System for Real-Time Measurement of Thermally Induced PWB/PWA Warpage

1997 ◽  
Vol 119 (1) ◽  
pp. 1-7 ◽  
Author(s):  
M. R. Stiteler ◽  
I. C. Ume
Keyword(s):  
Real Time ◽  
Measurement System ◽  
Printed Wiring Board ◽  
Reflow Soldering ◽  
Thermally Induced ◽  
Operational Conditions ◽  
Soldering Process ◽  
Before And After ◽  
On Line ◽  
Wiring Board

An automated on-line warpage measurement system for printed wiring board assemblies (PWBAs) has been developed. The system is capable of simulating an infrared reflow soldering process and performing real-time PWBA warpage measurements using the shadow moire´ technique. The system can be used to characterize the warpage behavior of virtually any PWBA during infrared soldering processes as well as during operational conditions. Using this system, warpage of PWB test vehicles was measured during simulated infrared reflow soldering. The measurement results and the measurement system will be presented. The measured warpage varied significantly during reflow soldering from that observed both before and after reflow. These results help us to understand how the board deforms at every stage of the reflow process.

A New Prediction Model for Thermally Induced Errors of a Turning Center

2014 ◽  
Vol 625 ◽  
pp. 411-416
Author(s):  
Hua Wei Chi ◽  
Yo Ren Lin
Keyword(s):  
Prediction Model ◽  
Real Time ◽  
Measurement System ◽  
Thermal Error ◽  
Cutting Conditions ◽  
Widespread Application ◽  
Thermally Induced ◽  
Line Measurement ◽  
Turning Center ◽  
On Line

Thermally induced errors and geometric errors are two main sources that affect the machine tool accuracy when machining. In the last decade, real time compensation method had received wide attention for its ability to reduce the thermal error cost–effectively. Although real-time thermal error compensation techniques have been successfully demonstrated in laboratories, several difficulties hinder its widespread application. The selection of temperature variables and the setup of the error measurement system are the most critical ones among these difficulties. In this paper, a new on line measurement system and a new model that predicts the thermal error of a turning center are developed. The on-line measurement system using a Renishaw’s LT02S probe system is capable of measuring thermal error of a CNC turning center in real cutting conditions. The neural network uses the cutting conditions as the mapping inputs to avoid problems occurred in the traditional temperature-error mapping model. Results show the proposed measurement system and prediction model can be used to accurately estimate the thermally induced error in real cutting conditions.

Thermoelastic Modeling of a PWB With Simulated Circuit Traces Subjected to Infrared Reflow Soldering With Experimental Validation

1999 ◽  
Vol 121 (4) ◽  
pp. 263-270 ◽  
Author(s):  
Y. Polsky ◽  
I. C. Ume
Keyword(s):  
Experimental Validation ◽  
Effective Properties ◽  
Experimental System ◽  
Thermal Gradients ◽  
Printed Wiring Board ◽  
Reflow Process ◽  
Reflow Soldering ◽  
Lamination Theory ◽  
Support Conditions ◽  
Wiring Board

A bare, four copper layer printed wiring board with simple trace patterns was built for modeling and experimental validation purposes. In-plane elastic properties of the core materials in the board were measured as a function of temperature. Thermoelastic lamination theory was utilized to predict the warpage of the board when subjected to an infrared reflow process, with emphasis on studying the influence of thermal gradients through the board, its support conditions and CTE differential on the warpage process. Board layers with traces were approximated with quasi-homogeneous effective properties obtained using micromechanics theory. An experimental system that employs the shadow moird technique in a simulated infrared reflow environment was used to evaluate the warpage for comparison to modeled results.

Design and Research on Online Sampling Device of New Cigarette Making Machine

2013 ◽  
Vol 416-417 ◽  
pp. 931-935
Author(s):  
Wei Ying ◽  
Guang Bin Yi ◽  
Yi Zhou
Keyword(s):  
Real Time ◽  
Measurement System ◽  
High Speed ◽  
Physical Parameters ◽  
Measuring Instrument ◽  
Sampling Device ◽  
Compact Structure ◽  
On Line ◽  
Online Sampling ◽  
Structure And Design

The paper introduces the structure and design principles of online sampling device of a new high-speed cigarette machine. The device is an important part of C2 cigarette online sampling and measurement system, it gets samples from the high-speed cigarette maker machine's conveiying line and send samples to C2 measuring instrument for testing, and it achieved the goal of automatic on-line monitoring of cigarette physical parameters. The device has compact structure and expediently installation, which makes it not only replace manual sampling of high-speed cigarette making machine, but also detect and display various physical parameters of cigarette in real time.

Predicted Residual Bow of Thin Plastic Packages of Integrated Circuit Devices

1992 ◽  
Vol 114 (4) ◽  
pp. 467-470 ◽  
Author(s):  
E. Suhir
Keyword(s):  
Integrated Circuit ◽  
Effective Means ◽  
Thermal Contraction ◽  
Element Solution ◽  
Printed Wiring Board ◽  
Thermally Induced ◽  
Plastic Packages ◽  
Plastic Package ◽  
Thin Plastic ◽  
Wiring Board

Thin plastic packages are prone to residual bows caused by the thermal contraction mismatch of the constituent materials: silicon (chip), metal (leadframe), and epoxy (encapsulant). Since excessive bow can make normal mounting of a plastic package on a printed wiring board difficult, it is important that such a bow can be predicted, minimized, and, if possible, avoided. Accordingly, in this analysis we develop a simple and easy-to-apply calculation method for the prediction of the residual thermally-induced bow in a thin elongated plastic package. We use the obtained formula for the curvature to determine whether the chip/leadframe assembly can be positioned within the epoxy encapsulant in such a way that no residual bow occurs. We show that employment of epoxy encapsulants with elevated coefficients of thermal expansion can be an effective means to reduce the bow, and that application of thin and/or low expansion leadframes is also desirable. The calculated bow, obtained for a 1mm thick, 14mm long package, agrees satisfactorily with the finite-element solution. The results of our analysis can be utilized as a guidance in the evaluation of the expected bow, as well as for a rational physical design of thin plastic packages.

Real-Time and On-Line Measurement System for Trace Gas with Active Control Parameters

2018 ◽  
Vol 38 (5) ◽  
pp. 0530003
Author(s):  
孙明国 Sun Mingguo ◽  
马宏亮 Ma Hongliang ◽  
刘强 Liu Qiang ◽  
曹振松 Cao Zhensong ◽  
王贵师 Wang Guishi ◽  
...  
Keyword(s):  
Real Time ◽  
Active Control ◽  
Measurement System ◽  
Trace Gas ◽  
Control Parameters ◽  
Line Measurement ◽  
On Line

scholarly journals Evaluation of Warp of Printed Wiring Board under Reflow Soldering.

1997 ◽  
Vol 12 (6) ◽  
pp. 444-447
Author(s):  
Nobutaka ITOH ◽  
Mami NAGATAKE ◽  
Osamu IDO ◽  
Hitoshi KANEKO ◽  
Masaki OHNO
Keyword(s):  
Printed Wiring Board ◽  
Reflow Soldering ◽  
Wiring Board

A Novel Projection Moiré System for Measuring PWBA Warpage Using Simulated Optimized Convective Reflow Process

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Reinhard E. Powell ◽  
I. Charles Ume
Keyword(s):  
Measurement System ◽  
Flip Chip ◽  
Active Contours ◽  
Printed Wiring Board ◽  
Reflow Process ◽  
Shadow Moire ◽  
Shadow Moiré ◽  
Plastic Ball ◽  
Wiring Board ◽  
Projection Moire

The shadow moiré technique is a widely used method of measuring printed wiring board (PWB) warpage. It has a high resolution, high accuracy, and is suitable for use in an online environment. The shortcoming of the shadow moiré technique is that it cannot be used to measure PWBs populated with chip packages. In this paper, a novel warpage measurement system based on the projection moiré technique is presented. The system can be used to measure bare PWBs, as well as PWBs populated with chip packages. In order to use the projection moiré system to accurately determine the warpage of PWBs and chip packages separately, an automated chip package detection algorithm based on active contours is utilized. Unlike the shadow moiré technique, which uses a glass grating, the projection moiré technique uses a virtual grating. The virtual grating sizes can be adjusted, making it versatile for measuring various PWB and chip package sizes. Without the glass grating, which is a substantial heat inertia, the PWB/printed wiring board assembly (PWBA) sample can be heated more evenly during the thermal process. The projection moiré system described in this paper can also be used to measure the warpage of PWBs/PWBAs/chip packages during convective reflow processes. In this paper, the characteristics of the projection moiré warpage measurement system will be described. In addition, the system will be used to measure the warpage of a PWB and plastic ball grid array packages during a Lee optimized convective reflow process (Lee, N.-C., 2002, Reflow Soldering Processes and Troubleshooting SMT, BGA, CSP, and Flip Chip Technologies, Butterworth-Heinemann, MA). It is concluded that this projection moiré warpage measurement system is a powerful tool to study the warpage of populated PWBs during convective reflow processes.

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