VISHAY SILICONIX Power MOSFETs Application Note 914 "PowerPAK 1212-8", The Proven Automotive Package By Kandarp Pandya INTRODUCTION This application note presents useful information on the PowerPAK 1212-8 to facilitate SQE and design engineers. Vishay introduced the PowerPAK power MOSFET package family in the late 1990s to provide a thermally efficient solution for the computer and telecom markets. PowerPAK’s combination of a small form factor and high power handling capabilities quickly brought industry-wide acceptance in various applications such as dc-to-dc power supplies, point of load, and control actuators. In most such applications, the PowerPAK SO-8 and often the PowerPAK 1212-8 can replace the much larger and bulkier DPAK. The automotive industry embraces a new package type only after a track record has been established and extensive testing has been carried out both by manufacturers and systems engineers. The PowerPAK 1212-8 has undoubtedly won the industry’s acceptance and has been successfully tested for AEC-Q101 compliance. The package has also successfully been tested on a 16-layer PC board assembly for solder joint reliability, passing the temperature cycles, including the re-work, as per IPC 9701 test guidelines. Fig. 1 - PowerPAK 1212-8 Single Fig. 2 - PowerPAK 1212-8 Single and Dual TABLE 1 - PACKAGE COMPARISON PACKAGE PowerPAK 1212-8 SOIC-8 DPAK Document Number: 72146 Revision: 17-May-10 DIMENSION (mm) PCB AREA (mm2) COMPARABLE PART POWER RATING (W) 3.4 x 3.4 x 1.12 11.56 1.5 5.0 x 4.0 x 1.75 20 1.7 10.41 x 6.73 x 2.38 70.06 2.0 www.vishay.com 1 APPLICATION NOTE Automotive designers have ventured to use the PowerPAK 1212-8 in such crucial applications as engine control units (ECU) and fuel injection systems. These applications demand power cycling and some UIS capabilities. PowerPAK’s reliability has likewise encouraged designers to use the PowerPAK 1212-8 to replace die-level implementations, thereby eliminating the associated assembly costs while utilizing well established reflow processes. As of April 2010, more than 5.5 million PowerPAK power MOSFETs had been shipped to Vishay automotive customers worldwide. Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package 0.172 (4.369) 0.152 (3.861) 0.246 (6.248) 0.028 (0.711) 0.047 (1.194) 0.022 (0.559) Fig. 3 - SOIC-8 0.050 (1.270) Fig. 6 - SOIC-8 0.087 (2.202) 0.420 (10.668) 0.243 (6.180) 0.224 (5.690) 0.090 (2.286) Fig. 4 - DPAK RECOMMENDED MINIMUM PADS 0.180 (4.572) 0.152 (3.860) APPLICATION NOTE 0.039 (0.990) Fig. 7 - DPAK (TO-252) 0.068 (1.725) AEC-Q101 COMPLIANCE FOR AUTOMOTIVE APPLICATIONS 0.016 (0.405) 0.010 (0.255) 0.039 (0.990) 0.094 (2.390) 0.039 (0.990) 0.026 (0.660) 0.025 (0.635) 0.030 (0.760) Fig. 5 - PowerPAK 1212-8 Dual www.vishay.com 2 0.055 (1.397) The power temperature cycling test specified by Automotive Electronic Council document AEC Q101 for discrete components is one of the most crucial tests for automotive applications. The test requires temperature cycling of the die with a delta of 100 °C by means of active power dissipation in the die. This process puts severe thermal stresses on the package from the inside out. The solder joints on the PCB assembly must also sustain the thermal stress. PowerPAK 1212-8 was designed to address both these aspects of thermal stress and has thus achieved AEC Q101 qualification as well as passing further DV/PV tests at the automotive electronics design center. The AEC-Q101 qualification test definitions are given in the Document Number: 72146 Revision: 17-May-10 Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package following table: TABLE 2 - QUALIFICATION TEST DEFINITIONS # 10 10 alt STRESS ABRV Intermittent Operational Life Power and Temperature Cycle IOL PTC DATA TYPE 1 1 SAMPLE NOTE SIZE PER LOT DGTU WP DGTU W 77 77 # OF LOTS 1 Note B 1 Note B ACCEPT ON # FAILED 0 0 REFERENCE (CURRENT REVISION ADDITIONAL REQUIREMENTS MIL-STD-750 Method 1037 Tested per duration indicated in Timing Requirements table on Page 13. TA = 25 °C. Devices powered to insure TJ 100 °C (not to exceed absolute maximum ratings). Test before and after IOL as a minimum. JESD22 A-105 Perform PTC if TJ 100 °C cannot be achieved with IOL. Tested per duration indicated for Timing Requirements in Table 2A. Devices powered and chamber cycled to insure TJ 100 °C (not to exceed absolute maximum ratings). Test before and after PTC as a minimum. TABLE 2A - INTERMITTENT OPERATIONAL LIFE (TEST 10) OR POWER TEMP CYCLING (ITEM 10ALT) TIMING REQUIREMENTS PACKAGE TYPE Small (e.g. SMD SOTS thru DPAK, and all LEDs) Medium (e.g. TO-220, D2PAK) Large (e.g. TO-3, TO-247) Leadless Not to exceed: NUMBER OF CYCLES REQUIRED TJ 100 °C NUMBER OF CYCLES REQUIRED TJ 125 °C TIME PER CYCLE 15 000 7500 2 min. on/2 min. off 8572 4286 3.5 min. on/3.5 min. off 6000 3000 5 min. on/5 min. off 60 000/(x+y) 15 000 cycles 30 000/(x+y) 7500 cycles Fastest capable (minimum 2min. on/off) x min. on + y min. off Note • Example 1: A package capable of 2 min. on/4 min. off would require 10 000 cycles [60 000/(2 + 4)] at TJ 100 °C or 5000 cycles at TJ 125 °C • Example 2: A package capable of 1 min. on/1 min. off would require 15 000 cycles at TJ 100 °C or 7500 cycles at TJ 125 °C SOLDER JOINT RELIABILITY ON FR4 PC BOARDS The PowerPAK 1212-8 is qualified for Solder Joint Reliability based on the guidelines stated in IPC 9701. Two separate DOEs were conducted with different third-party vendors for PC board assembly and temperature cycle testing. The first DOE employed simple double-sided. 2-layer FR4 PCB measuring 50 mm x 50 mm x 1.5 mm with 0.076 mm (2 oz.) copper on both sides. A detailed test description is covered in application note AN825 "The Solderability of the PowerPAK SO-8 and PowerPAK 1212-8 when using Document Number: 72146 Revision: 17-May-10 different solder paste and reflow profiles," web link: http://www.vishay.com/docs/72116/72116.pdf. The second DOE used a16-layer FR4 PC board with dimensions of 130 mm x 115 mm x 3.175 mm. Refer to figure 8. This considerable thermal mass subjects the solder joint to considerably severe stress during temperature cycling. Such a PCB design thus covers most of the extreme applications. The layer stack comprised two outer copper layers of 35 μm (1.0 oz.) and 14 inner copper layers of 12 μm (0.5 oz.). Each insulation layer of the FR-4 in between is 231 μm (7709 μin.). Appendix A covers the PCB specifications. For this experiment, an immersion silver board finish was used as per recommendations from external contract manufacturers. www.vishay.com 3 APPLICATION NOTE All Vishay Siliconix automotive grade, AEC-Q101 qualified power MOSFETs are numbered with an SQ prefix, i.e. SQxxx. Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package each part. Refer to figure 10. Fig. 9 - Daisy Chain Layout Pin 1 Fig. 8 - FR4 16-layer PCB Overview of Assembly Process (1) (2) APPLICATION NOTE (3) Lead (Pb)-free and tin-lead solder paste test samples were used: a. Lead (Pb)-free solder paste SAC-387 (Tamura TLF-206-93G) b. Tin-lead (Sn-Pb) no-clean solder paste Sn63-Pb37 (Alpha Metal UP78) A suitable lead (Pb)-free reflow assembly process was developed by multiple experiments involving different parameters such as aperture, stencil thickness, solder paste printing pressure. Also various solder pastes were experimented with to determine suitability of a paste. In addition, a control lot was employed using regular parts and tin-lead (Sn-Pb) solder paste. The latter establishes a base line for comparison. Fig. 10 - Component Modification for Daisy Chain Connection Evenly distribute the samples on 6 PC board. Each PCB consisted of seven PowerPAK 1212-8 dual parts. Thus the 8th loaction on the PBC is unused. Identify and re-work last two parts from the first five PC boards. Total 10 re-worked parts. Re-Work Steps • Removing existing part using hot air BGA re-work station (laboratory setup) IPC 9710 GUIDELINES FOR TEMPERATURE CYCLING TEST FOR SOLDER JOINT RELIABILITY • Clean up pads using soldering iron and de-soldering wick Sample size: 42 pieces of PowerPAK 1212-8 dual • Apply no clean gel flux on pads Test vehicle: PCB designed to connect each pin of a part in a daisy chain and terminated on end connector to facilitate monitoring the daisy chain for each part on an automatic scanner. The PCB design also facilitates isolating each part and remove from the PCB assembly for further analysis, without disturbing the remaining parts’ daisy chains. Refer to figure 9. This DOE involves the part modifications: (a) Dies are dummy - no electrical connections. (b) Place internal bond wire jumpers - shown dotted blue lines - between two consecutive pins in pairs. The later in conjunction with the PCB layout facilitates a single daisy chain connection for • Place fresh component using hot air BGA rework station www.vishay.com 4 • Solder bump pads using a soldering iron and solder wire SAC 305 • Solder the component using hot-air BGA rework station using reflow profile shown in figure 12 DOE Reflow Process Development The goal here is to develop/define a reflow process that can maintain the solder void level = < 20 %. The key variables are solder paste and stencil design - aspect ratio, aperture opening, machine parameters such as solder paste printing speed, pressure etc. All this eventually turns into in-house expertise of the assembly house/contract manufacturers. 2DX and if necessary 5DX x-ray results help narrow down Document Number: 72146 Revision: 17-May-10 Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package the solder paste selection and profile tweaking. Equipment and Material • EKRA E5 solder paste printer • Juki E2060 pick and place machine • BTU Pyramax 98 reflow oven • Agilent 5DX Series 5300 laminography X-ray • Nicolet NXR-1400 transmission X-ray • 30x microscope • Lead (Pb)-free solder paste SAC-387 (Tamura TLF-206-93G) • Tin-lead (Sn-Pb) no-clean solder paste Sn63-Pb37 (Alpha Metal UP78) • 4-mil and 5-mil stencils with a variety of aperture and aspect ratios • Vishay PowerPAK components • Vishay Siliconix PCB version SMD125T16L_Ver C Side A Reflow Profile Definitions • Ramp-to-spike: RTS, figure 11 • Ramp-soak-spike: Reg RSS, figure 12 • Ramp-long-soak-spike: Long RSS, figure 13 • Ramp-soak-spike: Reg RSS for tin-lead (Sn63/Pb37) solder paste, figure 14 Peak temp. 235 °C Time above 220 °C: 30 s Soak time (120 °C to 200 °C): 70 s Fig. 11 - RTS Profile for Lead (Pb)-free Solder Paste Document Number: 72146 Revision: 17-May-10 www.vishay.com 5 APPLICATION NOTE Peak temp. 237 °C Time above 220 °C: 30 s Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package Fig. 12 - RSS Profile for Lead (Pb)-free Solder Paste Peak temp. 235 °C Time above 220 °C: 30 s Soak time (120 °C to 200 °C): 159 s Fig. 13 - LRSS Profile for Lead (Pb)-free Solder Paste Peak temp. 215 °C Time above 183 °C: 54 s Soak time (140 °C to 160 °C): 54 s APPLICATION NOTE Fig. 14 - RSS Profile for Tin Lead (Sn63/Pb37) Solder Paste TABLE 3 - ASSEMBLY PARAMETERS VERSION AA www.vishay.com 6 APERTURE DESIGN COMP TYPE BUILD QTY PROFILE STENCIL THICKNESS SIGNAL (MILS) GROUND PowerPAK 1212D 7 RSS 4 mils 16.8 x 44 Equal to Comp. Document Number: 72146 Revision: 17-May-10 Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package Fig. 16 - Worst Case Soldering Fig. 15 - Best Case Soldering Conclusions and Recommendations of the DOE • • • • The minimum acceptable aspect ratio (smallest aperture opening/stencil thickness) is 2.5 The minimum acceptable area ratio (LxW / 2(L + W)T) is 0.8 The RSS profile shown in figure 12 is recommended for lead (Pb)-free solder paste The RSS profile shown in figure 14 is recommended for tin-lead solder paste PHASE II SOLDER JOINT RELIABILITY STUDY Temperature Cycling • 3000 cycles of 0 °C to 100 °C temp. cycling with event recording for Daisy-Chain solder joint 19:35 19:30 19:25 19:20 19:15 19:10 19:05 19:00 18:55 18:50 18:45 18:40 TC 15 Time Vishay PCB A IPC9701 Cycling Solderability Data • Status • 3000 Temp. cycles completed • Statistics 0/100 40 min cycle PACKAGE PPAK 1212D Document Number: 72146 Revision: 17-May-10 FIRST FAIL # FAILED % FAILED SOLDER 0 0% Lead-free www.vishay.com 7 APPLICATION NOTE 120 110 100 90 80 70 60 50 40 30 20 10 0 - 10 - 20 18:35 °C Vishay board # 1 0 °C to 100°C 10 min. ramp and 10 min. dwell Application Note 914 Vishay Siliconix APPLICATION NOTE "PowerPAK 1212-8", The Proven Automotive Package SLOT # BOARD # PACKAGE PCB DES. PCB SIDE SITE ID NET # 7 1 PowerPAK 1212D A Front U1 97 7 1 PowerPAK 1212D A Front U2 98 7 1 PowerPAK 1212D A Front U3 99 7 1 PowerPAK 1212D A Front U4 100 7 1 PowerPAK 1212D A Front U5 101 7 1 PowerPAK 1212D A Front U6 102 7 1 PowerPAK 1212D A Front U7 103 7 1 N/A A Front U8 104 8 2 PowerPAK 1212D A Front U1 113 8 2 PowerPAK 1212D A Front U2 114 8 2 PowerPAK 1212D A Front U3 115 8 2 PowerPAK 1212D A Front U4 116 8 2 PowerPAK 1212D A Front U5 117 8 2 PowerPAK 1212D A Front U6 118 8 2 PowerPAK 1212D A Front U7 119 8 2 N/A A Front U8 120 9 3 PowerPAK 1212D A Front U1 129 9 3 PowerPAK 1212D A Front U2 130 9 3 PowerPAK 1212D A Front U3 131 9 3 PowerPAK 1212D A Front U4 132 9 3 PowerPAK 1212D A Front U5 133 9 3 PowerPAK 1212D A Front U6 134 9 3 PowerPAK 1212D A Front U7 135 9 3 N/A A Front U8 136 10 4 PowerPAK 1212D A Front U1 145 10 4 PowerPAK 1212D A Front U2 146 10 4 PowerPAK 1212D A Front U3 147 10 4 PowerPAK 1212D A Front U4 148 10 4 PowerPAK 1212D A Front U5 149 10 4 PowerPAK 1212D A Front U6 150 10 4 PowerPAK 1212D A Front U7 151 10 4 N/A A Front U8 152 11 5 PowerPAK 1212D A Front U1 161 11 5 PowerPAK 1212D A Front U2 162 11 5 PowerPAK 1212D A Front U3 163 11 5 PowerPAK 1212D A Front U4 164 11 5 PowerPAK 1212D A Front U5 165 11 5 PowerPAK 1212D A Front U6 166 11 5 PowerPAK 1212D A Front U7 167 11 5 N/A A Front U8 168 12 6 PowerPAK 1212D A Front U1 177 12 6 PowerPAK 1212D A Front U2 178 12 6 PowerPAK 1212D A Front U3 179 12 6 PowerPAK 1212D A Front U4 180 12 6 PowerPAK 1212D A Front U5 181 12 6 PowerPAK 1212D A Front U6 182 12 6 PowerPAK 1212D A Front U7 183 12 6 N/A A Front U8 184 www.vishay.com 8 FAIL CYCLE N/A N/A N/A N/A N/A N/A Document Number: 72146 Revision: 17-May-10 Application Note 914 Vishay Siliconix "PowerPAK 1212-8", The Proven Automotive Package Summary • PowerPAK 1212 can replace the SOIC-8 and DPAK in applications requiring power dissipation up to 1.5 W. • AEC-Q101 qualification proves the demanded by automotive applications. ruggedness • IPC-9701 qualification establishes solderability, both for the simple two-layer PCB described in the application note AN825 and in the toughest board design described in the DOE above. • The purpose of the DOE is to exemplify a successful assembly for a given PCB board assembly and manufacturing process. However, these simple guidelines can be used for developing the pad designs, solder profiles, aperture design and other manufacturing process parameters for successful reflow assembly of PowerPAK 1212-8 package in other PC board designs. However, we should note that each individual assembly may necessitate parameter tweaking to match the assembly house set-up. The assembly house internal expertise usually evolves the suitable process. www.vishay.com 9 APPLICATION NOTE Document Number: 72146 Revision: 17-May-10