osp the high performance surface finish
TRANSCRIPT
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1997 Electronic Interconnect Conference
Dan Parquet Eric StafstromMerix Corp. Enthone - OMIForest Grove
OSPThe High PerformanceSurface Finish
Merix: Meeting in The Winner’s Circle
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+ Interactive Breakout Session$ Opportunity to share PWB
manufacturing experiences, assembly,and design technologies with OSPfinish$ We are seeking your input for process
technology benefits and limitations$ Combine our capabilities for success
with current and emerging technologies
Merix: Meeting in The Winner’s Circle
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+ What is OSP?
$ OSP is - Organic– Solderability
– Preservative
$ OSP is an alternative surface finishto HASL on printed circuit boards
Merix: Meeting in The Winner’s Circle
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+ Breakout Session Agenda
$ PWB Manufacturing Experience
– FY 97 Merix Manufacturing Information
$ OSP Technical Discussion
– Enthone - OMI
Merix: Meeting in The Winner’s Circle
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+ Manufacturing Experience
$ Industry benchmark data$ Merix Surface finish volumes$ Manufacturing process rework$ Manufacturing costs, and customer
returns
Merix: Meeting in The Winner’s Circle
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+U.S. Industry Benchmark Data*
$ HASL is used on >70% of U.S. PWB’s$ HASL is predicted to be the
dominant U.S. finish for the next fiveyears$ OSP gaining wide-scale acceptance
with 15% market share (1995)
*Source - ‘97 IPC Surface Finish Summit
Merix: Meeting in The Winner’s Circle
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U.S. Industry BenchmarkData*$ “OSP is great for water soluble fluxes”$ “Nitrogen is required for multiple
soldering operations”$ “OSP thickness control important for
no-clean fluxes”$ “Benzimidazole OSP used in military
applications”
*Source - ‘97 IPC Surface Finish Summit
Merix: Meeting in The Winner’s Circle
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+Other Industry Benchmark Data
$ Other surface finishes being investigated 1
– Immersion Silver, Immersion Tin, Electroless Palladium
$ HASL is used on <5% of customer productsat one major German PWB manufacturer.Electroplated gold is main surface finish2
$ HASL is used on <5% of customer productsat one major Japanese PWB manufacturer.OSP is main surface finish 2
1 ‘97 IPC Surface Finish Summit2 Merix competitive benchmark
Merix: Meeting in The Winner’s Circle
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+ Process Flow
�Hot Air Solder Level: 9 Steps
Preclean -> Rinse -> Flux Coat -> Solder Coat ->
-> Hot Air Level -> Cool -> Soft Brush ->
-> Post Clean Rinse -> Dry
Merix: Meeting in The Winner’s Circle
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+ Process Flow
�OSP: 5 Steps
Preclean -> Rinse -> OSP Coat -> Rinse -> Dry
Merix: Meeting in The Winner’s Circle
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+ Design Attribute Challenges
$ Hot Air Solder Level:– Selective gold contact masking
– <0.020” pitch QFP
– >0.125” thick PWB’s
– <0.020” dia. hole clearance
– 50-1500 microinch solder control
– Pad geometry : fine pitch QFP/ground planes
Merix: Meeting in The Winner’s Circle
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+ Design Attribute Challenges
$ OSP:– Contact insulation at assembly (shielding,
ground planes)
– U.S. market acceptance
Merix: Meeting in The Winner’s Circle
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Merix Forest Grove SurfaceFinish Product Mix
0 %
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
23-M
ar
30-M
ar
6-A
pr
13-A
pr
20-A
pr
27-A
pr
4-M
ay
11-M
ay
18-M
ay
25-M
ay
1-Ju
n
8-Ju
n
15-J
un
22-J
un
29-J
un
6-Ju
l
13-J
ul
20-J
ul
27-J
ul
3-A
ug
10-A
ug
17-A
ug
24-A
ug
31-A
ug
7-S
ep
14-S
ep
WEEK
PE
RC
EN
T O
F T
OT
AL
TH
RO
UG
HP
UT
HASL
O S P
OTHER
Merix: Meeting in The Winner’s Circle
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+ Manufacturing Rework
HAL OSP0
500
1000
1500
2000
IMA
GE
S
HAL OSP
PROCESS
$ HASL– Set up intensive
process
– Narrow processingwindow
$ OSP– Single set up for ALL
product types
– Stable process
Merix: Meeting in The Winner’s Circle
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+ Manufacturing Rejects
HAL OSP0
500
1000
1500
2000
2500
3000
3500
IMA
GE
S
HAL OSP
PROCESS
$ HASL– Complex process
– High temperatureslimit rework
$ OSP– Stable process ð high
first pass yield
– Reworking has littleeffect on product
Merix: Meeting in The Winner’s Circle
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+ Manufacturing Cost
$ HASL– Operation and
inspection requiresfour times theworkforce
– Treatment ofhazardous waste.
$ OSP– Quality built into the
process.
– Non hazardous waste.
HAL OSP0%
20%
40%
60%
80%
100%
HAL OSP
PROCESS
Merix: Meeting in The Winner’s Circle
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+ Customer Returns
HAL OSP0
1000
2000
3000
4000
5000
6000
IMA
GE
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HAL OSP
PROCESS
$ HASL– Random high solder,
plugged holes, missingand non- wetting Pads
$ OSP– Darken copper,
cosmetic only
– Zero returns forsolderability issues
Merix: Meeting in The Winner’s Circle
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+ Technical Discussion
$ OSP chemistry applications andbenefits$ Industry performance data$ Advanced technologies with OSP
Merix: Meeting in The Winner’s Circle
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+ TECHNICAL DISCUSSION
– OSP chemistry applications and benefits
– Advance technologies with OSPs
– Industry performance data
Merix: Meeting in The Winner’s Circle
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ENTEK PLUS ®
TYPE THICKNESS SHELF LIFE NUMBER OF FLUX REFLOWS COMPATIBILITY
Inhibitor 50-200 Ä 3-6 Months 1 All
Rosin/Resin 1-2 Microns 6-12 Months 3 Maximum Rosin/ResinPre-flux
OSP 0.2-0.5 Microns 12 Months 3 Minimum All2000-5000 Ä
PWB ORGANIC COATINGS -COMPARISON
Merix: Meeting in The Winner’s Circle
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+ ENTEK PLUS®
$ An organic solderability preservative(OSP) that selectively protects andmaintains solderability of copperpads and through-holes– Provides thermal protection against copper
solderability degradation during SMT andmixed-technology PWB assembly
– Is an alternative to hot air solder leveling(HASL) and metallic PWB surface finishes
Merix: Meeting in The Winner’s Circle
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COATING DEPOSITIONMECHANISM
$ Substituted benzimidazole type$ Coating deposition mechanism
– Complexing reaction with copper
– Forms organometallic bond (~1500 Ä Thick)
– Build-up of benzimidazole to requisite finalthickness
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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$ PWB Fabrication– Aqueous, reworkable process– Reduced maintenance, labor requirements– Eliminates fire hazard, major lead source
$ PWB Assembly– Flat SMT pads– Facilitates solder paste printing– Increased first pass yields For FPT, BGA– Compatible with DCA technologies
WHY OSPs?
ENTEK® PLUS BENEFITS
Merix: Meeting in The Winner’s Circle
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+ ENTEK® PLUS BENEFITS
$ PWB Integrity– Reduces ionic contamination levels
– Stronger, more consistent solder joints
– Maintains PWB linear stability (X-Y Axes)
– Maintains PWB structural integrity (Z-Axis)
WHY OSPs?
Merix: Meeting in The Winner’s Circle
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$ Compatible with all solder paste types$ Allows high solder paste transfer efficiency
for small stencil artures (FPT, UFPT, BGA,µ-BGA, Flip Chip)$ No “extra” solder paste required versus HASL$ Color contrast aids in
– Printer/stencil alignment set-up– PWB fiducial recognition– Poor solder paste deposit detection
ASSEMBLY PROCESS: SMT
Merix: Meeting in The Winner’s Circle
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$ Existing reflow profiles are OK$ Optimized profiles include
– First side peak reflow temperature <240ºC– Increased PWB cool-down rate (to <100ºC)
$ N2 inerting is beneficial but not mandatory$ Hold times between soldering operations
– Dependent on assembly process variables– Benzotriazoles: typically hours– Substituted benzimidazoles: typically days
ASSEMBLY PROCESS: SMT
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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$ Solderability of all organics degrade withthermal processing– Unique chemical structure determines protective
capabilities
$ Mixed technology assembly (in air) using no-clean fluxes (LSF, VOC-free): OPTIMIZATION– Flux formulation/selection– Flux application method/equipment– Assembly process
ASSEMBLY PROCESS:WAVE SOLDERING
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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ASSEMBLY PROCESSCONSIDERATIONS -General$ Exposed/Non-Wetted Copper
– Copperself limiting passivating film– Historically, “all copper” PWBs have been used for 25 years
without reliability issues• Computers• Telecommunications
– In a no-clean environment, contaminants from HASL aremore likely than exposed copper to compromise reliability*
• Catalyze Corrosion• Metal Migration *Based on testing performed by two major
computer manufacturers
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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ASSEMBLY PROCESSCONSIDERATIONS -General$ Workmanship criteria for exposed/non-
wetted copper: SMT– Typically a maximum of 5 to 10% of the solderable
SMT pad area– Cannot interfere in solder joint formation– Along the periphery of the SMT pad
$ Workmanship criteria for exposed/non-wetted copper: PTH– Typical for computer, telecommunication industries
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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Hole fill Top Side Fillet
Minimum Preferred Minimum Preferred
PTH with Component 75% 100% None 360°, Some Exposed Copper
Electrical via Bottom Side >75% None Partially CappedCapped
ASSEMBLY PROCESSCONSIDERATIONS - General
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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ASSEMBLY PROCESSCONSIDERATIONS - FPT$ Flat Co-planar
Surface– Solder paste printing
– Component placement
– Fiducial reconigition
– Solder joint strength
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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SOLDER JOINT STRENGTH:BGA & Flip Chip
$ Delta in coefficientof expansion– Interstructural strength
– Noble metal in solderjoint
$ Heat sinking– Wetability of surface
Merix: Meeting in The Winner’s Circle
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+SOLDER JOINT RELIABILITY
$ Three-Point Bend Test– 0.045” thick FR-4, BGAs with 41 I/O (0.52” x
0.47”)– PWBs coated with ENTEK PLUS, HASL or
Ni-Au– Reflowed through standard SMT profile– PWBs then exposed to 1 additional SMT reflow– Assembled PWBs aged for 24 hours at 100°C– Measured load displacement required for
solder joint fracture
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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SOLDER JOINT STRENGTH:3 POINT BEND FLEX TEST
Schematic of Set-UpForce
Load AnvilBGA
PWB
1.00”Support Span
Merix: Meeting in The Winner’s Circle
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SOLDER JOINT STRENGTH:3 POINT BEND FLEX TEST RESULTS
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160
Ni-Au OSP HASL
SolderJoint
FractureLoad(lbs.)
Range of Solder Joint Fracture Load
Merix: Meeting in The Winner’s Circle
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+ SOLDER JOINT STRENGTH:
$ With ENTEK®
PLUS– Intermetallic formed
during SMT reflow– Thin uniform
intermetallic
– Highest, most uniformbond strength
– Flat solderable co-planar surface
Merix: Meeting in The Winner’s Circle
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$ 5+ Yrs In All Major Sectors OfElectronics Industry– Automotive: mixed technology, no clean, N2 wave (3 Years)
– Telecommunications: double sided SMT, no clean, air (3 Years)
– Computers: mixed technology, no clean, air (3 Years)
– EMSI: double sided SMT, water soluble, air (4 Years)
– EMSI: mixed technology, no clean (VOC-free), air (3 Years)
ENTEK® PLUS
PRODUCTION EXPERIENCE
Merix: Meeting in The Winner’s Circle
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$ Fine pitch (25, 20 Mil) - enabling$ Ultra fine pitch (< 20 Mil) - enabling$ BGAs, micro-BGAs, mini-BGAs - enabling$ Tape automated bonding (TAB) - compatible$ Chip-on-Board (COB) - compatible$ Flip chip - enabling$ PCMCIA cards - enabling$ Flex circuits - enabling$ HDIS - enabling
ENTEK® PLUS
ADVANCED PACKAGINGTECHNOLOGIES
Merix: Meeting in The Winner’s Circle
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$ Reliable alternatives for 25 years$ Essential for high first pass yields
with FPT, BGAs, flip chip$ Future
– OSPs enabling advanced technologies
– Substituted benzimidazoles: high volume, lowcost HASL Alternative
SUMMARY
ENTEK PLUS ®
Merix: Meeting in The Winner’s Circle
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+ Thank you for your input!
$ Advanced packaging technologieswill continue to challenge both PWBmanufacturing, assembly and design$ Surface finishes and their
applications are key to our mutualsuccess