Ball Shear Strength Research Articles

DEVELOPMENT AND CHARACTERIZATION OF SELF-HEALING TRANSDERMAL PATCH OF LIDOCAINE FOR THE MANAGEMENT OF PAIN

Pain management is a significant challenge due to the side effects associated with commonly prescribed medications like NSAIDs and opioids. Local anesthetics, such as lidocaine, offer an alternative with fewer side effects when formulated in topical patches. Transdermal delivery systems, including heated patches, enhance drug absorption and provide targeted pain relief. This research paper aims to develop and characterize a self-heating transdermal patch of lidocaine for pain management. The drug sample of lidocaine was characterized using UV-visible spectrophotometric analysis, melting point determination, and differential scanning calorimetry. The results confirmed the purity of the drug sample. Pre-formulation studies were conducted to determine the solubility and partition coefficient of lidocaine, as well as drug-excipient interaction studies. The formulation of the lidocaine transdermal patch included the selection of excipients such as solvents, adhesives, solubilizers, and permeation enhancers. The patch was developed in three trial batches, with the final batch prepared using a drug-in-adhesive type approach. The developed patch was evaluated for physical characteristics, solvent residual content, rolling ball test, shear strength, drug crystallization, drug content, and in-vitro permeation. The results of the evaluation showed that the developed lidocaine transdermal patch had the desired physical characteristics, uniform thickness, good folding endurance, and appropriate solvent residual content. It exhibited satisfactory rolling ball test and shear strength. Microscopic examination confirmed the absence of drug crystallization. The drug content of the patch was determined to be within the desired range, and the in-vitro permeation study demonstrated successful drug release through the dialysis membrane. In conclusion, the development and characterization of a self-heating transdermal patch of lidocaine for pain management provide a promising approach for effective and targeted pain relief. The patch formulation demonstrated suitable physical properties, drug content, and permeation characteristics, suggesting its potential as an alternative pain management solution. KEYWORDS: Lidocaine, transdermal patch, pain management, self-heating, drug delivery

Au-coated Ag alloy bonding wires with enhanced oxidation resistance for electronic packaging applications

PurposeThe purpose of this paper is to develop high-performance Au-coated Ag alloy wires (ACAA wires) and demonstrate the effect of Au coating layers on the bonding performance and oxidation resistance for stable and reliable electronic packaging applications.Design/methodology/approachACAA wire with a diameter of approximately 25 µm and Au layer thickness of approximately 100 nm were prepared by the continuous casting, plating and wire drawing method. The bonding performance of the ACAA wires were studied through bonding on 3,535 chips. The oxidation resistance of ACAA wires and Ag alloy wires (AA wires) were comparatively studied by means of chemical oxidation tests, accelerated life tests and electrochemical tests systematically.FindingsACAA wires could form axi-symmetrical spherical free air balls with controllable diameter of 1.5∼2.5 times of the wire diameter after electric flame-off process. The ball shear strength of ACAA wire was higher than that of AA wires. Most importantly, because of the surface Au coating layer, the oxidation resistance of ACAA wires was much enhanced.Research limitations/implicationsACAA wires with different lengths of heat affected zone were not developed in this study, which limited their application with different loop height requirements.Practical implicationsWith higher bonding strength and oxidation resistance, ACAA wires would be a better choice than previous reported AA wire in chip packaging which require high stability and reliability.Originality/valueThis paper provides a kind of novel ACAA wire, which possess the merits of high bonding strength and reliability, and show great potential in electronic packaging applications.

Statistical analysis on the mechanical and micro-structural characteristics of thermosonic Cu[sbnd]Al interconnection

In this study, Cu wire-Al bond pad (CuAl) samples were produced by means of Thermosonic wire bonding technique. Both IMC and ball shear strength were assessed for samples produced with different bonding temperatures, HTS duration and forming gas supply. The experiments were carried out using Taguchi and conventional “one parameter at a time” approaches. For Taguchi method, experiment was managed with L9 orthogonal array for optimizing the wire bonding process. It was observed that the process was optimized with forming gas supply ON, bonding temperature of 400 °C and after 1000 h of HTS treatment. This was achieved by a continuous and uniform growth of the IMC across the bonding interface. As for experiment based on “one parameter at a time” approach, a linear proportionality between IMC thickness and ball shear strength was observed. This indicated no void formation at the bonding interface of the sample. In addition, with increased number of run in this experiment, the regression analysis involving interaction of factors was allowed. The measurements' data was found to fit better in the additive model including the interaction of factors. Besides, an additional model based on the fundamental IMC growth behaviour with regards to the bonding temperature and HTS duration was proposed. Regression analysis of this model showed an agreement with measurement data.

The Optimization of Ball Shear Strength Using a Computational Model

Nowadays, Ball Grid Array, BGA technologies are prevalent through the IC packaging industry. Among them are larger numbers of I/Os, leading to many advantages over conventional ones and low cost assemblies for mass production. BGA packages are compatible with surface mount technology (SMT). BGA uses solder joints as surface mount components (SMC). It is not only used for the conduction of electrical signals, power and ground. It also acts as mechanical support to hold the package in position on a printed circuit board (PCB). Thus, solder joint strength is a major concern for BGA packages. To evaluate the strength of the solder joint attached to the package and PCB, a popular method to use is the ball shear test. In this study, the focus of interest was on the size of the ball, the diameter of solder resistance opening, ball height and shear tool clearance by using finite element method. The experiment design aimed to find out the best conditions for the ball. The results were validated by other authors for suitable correlation. The standard deviation of the parameters concerning ball shear test value was also defined

Influence of laser power on bonding strength for low purity copper wire bonding technology

The drive for improving copper wire bonding has been more rampant with continued rise in gold prices. The global increase in gold price directly resulted the semiconductor packaging industry to rapidly replace gold as a medium of interconnection to copper wire. This is a cost effective solution for creating viable interconnections for integrated circuit packaging. However, through past research it is well known the hardness of copper wire is significantly higher compared to gold wire and the usage of copper poses various challenges in electronic packaging. These challenges, resulting from the usage of copper wire is primarily due to the high hardness of copper. Higher hardness of copper as compared to gold will require higher bonding force and ultrasonic energy to create bonding to the bond pads. The higher bonding force makes copper wire bonding unsuitable for fragile structures and possible damage to underlying circuitry. Past research has also exhibited the hardness of copper wire decreases as the purity levels increase, however the usage of higher purity copper wires in high volume manufacturing may significantly increase manufacturing cost. This research therefore investigates the application of laser assisted heating for enabling improved copper wire bonding strength and improved grain structures for low purity copper wires. Experimentations were conducted accordingly on three copper wire purity types, 99.9% purity (3 N), 99.99% purity (4 N) and 99.999% purity (5 N) copper wires, so as to evaluate the impact of laser assisted heating on various copper purity levels. The result of this study shows laser assisted heating is able to improve the bonding strength and improve the grain structure by means of reduced columnar grains for copper wires with lower purity levels. It is shown, higher as-bonded ball shear strengths with fewer columnar grains were observed when the highest laser heating intensity was applied. The results of this study can be helpful for integrated circuit packaging especially to enable interconnections using copper wire materials with lower purity levels, enabling a more cost effective manufacturing.

Bond strength evaluation of heat treated Cu-Al wire bonding

Bond strength evaluation of wire bonding in microchips is the key study in any wire bonding mechanism. The quality of the wire bond interconnection relates very closely to the reliability of the microchip during performance of its function in any application. In many reports, concerns regarding the reliability of the microchip are raised due to formation of void at the wire-bond pad bonding interface, predominantly after high temperature storage (HTS) annealing conditions. In this report, the quality of wire bonds prepared at different conditions, specifically annealed at different HTS durations are determined by measurements of the strength of the interface between the bond wire and the bond pad. The samples are tested in pull test and bond shear test. It was observed that the higher bonding temperature as well as the longer duration of HTS increased the bond strength. This is represented through the analysis of the measurements of ball shear strength. This is due to the fact that higher bonding temperature and longer HTS promoted better growth of the Cu-Al IMC layer. A transmission electron microscopy - energy dispersive X-ray analysis (TEM-EDX) has been carried out to observe the formation of the Cu-Al IMC layer in the sample.

The mechanism of Pd distribution in the process of FAB formation during Pd-coated Cu wire bonding

The palladium (Pd) distribution over the free air ball (FAB) and its effect on the ball’s shear strength were investigated in the Pd-coated copper (Cu) wire bonding process. It was found that for the same FAB/wire diameter ratio of 1.5, the bigger the electrical flame-off (EFO) current was, the larger would be the exposed Cu regions over FAB without Pd distribution. Combining experimental observations, a model of Pd distribution over FAB was first proposed by changing the EFO current and firing time. As the firing time increased, the coated Pd element could be dissolved into the Cu base to form a PdCu alloy at the FAB surface, to protect the bonded ball from corrosion. The Pd-coated Cu wire has higher bonding shear strength than the bare Cu wire. However, the FAB with the largest Pd coverage had the smallest ball shear strength, which revealed that the control of Pd distribution over FAB is very critical for a high-quality bonding interface.

Effect of solder resist dissolution on the joint reliability of ENIG surface and Sn–Ag–Cu solder

The electroless nickel immersion gold (ENIG) process results in surface defects, such as pinholes and black pads, which weaken the solder joint and eventually degrade the reliability of the PCB. Contamination of the plating solutions, including dissolution of the solder resist (SR), can be a cause of the pinholes and black pads. This study examined the effects of SR dissolution on the solder joint reliability and electroless Ni plating properties. Electroless Ni plating was performed by adding 1 to 10 ppm hardener (melamine) to the fresh Ni solution. Many black pads were observed in the 7 and 10 ppm hardener-added surfaces. In addition, the content of P was highest when 7 and 10 ppm hardener was added. The ball shear tests were carried out to confirm the joint reliability between the ENIG surface with hardener-added and the Sn-3.0Ag-0.5Cu solder (SAC 305). The ball shear strength decreased with increasing dissolution of the hardener. In particular, the shear strength was the lowest at 7 and 10 ppm hardener addition. In addition, the failure mode of the solder joint was changed from ductile to brittle mode with increasing hardener addition. That is, as the hardener additive increases, intermetallic compound (IMC) phases were changed from (Cu,Ni)6Sn5 to (Cu,Ni)3Sn4 and Cu6Sn5 (brittle structure).

Effect of the size of carbon nanotubes (CNTs) on the microstructure and mechanical strength of CNTs-doped composite Sn0.3Ag0.7Cu-CNTs solder

Carbon nanotubes (CNTs) with three different diameter ranges (10–20, 40–60, and 60–100 nm) were doped into tin-silver-copper (SAC) solder, to study the performance of the composite SAC-CNTs solder materials – as well as the effect of the size of the CNTs. It was found that all the CNTs-doped composite solder samples displayed refined microstructure, inhibited interfacial intermetallic compound (IMC) growth, and reinforced mechanical strength – while the melting point of the composite solder was close to that of the pristine solder. The reinforcement in mechanical strength was due to the doped CNTs pinned at the solder grain boundaries, which acted as second-phase particles that refined the microstructure and increased the dislocation density. The adsorbed CNTs destroyed the integrity of the interfacial IMCs, leading to reduced growth rate. Among these composite solders, CNTs with a diameter of 40–60 nm provided superior performance in refining the microstructure, lowering the IMC growth rate by 30.9% – and reinforcing the ball shear strength by 15.3% and the hardness by 16.1%. This size effect on the performance of composite solders was due to the various surface energy values for CNTs – that led to the agglomeration and adsorption of CNTs in the solder matrix and interfacial IMCs.

Application of laser heating and its effects on bonding strengths for varied copper wire purity levels

Gold as the medium of interconnection is rapidly being replaced by copper as a means of creating connectivity in integrated circuit packaging. However, the use of copper wire is known to pose many threats in integrated circuit packaging, especially for devices with very thin die structures. The process of wire bonding which involves the formation of free air ball can be risky to the quality of integrated circuit packaging. The impact of hard copper free air ball onto the bonding surfaces may damage the bond pad and the silicon die. These challenges require innovative solutions that are able to be applied to integrated circuit packaging with minimal thermal and mechanical effect on the device. Through recent research, it is apparent that the laser processing technology can provide viable innovative solutions to electronic packaging. This research paper investigates the application of laser heating on copper wire bonding technology and its effects on bonding strength for three copper wire purity types, 99.9% purity (3 N), 99.99% purity (4 N), and 99.999% purity (5 N) copper wires. Wire bonding was performed on bond pads consisting of NiPdAu metallization under 16 different temperature conditions. Results of this study showed that different copper purity levels exhibit different bonding strengths with the application of laser heating. It is shown in this research that significantly higher as-bonded ball shear strengths were obtained when laser heating was applied at all three copper wire purity types. The results of this study can be helpful for integrated circuit packaging with copper wire bonding on thin die structures. Copper wires with lower purity levels are shown as a viable option by further improving the wire bonding quality with the application of laser heating without the need to use excessive bonding temperature, higher bonding force, and excessive ultrasonic energy.Gold as the medium of interconnection is rapidly being replaced by copper as a means of creating connectivity in integrated circuit packaging. However, the use of copper wire is known to pose many threats in integrated circuit packaging, especially for devices with very thin die structures. The process of wire bonding which involves the formation of free air ball can be risky to the quality of integrated circuit packaging. The impact of hard copper free air ball onto the bonding surfaces may damage the bond pad and the silicon die. These challenges require innovative solutions that are able to be applied to integrated circuit packaging with minimal thermal and mechanical effect on the device. Through recent research, it is apparent that the laser processing technology can provide viable innovative solutions to electronic packaging. This research paper investigates the application of laser heating on copper wire bonding technology and its effects on bonding strength for three copper wire purity types, 99.9...

Using improved simulated anneal arithmetic to improve semiconductor packaging ball placement process capability

This study used improved simulated annealing arithmetic to improve the semiconductor packaging ball placement process capability. The simulated annealing computing process was combined with an artificial neural network, Metropolis algorithm, and sequential Gaussian simulation. Grey relation analysis was used as the target value, which is intended to obtain the optimum parameter design of process capability. The results showed that the substrate design-Pad Open is 0.30 mm ball size, 0.275 mm Pad open, Profile type B, maximum temperature 236 (°C), solder melting time 53 (s), preheating temperature 176 (°C), and a solder ball component, as SAC405 can result in a parameter design for optimal solder ball shear strength of Cpk = 2.38 and [Formula: see text]. This optimum parameter design process is better than other methods, and it reduces the cost waste of extra defectives.

Development of Model for Identification of Process Parameters for Wet Decapsulation of Copper–Aluminum Wirebond in PEMs

Decapsulation is a failure analysis technique often used to expose the die and first-level interconnects such as wirebonds by dissolving the surrounding epoxy molding compound (EMC). The wet decapsulation technique, which uses fuming acids, works very well for traditional gold (Au) wirebonds. On the other hand, its latest alternative, copper (Cu) wirebond, reacts with the nitric acid vigorously and undergoes severe corrosion. It is important to develop an acid chemistry that can be used to perform decapsulation of Cu–Al incorporated plastic encapsulated microelectronics (PEMs) without damaging the Cu wires. This paper presents the wet decapsulation technique based on different ratios of the red fuming nitric acid and concentrated sulfuric acid. Quality of post-decap part was examined using reduction in the wire diameter and changes in ball shear strength. Reduction in wire diameter was monitored with the scanning electron microscopy (SEM), and shear strength was measured using a DAGE2400 shear tester. These tests were performed on the PEMs molded with different EMCs, wire diameters, and pad thickness to cover process as well as geometric variability. Artificial neural network with Bayesian regularization-based model has been developed correlating the decapsulation process parameters with the post-decap wire diameter reduction and shear strength of the wirebond. Stepwise regression was used to identify the significant variables that affect the decap process. The influential variables were then used to develop a predictive model for prediction of the percent reduction in wire diameter and change in shear strength separately. Models were then validated with the test data set.

Effect of in-situ free air ball laser heating on bonding strength and grain structure for copper wire bond

As the need for integrated circuits increase year after year, researchers around the globe are constantly experimenting for innovative approaches to use copper wire as a medium of interconnectivity. Copper is being used as an alternative to replace gold to produce interconnections in microelectronics. However, the use of copper wire is known to pose threats to low-k devices with thin structure. The impact of hard copper free air ball onto bonding surfaces is undesirable as it can damage the bond pad and the silicon die. In-situ heating of free air ball is expected to reduce its hardness and mitigate columnar grains. This research paper investigates the effects of in-situ free air ball laser heating on bonding strength and grain structure for 99.999% purity (5N) copper wire bonding. Wire bonding was performed on bond pads consisting of NiPdAu metallization and was wire bonded under 16 different temperature conditions. Results of this study showed significantly higher as-bonded ball shear strengths and reduced columnar grains when in-situ laser heating is applied. The results of this study can be helpful for semiconductor plastic packaging with copper wire bonding on thin die structures by further improving copper wire bonding quality without the need to use excessive bonding temperature, higher bonding force and excessive ultrasonic energy.

Interfacial reaction, ball shear strength and fracture surface analysis of lead-free solder joints prepared using cobalt nanoparticle doped flux

In this research study, we investigated the interfacial reaction and fracture modes in BGA solder joints prepared using Co nanoparticles doped flux. Solder joints were formed in a reflow oven at 240 °C for 45s and subsequently aged at 150 °C up to 1008 h. One set of aged solder joints was used in both microstructural characterization to examine the morphology and growth of interfacial IMC layer and nano-mechanical characterization to determine the hardness and Young's modulus of different phases. Another set was experimented in ball shear test to determine the average shear strength and crack paths in different failure modes. Results showed that the growth of Cu6Sn5 enhanced and that of Cu3Sn suppressed due to the profound stability of Cu6Sn5 in the presence of Co atoms. In the case of undoped condition, the direction of crack changed from a ductile failure mode to a brittle failure mode with respect to aging time. No catastrophic brittle failure mode was observed for Co doped solder joints. The mechanisms for the better fracture behavior in Co-doped solder joints are suggested and correlated to Cu6Sn5/Cu3Sn interfacial reaction.

Effect of Pedestal Temperature on Bonding Strength and Deformation Characteristics for 5N Copper Wire Bonding

In recent years, copper has increasingly been used to replace gold to create wire-bonded interconnections in microelectronics. While engineers and researchers in the semiconductor packaging field are continuously working on this transition from gold to copper wires to reduce costs, the challenge remains in producing robust and reliable joints for semiconductor devices. This research paper investigates the effect of pedestal temperature on bonding strength and deformation for 99.999% purity (5N) copper wire bonding on nickel-palladium-gold (NiPdAu) bond pads. With increasing pedestal temperature, significant thinning of the copper ball bond can be achieved, resulting in higher as-bonded ball shear strengths while producing no pad damage. This can be helpful for low-k devices with thin structures, so as to prevent the use of excessive bond force and ultrasonic energy during copper wire bonding.

Multiple Quality Characteristics Optimization of Ball Grid Array Wire Bonding Process

This paper presents an integrated approach combining principal component analysis (PCA) and Taguchi methods to develop a ball grid array (BGA), gold (Au) wire bonding process with multiple quality characteristics optimization. Eight main process factors of BGA wire bonding technology are selected as the control factors for parameter design. They are the factor A (seating ultrasonic generator (USG)), factor B (TIP height), factor C (C/V), factor D (USG current), factor E (USG bond time), factor F (bond force), factor G (FS threshold), and factor H (FAB size). The quality characteristics of the process in the study, including the wire pull strength, the ball shear strength, the ball thickness difference, the ball size difference, and the percentage of the Au–Al intermetallic compound (IMC) are measured. The optimal process parameters that meet the requirements for multiple quality characteristics are A1B3C1D3E3F1G1H2. They are then used to be tested for verification. Experimental results confirm that the optimal process design indeed enhances the quality characteristics investigated. The analysis of variance (ANOVA) results also show that the most important control factors affecting the quality characteristics are factor B (TIP height), factor C (C/V), and factor G (FS threshold), which accounts for 72.34% of total process variance. Thus, they must be strictly monitored during processing.

Solder Ball Robustness Comparison between SAC 387 and Polymer Solder Balls under AC and TC Reliability Test

Environment and the health concerns due to the hazardous effects of lead resulted in significant activities to find a replacement for lead-contained solders for electronics industrial. Majority of the semiconductor industrial are now replacing lead solders with Tin-Silver-Copper (SAC 387) solder balls. However, dropped balls in SAC 387 for Ball Grid Array (BGA) products due to poor solder joint strength caused by high thermal stress are a major concern in the semiconductor industries. Polymer core inside the solder ball (polymer core/Cu/Sn) is thus integrated to improve the solder ball joint strength. The function of polymer core inside the solder ball is to absorb and released the stress better as compared to the SAC 387 solder ball. Since the diffusion rate of Cu is faster than the diffusion rate of Sn, hence, this could caused the Kirkendall voids tends to form in between the Cu and Sn IMC layer. This would affect the solder ball joint strength and causing drop balls issue. By implement with an extra of Ni layer to the polymer core solder ball (core/Cu/Ni/Sn), could reduce the diffusion from Cu to Sn, thus to overcome the Kirkendall voids and to further improve the solder ball joint strength. This research work studies the performance of the solder ball shear strength of the two types of solder balls applied to MAPBGA device. In this research, both SAC 387 and polymer solder balls were went through under AC (Autoclave) and TC (Temperature Cycle) reliability test up to 144 hours and 1000 cycles, respectively. Solder ball shear strength test was conducted via Dage 4000 series bond tester. From the research work results of the two types of solder balls, the ball shear strength were decreased with an increased of aging and cycles. Overall, it can be concluded that the polymer core solder ball with an additional of Ni layer showed better performance than the polymer core without Ni layer and SAC 387 solder balls, after subjected to the AC and TC reliability test.

Ball shear strength and fracture modes of lead-free solder joints prepared using nickel nanoparticle doped flux

Miniaturization and the need for the replacement of lead (Pb) based solders in microelectronic devices raise concerns over their reliability in the recent years. Particularly, the rapid growth of interfacial intermetallic compound (IMC) layers in Pb free solders can lead to brittle fracture. A novel nanoparticle doped fluxing method was used to prepare ball grid array solder joints between Sn-3.0Ag-0.5Cu solder balls and Cu pads. In this method, nickel nanoparticles were mixed with a water soluble flux prior to its use. The shear strength and fracture modes of the resulting solder joints were investigated as a function of aging time. Results showed that IMC layer growth was suppressed in solder joints prepared with 0.1 wt.% Ni doped flux. The average shear strength was marginally higher for solder joints prepared using 0.1 wt. % Ni doped flux compared with the joints prepared with undoped flux. Samples prepared using Ni doped flux showed a better resistant against brittle fracture for up to 30 days of aging. Open image in new window

Reliability Study of Silver, Copper and Gold Wire Bonding on IC Device

Copper wire bonding in IC packages is not always suitable for devices with active circuit under bonding pad because higher bonding power required for copper wire bonding may cause top aluminum metal splash and mechanically impact the circuit underneath. Silver wire is an alternative solution to this problem based on its physical properties and lower cost compared to gold wire. Ag88%Au8.5%Pd2.5%X1% and Ag95%Au1.5%Pd2.5%X1% alloyed silver wires are used in the study to compare with copper and gold wires of 99.99% in purity. As bonding power plays a dominating role in wire bonding, we focused on the effects of silver, copper and gold bonding wires with different bonding power on the top aluminum metal splash of power device by Optical Microscope(OM) and Scanning Electron Microscope(SEM). The ball shear strength of the bonding wires with different bonding power in samples without mold compound encapsulation was investigated before and after 24, 48, 96 and 192 hours of pressure cooker test (PCT). The intermetallic compound (IMC) formed between silver and aluminum was confirmed by focus ion beam (FIB) and transmission electron microscope (TEM). Although the top surface of the silicon device shows no significant difference after aluminum layer removal for all three wire types, the severity level of vertical deformation and side splash of aluminum layer due to copper wire bonding is much more than silver or gold wire using same amount of bonding power. Ball shear strength of non-encapsulated silver wire decreases dramatically after PCT aging compared with copper wire or gold wire and some samples show zero shear strength after PCT 96 hours and PCT 192 hours for silver wires doped with Pd/Au. Furthermore, larger bonding power induces higher ball shear strength. The major IMC compositions between silver and aluminum are Ag3Al and Ag2Al. A thermo dynamic model was built to explain why silver wire is prone to corrosion compared with copper wire by humidity although copper is easier to be ionized than silver. No electrical test was performed as the samples cannot be tested without package encapsulation and singulation. Furthermore, silver wire samples in SO8 package with mold compound encapsulation were subjected to highly accelerated stress test (HAST), PCT, temperature cycle test (TCT) after MSL1 preconditioning test as well as high temperature operation life test (HTOL) according to JEDEC procedures. The encapsulated samples using either Ag 88wt% or Ag95wt% alloys all passed MSL1 and PCT/HAST/TCT/HTOL. Drain to source on-resistance (Rdson) of the device including package parasitics was measured and it has no significant difference between silver wire and gold wire. The results from this study shows promising data using silver alloy wires but care should be taken to further understand the degradation of silver-aluminum interface under severe humidity condition. Using other metallization on silicon top surface such as NiAu or CuAu can significantly alleviate the interface problem related to AgAl.

Shear strengths of CBGA/PBGA solder ball joints with lead-free solder pastes

The present study is carried out to characterise the ball shear strengths of ceramic ball grid array (CBGA) and plastic ball grid array (PBGA) packages with lead-free solder pastes. Three commercially available Sn/Ag/Cu (SAC) solder pastes such as Sn 96.5/Ag3.0/Cu0.5 and 95.5/Ag3.8/Cu0.7 with a no-clean flux are employed. The effects of temperature profiles during reflow on the strength of solder joints are studied. Their printing abilities are also observed. Of particular concern for ceramic ball grid array packages is the interaction between 90/10 Pb/Sn compound solder balls and SAC solder pastes. The composition of the solder paste region between the I/O pad and the solder ball is analysed using the energy dispersive X-ray (EDX) machine.