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Carrier Usage with the x6000 Automated X-ray Inspection System

There are several reasons that a panel cannot be inspected in the x6000 automated x-ray inspection system without the use of a carrier. The following is a list of reasons to use a carrier:

  • On the parallel edges of the panel that would be clamped in the system, the component to panel edge clearance does not meet the minimum specifications.
  • The panel is not square or rectangular shaped.
  • The panel size does not meet the minimum board specifications.
  • The panel is susceptable to warpage and requires support.

Carriers can be used successfully in the x6000 if they are implemented correctly. There are several factors to consider when designing a carrier. All factors ensure the panel does not shift or bounce in the carrier during the inspection. The following sections outline the factors that should be considered in the design.

Material Used for Implementing a Carrier

When designing a carrier a little pre-planning in the type of material used for the carrier construction will help alleviate possible problems that may be encountered during testing. The following guidelines should be used in the carrier design and use of materials:

  • Use material that is durable and will continue to hold the panel tightly in place.
  • Use material that is more transparent to x-rays and that does not impose additional shading on the panel.
  • Aluminum and ESD safe composite materials are generally used for carriers since they are light weight and durable.
  • Softer materials will wear and cause inconsistent alignment and ultimately an increase in False Calls.
  • If hold downs, clamps, and supports use material that may impose shading on the panel, strategically place them so that they are in less densely populated areas.
  • Minimize the height of hold downs and clamps as they may impose shading across a larger region.

Dimensions of the Carrier

If possible, standardize the size of the carrier and use the following as dimension guidelines: Refer to Figure 1 for details.

  • The carrier and the associated panel should not exceed the system specifications for the minimum and maximum panel size, top and bottom clearances, minimum and maximum panel thickness, and maximum weight. Refer to the Keysight Medalist x6000 Automated X-ray System Data Sheet for the exact numbers.
  • The carrier should be either square or rectangular and the corners should not be rounded.
  • The parallel edges of the carrier that ride on the converyor rails should be the same thickness as the panel.
  • The minimum carrier edge thickness ahould be 1.8 mm (70 mils). If the panel thickness is less the 1.8 mm, it will be recessed into the panel cavity and will require hold downs or clamps that extend into the cavity to make contact with the panel.
  • The bottom of the carrier edge that rides on the conveyor belt should be on the same plane as the bottom of the panel in the carrier.
  • The edge clearance should be greater than 5 mm (200 mils) to avoid contact with the inside edges of the conveyor.
  • The clearance between the panel edge and edge of the carrier recessed cavity should be ~0.5 mm (25 mils).
  • Offset carriers (the bottom of the panel is not at the same plane as the bottom of the carrier edge) will not work in the x6000 system.
  • The tolerances for building multiple carriers should be the same as or better than the tolerances for PCB’s.
 Figure 1
 Figure 1

Panel Mounting in the Carrier

Ensuring that the panel is mounted in the carrier so that it does not move during the inspection is the most important factor to consider when designing a carrier. Tooling pins, panel clamps / hold downs, and panel support areas should be used for best results. Refer to Figures 2 and 3 for example of a carrier design.

  • Use tooling pins that are located diagonally across the panel from each other to ensure that the panel is properly placed in the carrier with a minimum of panel skew.
  • Use panel clamps / hold downs spaced around the panel so that they provide sufficient downward force on the panel. An easy test to see if the clamps are providing enough downward force is to push up on the bottom of the panel. The panel should not easily move.
  • The cavity where the panel rests should provide enough support for the panel so that is does not bounce or move during inspection. It may be necessary to add more carrier supports that cross the panel if it is susceptable to warping or will bounce during inspection.

Test the Carrier

  • Before you actually put the carrier into the system, it is a good idea to test out the effectiveness of the carrier to hold the panel in place. If the panel moves during any of the tests below, modifications to the design of the carrier may need to be implemented before it is released for production use.
  • Try to move the panel side–to-side in the carrier.
  • Verify that all corners of the panel are properly supported. For oddly shaped panels, verify that all sections are supported.
  • Push up on the bottom of the panel to verify the hold downs or clamps are providing sufficient down force.
  • Shake the carrier and verify that the carrier provides enough support across the panel.

Panel Program

A drawing of the carrier with measurements will ensure that the correct values are entered when defining the carrier size and offsets of the panel during the development process. Using the correct measurements will ensure that the panel CAD will match the panel under inspection after an alignment is performed.

 Figure 2
 Figure 2
 Figure 3
 Figure 3