Leiterplattenoberflächen im Fokus

Transcription

1 Leiterplattenoberflächen im Fokus Auswahl der besten technischen und kommerziellen Lösung für Ihre Anwendung Hubert Haidinger Director PE/CAM BU Industrial & Automotive 28. Februar Austria Technologie & Systemtechnik Aktiengesellschaft Fabriksgasse13 A-8700 Leoben Tel +43 (0)

2 Requirements for the PCB surface Major Decision drivers Application? Shelf Life? Rework? Solderability? Cost? Wire Bond process? Mechanical Requirements? 1

3 Agenda Requirements for the PCB Surface Which surfaces are available? Cost of surfaces & Cost Driver Environmental & Recycling Surface Recommendations from AT&S 2

4 Surface finish - OSP Widely used surface finish for all kinds of products +Easy and cheap process +Even surface +Very well known +Very robust solder joint -More assembly issues due to LF requirements -Not suitable for wire bonding or contact pads -Inspection Thickness: Thin ones (one solder step) 0,1µm; normal ones 0,2µm to 0,5 µm 3

5 Surface finish - HAL Very common surface finish for automotive and industrial applications +Very cheap and easy process +Very reliable +Very easy to solder +Shelf life +Less problems -Uneven surface (thickness range from 1to 40 micrometer) -Thermal shock for PCB -Environmental issues (Lead Free) -Not suitable for small design and contact pads or wire bonding Thickness: HAL on pad 1 40 µm, edge of holes should be covered 4

6 Surface finish Immersion Tin More and more common surface finish for industrial and automotive applications (replacement for HAL) +Very even surface +Good solderjoint reliability +Lead free +Easy to solder +Perfect for pin in or press fit -Complex and expensive process -Aggressive chemistry (attacks soldermask) -Sensitive to contamination -Not suitable for contact pads Thickness: 0,8 to 1,2 µm; For LF applications 1,0 to 1,4 µm is prevered) 5

7 Surface finish Immersion Silver Used for industrial and automotive applications (North America) +Very even surface +Easy process (compared to ENIG+Imm Tin) +Good solderjoint reliability +Easy to solder +Lead free +Not aggressive process +Suitable for wire bonding -Risk of tarnishing (must be packed within short time) -Sensitive to sulfur -Not suitable for contact pads -Studies show that there is the risk of migration, especially in the precence of copper Thickness: 0,15 to 0,4µm 6

8 Surface finish - ENIG Very popular surface finishing for all kinds of PCB (industrial, automotive, telecom application) +Even surface +Reworkable (solderpaste misprinting) +Long storage time + Easy to solder +Multi reflow approved +Can be used for wire bonding +For soldering and contact pads -High process costs (Chemistry and long cycle time) -Process is very complex -Ni-Corrosion/Black pad -Risk of brittle solder joint (Too much Au in solder, P content, ) -For small BGAs solderjoint reliability is lower as on other surfaces Thickness: Ni thickness normally 3 6 µm, Au thickness 0,05 to 0,12 µm 7

9 Available surfaces Surface Soldering AL Wire Bondable Gold Wire Bondable Mechanical Strength OSP Yes No No Pure ( Copper ) Carbon No No No High & Reliable ( new Ink types ) HAL SNPB Yes No No Pure HAL Pb-free Yes No No Pure Imm. Sn Yes No No Pure ( 1µm ) Imm. Au Yes Yes No Ok ( Low Gold Layer ) Imm.Ag Yes Yes Yes Pure ENEPIG Yes Yes Yes OK ( Low Gold Layer ) Electrolytic Ni/Au No Yes No High Very Reliable ( Edge Connector ) Electrolytic Sn Yes No No Pure Electrolytic Soft Gold Immersion Soft Gold Yes ( but Risk ) Yes Yes Yes ( but Risk ) Yes Yes Ok ( higher Layer of Gold ) OOk ( higher Layer of Gold ) 8

10 Agenda Requirements for the PCB Surface Which surfaces are available? Cost of surfaces & Cost Driver Environmental & Recycling Surface Recommendations from AT&S 9

11 Cost of surfaces & Cost Driver 10

12 Cost of surfaces & Cost Driver Cost based on a 2 Layer PTH PCB with Format 160 mm x 100 mm 1,55 mm / 18 µm Copper 240% 220% 200% 180% 160% 140% 120% 100% 80% OSP HAL ( Lead Free ) Immersion Tin 1 µm ENIG ENEPIG ENIG + Plated Gold 11

13 Agenda Requirements for the PCB Surface Which surfaces are available? Cost of surfaces & Cost Driver Environmental & Recycling Surface Recommendations from AT&S 12

14 Environmental & Recycling Information Surface Energy [kwh/m²] Water consumption [l/m²] Potential Risk Recycling OSP 1 23 No significant Risk No Imm. Ag 3 0,02 HAL Pb-frei 5 19 Imm. Au 7 0,04 Imm. Sn No significant Risk No significant Risk Kaliumgoldcyanid high Risk for the employee high security and control Monitoring needed No significant Risk Silver recycling internal Tin from the process is recycled and reused Gold Bath and rinse water are external recyled No ENEPIG 18 0,11 Kaliumgoldcyanid high Risk for the employee high security and control Monitoring needed Gold is recyled external Galv. Ni/Au Kaliumgoldcyanid same as Imm.Au Nickelchlorid /-sulfat: Risk for cancer High security needed and regular medical examination Gold is recyled external 13

15 Agenda Requirements for the PCB Surface Which surfaces are available? Cost of surfaces & Cost Driver Environmental & Recycling Surface Recommendations from AT&S 14

16 Guideline for Industrial and Automotive Area Immersion Tin displays a very good choice for many applications in Industrial and Automotive ENIG is loosing Ground to Cost reasons For improved drop-test performance OSP is the most favourable surface ENEPIG was developed further and displays now a real Universal Finish that fulfills also the demand for no bond failures. 15

17 However your the needs of your specific application defines the right surface Surface Pros Cons OSP Organic Surface Preservative ENIG Electroless Nickel Immersion Gold Cheap, good joint integrity, easy to apply Best Solder ability, good joint integrity, multiple reflow possible Poor solder wetability No testing through OSP possible Cost intensive, failure black-pads Poor resistivity against SO 2 ENEPIG Electroless Nickel Electroless Palladium Immersion Gold Silver Similar to ENIG, additional feature: bonding is possible Simple application, multiple application possible, mixed finishes possible Cost intensive, failure black-pads Poor resistivity against SO 2 Mid range solder ability, poor joint integrity, risk of silver voids Tin Good solder joint, good prize Mid range joint integrity, discoloration, no multiple reflow possible 16

18 AT&S Well Positioned for the Future