p..l.e..m...e..n..t.i.n..g.. .li.n..e..a..r. .r..a..m...p..-.u.p profile
......................................................................................1..1....1..0.. .C..o..nclusion
..........................................................1..2.. .L..e..a..d..-.f..r.e..e.. .S..o..ldering
...............................................................................1..2....1.. .I.n..i.t.i.a..l. .activities
.........................................................................1..2....2.. .R...e..c..e..n..t. .activities
.................................1..2....3.. .I.m...p..a..c..t. .o..f. .J..a..p..a..n..e..s..e.. .activities
12.4 US reactions..................................................................................................
..........................1..2....5.. .W...h..a..t. .i.s.. .l.e..a..d..-.f.r.e..e.. .i.n..t.e..r.c.onnect?
..........................................1..2....6.. .C...r.i.t.e..r.i.a.. .o..f. .le..a..d..-..f.r.e.e solder
.......................................................1..2....7.. .V..i.a..b..l.e.. .l.e..a..d..-.f.r.e.e alloys
....................................................................................1..2....7....1.. .S..n..9..6..5/Ag3.5
...................................................................................1..2....7....2.. .S..n..9..9..3/Cu0.7
.................................................................................................1..2....7....3.. .Sn/Ag/Cu
..........................................................................................1..2....7....4.. .S..n../Ag/Cu/X
............................................................................................1..2....7....5.. .S...n/Ag/Bi/X
............................................................................................................1..2....7..6 Sn/Sb
.....................................................................................................1..2....7....7. Sn/Zn/X
..............................................................................................................1..2....7.8 Sn/Bi
...............................................................................................................1..2.8 Cost
....................................................................................1..2....9.. .P..C...B.. finishes
.................................................................................1..2....1..0.. .C...o..m..ponents
...................................................................1..2....1..1.. .T...h..e..r.m...a..l. damage
........................................................................1..2....1..2.. .O...t.h..e..r. .p.roblems
...................................................................1..2....1..3.. .C...o..n..s..o..r.t.i.a activity
......................................................1..2....1..4.. .O..p..i.n..i.o..n..s.. .o..f. .c.onsortia
......................................1..2....1..5.. .T..h..e.. .s..e..l.e..c.t.i.o..n..s.. .o..f. .pioneers
..............................................................................1..2....1..6.. .P...o..s.s..ible path
..................................................................1..2....1..7.. .I.s.. .l.e..a..d..-.f.r.ee safe?
........................1..2....1..8.. .S..u..m...m...a..r.y.. .o..f. .l.e..a..d..-.f.r.e..e.. .adoption
........1..2....1..9.. .T..r.o..u..b..l.e..s..h..o..o..t.i.n..g.. .le..a..d..-..f.r.e..e.. .s.oldering
...................1..2....1..9....1.. .C..o..m...p..a..t.i.b..i.l.it.y.. .w...i.t.h.. .r.e..f.l.o..w. process
.........................................................................................1..2....1..9....2.. .F..illet lifting
......................................1..2....1..9....3.. .C...o..n..d..u..c..t.iv..e.. .a..n..o..d..e. filament
............................................................................1..2....1..9....4.. .G...r.a..i.n..y surface
12.19.5 Sn../.P..b../.B...i .t.e..r..n..a..r.y.. .lo..w... .m...e..l.t.in...g. .e..u...t.e.c..tic phase
......................................................................................1..2....2..0.. .C..o..nclusion
................................................................................................................. Index