Technical Library | 2019-10-21 09:58:50.0
An ACI Technologies customer inquired regarding printed circuit board(PCB) failures that were becoming increasingly prevalent after the SMT (surface mount technology) manufacturing process. The failures were detected by electrical testing, but were undetermined as to the location and specific devices causing the failures. The failures were suspected to be caused predominately in the BGA (ball grid array) devices located on specific sites on this 16 layer construction. Information that was provided on the nature of the failures (i.e., opens or shorts) included high resistance shorts that were occurring in those specified areas. The surface finish was a eutectic HASL (hot air solder leveling) and the solder paste used was a water soluble Sn/Pb(tin/lead).
Technical Library | 2007-06-21 17:03:16.0
The rapid assimilation of Ball Grid Array (BGA) and other Area Array Package technology in the electronics industry is due to the fact that this package type allows for a greater I/O count in a smaller area while maintaining a pitch that allows for ease of manufacture (...) While there have been several studies comparing these two attachment methods, this study highlights the effect of rework technique on the electrical characteristics and reliability of reworked BGAs.
Technical Library | 2015-08-13 15:52:40.0
Pad cratering has become more prevalent with the switch to lead free solders and lead free compatible laminates. This mainly is due to the use of higher reflow temperature, stiffer Pb-free solder alloys, and the more brittle Pb-free compatible laminates. However, pad cratering is difficult to detect by monitoring electric resistance since pad cratering initiates before an electrical failure occurs. Several methods have been developed to evaluate laminate materials' resistance to pad cratering. Pad-solder level tests include ball shear, ball pull and pin pull. The detailed methods for ball shear, ball pull, and pin pull testing are documented in an industry standard IPC-9708. Bansal, et al. proposed to use acoustic emission (AE) sensors to detect pad cratering during four-point bend test. Currently there is an industry-working group working on test guidelines for acoustic emission measurement during mechanical testing.
Technical Library | 2015-04-16 16:11:43.0
Solder ball height inspection is essential to the detection of potential connectivity issues in semi-conductor units. Current ball height inspection tools such as laser profiling, fringe projection and confocal microscopy are expensive, require complicated setup and are slow, which makes them difficult to use in a real-time manufacturing setting. Therefore, a reliable, in-line ball height measurement method is needed for inspecting units undergoing assembly. (...) In this paper, an automatic, stereo vision based, in-line ball height inspection method is presented. The proposed method includes an imaging setup together with a computer vision algorithm for reliable, in-line ball height measurement.
Technical Library | 2022-12-19 18:59:51.0
Material and Process Characterization studies can be used to quantify the harmful effects that might arise from solder flux and other process residues left on external surfaces after soldering. Residues present on an electronic assembly can cause unwanted electrochemical reactions leading to intermittent performance and total failure. Components with terminations that extend underneath the package can trap flux residue. These bottom terminated components are flush with the bottom of the device and can have small solderable terminations located along the perimeter sides of the package. The clearance between power and ground render high electrical forces, which can propagate electrochemical interactions when exposed to atmospheric moisture (harsh environments). The purpose of this research is to predict and understand the functional performance of residues present under single row QFN component packages. The objective of the research study is to develop and collect a set of guidelines for understanding the relationship between ionic contamination and electrical performance of a BTC component when exposed to atmospheric moisture and the trade-offs between electrical, ionic contamination levels, and cleanliness. Utilizing the knowledge gained from undertaking the testing of QFN components and associated DOE, the team will establish a reference Test Suite and Test Spec for cleanliness.
Technical Library | 2009-11-05 11:17:32.0
Head-in-pillow (HiP), also known as ball-and-socket, is a solder joint defect where the solder paste deposit wets the pad, but does not fully wet the ball. This results in a solder joint with enough of a connection to have electrical integrity, but lacking sufficient mechanical strength. Due to the lack of solder joint strength, these components may fail with very little mechanical or thermal stress. This potentially costly defect is not usually detected in functional testing, and only shows up as a failure in the field after the assembly has been exposed to some physical or thermal stress.
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