Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness...Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness,diameter and shape on current density and temperate distributions were investigated respectively.It was found that pads with larger thickness or/and diameter could reduce current density and temperature in solder bump significantly.Pad shapes affected the current density and temperature distributions in solder bumps.The relatively low current density and temperature didn＇t occur in the bump joint with traditional rounded pad but occurred in bump joints with octagonal and nonagonal pads respectively.Therefore,optimized pad geometry may be designed to alleviate the current crowding effect and reduce the bump temperature,and therefore delay electromigration failure and increase the mean-time-to-failure.展开更多
Solder bump technology has been widely used in electronic packaging. With the development of solder bumps towards higher density and finer pitch, it is more difficult to inspect the defects of solder bumps as they are...Solder bump technology has been widely used in electronic packaging. With the development of solder bumps towards higher density and finer pitch, it is more difficult to inspect the defects of solder bumps as they are hidden in the package. A nondestructive method using the transient active thermography has been proposed to inspect the defects of a solder bump, and we aim at developing an intelligent diagnosis system to eliminate the influence of emissivity unevenness and non-uniform heating on defects recognition in active infrared testing. An improved fuzzy c-means(FCM) algorithm based on the entropy weights is investigated in this paper. The captured thermograms are preprocessed to enhance the thermal contrast between the defective and good bumps. Hot spots corresponding to 16 solder bumps are segmented from the thermal images. The statistical features are calculated and selected appropriately to characterize the status of solder bumps in FCM clustering. The missing bump is identified in the FCM result, which is also validated by the principle component analysis. The intelligent diagnosis system using FCM algorithm with the entropy weights is effective for defects recognition in electronic packages.展开更多
This paper describes a technique that can obtain ternary Sn-Ag-In solder bumps with fine pitch and homogenous composition distribution.The main feature of this process is that tin-silver and indium are electroplated o...This paper describes a technique that can obtain ternary Sn-Ag-In solder bumps with fine pitch and homogenous composition distribution.The main feature of this process is that tin-silver and indium are electroplated on copper under bump metallization（UBM） in sequence.After an accurate reflow process,Sn_（1.8）Ag_（9.4）In solder bumps are obtained.It is found that the intermetallic compounds（IMCs） between Sn-Ag-In solder and Cu grow with the reflow time,which results in an increase in Ag concentration in the solder area.So during solidification, more Ag_2In nucleates and strengthens the solder.展开更多
Solder bumps are widely used in surface mount components, which provide electrical and mechanical connection between the chip/package and the substrate. As the solder bump getting smaller in dimension and pitch, it be...Solder bumps are widely used in surface mount components, which provide electrical and mechanical connection between the chip/package and the substrate. As the solder bump getting smaller in dimension and pitch, it becomes more difficult to inspect the solder defects hidden in the IC package. In this paper, an intelligent inspection method using the scanning acoustic microscopy(SAM) and the fuzzy C-means(FCM) algorithm was investigated. A flip chip package of FA10 was chosen as the test sample. The SAM tests of FA10 were carried out in C-scan mode. The sub-image of every solder bump was segmented from the SAM image. The statistical features were then calculated and adopted for clustering of solder bumps using the FCM algorithm. The recognition results of FCM reached a high accuracy of 94.3%. The intelligent system is effective for defect inspection in high density packages.展开更多
文摘Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness,diameter and shape on current density and temperate distributions were investigated respectively.It was found that pads with larger thickness or/and diameter could reduce current density and temperature in solder bump significantly.Pad shapes affected the current density and temperature distributions in solder bumps.The relatively low current density and temperature didn＇t occur in the bump joint with traditional rounded pad but occurred in bump joints with octagonal and nonagonal pads respectively.Therefore,optimized pad geometry may be designed to alleviate the current crowding effect and reduce the bump temperature,and therefore delay electromigration failure and increase the mean-time-to-failure.
基金supported by the National Natural Science Foundation of China(Grant Nos.51305179&51305177)the Natural Science Foundation of Jiangsu Higher Education Institutions(Grant No.13KJB510009)
文摘Solder bump technology has been widely used in electronic packaging. With the development of solder bumps towards higher density and finer pitch, it is more difficult to inspect the defects of solder bumps as they are hidden in the package. A nondestructive method using the transient active thermography has been proposed to inspect the defects of a solder bump, and we aim at developing an intelligent diagnosis system to eliminate the influence of emissivity unevenness and non-uniform heating on defects recognition in active infrared testing. An improved fuzzy c-means(FCM) algorithm based on the entropy weights is investigated in this paper. The captured thermograms are preprocessed to enhance the thermal contrast between the defective and good bumps. Hot spots corresponding to 16 solder bumps are segmented from the thermal images. The statistical features are calculated and selected appropriately to characterize the status of solder bumps in FCM clustering. The missing bump is identified in the FCM result, which is also validated by the principle component analysis. The intelligent diagnosis system using FCM algorithm with the entropy weights is effective for defects recognition in electronic packages.
文摘This paper describes a technique that can obtain ternary Sn-Ag-In solder bumps with fine pitch and homogenous composition distribution.The main feature of this process is that tin-silver and indium are electroplated on copper under bump metallization（UBM） in sequence.After an accurate reflow process,Sn_（1.8）Ag_（9.4）In solder bumps are obtained.It is found that the intermetallic compounds（IMCs） between Sn-Ag-In solder and Cu grow with the reflow time,which results in an increase in Ag concentration in the solder area.So during solidification, more Ag_2In nucleates and strengthens the solder.
基金supported by the National Natural Science Foundation of China(Grant Nos.51675250&51705203)the Natural Science Foundation of Jiangsu Province(Grant No.BK20160183)the Open Foundation of State Key Lab of Digital Manufacturing Equipment&Technology(Grant No.DMETKF2016005)
文摘Solder bumps are widely used in surface mount components, which provide electrical and mechanical connection between the chip/package and the substrate. As the solder bump getting smaller in dimension and pitch, it becomes more difficult to inspect the solder defects hidden in the IC package. In this paper, an intelligent inspection method using the scanning acoustic microscopy(SAM) and the fuzzy C-means(FCM) algorithm was investigated. A flip chip package of FA10 was chosen as the test sample. The SAM tests of FA10 were carried out in C-scan mode. The sub-image of every solder bump was segmented from the SAM image. The statistical features were then calculated and adopted for clustering of solder bumps using the FCM algorithm. The recognition results of FCM reached a high accuracy of 94.3%. The intelligent system is effective for defect inspection in high density packages.
