Baking from 24hrs change to 16hrs Reliability plan
各位前輩先進好~如果有Module(長29.5mm*寬22.0mm) Baking要從24hrs變更到16hrs,可靠度實驗要如何設計?要怎麼做?
Module相關的資訊如下:
1.The MSL of module is level 4 (Reference Document : IPC-JEDEC J-STD-033).
2.The baking temperature is 125ºC for 24hours or 60ºC for 13 days.
3.The allowable time period, after removal from a moisture barrier bag and before the solder reflows process, for a moisture-sensitive device to be exposed to a factory ambient not exceeding 30°C and 60% RH.
4.After the PCB is baked, it will be expired after 72 hours. Do the SMT process within 48 hours after baking is the best condition.
以上懇請多多指教~Thanks a lot.
Using Kelvin for baking Temp., by Arrhenius rule:)
1. AF1 =13 = exp; ==> Ea = 0.451
2. AF2 = 24/16 =1.5 = exp; ==> Tacc = 410.6 K = 137.6 C 本帖最後由 hlperng 於 2013-3-28 20:25 編輯 <br /><br /><div><b>J-STD-020, <span style="line-height: 1.5;">Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices</span></b></div><div>5.4 Bake. Bake the sampe for 24 hours minimum at 125 +5/-0 °C. This step is intended to remove moisture from the package so that it will be "dry".</div><div><br></div><div>Table 5-1 Moisture Sensitivity Level. ... </div><div>Level 4: Floor Life = 72 hours @ ≤ 30 °C/60 %RH. ⇒ Test @ 30 °C/60 %RH for 96 hours or Test @ 60 °C/60 %RH for 20 hours (Ea=0.40 eV ~ 0.48 eV) or 24 hours (Ea=0.30 eV ~ 0.39 eV) </div><div>72 hours = 96 hours - 24 hours (MET)</div><div>MET = Semiconductor Manufacturer's Time. Default MET = 24 hours. </div><div><br></div><div>Note 1. ... Alternatively, if the known activation energy for moisture diffusion of the package materials is in the range of 0.40 eV ~ 0.48 eV or 0.30 eV ~ 0.39 eV, the "acceleration equivalent" may be used. ...</div><div><br></div><div><ul><li><span style="line-height: 1.5;">0.40 eV ~ 0.48 eV ⇒ </span><span style="line-height: 1.5;">0.445 eV</span></li><li><span style="line-height: 1.5;">0.30 eV ~ 0.39 eV ⇒ 0</span><span style="line-height: 1.5;">.35 eV</span></li></ul></div><div><br></div><div><br></div><div><b>J-STD-033, Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices</b></div><div>4. Drying</div><div>Table 4-1, 4-2 and 4-3 give reference conditons for drying SMD packages. Table 4-1 gives conditions for rebake of SMD packages at a user site after the floor life has expired or other conditions have occurred to indicate excess moisture exposure. </div><div><br></div><div>Package Body Thickness determines the Bake Conditions. (Bake Temperature and corresponding bake time)</div><div><br></div><div>For MSL=4, </div><div>If Thickness ≤ 1.4 mm, Bake @ 125 °C for 11 hours (Floor Life > 72 hours) or 7 hours (Floor Life ≤ 72 hours); or Bake @ 90 °C ≤ 5 %RH for 37 hours (Floor Life > 72 hours) or 23 hours (Floor Life ≤ 72 hours); or Bake @ 40 °C ≤ 5 %RH for 15 days (FLoor Life > 72 hours) or 9 days (Floor Life ≤ 72 hours)</div><div>For Thickness >1.4 mm and ≤ 2.0 mm, Thickness > 2.0 mm and ≤ 4.5 mm, and BGA Package > 17 mm x 17 mm or any stacked die package, See Table 4-1. </div><div><br></div><div>4.2.7.1 Oxidation Risk. </div><div>... Unless otherwise indicated by the supplier, the cumulative bake time at a temperature greater than 90 °C and up to 125 °C shall not exceed 96 hours. ... Bake temperatures higher than 125 °C are not allowed without consulting the supplier.</div><div><br></div><div>7. Derating due to Factory Environmental Conditions</div><div>...</div><div>1. Activation Energy for Diffusion Ea= 0.35 eV (smallest known value) (NOTE. <span style="line-height: 1.5;">濕度擴散的活化能FIDES建議值為0.90 eV。)</span></div><div>2. For ≤ 60 %RH, use Diffusivity = 0.121 exp ( - 0.35/KT) mm2<span style="line-height: 1.5;">/s (this uses smallest known Diffusivity @ 30 °C)</span></div><div><span style="line-height: 1.5;">3. For ≥ 60 %RH, use Diffusivity =1.320 exp ( - 0.35/KT) mm</span><span style="line-height: 1.5;">2/s (this uses largest known Diffusivity @ 30 °C)</span></div><div><br></div><div><br></div><div>Appendix B.</div><div>...</div><div>2. Diffiusivity = 6.2 exp (- 0.445 /KT) ⇐ Ea = 0.445 eV</div><div><br></div><div><br></div><div><br></div>參考資料：<ul type="1" class="litype_1"><li><a href="http://www.jedec.org/sites/default/files/docs/jstd020d-01.pdf">J-STD-020D.1</a>, Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices, 2008.</li><li><a href="http://desco.descoindustries.com/pdf/JEDEC_Jstd033b.pdf" target="_blank">J-STD-033B</a>, Handling, Packaging, Shipping and Ues of Moisture / Reflow Sensitive Surface Mount Devices, 2005.</li><li>R.L. Shook and J.P. Goodelle, <a href="http://www.aecouncil.com/Papers/aec8.pdf" target="_blank">Handling of Highly-Moisture Sensitive Components - An Analysis of Low-Humidity Containment and Baking Schedules</a>, ECTC, 1999, pp. 809-15. Paper Referenced in Appendix B of J-STD-033. <br></li></ul><br>
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