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This paper reports on thermal strain analysis of integrated circuit (IC) packages using the optical, atomic force microscope (AFM), and scanning electron microscope (SEM) Moiré methods. The advantages and disadvantages of a full field optical Moiré, a micro‐optical Moiré, AFM Moiré, and SEM Moiré methods are compared. The full field Moiré interferometry is used to investigate the deformations and strains induced by thermal loading in various packages at the macrolevel. The micro Moiré interferometry is used to study the strains in the small solder joints. An optical Moiré interferometer with a mini thermal‐cycling chamber can be used for real time measurements of thermal deformations and strains of IC packages under thermal testing. Furthermore, the novel methods, AFM Moiré and SEM Moiré, can be also utilized to measure thermally induced deformations and strains of IC packages conveniently using the equipment that is commonly and primarily used for many other applications.

Describes the setting up of a moiré topographic system to measure three‐dimensional convex and concave surfaces of moulded brassière cups. The essential features of the system consisted of a photographic instrument which precisely controlled the position of the light source, the camera, the grid and the cup sample. As the uniformity of the grid was most crucial to produce a high contrast moiré picture, a photochemical‐machined grid plate was developed, and a pneumatic grid translation device was incorporated into the system to produce a clear image. The tolerance of the instrumental error was derived by the law of error propagation and the confidence with the moiré set‐up was assured.

In this paper, two transform methods, the Fourier transform (FT) and the wavelet transform (WT) methods, are utilized to process moiré fringes for the strain analysis of electronic packaging. With the introduction of fringe carriers, those transform techniques need only one fringe pattern for each deformation state. The strain modulation to the carrier frequency can be subtracted by filtering as the pattern is transformed into spectrum domain by the fast‐FT processing, and the deformation field can thus be restored by the inverse FT transform after spectral shifting. The WT method expands the pattern information involved in the fringe carrier in both spatial domain and spectral domain to analyze the deformation distribution in this combined space. By changing the transform scales in the processing, the wavelet transform offers multi‐resolution analysis for the deformation field with high gradients.

With the introduction of three new linear transducer assemblies and a new counter unit the Ferranti Measurement and Inspection Group, Dalkeith, Scotland, now offer, within the Acculin range, six different digital read‐out (DRO) systems for machine‐tools.

Researchers in the past have used Fourier transformation method to determine the in‐plane displacement components from moiré fringes generated by a pair of overlapping circular gratings. In this approach it is necessary to assume that the transmittance is sinusoidal. The purpose of this paper is to propose a graphical method for determining the 2D displacement components from the moiré patterns more easily instead of the complex Fourier transformation method.

The moiré patterns were spatially transformed from Cartesian‐to‐polar coordinate system. The morphological grayscale dilation operation was used to eliminate the residual gratings in the transformed pattern while preserving the moiré fringes. The center line of the moiré fringe was fitted with a sine curve and the in‐plane displacement values were determined directly from the peak‐to‐valley height and the position of the peak in the fitted curve.

Experimental results showed that the proposed moiré pattern analysis method is able to give in‐plane displacement accuracies of 0.002 mm in the x‐direction and 0.01 in the y‐direction without the need for complex computation.

Resolution of the proposed method is limited only by the resolution of the imaging system.

The proposed graphical method for determining 2D displacement components from the moiré patterns can be applied to low‐frequency circular gratings whose transmittance is not sinusoidal.

The graphical analysis method is novel and allows the displacements components to be determined more easily.

This paper reports on a study of the scanning electron microscope (SEM) Moiré method. Tests were carried out by rotating the specimen grating slightly with respect to the electron scanning raster lines, to verify that the Moiré images captured were really due to the interference between specimen and reference gratings. The experimental results coincided well with the calculated theoretical values and with small measurement errors. Then, the shear strains experienced by the solder joints of a flip‐chip ball grid array specimen were investigated using the SEM Moiré method. The results were compared with those obtained using the optical Moiré method.

Moiré fringe transducers have much potential — but they are being under‐utilised according to PA Technology. Sarah Gardner reports.

The bending stresses in plate models can be determined by means of the experimentally produced moire fringes, which Rive directly the gradients at all points of the surface of the model. It is shown that this technique can be used for cantilever plates with either uniform or non‐uniform thickness provided that, in the latter case, the thickness is not large. The technique and apparatus is described, details of the experimental technique are given and discussed, and some resultant experimental fringe patterns are shown and analysed.

Details are given of a simple extensometer with a gauge length of 0·50 in. which uses the mechanical interference of two sets of parallel straight lines as the means by which to measure displacement and hence strain. The interference effect exhibited by two pieces of Dufaycolor reseau placed in surface contact has been employed for development purposes since the reseau provides a convenient and ready‐made source of fine parallel rulings, after the removal of the photographic emulsion. Some of the related aspects of mechanical interferometry and its possibilities are discussed by way of introduction.