Improving the Solder Joint Reliability of VQFN Packages

Stoeckl, S.; Pape, H.

doi:10.1109/eptc.2005.1614501

Cited by 10 publications

(7 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both larger board thickness and larger number of Cu-layers increase the stiffness of the board (if other material parameters remain unchanged) and result in earlier failure of QFN solder joints. Our results match well with predictions by FE-simulations [6]. Thus, QFNs on thick boards with many metal layers require more attention regarding temperature cycling reliability than on typical thin boards e.g.…”

Section: Methodssupporting

confidence: 93%

“…It is linked to fatigue life by analytical equations with experimentally determined crack growth constants. We used modified crack growth constants, which we determined from a correlation to experimental board level temperature cycling data for QFNs [6].…”

Section: Diementioning

confidence: 99%

“…4,5]. In addition also investigations by finite element (FE) simulations are available [5,6,7,8]. The existing experimental data were mainly generated only with SnPb solder and up to board thicknesses of 1.6 mm.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reliability Investigations of Leadless QFN Packages until End-of-Life with Application Specific Board Level Stress Tests

Birzer

Stoeckl

Schuetz

et al.

56th Electronic Components and Technology Conference 2006

Self Cite

View full text Add to dashboard Cite

We report board level stress tests of leadless QFN packages (pitch 0.5 mm) with focus on different application fields. We did temperature cycling tests, drop test, bend test, and power cycling tests, with special focus on the influences of board design and soldering technology. We performed the stress tests until end-of-life and determined the dominating failure modes. In our temperature cycling study on 2.35 mm thick boards solder joints of SnAgCu performed slightly worse than SnPbAg. We were able to optimize the thermal pad design on the PCB to improve the temperature cycling reliability. For drop test we achieved an excellent reliability by comparing different board designs. This was achieved by avoiding copper trace cracking within the board. This failure mode we verified also with cyclic bend tests. Additionally we performed power cycling investigations using different power consumptions and solder pastes for board assembly (SnAgCu and SnPbAg). A strong lifetime dependence on power and a superior behavior of SnAgCu solder was found. The results were successfully correlated with finite element simulations. In our stress tests we observed clear evidence for influence of soldering technology and board design/technology on board level reliability performance. For different application fields satisfactory reliability can be achieved in case specific measures on board assembly and printed circuit board design are taken. IntroductionDuring the last years Quad Flat No-lead (QFN) packages became very popular as cost effective solution for low pincount IC products. A QFN is a plastic encapsulated package with a copper leadframe, which is exposed on the package bottom side. The peripheral leads as well as the exposed die pad can be soldered to the printed circuit board (PCB) by standard SMT processes. Figure 1 shows a schematic cross section of a QFN on a PCB.

show abstract

Section: Methodssupporting

confidence: 93%

Section: Diementioning

confidence: 99%

See 1 more Smart Citation

Reliability Investigations of Leadless QFN Packages until End-of-Life with Application Specific Board Level Stress Tests

Birzer

Stoeckl

Schuetz

et al.

56th Electronic Components and Technology Conference 2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Anand visco-plastic constitutive model was used to represent the deformation behaviour of the solder. In the Anand model, plasticity and creep are unified and described by the same set of flow and evolution relations; the details of these equations can be found in the literature [5], while the Anand constants for Sn62/Pb361 Ag2 solder that were used in this work were taken from the literature [6].…”

Section: Modelling Methodologymentioning

confidence: 99%

Modelling the impact of conformal coating penetration on QFN reliability

Yin

Stoyanov

Bailey

et al. 2017

2017 18th International Conference on Electronic Packaging Technology (ICEPT)

View full text Add to dashboard Cite

The impact of conformal coating penetration on the solder joints' thermal fatigue reliability in QFNs was studied using computational modeling techniques. 3D finite element models were developed with consideration of realistic solder joint shape and the actual coating profile. Thermal mechanical simulations were carried out for three cycles under accelerated thermal test conditions of-25 to 100°C, 10 minutes ramp and 10 minutes dwell. The inelastic strain energy density accumulated over one temperature cycle was used as an indicator for solder damage in the QFNs under the applied thermal cycling load. The impact of coating penetration level on the solder damage in QFNs was investigated for two types of coatings with different properties. The results show that coating penetrated underneath the package has significant impact on the solder joint damage in QFNs and the level of this impact depends on the coating properties and penetration level. When coating penetration level decreases, damage in the solder joint does not always decrease. In order to prevent coating penetration underneath the package, an edgebond adhesive was applied on the edge of the QFN assemblies prior to the application of the conformal coating. The modelling results show that using edgebond adhesive can reduce the solder joint damage in the investigated QFNs and thus improve their thermal fatigue reliability. When edgebond adhesive is used, the impact of conformal coating on the reliability of solder joints in QFNs is significantly reduced.

show abstract

“…Solder joint reliability during Temperature Cycling on Board (TCOB) is a critical issue not only for BGA but also QFN type packages. We made a parameter study based on Robert Darveaux's model and applied it to different VQFN packages to identify most sensitive parameters (for details see [8]). …”

Section: The Importance Of Design For Reliabilitymentioning

confidence: 99%