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In SMT manufacturing, automation is the key to achieving the highest throughput at the lowest cost. Complex devices of various shapes and sizes often require final electrical adjustments under operating conditions to ensure conformance to electrical specifications. This paper describes the process of laser trimming completed SMT devices and the advantages it has over conventional trimming methods. The material presented is based on laser trimming systems currently used in SMT production applications that will also be described.

Large ohm film resistors that guard sensitive telecommunication devices against the hazards of lightning require a set of exacting characteristics for tolerance, endurance, and productivity. These characteristics largely depend on how the resistor is trimmed. Conventional laser trimming is unable to provide all the requirements for this important resistor application. A new technique developed by Teradyne Inc. called Algorithmic Trimming employs an algorithm and data base to calculate real‐time trim vectors that are used in a trimming hardware processor to overcome the drawbacks of conventional trimming. With this new technique 50‐ohm film resistors were trimmed to specification with 0·1% tolerance while attaining high resistor stability and a trim time of 300 milliseconds.

High speed chip resistor trimming requires a more advanced technology than just passive network‐trimming. Some guidelines have to be observed to obtain a good approach to the desired goal. One fast and inexpensive way of finding the best parameters for a trim cut, i.e., maximum speed and best accuracy, is CAD‐network simulation. Last but not least several parameters should be checked and controlled continuously to optimise yield.

The purpose of this paper is to investigate the surface integrity features, including surface roughness (SR), recast layer (RL), material migration, topography and wire wear pattern in rough and trim-cut wire electric discharge machine (WEDM) of hybrid composite (Al6061-90%/SiC-2.5%/TiB₂-7.5%).

Effects of four important factors, namely, rough-cut history (RCH), pulse on time (T_on), peak current (IP) and wire offset (WO) have been assessed on the responses of interest for trim-cut WEDM. Box–Behnken design (RSM) was used to formulate the experimentation plan. Quantitative indices of surface integrity, namely, SR and RL, and selected samples have been investigated for qualitative analysis, namely, surface topography, material migration and wire wear pattern.

T_on and IP are found to be most significant, whereas RCH and WO are found insignificant for SR. T_on and WO were found to be the most significant factors affecting RL. After trim cut, an RL of thickness 8.26 µm is observed if the initial rough cut has been accomplished at high discharge energy setting. Whereas the best value of RL thickness, i.e. 5.36 µm, can be realized with low level of RCH. A significant decrease in the presence of foreign materials is recorded, indicating its strong correlation with the discharge energy used during machining.

Investigation on surface integrity features for machining of hybrid composite through rough and trim-cut WEDM has been reported by only a limited number of researchers in the past. This study is attempted at fulfilling few vital gaps by addressing the issues such as evaluation of the efficacy of trim cutting under different discharge energy conditions (using RCH), analysis of wire wear pattern in both rough and trim-cut modes and investigation of the wire breakage phenomenon during machining.

This chapter develops robust panel estimation in the form of trimmed mean group estimation for potentially heterogenous panel regression models. It trims outlying individuals of which the sample variances of regressors are either extremely small or large. The limiting distribution of the trimmed estimator can be obtained in a similar way to the standard mean group (MG) estimator, provided the random coefficients are conditionally homoskedastic. The authors consider two trimming methods. The first one is based on the order statistic of the sample variance of each regressor. The second one is based on the Mahalanobis depth of the sample variances of regressors. The authors apply them to the MG estimation of the two-way fixed effects model with potentially heterogeneous slope parameters and to the common correlated effects regression, and the authors derive limiting distribution of each estimator. As an empirical illustration, the authors consider the effect of police on property crime rates using the US state-level panel data.

With increased application of hybrids, methods have been developed enabling resistor films to be cut away until the resistor has precisely the required value for correct functioning. Passive trimming is giving way to active or functional trimming where the frequency response itself is adjusted using a sine wave generator and waveform analysis equipment. Some of the problems encountered in trimming are discussed, including those caused by the high energy laser light itself; the effect on active circuits caused by the generation of Ipp currents; and DC offset or level shifts produced by low level light. The importance of producing a system in which laser, instrumentation and computer are programmed in one language is emphasised. Finally the advantages of functional trimming are summarised.

Practically all salmon fillets produced in Norway are trimmed clean of unwanted fat, bone remnants and other defects according to customer requirements. In today’s modern salmon-processing plants, the trimming operation is performed by a combination of automated trimming machines and manual post-trimming. Manual post-trimming is necessary due to the inability of current trimming machines to obtain satisfactory trimming. The purpose of this paper is to describe the work done so far toward a robotic post-trimming of salmon fillets.

A prototype concept system was developed to explore the possibility of robotic post-trimming. The concept is based on 3D machine vision, a high-speed robot manipulator and a flexible light-weight cutting knife.

The developed prototype demonstrated the feasibility of detecting a pre-defined object to be trimmed in 3D, and performing the specified trimming cut along a 3D cutting trajectory.

The developed prototype system was built and integrated – focusing so far only on a single trimming operation: the tail cut.

The originality in the paper is the description of a prototype integrated system, focused on robotic post-trimming of salmon fillets. The value is in providing a starting point for further development toward a complete robotic post-trimming of salmon fillets.

The purpose of this paper is to consider the monetary valuation implications arising from local government tree trimming, by calculating the loss of local government authority’ monetary tree value arising from trimming trees under power lines.

A city council model of estimation of the monetary value of city trees in a sample of three streets in a suburb of the Perth Metropolitan Area in Western Australia is applied to ascertain the loss of monetary value to the local government authority arising from tree trimming.

Using a sample of 274 city trees, the results of the study show that 156 city trees did not get trimmed thus incurring no monetary loss. However, the average loss of monetary value from 118 city trees that were trimmed was AU$2,816 per tree, suggesting a substantial loss of value to the council.

The use of monetary tree valuation should be treated with caution as there is a focus on monetary calculations rather than non-monetary evaluations of trees. Further, the analysis does not take into account increases in value of city trees resulting from their growth.

In trimming trees, monetary value and canopy cover of trees may be reduced. In terms of property management, it may be helpful for the city council to take into account loss of city tree value from tree trimming when considering a cost-benefit analysis of the above ground/underground trade-off of power line installation.

With increasing populations and demand on services, local government authorities may use monetary valuation techniques of trees to provide an accountability to ratepayers.

The results highlight the value loss of trimming a tree. The study’s originality rests in providing local government authority a valuation.

Understanding the performance and flight envelope of a damaged aircraft is a preliminary requirement to recover the aircraft after damage. This paper aims to provide a comprehensive understanding of wing damage effect on airplane performance, local stability, and flying quality of each trim state inside the achievable flight envelope.

This paper demonstrates the use of attainable equilibrium points which are referred as trim states in order to estimate a damaged airplane manoeuvring flight envelope using a numerical computation method.

Wing damaged airplane manoeuvring flight envelope is estimated for different portions of the wing tip loss. Local stability at each trim condition inside the estimated flight envelope is analysed, and also motion flight modes and flying quality sensitivity to the wing damage are explored.

Local stability and flying quality analysis at each trim condition inside the flight envelope which demonstrate the effect of damage provides a criterion to prioritize the choice of trimmed flight condition as motion primitives for the airplane post‐damage flight and safe landing.

This paper aims to study the effects of varying laser trim patterns on several performance parameters of thin film resistors such as the temperature coefficient of resistance (TCR) and target resistance value.

The benefits and limitations of basic trim patterns are taken into consideration, and the plunge cut, double plunge cut and the curved L-cut were selected to be modelled and tested experimentally. A computer simulation of the laser trim patterns has been developed for the modelling process of the resistors. The influence of the trim length and resistor dimensions on the TCR performance and resistance value of the resistors is investigated.

It is found that variation in trim length, within the range of 5 to 15 mm, can give significant increases in the TCR of the thin films. Thus, for the plunge cut, TCR can reach up to 11.51 ppm/oC, for the double plunge cut up to 14.34 ppm/oC and for the curved L-cut up to 5.11 ppm/oC.

Research on the effects of various laser trimming geometries on the TCR and target resistance accuracy is limited, especially for patterns such as the curved L-cut, which is investigated in this paper.