Superior Drop Test Performance of BGA Assembly Using SAC105Ti Solder Sphere

2012 ◽  
Vol 2012 (1) ◽  
pp. 000829-000843
Author(s):  
Weiping Liu ◽  
Ning-Cheng Lee ◽  
Simin Bagheri ◽  
Polina Snugovesky ◽  
Jason Bragg ◽  
...  
Keyword(s):  
Test Performance ◽  
Electrical Response ◽  
Threshold Value ◽  
Drop Test ◽  
Data Sets ◽  
Solder Paste ◽  
Partial Fracture ◽  
Pasty Range ◽  
Reflow Temperature ◽  
Complete Fracture

Board-level drop test performance was evaluated and compared for the following four different solder combinations in BGA/CSP assembly: 1) SnPb paste with SnPb balls, 2) SnPb paste with SAC105Ti balls, 3) SAC305 paste with SAC105Ti balls, and 4) SAC305 paste with SAC105 balls. Presence of Ti improved the drop test performance significantly, despite the voiding side effect caused by its oxidation tendency. It is anticipated that the voiding can be prevented with the development of a more oxidation resistant flux. The consistently poor drop test performance of 105Ti/SnPb is caused by the wide pasty range resulted from mixing SAC105 with Sn63 solder paste. The effect of Ti in this system is overshadowed by the high voiding outcome due to this wide pasty range material. In view of this, use of SAC105 BGA with SnPb solder paste is not recommended, with or without Ti addition. High reflow temperature drove fracture shift to interface at package side, presumably through building up IMC thickness beyond the threshold value. A lower reflow temperature is recommended. Electrical response is consistent with complete fracture data. But, complete fracture trend is inconsistent with that of partial fracture trend, and neither data can provide a full understanding about the failure mode. By integrating complete fracture and partial fracture into “Virtual Fracture”, the failure mechanism becomes obvious and data sets become consistent with each other.

Voiding and Reliability of Assembly of BGA with SAC and 57Bi42Sn1Ag Alloys

2013 ◽  
Vol 2013 (1) ◽  
pp. 000128-000139 ◽  
Author(s):  
Yan Liu ◽  
Joanna Keck ◽  
Erin Page ◽  
Ning-Cheng Lee
Keyword(s):  
Test Performance ◽  
Shear Test ◽  
Solder Joints ◽  
Low Cost ◽  
Drop Test ◽  
Solder Paste ◽  
Weakest Link ◽  
Solder Bumps ◽  
Pasty Range ◽  
Homogenization Temperatures

Low melting 57Bi42Sn1Ag (BiSnAg) was explored for replacing SAC solders as a low-cost solution. In this study, BGAs with SAC105, SAC305, and BiSnAg balls were assembled with SAC105, SAC305 or 57Bi42Sn1Ag solder paste. Joint mechanical strength, drop test performance, and voiding performance were evaluated against the reflow profile. SnPb was included as a control. The findings are as follows: (1) The microstructure of solder joints showed that, among all of the combinations, only BiSnAg-105 LT and BiSnAg-305 LT exhibited well-distinguishable alloy regions. For SAC-BiSnAg systems, Sn-dendrites were noticeable at LT, while Ag3Sn needles developed at HT. The joints were homogeneous for the rest of the combinations. (2) In the shear test, combinations involving BiSnAg solder were brittle, regardless of the Bi alloy location and reflow profile, as evidenced by stress-strain curves and morphology of the ruptured surface. The strong influence of Bi on the rupture site may have been caused by the stiffening effect of solder due to the homogenized presence of Bi in the joint. With the stiffened solder, the brittle IMC interface became the weakest link upon shearing, although the brittle BiSn crystalline structure also contributed to the rupture. (3) In the drop test, all Bi-containing solder joints performed poorly compared with Bi-free systems, which was consistent with shear test results. Drop numbers increased with increasing elongation at break of solder bumps as measured in the shear test. (4) Voiding was affected by flux chemistry and reduced by low alloy homogenization temperatures and solid top factors, but was increased by low surface tension factor, melting sequence factor, overheating factor and wide pasty range factor. Compared to SAC or SnPb systems, the BiSnAg system is low in voiding if reflowed at LT. In this study, voiding had an insignificant effect on shear strength and drop test performance.

Reliability of PCB Solder Joints Assembled with SACm™ Solder Paste

2014 ◽  
Vol 2014 (1) ◽  
pp. 000367-000373 ◽  
Author(s):  
Arnab Dasgupta ◽  
Fengying Zhou ◽  
Christine LaBarbera ◽  
Weiping Liu ◽  
Paul Bachorik ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thermal Aging ◽  
Test Performance ◽  
Solder Joints ◽  
Ductile Failure ◽  
Drop Test ◽  
Bulk Property ◽  
Solder Paste ◽  
Fatigue Reliability ◽  
Sac305 Solder

The solder alloy SACm™0510 has been reported to be a superior alloy when used as BGA balls, exhibiting not only an outstanding drop test performance when compared to SAC105, but also as having high thermal fatigue reliability when compared to high Ag SAC solders. In this study, SACm0510 solder was evaluated as a solder paste. The voiding behavior of SGA solder joints was comparable for SACm0510, SAC105, and SC305. When evaluating SGA assemblies on a customized drop test, SACm0510 outperformed SAC105 considerably, which in turn was much better than SAC305. The drop test performance was found to improve upon thermal aging at 150°C, and the difference between the alloys reduced significantly. This was explained by the speculated grain coarsening which resulted in a softened solder joint, and consequently, a shift of fracture mode from brittle failure toward ductile failure. This model was supported by the observation of the fractured surface moving away from the interface upon thermal aging. The improvement in drop test performance upon thermal aging can be further explained by the large solder joint size of the SGA employed in this study, where the bulk property of solder weighed more than a small solder joint. When the assembled chip resistors were evaluated with a −55°C/+125°C TCT test, no failure was observed after 369 cycles for all three alloys. SAC305 appeared to be the best in maintaining the integrity of the interfacial IMC layer. SACm0510 showed a few crack lines, but less than that of SAC105. SACm0510 solder paste was found to be very compatible with BGAs with SAC305 solder joints, and no abnormal microstructure was observed after thermal aging at 150°C for 1000 hours.

Package-Interposer-Package (PIP): A Breakthrough Package-on-Package (PoP) Technology for 3D-Integration

2012 ◽  
Vol 2012 (1) ◽  
pp. 000561-000567
Author(s):  
Rabindra N. Das ◽  
Frank D. Egitto ◽  
Barry Bonitz ◽  
Erich Kopp ◽  
Mark D. Poliks ◽  
...  
Keyword(s):  
System Integration ◽  
Integrated Approach ◽  
Power Delivery ◽  
Solder Paste ◽  
3D Integration ◽  
Electrically Conductive ◽  
Reflow Temperature ◽  
Electrically Conductive Adhesive ◽  
The Stability ◽  
Electrical Connections

Package on Package (PoP) stacking has become an attractive method for 3D integration to meet the demands of higher functionality in ever smaller packages, especially when coupled with the use of stacked die. To accomplish this, new packaging designs need to be able to integrate more dies with greater function, higher I/O counts, smaller pitches, and greater heat densities, while being pushed into smaller and smaller footprints. A new 3D “Package Interposer Package” (PIP) solution is suitable for combining multiple memory, ASICs, stacked die, stacked packaged die, etc., into a single package. This approach also favors system integration with high density power delivery by appropriate interposer design and thermal management. Traditional Package on Package (PoP) approaches use direct solder connections between the substrates and are limited to use of single (or minimum) die on the bottom substrate, to reduce warpage and improve stability. For PIP, the stability imparted by the interposer reduces warpage, allowing assemblers of the PIP to select the top and bottom components (substrates, die, stacked die, modules) from various suppliers. This mitigates the problem of variation in warpage trends from room temperature to reflow temperature for different substrates/modules when combined with other packages. PIP facilitates more space-efficient designs, and can accommodate any stacked die height without compromising warpage and stability. PIP can accommodate modules with stacked die on organic, ceramic, or silicon board substrates, where each can be detached and replaced without affecting the rest of the package. Thus, PIP will be economical for high-end electronics, since a damaged, non-factional part of the package can be selectively removed and replaced. A variety of interposer structures were used to fabricate Package Interposer Package (PIP) modules. Electrical connections were formed during reflow using a tin-lead eutectic solder paste. Interconnection among substrates (packages) in the stack was achieved using interposers. Plated through holes in the interposers, formed by laser or mechanical drilling and having diameters ranging from 50 μm to 250 μm, were filled with an electrically conductive adhesive and cured. The adhesive-filled and cured interposers were reflowed with circuitized substrates to produce a PIP structure. In summary, the present work describes an integrated approach to develop 3D PIP constructions on various stacked die or stacked packaged die configurations.

Drop Reliability of Corner Bonded CSP in Portable Products

2003 ◽  
Author(s):  
Guoyun Tian ◽  
Yueli Liu ◽  
Pradeep Lall ◽  
R. Wayne Johnson ◽  
Sanan Abderrahman ◽  
...  
Keyword(s):  
Capillary Flow ◽  
Drop Test ◽  
Mechanical Shock ◽  
Solder Paste ◽  
Test Results ◽  
Mechanical Coupling ◽  
Small Areas ◽  
Common Solution ◽  
Four Corners ◽  
Capillary Underfill

The use of CSPs has expanded rapidly, particularly in portable electronic products. Many CSP designs will meet the thermal cycle or thermal shock requirements for these applications. However, mechanical shock (drop) and bending requirements often necessitate the use of underfills to increase the mechanical strength of the CSP-to-board connection. Capillary flow underfills processed after reflow, provide the most common solution to improving mechanical reliability. However, capillary underfill adds board dehydration, underfill dispense, flow and cure steps and the associated equipment to the assembly process. Corner bonding provides an alternate approach. Dots of underfill are dispensed at the four corners of the CSP site after solder paste print, but before CSP placement. During reflow the underfill cures, providing mechanical coupling between the CSP and the board at the corners of the CSP. Since only small areas of underfill are used, board dehydration is not required. This paper examines the manufacturing process for corner bonding including dispense volume, CSP placement and reflow. Drop test results are then presented. A conventional, capillary process was used for comparison of drop test results. Test results with corner bonding were intermediate between complete capillary underfill and non-underfilled CSPs. Finite element modeling results for the drop test are also included.

scholarly journals A dynamic K-means clustering for data mining

2019 ◽  
Vol 13 (2) ◽  
pp. 521
Author(s):  
Md. Zakir Hossain ◽  
Md.Nasim Akhtar ◽  
R.B. Ahmad ◽  
Mostafijur Rahman
Keyword(s):  
Data Mining ◽  
Clustering Algorithm ◽  
Large Data ◽  
Threshold Value ◽  
Specific Pattern ◽  
Large Data Sets ◽  
Data Sets ◽  
Data Set ◽  
Number Of Clusters ◽  
Data Points

<span>Data mining is the process of finding structure of data from large data sets. With this process, the decision makers can make a particular decision for further development of the real-world problems. Several data clusteringtechniques are used in data mining for finding a specific pattern of data. The K-means method isone of the familiar clustering techniques for clustering large data sets.  The K-means clustering method partitions the data set based on the assumption that the number of clusters are fixed.The main problem of this method is that if the number of clusters is to be chosen small then there is a higher probability of adding dissimilar items into the same group. On the other hand, if the number of clusters is chosen to be high, then there is a higher chance of adding similar items in the different groups. In this paper, we address this issue by proposing a new K-Means clustering algorithm. The proposed method performs data clustering dynamically. The proposed method initially calculates a threshold value as a centroid of K-Means and based on this value the number of clusters are formed. At each iteration of K-Means, if the Euclidian distance between two points is less than or equal to the threshold value, then these two data points will be in the same group. Otherwise, the proposed method will create a new cluster with the dissimilar data point. The results show that the proposed method outperforms the original K-Means method.</span>

Determination of Optimal Clusters Using a Genetic Algorithm

2008 ◽  
pp. 98-117 ◽  
Author(s):  
Tushar ◽  
Tushar ◽  
Shibendu Shekhar Roy ◽  
Dilip Kumar Pratihar
Keyword(s):  
Genetic Algorithm ◽  
Threshold Value ◽  
Data Sets ◽  
Self Organizing Map ◽  
Data Set ◽  
Fcm Algorithm ◽  
Data Points ◽  
The Relationship

Clustering is a potential tool of data mining. A clustering method analyzes the pattern of a data set and groups the data into several clusters based on the similarity among themselves. Clusters may be either crisp or fuzzy in nature. The present chapter deals with clustering of some data sets using Fuzzy C-Means (FCM) algorithm and Entropy-based Fuzzy Clustering (EFC) algorithm. In FCM algorithm, the nature and quality of clusters depend on the pre-defined number of clusters, level of cluster fuzziness and a threshold value utilized for obtaining the number of outliers (if any). On the other hand, the quality of clusters obtained by the EFC algorithm is dependent on a constant used to establish the relationship between the distance and similarity of two data points, a threshold value of similarity and another threshold value used for determining the number of outliers. The clusters should ideally be distinct and at the same time compact in nature. Moreover, the number of outliers should be as minimum as possible. Thus, the above problem may be posed as an optimization problem, which will be solved using a Genetic Algorithm (GA). The best set of multi-dimensional clusters will be mapped into 2-D for visualization using a Self-Organizing Map (SOM).

White Blood Cells Segmentation and Classification Using Swarm Optimization Algorithms and Multilayer Perceptron

2021 ◽  
Vol 13 (2) ◽  
pp. 16-30
Author(s):  
Shahd Tarek ◽  
Hala M. Ebied ◽  
Aboul Ella Hassanien ◽  
Mohamed F. Tolba
Keyword(s):  
Multilayer Perceptron ◽  
Blood Cells ◽  
White Blood Cells ◽  
Threshold Value ◽  
Leukemia Cells ◽  
Second Phase ◽  
Gray Wolf ◽  
Data Sets ◽  
Classification Problems ◽  
Third Phase

This study proposes a segmentation and classification system for early detection of blood disease; the proposed system consists of three phases. The first phase is segmenting white blood cells using multi-level thresholding optimized by the butterfly optimization algorithm to select the optimal threshold value to increase the accuracy. The second phase is extracting geometric and shape features of the segmented cells. The third phase is using the gray wolf optimizer to adopt the weights and biases of the multilayer perceptron to enhance the accuracy of classification between normal and leukemia cells, classify the normal cells to their five categories, and classify the leukemia to their four categories. The proposed system applies to different data sets (ALL-IDB2, LISC, and ASH-Image bank) and overcomes the segmentation and classification problems of microscopic images and shows an outstanding segmentation result, 98.02%; and the average classification accuracy between normal and leukemia cells is 98.58%, between white blood cell categories is 98.9%, and between leukemia types is 98.93%.

Larger Array Fine Pitch Wafer Level Package Drop Test Reliability

2009 ◽  
Author(s):  
Tiao Zhou ◽  
Robert Derk ◽  
Kaysar Rahim ◽  
Xuejun Fan
Keyword(s):  
Finite Element ◽  
Failure Mechanism ◽  
Solder Alloy ◽  
Test Data ◽  
Test Performance ◽  
Drop Test ◽  
Test Reliability ◽  
Array Size ◽  
Wafer Level ◽  
Test Experiment

In this study, drop test reliabilities of wafer level packages (WLP) are investigated. Failure mechanism, crack map and crack initiation location are presented. Failure rates of six groups defined by JEDEC are examined through both drop test experiment and finite element (FE) analysis with ANSYS software. Effects of component placement, PCB design, WLP structures, array size, pitch, and solder alloy are studied through drop test experiment per JESD22-B111 and finite element modeling. It is found that the primary failure mechanism of WLP drop test failures is fracture of intermetallic compound (IMC) at WLP side. During the drop test, solder joints at outer columns experience most stress and will fracture first. And the corner balls always fail first. The crack initiates at inner side of solder joint and propagates to the opposite side. When JEDEC recommended PCB is used for WLP drop test, the corner components fail first. This is different from the findings from BGA packages. It is confirmed that the dominant failure rate of corner WLP components is mainly due to the effect of mounting screws, rather than the intrinsic drop test reliability of WLP. Therefore, it is not appropriate to judge the drop test reliability of WLP with the drop test data for the corner components. Instead, middle component drop test data represent intrinsic shock resistance of WLP, and they should be used to represent the drop test performance of WLP. Drop test DOE results showed that WLP structure and material make visible difference. Non-soldermask defined (NSMD) PCB pad designs result in better drop reliability than SMD pads. With a given ball array, WLP with smaller pitch has worse drop reliability. As array size increases from 6×6 to 10×10 and 12×12, the drop test performance drops significantly. In addition, choice of solder alloy makes visible difference for WLP.

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