Ball Grid Array Components Research Articles

Solder Joint Reliability Assessment for Flip Chip Ball Grid Array Components with Various Designs in Lead-Free Solder Materials and Solder Mask Dimensions

This study investigates the reliability of flip chip ball grid array (FCBGA) components with three types of solder materials: eutectic solder with a composition Sn63Pb37 and the lead-free solders SnAg3.0Cu0.5 and SnAg4.0Cu0.5. Two substrate-side solder mask (S/M) opening sizes, 0.4 mm and 0.525 mm, were used. Both the monotonic and cyclic mechanical four-point bend tests are conducted for the reliability assessment. It is found that the FCBGA components with SnAg3.0Cu0.5 solder have the best durability during the cyclic bend test, yet the eutectic solder is the strongest during the monotonic bend test. Besides, the FCBGA components with 0.525-mm S/M opening have around 3 times more life cycles than those with the 0.4-mm S/M opening in the cyclic bend test. It is also noteworthy that the lead-free solder materials have much variation in the failed cycles during the cyclic test. Moreover, the failure locations for those components with 0.4-mm S/M openings are found to be at the interface between the package side metal pad and the solder ball, and those with an S/M opening of 0.525 mm are observed to be failed mostly at the interface between the printed circuit board (PCB) side metal pad and the solder ball.

Lead‐free PCB assembly and effects of process conditions on the profile and reliability of solder joints

PurposeTo study the effects of design and assembly process conditions on lead‐free solder joints for an area array component.Design/methodology/approachExperiments using SnAgCu solder for assembling plastic ball grid array components on printed circuit boards (PCBs) were carried out to investigate the reliability of the solder joints made under various conditions. The process variables studied include solder pad diameters, solder paste volume and reflow peak temperatures.FindingsThe average joint diameter increased with the peak reflow temperature, stencil thickness and pad diameter. The average joint height decreased with the increasing peak reflow temperature and pad diameter. However, increased stencil thickness would lead to increased solder paste volume and therefore increases both joint diameter and height. The assembled boards were subjected to a temperature cycling test (−40 to +125°C) for 5,700 cycles and no failures of the daisy chained resistance loops were found, indicating that the thermal fatigue resistance of the SnAgCu solder joints was good.Originality/valueThe findings provide greater confidence to implement a lead‐free soldering process without compromising reliability. Reliable lead free soldering can be made over a wide process window allowing flexibility in design and manufacturing.

The influence of multiple reflow cycles on solder joint voids for lead‐free PBGAs

Lead‐free soldering is becoming a common practice in the electronics industry because of the growing general opposition to lead‐containing solders. The reliability of lead‐free solders has been studied a lot recently, but knowledge of it is still incomplete and many issues related to them are under heavy debate. This paper presents results from a study of the formation of voids with regard to the number of reflow cycles in three different kinds of solder joints: first the ones prepared with lead‐free solder paste and lead‐free plastic ball grid array (PBGA) components, next the ones prepared with lead‐free solder paste and tin‐lead‐silver PBGA components, and last the ones prepared with tin‐lead solder paste and tin‐lead‐silver PBGA components.

An analytical comparison of the thermal performance of various ball grid array packaging technologies

This paper provides a summary of thermal modeling and simulation of a variety of ball grid array components in leading-edge application environments using computational fluid dynamics tools.

Reduction of voiding in eutectic ball grid array solder joints

The rapid progress of ball grid array (BGA) component technology has served to alleviate many problems associated with the placement and soldering of high lead count, fine pitch surface mount technology (SMT) packages. An unfortunate result of this process, however, is the occurrence of voids in the interconnecting eutectic solder balls of these packages. Large voids can affect the mechanical and thermal properties of the interconnect, which can reduce a component’s mean time‐to‐failure and may also affect the transmission of high frequency electrical signals through the solder ball. For this reason, several experiments were conducted to investigate the manner and mechanisms in which voids are introduced into eutectic BGA solder ball joints. The following process parameters were found to be the primary parameters responsible for the voiding phenomenon: condition of the component’s alloy and substrate, oxygen concentration in the reflow atmosphere, solder paste properties and the reflow profile. Through modification and optimization of process parameters in the manufacturing environment, BGA solder joint voiding was greatly reduced.

Optimizing BGA to PCB interconnections using multi‐depth laser drilled blind vias‐in‐pad

Ball grid array (BGA) component packages challenge the circuit board design with signal routing and layout, creating in some cases extra board layers and added vias all resulting in increased costs for the printed circuit board (PCB). As component densities increase and microBGA (μBGA) and other fine pitch components become more common, microvia‐in‐pad technology will ease the transition to these fine pitch components. This paper presents and profiles a cost‐effective solution to interconnecting BGAs on PCBs using laser drilled blind vias connecting the outer three or more layers of a multilayer circuit board. Following a discussion on the design advantages, a comprehensive outline of the PCB fabrication process explores a new procedure for the rapid production of via‐in‐pad multi‐depth blind via laser drilling.

Plastic Ball Grid Array Attachment: Assembly and Reliability Performance

As plastic ball grid array (PBGA) components proliferate, card assembly questions arise about the robustness of the module to card attachment process. A designed experiment was performed to measure the sensitivity of card assembly yields to normal assembly process variation. Experimental variables include card thickness, ball pad size on the card ball grid array (BGA) site, module moisture exposure and ball planarity of a 225 I/O PBGA. Another set of PBGA test cards, assembled under optimum process conditions, was subjected to accelerated thermal cycle (ATO) testing. ATC testing also included a rework cell. Overall, the PBGA module attachment process demonstrated robustness. The initial attach and reworked modules proved to be reliable. This paper focuses on the details of the test conditions and the results.

REWORK OF BGA COMPONENTS

Area array packages are being increasingly used in the surface mount printed circuit board assembly domain due to their unique characteristics and high process yields. Several researchers have indicated that the process defects associated with the ball grid array components on printed circuit board assemblies are dramatically lower than those experienced with traditional leaded components. However, there are a number of other reasons to remove and replace components including package defects, engineering changes that are required after a number of components have been assembled, device or system upgrades, misregistration, wrong component orientation, etc.The rework of ball grid array components is a challenging task since the solder joints are hidden from view and cannot be readily accessed. Traditional approaches to rework that are applied to peripheral leaded or leadless components might not be applicable to ball grid array components. This paper provides a detailed discussion of the rework process for ball grid arrays. Topics that are addressed include the characterization of the rework system, nozzle design, the component removal process, the need for site redressing and the technique to be used, solder and flux application, and the component replacement process. A comprehensive set of process-related recommendations is provided for the rework of ball grid arrays.