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Product category: Stand-Alone Instruments
News Release from: HumiSeal Europe | Subject: Must System II Plus
Edited by the Electronicstalk Editorial Team on 02 June 2003

Solderability tester takes in smallest
SMDs

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The industry benchmark Must solderability tester has been improved to accommodate the enhanced test accuracy needs demanded by the smallest surface mount devices.

The long established industry benchmark Must solderability tester from electronics reliability measurement specialist Concoat Systems (formerly available from Multicore Solders) has been even further improved to accommodate the enhanced test accuracy needs demanded by the smallest surface mount devices The Must System II Plus also offers a host of new features designed to accelerate test cycle times and make it even easier to use

To enhance measured solderability resolution of the smallest SM devices, the Must System II Plus now incorporates an even more sensitive "microwetting balance".

It also greatly improves its operational productivity by reducing the steps necessary to complete solderability testing tasks, and offers improved reproducibility of test results thanks to an enhanced alignment accuracy capability.

The Must System II Plus is also now supplied with an easy-to-use Windows XP Software operating system as standard (available as an upgrade for users of earlier systems based on the former MS-DOS operating system) and heavily revised firmware.

This significantly simplifies and speeds many operational tasks and procedures.

This includes, for example, the ability to produce pass/fail printouts (support for over 600 printers is included) where for easy identification failed components are highlighted in different colours.

Test results can also now be exported into all major spreadsheet packages such as Microsoft Excel for further statistical analysis and evaluation.

This also eases the inclusion of quantifiable test result data in written management reports.

Results can also be customised by adding explanatory text to individual graphs on screen that will print out with the graphs, and up to 13 wetting curves can now be simultaneously displayed on screen and printed out.

Component test database creation has also been simplified and includes the assignment of parameters to different component types in accordance with all major international standard methods such as IEC60068-2-54 and 60068-2-69, IPC/EIA J-STD-003A and MIL-STD-883 Method 2022.

As the need for solderability testing increases, with the higher temperature demands of lead-free soldering, Must System II Plus has been evolved to include testing of a variety of lead-free alloys.

"Although this product has traditionally been sold to high end, high reliability manufacturers, it is becoming an increasingly popular choice for even consumer electronics manufacturers wishing to avoid the massive cost of unnecessary rework, repair and worst of all: premature field failure", comments Concoat Systems Managing Director, Graham Naisbitt.

"Now, in its latest Must System II Plus version this tester enables even faster and more accurate solderability testing of surface mount and through-hole devices, PCB pads and plated through-holes, plus laboratory testing of surface finishes, fluxes and other soldering materials".

Solderability is a metallurgical function of any solid metallic surface and determines how easily (or well) a given termination will solder: both in terms of speed of wetting and strength of adhesion.

It is one of the most important parameters in any soldering operation because it reflects the likelihood of a termination forming a good alloy with the solder to produce a high quality solder fillet.

Although components and assemblies are generally assembled from parts of known (good) solderability, there is no way of guaranteeing this without testing.

This is especially true given the fact that a prime cause of poor solderability is how well a part has been stored and its age.

Moreover, as boards and components continue to shrink in size and become ever more fine pitch, the soldering process window narrows and the ability for a soldering process to accommodate even mild deteriorations in solderability is diminishing all the time.

The most effective method for measuring, testing and recording solderability (used by the Must System II Plus) is the wetting balance procedure.

In essence, this exploits the fact that if a metallic body is dipped into a bath of molten solder, the weight and speed with which the solder meniscus climbs upwards on the bodyûs immersed surface indicates how well the solder wets it and thus its solderability.

The greater the solderability, the higher a meniscus will climb, which can be measured as a change in the vertical force acting on a suspended specimen.

Although the type of wetting balance used for SM and TH specimens differs, the test principles are the same.

For TH devices, the component lead, or surface to be tested, is fluxed with a standard flux and dried.

It is then suspended from the wetting balance and immersed to a pre-set depth in a small, oxide-free molten solder bath, and raised upwards at a given speed to meet it.

The wetting balance measures the vertical force acting on the specimen over time.

This data is analysed by the Must System II Plus to produce a graph of force against time (a wetting curve) from which the wetting forced is calculated.

The larger the wetting force the better the solderability of a component.

Although the same solder bath method as used for TH components can be used to test SM devices, it can suffer from poor resolution because the buoyancy of small components in molten solder is close to the size of the wetting force that is being attempted to be measured.

Much greater resolution is obtained by using the "microwetting balance" procedure in which the solder bath is replaced by a small globule of molten solder weighing either 25 or 200mg (2 or 4mm diameter) which replaces the solder bath.

This method produces a larger wetting force for signal analysis and also allows individual leads to be tested on a multileaded component.

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