scholarly journals Design of Solder Connections for Self-Assembly of Optoelectronic Devices

2019 ◽  
Vol 16 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Thomas F. Marinis ◽  
Joseph W. Soucy
Keyword(s):  
Surface Tension ◽  
Flip Chip ◽  
Equilibrium Shape ◽  
High Surface ◽  
Optoelectronic Devices ◽  
Analytical Models ◽  
Volume Control ◽  
Surface Evolver ◽  
Solder Volume ◽  
Connected Set

Abstract In surface mount assembly, advantage is taken of the high surface tension of molten solder to self-align ball grid array packages and flip chip die. However, in these applications, the volume of solder applied as paste by stencil printing is not sufficiently well controlled to achieve the precise alignment required for optoelectronic devices. We believe that the requirement on solder volume control for assembly of optoelectronic devices can be relaxed by designing the bond pads so that the height or alignment of connections is controlled by the surface tension of the solder rather than its volume. Our design approach to accomplishing this is to connect auxiliary pads to the primary attachment pad, which act as solder reservoirs. Surface tension causes the solder to be redistributed among these pads to achieve a uniform pressure throughout the solder volume. This phenomena is governed by the Young-Laplace equation, ΔP = γκ, in which ΔP represents the difference in pressure within and outside the solder, γ the surface tension of the solder, and κ the local curvature of the solder surface. Thus, the design of the set of primary and auxiliary pads is critically important to realizing the desired control of joint height. In this article, we describe the use of the Surface Evolver software package in combination with analytical models, to analyze the behavior of various connection configurations with respect to variations in printed solder volume. Specifically, we calculate the equilibrium shape of the solder surface over the connected set of pads and examine how control of joint height is affected by the number, size, and geometry of auxiliary pad configurations.

Design of Solder Connections for Self-Assembly of Optoelectronic Devices

2018 ◽  
Vol 2018 (1) ◽  
pp. 000393-000402
Author(s):  
Thomas F. Marinis ◽  
Joseph W. Soucy
Keyword(s):  
Surface Tension ◽  
Flip Chip ◽  
Equilibrium Shape ◽  
Optoelectronic Devices ◽  
Circuit Board ◽  
Analytical Models ◽  
Volume Control ◽  
Solder Paste ◽  
Solder Volume ◽  
Connected Set

Abstract The cost of optoelectronic assemblies is significantly higher than that of electronic assemblies due in large part to the method of assembly. A typical computer circuit board is built by screen printing solder paste onto a printed wiring board, placing components on the board at rates of several thousand per hour, and then reflowing the solder paste in a conveyor oven. By contrast, optoelectronic assemblies are built up in a sequential process in which epoxy is dispensed for a single component, which is placed and held in position until the epoxy is cured. Many minutes are required to build an optoelectronic assembly, such as a laser module, by this approach, also the precision robotic placement tool needed for this process costs in excess of a million dollars. The demand for all types of optoelectronic components in communications, computing, automotive, medical and aerospace applications is great, but the high cost of manufacture is constraining growth, so clearly a better method of assembly is needed. In surface mount assembly, advantage is taken of the high surface tension of molten solder to self-align ball grid array packages and flip chip die. However, in these applications, the volume of solder applied as paste by stencil printing is not sufficiently well controlled to achieve the precise alignment required for optoelectronic devices. We believe that the requirement on solder volume control for assembly of optoelectronic devices can be relaxed by designing the bond pads so that the height or alignment of connections is controlled by surface tension of the solder rather than its volume. Our design approach to accomplishing this is to connect auxiliary pads to the primary attachment pad, which act as solder reservoirs. Surface tension causes solder to be redistributed among these pads to achieve a uniform pressure throughout the solder volume. This phenomena is governed by the Young-Laplace equation, ΔP = γκ, in which ΔP represents the difference in pressure within and outside the solder, γ the surface tension of the solder and κ the local curvature of the solder surface. Thus, the design of the set of primary and auxiliary pads is critically important to realizing the desired control of joint height. In this paper we describe the use of the Surface Evolver software package in combination with analytical models, to analyze the behavior of various connection configurations with respect to variations in printed solder volume. Specifically, we calculate the equilibrium shape of the solder surface over the connected set of pads and examine how control of joint height is affected by the number, size and geometry of auxiliary pad configurations. We also discuss results from some preliminary experiments that we are conducting to validate our modeling results.

Misaligned Flip-Chip Solder Joints: Prediction and Experimental Determination of Force-Displacement Curves

2002 ◽  
Vol 124 (3) ◽  
pp. 227-233 ◽  
Author(s):  
D. Josell ◽  
W. E. Wallace ◽  
J. A. Warren ◽  
D. Wheeler ◽  
A. C. Powell
Keyword(s):  
Flip Chip ◽  
Solder Joints ◽  
Minimum Energy ◽  
Computer Code ◽  
Silicon Substrates ◽  
Surface Evolver ◽  
Solder Volume ◽  
Lateral Offset ◽  
Force Displacement

The results of wetting experiments between eutectic lead-tin solder and copper pads on silicon substrates in geometries relevant to flip-chip applications are presented. Measurements of solder joint dimensions, specifically stand-off height and lateral offset (i.e., misalignment), as functions of the applied force (normal and shear), solder volume and pad diameter are presented. The experimentally-measured force-displacement relationships are compared with predictions obtained from the minimum energy model of the Surface Evolver computer code. For the case of the axisymmetric joint (zero shear) an exact solution to the capillary equations is also presented. The comparison of experimental and modeling results indicates that such models are accurate as well as extremely sensitive means for predicting the geometry of these solder joints.

Flow Induced Dynamics of a Pinned Droplet on the Surface of a Channel

2005 ◽  
Author(s):  
Amirreza Golpaygan ◽  
Nasser Ashgriz
Keyword(s):  
Surface Tension ◽  
Stokes Equations ◽  
Liquid Droplet ◽  
Equilibrium Shape ◽  
High Surface ◽  
Droplet Surface ◽  
Navier Stokes ◽  
Fluid Viscosity ◽  
Droplet Deformation ◽  
Newtonian Liquids

Dynamic behavior of a droplet adhering to the surface of a channel has been modeled under the influence of surrounding fluid. The numerical solution is based on solving Navier-Stokes equations for Newtonian liquids. The study includes the effect of interfacial forces with constant surface tension, also effect of adhesion between the wall and droplet accounted by implementing contact angle at the wall. The Volume-Of-Fluid method is used to numerically determine the deformation of free surface. Droplet deformation and final shapes have been predicted. A reduction in the surface tension allows the droplet to deform much easier. However, an increase in the fluid viscosity, although increases the shear force on the droplet, may not result in the deformation at high surface tension. It is shown that deformation of droplet significantly influences structure of channel flow. Effects of liquid droplet and channel fluid properties, namely density and viscosity, inlet velocity, surface tension and channel geometry on dynamics of the problem have been studied. Two different outcomes have been considered: the first one droplet with equilibrium shape and the other one when breakup of the droplet occurs. The border line between the disintegration region and equilibrium region is determined for different droplet surface tensions.

Predicting the Liquid Formation for the Solder Joints in Flip Chip Technology

2005 ◽  
Vol 128 (4) ◽  
pp. 331-338 ◽  
Author(s):  
Wen-Hwa Chen ◽  
Shu-Ru Lin ◽  
Kuo-Ning Chiang
Keyword(s):  
Surface Tension ◽  
Solder Joint ◽  
Flip Chip ◽  
Solder Joints ◽  
Geometric Method ◽  
External Loading ◽  
Surface Evolver ◽  
Eutectic Solder ◽  
Chip Technology ◽  
Interfacial Surface

An accurate and efficient analytical geometric method is presented for predicting the geometric parameters of the controlled collapse chip connection type solder joint using direct chip attach technology after a reflow process. By this method, the meridian of the solder joint is first discretized as a series of sufficiently fine fragmental arcs. After calculating the internal pressure inside the molten eutectic solder from the forces balance, the meridional and circumferential radii of curvature of each arc are then obtained from the Laplace-Young equation. As a result, the coordinates of each node of the arc and the solder joint geometry can be determined in turn. The factors that affect the final shape of the molten eutectic solder joints, including the solder volumes, external loading, pad size, surface tension of molten eutectic solder, and interfacial surface tension between the molten eutectic solder and the solid high-lead bump are considered herein. The results computed by the analytical geometric method are also compared with those obtained using the Surface Evolver program, the extended Heinrich’s model, and the experimental results. The results of the various approaches are mutually consistent.

Fully integrated low-power flip chip bonding of arrayed optoelectronic devices on SOS

2002 ◽  
Author(s):  
Ronald E. Reedy ◽  
Hal Anthony ◽  
Charles Kuznia ◽  
Mike Pendelton ◽  
Jim Cable ◽  
...  
Keyword(s):  
Low Power ◽  
Flip Chip ◽  
Optoelectronic Devices ◽  
Fully Integrated ◽  
Flip Chip Bonding

Tracing surfactant transformation from cellular release to insertion into an air-liquid interface

2004 ◽  
Vol 286 (5) ◽  
pp. L1009-L1015 ◽  
Author(s):  
T. Haller ◽  
P. Dietl ◽  
H. Stockner ◽  
M. Frick ◽  
N. Mair ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cultured Cells ◽  
High Surface ◽  
Lamellar Body ◽  
Liquid Interface ◽  
Alveolar Type ◽  
Tensile Forces ◽  
Modify Surface ◽  
Fluorescence Imaging Microscopy ◽  
Air Liquid Interface

Pulmonary surfactant is secreted by alveolar type II cells as lipid-rich, densely packed lamellar body-like particles (LBPs). The particulate nature of released LBPs might be the result of structural and/or thermodynamic forces. Thus mechanisms must exist that promote their transformation into functional units. To further define these mechanisms, we developed methods to follow LBPs from their release by cultured cells to insertion in an air-liquid interface. When released, LBPs underwent structural transformation, but did not disperse, and typically preserved a spherical appearance for days. Nevertheless, they were able to modify surface tension and exhibited high surface activity when measured with a capillary surfactometer. When LBPs inserted in an air-liquid interface were analyzed by fluorescence imaging microscopy, they showed remarkable structural transformations. These events were instantaneous but came to a halt when the interface was already occupied by previously transformed material or when surface tension was already low. These results suggest that the driving force for LBP transformation is determined by cohesive and tensile forces acting on these particles. They further suggest that transformation of LBPs is a self-regulated interfacial process that most likely does not require structural intermediates or enzymatic activation.

Condensation of Low-Surface-Tension Fluids on Microstructured Surfaces at Low Temperature

2017 ◽  
Author(s):  
Abulimiti Aili ◽  
Qiaoyu Ge ◽  
TieJun Zhang
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Low Temperature ◽  
High Surface ◽  
Condensation Heat Transfer ◽  
Lubricant Oil ◽  
Microstructured Surfaces ◽  
Performance Deterioration ◽  
Coated Surface ◽  
Coated Surfaces

Filmwise condensation of a low surface tension fluid (i.e. refrigerant) on microstructured aluminum surfaces is studied to investigate the effect of the structures on condensation heat transfer at low temperature. The hypothesis is that the structures may cause thinning of the condensate film at micro-scales, thus resulting in an enhancement of condensation heat transfer. However, the structures may also decrease the mobility of the condensate near the surface due to increased friction, thus potentially leading to performance deterioration. The aim of this work is to investigate which of the two counteracting mechanisms dominate during filmwise condensation. Condensation experiments are carried out in a low-temperature vacuum chamber. Compared with the Nusselt model of condensation, the microstructured surfaces, either coated or uncoated, show similar performance, with potentially slight enhancement at low subcooling degree and slight deterioration at high subcooling degree. When the microstructured and silane-coated surface is infused with a non-volatile and very low-surface-tension lubricant oil, the lubricant is displaced by the condensate and there is almost no change in the condensation performance. Our results show that, unlike the case of dropwise condensation of high-surface tension fluids, microstructured and coated surfaces with/without infusing oil is not exciting to enhanced filmwise condensation of low-surface-tension fluids.

High surface tension pulmonary edema induced by detergent aerosol

1985 ◽  
Vol 58 (1) ◽  
pp. 129-136 ◽  
Author(s):  
G. F. Nieman ◽  
C. E. Bredenberg
Keyword(s):  
Surface Tension ◽  
Pulmonary Edema ◽  
High Surface ◽  
Water Volume ◽  
Oncotic Pressure ◽  
Static Compliance ◽  
Surfactant Activity ◽  
Dioctyl Sodium Sulfosuccinate ◽  
Alveolar Surface

The effect of the detergent dioctyl sodium sulfosuccinate on pulmonary extravascular water volume (PEWV) was studied in adult anesthetized mongrel dogs. The detergent was dissolved as a 1% solution in a vehicle of equal volumes of 95% ethanol and normal saline and administered by ultrasonic nebulizer attached to the inspiratory tubing of a piston ventilator. Two hours following detergent aerosol PEWV measured gravimetrically was increased compared with either animals receiving no aerosol or those receiving an aerosol of vehicle alone. Loss of surfactant activity and increased alveolar surface tension were demonstrated by Wilhelmy balance studies of minced lung extracts, by a fall in static compliance, and by evidence of atelectasis and instability noted by gross observation and by in vivo microscopy. No significant changes in colloid oncotic pressure or pulmonary microvascular hydrostatic pressure were observed. These data suggest that pulmonary edema can be induced by increased alveolar surface tension and support the concept that one of the major roles of pulmonary surfactant is to prevent pulmonary edema.

scholarly journals Surfactant Protein B Deficiency Induced High Surface Tension: Relationship between Alveolar Micromechanics, Alveolar Fluid Properties and Alveolar Epithelial Cell Injury

2019 ◽  
Vol 20 (17) ◽  
pp. 4243 ◽  
Author(s):  
Nina Rühl ◽  
Elena Lopez-Rodriguez ◽  
Karolin Albert ◽  
Bradford J Smith ◽  
Timothy E Weaver ◽  
...  
Keyword(s):  
Surface Tension ◽  
Lung Injury ◽  
High Surface ◽  
Surfactant Protein ◽  
Epithelial Injury ◽  
High Surface Tension ◽  
Alveolar Epithelial ◽  
Surfactant Protein B ◽  
Fluid Properties ◽  
Alveolar Epithelial Injury

High surface tension at the alveolar air-liquid interface is a typical feature of acute and chronic lung injury. However, the manner in which high surface tension contributes to lung injury is not well understood. This study investigated the relationship between abnormal alveolar micromechanics, alveolar epithelial injury, intra-alveolar fluid properties and remodeling in the conditional surfactant protein B (SP-B) knockout mouse model. Measurements of pulmonary mechanics, broncho-alveolar lavage fluid (BAL), and design-based stereology were performed as a function of time of SP-B deficiency. After one day of SP-B deficiency the volume of alveolar fluid V(alvfluid,par) as well as BAL protein and albumin levels were normal while the surface area of injured alveolar epithelium S(AEinjure,sep) was significantly increased. Alveoli and alveolar surface area could be recruited by increasing the air inflation pressure. Quasi-static pressure-volume loops were characterized by an increased hysteresis while the inspiratory capacity was reduced. After 3 days, an increase in V(alvfluid,par) as well as BAL protein and albumin levels were linked with a failure of both alveolar recruitment and airway pressure-dependent redistribution of alveolar fluid. Over time, V(alvfluid,par) increased exponentially with S(AEinjure,sep). In conclusion, high surface tension induces alveolar epithelial injury prior to edema formation. After passing a threshold, epithelial injury results in vascular leakage and exponential accumulation of alveolar fluid critically hampering alveolar recruitability.

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