A procedure is discussed wherein an infra‐red detector is used for controlling the quality of solder joints being formed by laser‐beam heating on printed circuit boards while, at…
Abstract
A procedure is discussed wherein an infra‐red detector is used for controlling the quality of solder joints being formed by laser‐beam heating on printed circuit boards while, at the same time, automatically inspecting the quality of each joint. The joint‐by‐joint soldering method avoids the thermally induced stresses between the components and the printed circuit board which can occur when the entire board is mass soldered by conventional means. It also eliminates the ‘after the fact’ human inspection process, while at the same time making available real‐time data for process control of the soldering operation.
A.C. Traub and J. Evans
Infra‐red thermal monitoring of drill bit temperatures is just coming into use for laminate drilling. Although not yet in production use, the method has been evaluated, with…
Abstract
Infra‐red thermal monitoring of drill bit temperatures is just coming into use for laminate drilling. Although not yet in production use, the method has been evaluated, with promising results, in the engineering laboratories of four major manufacturers. In addition, it has been used with excellent results as a research tool during studies of interactions between drill wear, drill temperature, compositions of entry and backup materials, hole quality, and other parameters of the drilling process. This paper will outline the principles of infra‐red thermometry and will then discuss the present and the anticipated applications to laminate drilling.
F. Lilley, C.A. Hobson and M. Koukash
Electronics manufacturing throughout the world now uses an increasing percentage of Surface Mount Technology (SMT). The compact and light‐weight surface‐mounted components offer a…
Abstract
Electronics manufacturing throughout the world now uses an increasing percentage of Surface Mount Technology (SMT). The compact and light‐weight surface‐mounted components offer a number of advantages to manufacturers. Unfortunately, however, these same beneficial characteristics make the quality of the product difficult to guarantee. As miniaturisation continues, the inspection problem becomes worse, and so advanced methods of inspection are required. Automatic inspection systems already exist, although an effective, inexpensive and reliable system has yet to be found. Recent work carried out within the Coherent and Electro‐Optics Research Group at Liverpool Polytechnic has looked at the feasibility of applying some of its established inspection methods to the problem of solder joint inspection. Extensive development must still take place; however, the methods employed have shown promise. The system uses structured light techniques to add height information to an image of the solder joint under inspection. In this way a 3‐D image of the joint may be built up, digitised and processed in a computer at high speed in order to determine its quality.
As announced in the May issue of Hybrid Circuits, ISHM‐Benelux is organising a one‐day conference on applications of hybrid circuit technology.
J.M. Kallis, A.H. Samuels and R.P. Stout
Great savings can be achieved by detecting and isolating design problems early in an electronic programme. Many design problems, including electrical overstress, poor thermal…
Abstract
Great savings can be achieved by detecting and isolating design problems early in an electronic programme. Many design problems, including electrical overstress, poor thermal design and circuit layout problems, are detectable by their infrared (I‐R) signature. A reliability and design improvement tool utilising current I‐R scanning technology has been developed. Specifically, an I‐R scanning method for making accurate temperature measurements for the purpose of electronic design reliability improvement and qualification has been developed and verified experimentally. Field‐actual conditions, in which radiative and convective heat losses from the components are negligible, are simulated with a thermally insulating enclosure. The enclosure is designed for rapid removal just before the scan, obviating the need for exotic materials that are transparent to I‐R in the scanner's passband. With typical hardware thermal lags, the method allows determination of true temperatures simulating field conditions. Corrections for unwanted scanner‐produced radiation and for the target emissivity are made with a three‐scan method and specially designed apparatus. An integral part of this apparatus is the aforementioned quickly removable thermal enclosure. The three scans take approximately an hour for a typical circuit board after initial set‐up time. True‐temperature measurements of circuit boards can be made with the I‐R design improvement tool now.
J. Lantaires, G. Forster, M.S. Setty and Nihal Sinnadurai
The venue for this year's ISHM‐Benelux Autumn Conference and ‘table‐top’ display meeting on 12 October will be the Institut Supérieur Industriel de l'Etat, Mons, Belgium.
An investigation involving the use of thermal imaging has been undertaken, both on trimmed thick film resistors and on wave soldered joints to surface mounted devices. The surface…
Abstract
An investigation involving the use of thermal imaging has been undertaken, both on trimmed thick film resistors and on wave soldered joints to surface mounted devices. The surface mounted devices were ‘zero‐ohm’ jumpers which in themselves did not generate appreciable heat if current was passed through them, but also at the same time allowed the passage of DC current flow through the soldered joints. Thermal imaging results have shown the degree of current bunching obtained for thick film resistors trimmed using air abrasion. Appreciable changes in heating and hence in current density are not observed until the resistor has been trimmed with a cut extending into approximately 50% of the total width. In the case of soldered joints on surface mounted devices, it was found that thermal imaging techniques could not easily detect appreciable temperature changes and hence the current flow in joints which had previously been subject to stress due to one test or another. As a result, measurements were made on artificially damaged joints in order to determine the degree of damage that was needed for thermal imaging to show any noticeable effect. The joints were cut with a miniature PCB saw (1 mm wide) and it was not until the cut extended through approximately 60% of the soldered joint height that any appreciable thermal effects could be observed. Conclusions are drawn from these observations on the applicability of thermal imaging techniques to the assessment of trimmed resistors and soldered joint analysis.
J. Nicolics and G. Hobler
Fast laser soldering processes are very attractive for the production of miniaturized interconnections with high reliability as they allow solder joint quality assurance during…
Abstract
Fast laser soldering processes are very attractive for the production of miniaturized interconnections with high reliability as they allow solder joint quality assurance during soldering. In order to evaluate the solder joint quality temporal changes of the temperature distribution inside the solder joint due to melting of the solder and wetting of the component and the pad metallizations must be well understood. In this paper we present thermal simulations of fast laser soldering processes taking the essential changes of the solder geometry into account. Moreover, we use a new relation for the calculation of the moment of wetting in dependence of the interface temperature. With this model the influence of the wettability of the pad and the component metallization and of the position of the laser beam on the temperature distribution inside the solder joint are investigated.
Dilpreet Kaur Dhillon, Pranav Mahajan and Kuldip Kaur
Distancing people socially as a precautionary measure against the mushrooming of COVID-19’s health and economic crisis has deleteriously affected the performance of the eatery…
Abstract
Purpose
Distancing people socially as a precautionary measure against the mushrooming of COVID-19’s health and economic crisis has deleteriously affected the performance of the eatery industry to a great extent. Many food outlets failed to cope up with crisis and opted to move out, and many still vie to survive through pandemic. It becomes vital for researchers to understand what factors influence the performance and survival of eateries during the pandemic? The study makes an attempt to fabricate new factors which affect the performance and contribute significantly towards the survival of eateries in this new COVID-19-prone world.
Design/methodology/approach
The present study is a cross-sectional analysis with the sample of 150 eateries from the walled city of Punjab (India), i.e. Amritsar. Factor analysis is employed to scrutinise the factors which influence the performance of eateries during the pandemic, and to analyse factors which contribute significantly for the survival of eateries, logistic regression is performed.
Findings
The empirical analysis reveals that at prior psychological factor, followed by turnover factor, external factor, financial factor and marketing factor influence the performance of eateries during the pandemic. Only three factors, namely turnover factor, external factor and financial factor, turned up to be significant towards the survival rate of an eatery. The marketing factor which is a crucial contributor for survival of business in literature has turned out to be insignificant during the times of pandemic.
Originality/value
With the arrival of pandemic, the preference of people has changed, and the business environment in which entities operate has turned more complex. The present study is one of the pioneer attempts to evaluate whether the factors responsible for performance or survival of an eatery during normal times is relevant during the pandemic as well. The study contributes to the literature of eatery industry by adding a new variable namely psychological factor, i.e. changes witnessed in customers’ preference to visit an eatery.