Test Methods for Copper-Clad Thermosetting Laminates for Printed Wiring Boards

10.1520/d5109 ◽  
2020 ◽  
Author(s):  
Keyword(s):  
Test Methods ◽  
Printed Wiring Boards

Influence of Secondary Impact on Printed Wiring Assemblies—Part II: Competing Failure Modes in Surface Mount Components

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Jingshi Meng ◽  
Abhijit Dasgupta
Keyword(s):  
Failure Modes ◽  
Test Methods ◽  
Design Guidelines ◽  
Printed Wiring Boards ◽  
Secondary Impact ◽  
Surface Mount ◽  
External Impact ◽  
Drop Tests ◽  
Board Level ◽  
Printed Wiring Assemblies

Portable electronic devices are commonly exposed to shock and impact loading due to accidental drops. After external impact, internal collisions (termed “secondary impacts” in this study) between vibrating adjacent subassemblies of a product may occur if design guidelines fail to prevent such events. Secondary impacts can result in short acceleration pulses with much higher amplitudes and higher frequencies than those in conventional board-level drop tests. Thus, such pulses are likely to excite the high-frequency resonances of printed wiring boards (PWBs) (including through-thickness “breathing” modes) and also of miniature structures in assembled surface mount technology (SMT) components. Such resonant effects have a strong potential to damage the component, and therefore should be avoided. When the resonant frequency of a miniature structure (e.g., elements of an SMT microelectromechanical system (MEMS) component) in an SMT assembly is close to a natural frequency of the PWB, an amplified response is expected in the miniature structure. Components which are regarded as reliable under conventional qualification test methods may still pose a failure risk when secondary impact is considered. This paper is the second part of a two-part series exploring the effect of secondary impacts in a printed wiring assembly (PWA). The first paper is this series focused on the breathing mode of vibration generated in a PWB under secondary impact, and this paper focuses on analyzing the effect of such breathing modes on typical failure modes with different resonant frequencies in SMT applications. The results demonstrate distinctly different sensitivity of each failure mode to the impacts.

Laboratory proficiency in susceptibility testing of Helicobacter pylori using agar dilution and E test methods

2001 ◽  
Vol 120 (5) ◽  
pp. A586-A587
Author(s):  
L BEST ◽  
S JO ◽  
V VANZANTEN ◽  
D HALDANE ◽  
V LOO ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Susceptibility Testing ◽  
Test Methods ◽  
Agar Dilution

Scientific and Standardization Committee Communications Comparison of Test Methods for the Lupus Anticoagulant: International Survey on Lupus Anticoagulants-I (ISLA-1)

1990 ◽  
Vol 64 (03) ◽  
pp. 478-484 ◽  
Author(s):  
Thomas Exner ◽  
Douglas A Triplett ◽  
David A Taberner ◽  
Margaret A Howard ◽  
E Nigel Harris
Keyword(s):  
Lupus Anticoagulant ◽  
Test Methods ◽  
Positive Sample ◽  
Direct Proportion ◽  
Clotting Time ◽  
Preliminary Screening ◽  
Activated Platelets ◽  
Tissue Thromboplastin ◽  
Kaolin Clotting Time ◽  
Induced Defects

SummarySix lyophilized plasma samples were sent to 20 “expert” laboratories for assessment of lupus anticoagulant (LA). Four samples contained pooled LA of graded potency mixed with aged normal plasma. One contained LA plus cephalin phospholipid and one contained a nonspecific venom anticoagulant. Sixteen methods were used overall with some participants using up to 8 methods. Results were scored in regard to the known potencies of LA in the samples and other known induced defects.Activated partial thromboplastin time (APTT) tests used by most participants for preliminary screening were relatively sensitive, but non-specific. Platelet or phospholipid neutralization procedures (PNP) appeared to be sensitive and specific but showed a non-linear response to increased LA content. Kaolin clotting time (KCT) tests showed the most sensitive response to increased LA content but the weaker LA were not scored as abnormal by most laboratories as the samples may have contained platelet fragments. Other commonly used tests such as the tissue thromboplastin inhibition (TTI) test and the dilute Russell’s viper venom test (DRVVT) were carried out somewhat inconsistently. The variability in performance of tests in different laboratories indicates that standardization of methodology is urgently required.Generally it seemed that most clotting tests were “bypassed” by the addition of phospholipid to a known LA-positive sample in apparently direct proportion to their sensitivity. Sample preparation, especially prevention of contamination with activated platelets is a vital preliminary part in the assay of LA.

A method for measuring the in-plane compressive strength and the compression behavior of coating layers

TAPPI Journal ◽  
2011 ◽  
Vol 10 (7) ◽  
pp. 29-34
Author(s):  
TEEMU PUHAKKA ◽  
ISKO KAJANTO ◽  
NINA PYKÄLÄINEN
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Coating Layer ◽  
Test Methods ◽  
Coating Films ◽  
Precipitated Calcium Carbonate ◽  
Coating Color ◽  
Mineral Coatings ◽  
Styrene Butadiene

Cracking at the fold is a quality defect sometimes observed in coated paper and board. Although tensile and compressive stresses occur during folding, test methods to measure the compressive strength of a coating have not been available. Our objective was to develop a method to measure the compressive strength of a coating layer and to investigate how different mineral coatings behave under compression. We used the short-span compressive strength test (SCT) to measure the in-plane compressive strength of a free coating layer. Unsupported free coating films were prepared for the measurements. Results indicate that the SCT method was suitable for measuring the in-plane compressive strength of a coating layer. Coating color formulations containing different kaolin and calcium carbonate minerals were used to study the effect of pigment particles’ shape on the compressive and tensile strengths of coatings. Latices having two different glass transition temperatures were used. Results showed that pigment particle shape influenced the strength of a coating layer. Platy clay gave better strength than spherical or needle-shaped carbonate pigments. Compressive and tensile strength decreased as a function of the amount of calcium carbonate in the coating color, particularly with precipitated calcium carbonate. We also assessed the influence of styrene-butadiene binder on the compressive strength of the coating layer, which increased with the binder level. The compressive strength of the coating layer was about three times the tensile strength.

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