New mode crack of LSI package in the solder reflow process

Adachi, M.; Ohuchi, Shinji; Totsuka, N.

doi:10.1109/33.239888

Cited by 17 publications

(7 citation statements)

References 3 publications

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“…Comparatively few articles relating to the mode II popcorn effect have been published so far. Especially thin packages (e.g., TSSOP, TQFP) are known to be most susceptible to the mode II popcorn cracking [5]- [8]. Here it was assumed that the die-attach material may play a no less important role than the MC.…”

Section: Introductionmentioning

confidence: 99%

On the mode II popcorn effect in thin packages

Alpern

Dudek

Schmidt

et al. 2002

IEEE Trans. Comp. Packag. Technol.

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Experiments were carried out using P-TQFP-176 packages to study the mode II popcorn effect in thin packages. The doming of the package backside was measured as a function of time and temperature. The measurements were performed using a line projection method. An "accelerated" increase in the doming was found to correlate with the onset of the package crack propagation. It was shown that when a constant critical doming angle is reached, package cracks begin to propagate toward the surface. This critical doming angle was found to be temperature independent between 170°C and 215°C. Furthermore the development of the package doming with time was described by a simple model based on the moisture diffusion from molding compound and die-attach material in combination with a bimaterial plate theory. The water content of the die-attach layer after preconditioning was calculated from the model and it was found to be in good agreement with the results of a three dimensional finite element simulation

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Section: Introductionmentioning

confidence: 99%

On the mode II popcorn effect in thin packages

Alpern

Dudek

Schmidt

et al. 2002

IEEE Trans. Comp. Packag. Technol.

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“…The popcorn cracking phenomena of thin plastic packages frequently occur during the solder reflow process [1][2][3][4]. The main reason for this occurrence is the hygroscopic property of EMCs.…”

Section: Introductionmentioning

confidence: 99%

Effects of chemical oxidations on the fracture toughness of leadframe/EMC interfaces

Lee

1999

Metals and Materials

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Cu-based leadframe sheets were oxidized by a chemical oxidation method, which formed two kinds of oxides on its surface, a brown one and a black one. The oxidation characteristics of each oxide were studied and then to measure the adhesion strength of the leadframe/EMC interface as a function of fracture toughness, the oxidized leadframe samples were molded with an epoxy molding compound (EMC) and machined to form sandwiched double-cantilever beam (SDCB) specimens. SEM and XRD studies on the surfaces of the oxidized leadframe as well as the measurement of fracture toughness showed that the interfacial fracture toughness is directly related to the formation of acicular CuO precipitates on the surface of the leadframe. However, once a continuous layer of CuO precipitates formed on the surface of the leadframe (brown oxide) or on the Cu20 layer (black oxide), the interfacial fracture toughness is found to saturate regardless of a further oxide thickening. The size of the acicular precipitates seems to have a secondary effect on the interfacial fracture toughness.

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“…The total amount of moisture that has entered the sheet at time is given by (4) Integrating the above equation and defining as the moisture in the sheet after infinite time (equilibrium moisture), the following expression is derived:…”

Section: B Simple Diffusionmentioning

confidence: 99%

“…The rapid heating causes the moisture at the delaminated interface between the die-pad, or the top of the die, and the molding compound to vaporize and it creates a high build-up of pressure at the interface. The pressure causes bulging at the interface and eventually the package cracks [4], [5].…”

mentioning

confidence: 99%

A comparison of the theory of moisture diffusion in plastic encapsulated microelectronics with moisture sensor chip and weight-gain measurements

Ardebili

Hillman

Natishan

et al. 2002

IEEE Trans. Comp. Packag. Technol.

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In this paper, the issues pertaining to moisture diffusion in PEMs are explored and discussed. The existing models of moisture diffusion in plastic molding compounds and PEMs are reviewed. Results, modeling and analysis of moisture sorption experiments performed in this study are presented. The moisture sorption experiments were conducted on a set of PEM samples with a common type of encapsulant material to 1) characterize sorption behavior; 2) compare weight gain measurement to the measurement of moisture concentration using a moisture sensor device at the die surface; 3) assess the moisture sensor measurement method. In the case of PEM samples tested in this study, simple Fickian diffusion was shown to agree closely with the experimental results. In one case, a relatively small anomaly from Fickian diffusion was observed and was attributed to swelling and relaxation phenomena at later stages of moisture sorption in the molding compound. The calibration constants determined for the sensors in this study were found to be significantly different from those collected by the manufacturer prior to the encapsulation of the devices. This problem is believed to be degradation in sensitivity of the moisture sensor due to exposure to high temperatures and storage conditions.

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New mode crack of LSI package in the solder reflow process

Cited by 17 publications

References 3 publications

On the mode II popcorn effect in thin packages

On the mode II popcorn effect in thin packages

Effects of chemical oxidations on the fracture toughness of leadframe/EMC interfaces

A comparison of the theory of moisture diffusion in plastic encapsulated microelectronics with moisture sensor chip and weight-gain measurements

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