目前有高密度零件設計問題在探討，以上為找到的相關的法規，再請各位先進確認手邊是否有這兩個法規資料可提供參考 (IPC-4671 for via on pad , IPC-7315B for pad design)，因為設計的建議也關於到PCB製程至數以及我方PCB板厚要求，請教是否有其他的設計驗證法規或手法來確認 PCBA 組裝後，驗證製程組裝 or PCB 來料 可靠度是符合高密度零件設計。
IPC 4761_2006, Design Guide for Protection of Printed Board Via Structures
May be seen at Website: https://docs.google.com/viewer?url=http%3A%2F%2Fhitech.com.mk%2FResources%2FDocuments%2FIPC-4761.pdf
3.4 Long-Term Reliabiity Concern
Single-sided via protection (Types I-1, II-a, and III-a) should not be used with bare copper hole walls. Any attempt to apply a surface finish to a hole wall that is not protected by the plug maerial resulting from a partial penetration into the via will result in a bare copper area at the plug material/hole barrel interface. This bare copper area will be attacked by any chemicals entrapped within the hole during board fabrication, as well as those trapped during assembly process (the partial plug process may have gaps between the plug material and the hole wall allowing entrapment of chemicals). The resulting contamination can combine with moisture and corrode the thickness of the hole wall plating to a degree where the plating is no longer able to withstand the stresses of operating temperature common in assembly processes as shown in Figure 3-5. Final finishes should be applied prior to pluging.
發表於 2013-5-16 09:50:11
分享
收藏
分享
發表於 2013-5-18 07:52:53