Mounting Leadless Chip Carriers onto Printed Circuit Boards

1982 ◽  
Vol 1 (1) ◽  
pp. 38-43 ◽  
Author(s):  
D. Fishman ◽  
N. Cooper
Keyword(s):  
Thermal Expansion ◽  
Thermal Cycling ◽  
Printed Circuit Boards ◽  
Coefficient Of Thermal Expansion ◽  
Cycling Performance ◽  
Circuit Board ◽  
Circuit Boards ◽  
Acceptable Solution ◽  
Printed Circuit ◽  
Chip Carrier

It is reasoned that wide penetration of chip carriers into equipment for professional and commercial applications depends on developing methods for mounting the leadless types directly on to conventional polymer type printed circuit boards. The main problem to be overcome is fatigue failure of the solder joints due to the mismatch in thermal expansion, evidenced by poor thermal cycling performance. In this paper the thermal cycling performance is compared when four sizes of ceramic leadless chip carrier are mounted on a selection of printed circuit board materials ranging from the conventional to those specially formulated, either on the basis of matching the coefficient of thermal expansion of the chip carrier material, or to provide a layer of compliant elastomer material underneath the layer bearing the copper contact layer, so that strain due to thermal expansion mismatch is not transmitted to the solder layer. Over 400 thermal cycles (−55 to + 125°C) were recorded using proprietary versions of elastomer coated substrates. For appropriate applications the basis is thus laid for an economic and technically acceptable solution. The practical implications of two methods of soldering—wave (jet) and vapour phase—are also discussed.

Influence of thermal cycling on reliability of solder joints executed on long and metal core PCBs

2015 ◽  
Vol 27 (3) ◽  
pp. 120-124 ◽  
Author(s):  
Janusz Sitek ◽  
Aneta Araźna ◽  
Kamil Janeczek ◽  
Wojciech Stęplewski ◽  
Krzysztof Lipiec ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Printed Circuit Boards ◽  
Solder Joints ◽  
Circuit Board ◽  
Circuit Boards ◽  
Thermal Cycles ◽  
Metal Core ◽  
Content Type ◽  
Printed Circuit ◽  
Reliability Of Solder Joints

Purpose – The purpose of this paper is to evaluate the reliability of solder joints made on long FR-4 and metal core printed circuit boards using the accelerated thermal cycling. Design/methodology/approach – Solder joints of diodes and resistors samples made on long FR-4 and aluminum (Al) core printed circuit boards were examined. Two kinds of solder pastes were used for the samples preparation. All samples were subjected to temperature aging cycles (−40°C – 3 hours/+85°C – 3 hours). Solder joints resistance, X-Ray inspection and metallographic cross-sections for samples as received and after 100, 500 and 1,000 hours of thermal cycles were utilized for solder joints assessment. Findings – It was stated that 1,000 hours of thermal cycles were enough to show reliability problems in solder joints on long and/or AL core printed circuit board assembly (PCBA). The solder joints of R1206 components were the most sensitive reliability elements. The solder joints of LED diodes are more reliable than solder joints of R1206 resistors. Solder joints made on FR-4 substrate were about two times more reliable than ones on AL core substrate. Cracks in solder joints were the visible reason of solder joints failures. Originality/value – The influence of thermal cycles on the reliability of solder joints on long, FR-4 and metal core printed circuit boards were presented. Findings from this paper can be used for planning of reliability trials during validation of reflow processes of products containing long or long metal core printed circuit boards (PCBs).

Dielectric Breakdown in Printed Circuit Boards at Elevated Temperatures

1996 ◽  
Author(s):  
P. Singh ◽  
G.T. Galyon ◽  
J. Obrzut ◽  
W.A. Alpaugh
Keyword(s):  
Experimental Data ◽  
Thermal Degradation ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Elevated Temperatures ◽  
Dielectric Breakdown ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Data Matching

Abstract A time delayed dielectric breakdown in printed circuit boards, operating at temperatures below the epoxy resin insulation thermo-electrical limits, is reported. The safe temperature-voltage operating regime was estimated and related to the glass-rubber transition (To) of printed circuit board dielectric. The TG was measured using DSC and compared with that determined from electrical conductivity of the laminate in the glassy and rubbery state. A failure model was developed and fitted to the experimental data matching a localized thermal degradation of the dielectric and time dependency. The model is based on localized heating of an insulation resistance defect that under certain voltage bias can exceed the TG, thus, initiating thermal degradation of the resin. The model agrees well with the experimental data and indicates that the failure rate and truncation time beyond which the probability of failure becomes insignificant, decreases with increasing glass-rubber transition temperature.

scholarly journals A model for the reflection of terahertz signals from printed circuit board surfaces

2018 ◽  
Vol 10 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Alexander Fricke ◽  
Mounir Achir ◽  
Philippe Le Bars ◽  
Thomas Kürner
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Simulated Annealing Algorithm ◽  
Specular Reflection ◽  
Circuit Board ◽  
Network Analyzer ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Propagation Modeling ◽  
Annealing Algorithm

AbstractBased on vector network analyzer Measurements, a model for the specular reflection behavior of printed circuit boards in the Terahertz range has been derived. It has been calibrated to suit the behavior of the measurements using a simulated annealing algorithm. The model has been tailored for integration to ray-tracing-based propagation modeling.

Advanced Build-up Materials for High Speed Transmission Application

2018 ◽  
Vol 2018 (1) ◽  
pp. 000305-000309 ◽  
Author(s):  
Shiro Tatsumi ◽  
Shohei Fujishima ◽  
Hiroyuki Sakauchi
Keyword(s):  
High Speed ◽  
Printed Circuit Boards ◽  
Transmission Loss ◽  
Coefficient Of Thermal Expansion ◽  
Strip Line ◽  
Circuit Boards ◽  
Additive Process ◽  
Printed Circuit ◽  
Low Dielectric ◽  
Transmission Speed

Abstract Build-up process is a highly effective method for miniaturization and high density integration of printed circuit boards. Along with increasing demands for high transmission speed of electronic devices with high functionality, packaging substrates installed with semiconductors in such devices are strongly required to reduce the transmission loss. Our insulation materials are used in a semi-additive process (SAP) with low dielectric loss tangent, smooth resin surface after desmear, and good insulation reliability. Actually, the transmission loss of strip line substrates and Cu surface roughness impact on transmission loss were measured using our materials. Furthermore, low dielectric molding film with low coefficient of thermal expansion (CTE) and low Young's modulus are introduced.

Advanced Build-up Materials and Processes for Packages with Fine Line and Space

2014 ◽  
Vol 2014 (1) ◽  
pp. 000444-000447 ◽  
Author(s):  
Yoshio Nishimura ◽  
Hirohisa Narahashi ◽  
Shigeo Nakamura ◽  
Tadahiko Yokota
Keyword(s):  
Printed Circuit Boards ◽  
Coefficient Of Thermal Expansion ◽  
High Reliability ◽  
Electronic Devices ◽  
Circuit Boards ◽  
Additive Process ◽  
Fine Line ◽  
Printed Circuit ◽  
Low Dielectric ◽  
Line Space

Printed circuit boards manufactured by a semi-additive process are widely used for packaging substrates. Along with increasing demands of downsizing electronic devices with high functionality, packaging substrates installed with semiconductors in such devices are strongly required to be miniaturized with high density of circuit wirings. We report our insulation build-up materials and processes for advanced packages with fine line/space and high reliability. The insulation materials we developed show low coefficient of thermal expansion (CTE), low dielectric loss tangent and good thinner insulation reliability. They can produce fine line and space (FLS) under 10μm pitch by a semi-additive process.

scholarly journals NotchPUF: Printed Circuit Board PUF Based on Microstrip Notch Filter

Cryptography ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 11
Author(s):  
Mitchell Martin ◽  
Jim Plusquellic
Keyword(s):  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Statistical Tests ◽  
Notch Filter ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
In Series ◽  
Commercial Off The Shelf ◽  
Using Data

Physical Unclonable Functions (PUFs) are primitives that are designed to leverage naturally occurring variations to produce a random bitstring. Current PUF designs are typically implemented in silicon or utilize variations found in commercial off-the-shelf (COTS) parts. Because of this, existing designs are insufficient for the authentication of Printed Circuit Boards (PCBs). In this paper, we propose a novel PUF design that leverages board variations in a manufactured PCB to generate unique and stable IDs for each PCB. In particular, a single copper trace is used as a source of randomness for bitstring generation. The trace connects three notch filter structures in series, each of which is designed to reject specific but separate frequencies. The bitstrings generated using data measured from a set of PCBs are analyzed using statistical tests to illustrate that high levels of uniqueness and randomness are achievable.

Downsizing an automotive junction box based on large current-carrying printed-circuit board optimization

2016 ◽  
Vol 231 (2) ◽  
pp. 267-278 ◽  
Author(s):  
Hansang Lim ◽  
Do-Hwan Jung ◽  
Geono Kwon ◽  
Young Jong Lee ◽  
Jun Seo Park
Keyword(s):  
Power Distribution ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Installation Space ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Overcurrent Protection ◽  
Large Current ◽  
Analytical Estimation

An automotive junction box distributes electric power to electric systems installed in a vehicle with overcurrent protection. As a larger number of electric systems are installed, the junction box is equipped with more components, functionalities and connections. However, owing to the fuse accessibility, its installation space is so restricted that a downsized design is required for the junction box. The junction box is composed of small signal circuitry for control and monitoring, and large current-carrying circuitry for power distribution which includes many parallel traces. Because of these unique features, widely used techniques for downsizing printed-circuit boards are not applicable. Also, there is no rule for designing large current-carrying parallel traces, and it is difficult to optimize the size of the printed-circuit board for the automotive junction box. This paper presents the design rules for a printed-circuit board when downsizing a junction box. First, the layout strategy for the power distribution components is presented, which is determined by the sum of the squares of the currents flowing through connector pairs. Then, the thermal effects of parallel traces are simulated for different conditions by using thermal analysis software. Based on the results, an analytical estimation of the additional temperature rises due to parallel traces and rules for a thermally effective arrangement of the parallel traces are presented.

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