ERA’s new system offers all the considerable capability of its predecessor but offers some significant technical enhancements. This article explains what these are and how they are already benefiting our customers.

Serving Industry for more than 35 years, ERA's Scanning Electron Microscopy (SEM) service embodies a highly professional capability for the observation and analysis of all types of vacuum-tolerant materials. ERA’s Reliability and Failure Analysis Group has recently invested in a state-of-the-art Variable Pressure EVO® 50XVP® SEM from Carl Zeiss SMT and an INCA® system with fully integrated Energy Dispersive X-ray (EDX) and Wavelength Dispersive X-ray (WDX) analysers from Oxford Instruments.

ERA’s new SEM system New features at a glance: Larger specimens accommodated Quicker location of regions to be examined ‘Difficult’ samples can be imaged better The sample need not be coated
The detection limit for trace elements has been improved by a factor of ten and is now in the ppm range for many elements – particularly important for RoHS directive analysis The ability to positively identify small amounts of a damaging or unwanted element in the presence of large amounts of other materials (e.g. traces of chlorine or sulphur in the presence of silver or lead) has been greatly improved – particularly important in corrosion studies Analysis of particulates or second phase inclusions and precipitates can be automated to detect, measure and record the morphology and chemistry of hundreds of particles within the sample

More flexibility in what can be analysed
The new variable vacuum capability allows all samples to be examined without prior coating, preserving features or contaminants that may have been hidden or modified by the coating and preparation techniques previously required for non-conducting samples. This makes it possible to examine samples in the SEM at various stages of a process or investigation without altering the nature of the surface. It also enables examination of samples that were previously impossible to view at all in an SEM due to outgassing or inability to form a continuous conducting coating. Examples of such samples are heavily corroded surfaces, and fine, fibrous materials such as the inside of an electrolytic capacitor (Figure 1).

Handling larger samples with ease
Sample size and ease of manipulation have also improved – we can now handle samples of up to 250mm diameter and weighing 0.5kg (tilted), 2.0kg(not tilted). A five-axis motorised stage and improved software, coupled with an in-chamber camera, makes it easy to select the areas for examination as shown in Figure 2.

	Figure 2. The in chamber camera allows easy sample area selection (left) and moving from sample to sample (right).

Improved detection sensitivity and elemental discrimination The INCA Energy+ microanalysis system combines energy and wavelength dispersive analysis (EDX & WDX) in one seamless package. EDX enables rapid analysis of elements in higher concentrations, while the new WDX is more sensitive and accurate for light and trace element analysis. The combination of the two techniques enables us to rapidly characterise the full elemental composition of your sample.
Figure 3. The SEM chamber showing the WDX detector attached to the left of the SEM column and the refrigerated EDX detector attached to the rear right.

Analysis of a corrosion product on a returned PCB Failure analysis relies crucially on determining the nature of materials. EDX, as shown in the yellow spectrum in Figure 4 confirms the presence of lead (Pb) but whether sulphur (S) or chlorine (Cl) is present on the circuit board remains uncertain due to the overlap of the relatively broad EDX peaks.
	t Figure 4. EDX spectrum of PCB corrosion product. EDX spectrum yellow. WDX pale blue.
WDX provides the key to unlock this secret. Having much greater resolution and sensitivity than EDX, WDX (pale blue spectrum) confirms the presence of both sulphur and chlorine in the corrosion product - thus providing insight into the source of the corrosion and hence the cause.

RoHS Analysis for Lead, Cadmium etc.
The restriction of certain hazardous substances directive, RoHS, renders illegal the sale of most electrical products if they contain lead, cadmium, mercury, hexavalent chromium and two brominated flame retardants. The SEM is being well used by producers to check for the restricted substances. The new WDX capability enables ERA to detect down to ~0.01% in many homogeneous materials as part of ERA’s RoHS product/component assessment service.

Dust and particulate analysis
The new system allows automated identification and collection of particle size and composition over large areas. This facility is particularly useful for dusts, filtered particulates, gun shot residues and other contaminants.

Figure 5. Particulate data is collected using software control of the sample stage (right) to produce a map of the particles found (left). Each particle can be analysed in more detail as required (top).

Want to know more?
To find out more call us on +44 (0)1372 367444 or email