Archive for October, 2014

Three Factors in Selecting an XRF for Circuit Board Quality Control

Anybody involved in the printed circuit board industry realizes that quality components, design, and development are critical to achieving reliable performance.  Found in a range of products from simple toys and common cell phones to critical automotive and aerospace uses; proper quality control testing can insure that reliability and make all the difference in a circuit board manufacturer, or user, building a repeat client base.

PCB manufacturers will test assemblies at various production points but a board may also be tested throughout the supply chain at incoming inspections to verify boards meet that users specifications.  X-ray fluorescence analyzers are one of several pieces of equipment commonly relied on in the quality assurance process of circuit boards.  These analyzers will measure coating thickness (Au/Ni/Cu, etc) while also providing composition analysis (solder, RoHS, etc) in some models.

There are a number of critical factors to consider when reviewing the XRF analyzer options available for PCB quality control.  The first thoughts of most interested organizations will be budgetary aspects, ease of use, and data management – but the following three factors should also be considered

Hitachi XRF Stage for Circuit Boards

XY Stage and Slot Depth of Hitachi FT110A

PCB COVERAGE: an XRF analyzer should be able to measure any area on the board, from side to side and corner to corner.  This can be difficult with larger circuit boards so when reviewing slotted chamber systems, one needs to consider the depth of the slot.  The minimum requirement is that a user can measure their largest board from the edge that sits against the interior of the system to the middle of the board (they can always turn the board 180 degrees to measure the other side).  Most PCB requirements will call for the analysis of multiple spots on a board.  In these situations, an efficient option is to have an XRF analyzer with a motorized and programmable stage.  The stage size and travel capabilities are two additional interests when considering PCB coverage…so make certain the largest board can sit on the stage and its movement will allow for analysis of points from side to side.

COLLIMATOR SIZE: Knowing the size of the spots that need to be measured is important in circuit board testing.  Errors in measurement can occur if a user selects a collimator that is too large for a measurement spot because other materials near the targeted areas can affect results.  The rule of thumb is that the measurement spot should be at lease twice as large as the collimator so most XRF analyzers will offer multiple collimator options to cover a variety of measurement spot sizes.  The popular Hitachi FT110A XRF Analyzer can be configured for PCB testing (motorized stage with a slotted chamber) that includes four of the most common collimators (0.025 x 4 mm, 0.05mm, 0.1mm, 0.2mm).

APPLICATION CONSIDERATIONS:  It’s important to try and cover all possible uses of an XRF in advance of installation.  This includes correctly identifying any additional software required (bath analysis capabilities, RoHS Screening, etc), installation of critical filters (most common for PCB applications, a Co filter, is available on the Hitachi FT110A for Ni/Cu applications – one of the most common being Au/Ni/Cu), and making certain the user has all the required calibration standards (ie Sn-Pb sets, ENEPIG, ENIG, Immersion Ag, Sn, Pd sets).

An organization investing in XRF technology for quality control of printed circuit boards will be able to insure that they efficiently meet their requirements when they takes these factors into account and work closely with an experienced XRF Sales Associate.  Contact Eastern Applied Research to discuss your PCB Quality Control requirements.

XRF Chamber for Circuit Boards