Park/Nelco N4000-11 Next Generation High Tg FR-4
Changing Industry Needs Improved CAF resistance Less than 20% resin recession after solder cycles Improved IST cycling performance and consistency -45°C to +125°C liquid to liquid cycling Low wicking / crazing (<2 mil wicking) 6X or higher solder floats Lead-free assembly tolerance Lower Z-CTE Ability to fill buried vias Processing attributes similar to current high-Tg FR-4 Lower cost (to the fabricator and OEM) Minimum 160°C Tg TMA
Next Generation High-Tg FR-4 Product Development Targets Robust in lead free assembly environments CAF resistant Superior to conventional high-Tg FR-4 in all thermal resistance tests (T260, T288, solder float, PCSD) Lower Z–CTE than existing high-Tg FR-4 Better moisture resistance than existing FR-4 systems Little or no degradation in processing attributes (compared to conventional high-Tg FR-4) No added cost of utilization for fabricators Cure cycle comparable to existing high-Tg FR-4
Phenolic Cure Resin System Advantages Reduced moisture sensitivity A factor in thermal performance Improves CAF resistance Improved thermal reliability Better IST, T260, T288 even though Tg is not significantly different. Lower Z-Axis CTE DICY curing agent suspected as a contributor to electromigration (CAF) Faster curing
DICY vs. Phenolic Curing Agents Investigated in response to customer / industry needs Higher cross link density Improved chemical and thermal resistance Decreased latency of cure Faster cure Narrow resin flow window Short prepreg shelf life Dicyandiamide (DICY) Conventional curing agent for FR-4 resin systems Inherent latency of cure Wide resin flow window Excellent shelf life Efficient removal of air from package Excellent thickness control DND
N4000-11 Product Summary Fully commercialized product FR-4 epoxy laminate and prepreg system Filled dielectric Superior thermal performance Low Z-Axis expansion rate Superior moisture resistance PCSD Wet relamination tolerance Outstanding performance in lead free assembly CAF resistant (> 750 hours) UL recognition under Nelco FR-4 family Available through NY, CA, and Singapore business units No plans to obsolete N4000-6 and N4000-6 FC
N4000-11 Property Comparison
N4000-11 Property Comparison
N4000-11 Prepreg Rheology
Tg as a Function of Cure Time Tg by DSC, N4000-11 170 175 180 185 190 195 200 50 100 150 250 Time at Cure Temperature (182 °C) Tg
N4000-11 Prepreg Aging Study Prepreg Tests 0 mo 1 mo 2 mo 3.5 mo 5 mo Gel / M.V. 87 / 0.9 83 / 0.6 85 / 0.5 83 / 0.8 83 / 0.5 87 / 0.6 TgI (30 min) 175ºC 176ºC 188ºC 182ºC N/A T260 35 min 42 min 36 min 29 min Pressure Cooker SD 0.3% 800 sec. 0.25% 650 sec. 570 sec. 0.27% 560 sec 0.30 % 570 sec Panel Appearance Normal Prepreg storage conditions: 66ºF (24ºC) and 44% RH Test laminate produced with 8 ply 7628 construction and N4000-6 FC press cycle
N4000-11 Dk vs. Resin Content
Resin Recession After Thermal Shock Sample N4000-6 FC N4000-11 Comments Production material Treater run material 1080 with ~50% RC Roll # C08012-02A B28091-04A Resin Recession after 3x20 sec Solder Shock >15% 0 % Resin Recession after 5x20 sec Solder Shock Resin Recession after 10x20 sec Solder Shock >50%, de-lamination <15%
Residual Moisture Tolerance
Residual Moisture Tolerance Processing Conditions N4000-6 FC Laminate Cycle Copper Etch Photo-resist Strip Alternative Oxide Conditioning Re-lamination Conditions = 60 min at 360°F (182 °C) with 10 °F (5.5 °C)/min Heat Rise Product N4000-11 Conditioning Ambient 24 h 75 °F / 75 RH, 24 h IPC TgI / TgU (w/o cu-pad), °C 172.1 / 172.9 170.0 / 172.1 IPC TgI / TgU (w/ cu-pad), °C 173.2 / 177.6 177.6 / 182.2 T-260 (w/o cu-pad), °C 26.4 25.5 T-260 (w/ cu-pad), °C 13.1 13.3
N4000-11 Heavy Innerlayer Cu Fill Capability 12 Layer Board with 4 oz. Cu innerlayers 6x Solder Float at 288oC Dark field photos at 100X No cracks or delamination
N4000-11 CAF Resistance N4000-11 @ 85 C / 85 % RH / 100 volt bias using Sun TV 1 vehicle at 10.4 mil min. via to via spacing
Samples Tested at 2.25 Gbs / sec. N4000-11 Eye Pattern Testing N4000-6 N4000-11 Samples Tested at 2.25 Gbs / sec.
Samples Tested at 5.0 Gbs / sec. N4000-11 Eye Pattern Testing N4000-6 N4000-11 Samples Tested at 5.0 Gbs / sec.
Samples Tested at 12.5 Gbs / sec. N4000-11 Eye Pattern Testing N4000-6 N4000-11 Samples Tested at 12.5 Gbs / sec.
PWB Processing Oxide Processing Lamination Drilling Desmearing No known issues with any commercial oxides or oxide alternatives Lamination Standard high-Tg FR-4 lamination process 60-70 minutes at 182 oC(360°F)cure Drilling Standard chiploads for high-Tg epoxy Maximum 1.5 mil chipload recommended Desmearing Standard permanganate or plasma desmear chemistries Resin attack rates approx. 20% lower than conventional FR-4
N4000-11 Test Site Evaluation Results 22-layer production part # Processing parameters (lamination, drilling, plating, etc.) identical to conventional high-Tg FR-4 Technical results Tg (DSC) > 180°C (356 °F) T260 = 46 min., T288 = 7.3 min. Passed 6 x 10 sec. solder float with 0 % resin recession and 10 x 10 sec. solder float with 6.6 % resin recession No voids, no dryness, hole wall roughness <0.2 mil Peel strength lower than N4000-6 FC materials
N4000-11 Thermal Shock Testing As Received After 6 x 10 sec. Solder After 10 x 10 sec. Solder
N4000-11 Test Site Evaluation Results 22-layer prototype part # Final board thickness of 0.180” (4.5 mm) Test evaluation of pad lifting, resin recession, and z-axis expansion N4000-7 used as outer prepreg layer for pad lifting comparison Processing parameters (lamination, drilling, plating, etc.) as per N4000-11 processing guidelines Direct comparison with competitive non-dicy cured material
Thermal Property Comparison Parameter / Sample N4000-11 N4000-11 / -7 N4000-6 FC Competitor # I Tg by DSC, TgI/IPC-TgU, °C 172.3 / 177.7 154, 172 / 144,176.7 176.5 / 173.9 181 / 183 TMA, Tg, °C 169.9 168.1 162.7 167.2 Z-CTE (50-260) 3.5% 3.7% 4.1% 4.2% T260, min 19.9 18.2 0.6 >30 DND
Pad Lifting Comparison
Resin Recession Testing
Lead Free Assembly Resin system TMA N4000-6 Finished PWB N4000-11 After Cu Plating ** T245 24.46 minutes 62.03 minutes 83.69 minutes T260 6.63 minutes 20.09 minutes 28.19 minutes T288 Delam before 288°C 2.97 minutes 3.40 minutes **Note – Results are for inner layers with full bare oxide Cu surface. DND
ITRI IST Testing Lead and Lead Free Assembly 24 Layer board, OSP finish 3 Laminate suppliers, x 2 materials each 2 Mini Panels (12 IST coupons) of each material processed through SMT reflow Tin/Lead reflow at 220 °C (428 °F) peak Lead-Free reflow at 255 °C (490 °F) peak Resistance read before and after each reflow process IST test vehicles cycled to failure
CDF vs. Cycles to Failure for 6x220C
CDF vs. Cycles to Failure 6x255C
Nelco IST Testing Lead Free Assembly Compatibility 22 layer PTH/Post generic test vehicle HASL final finish 0.120” (3.0 mm) thick min. 0.015” (0.38 mm) vias single ply 2116 construction (53% resin content) Three resin systems compared for; Tin/Lead reflow at 220 °C (428 °F) peak Lead-Free reflow at 255 °C (490 °F) peak Low mean Cu plating thickness in barrel 0.0006” - 0.0009” (0.015 – 0.022 mm) IST test vehicles cycled to failure
IST Test Summary Coupon Design Test Condition N4000-11 N4000-6 FC .015” vias / .040” grid As Received 390 615 374 3X @ 220 C 500 485 408 3X @ 255 C 440 574 3X NEMI SMT 580 647 401
Siemens Level C Automotive Qualification 1000 hours of preconditioning at 140 oC (284 °F) 1038 thermal cycles from -45 oC to +140 oC (-49 °F to 284 °F) Pass criteria: less than one decade resistance change All N4000-11 coupons passed
N4000-11 Attributes Highly thermally resistant high-Tg FR-4 Phenolic cure resin chemistry Slightly lower gel time and MV than traditional Dicy cured systems Higher Crosslink Density than N4000-6 (FC) Higher ∆Tg due to advancing cure Difficult to use Nelco ∆Tg test as a measure of degree of cure Product Tg can be ‘tuned’ by varying relamination conditions Target 175-185°C Tg (DSC) to meet 165°C TMA
N4000-11 Attributes Dramatically lower susceptibility to the effects of moisture inclusion No Tg suppression Stable T260 and PCSD Ability to hit minimum Tg values greatly enhanced compared to N4000-6 FC Material attributes are consistent after 170°C Tg by DSC Advanced cure may degrade drill results (>190°C DSC, internal test results indicate no change) More susceptible to hole roughness at high chip loads Chip loads >1.5 not recommended
N4000-11 Attributes Material has a slightly greater tendency to craze than N4000-6 (FC) Wicking is much better than N4000-6 FC <1 mil vs. >2 mils for N4000-6 FC Resin attack during desmear slightly lower than N4000-6 FC E/Cu deposition rate slightly lower than N4000-6 FC Z-CTE is very low (3.2% vs. 3.8-4.0% for N4000-6) Resin recession very low (<7% after 10x solder shock) Peel Strength is lower than traditional Dicy cured FR-4 systems N4000-7 outer layers to minimize pad lifting Investigating alternate Cu foils to improve adhesion
N4000-11 NFC Technology Attributes Product Enhancement for HDI Applications Greatly improved X / Y dimensional stability Improved curling characteristics, particularly in asymmetric constructions Improved dielectric breakdown performance Tighter thickness tolerance for ultra thin core Smoother surface finish Possible improvement in CAF resistance
N4000-11 NFC Dimensional Stability DND
N4000-11 Technical Data Most data available on line www.parknelco.com Users can register as a “web customer” Web customers have a unique password Web customers can access all data such as MSDS, processing guidelines and technical data as it becomes available Designers corner