Socket Algorithm Setup

Transcription

1 Socket Algorithm Setup 5 Purpose The purpose of this document is to assist trained 5DX programmers with setting up the Socket algorithms. In this document This document is divided into the following sections. Topic See Page Initial Socket setup 1 SPC setup with graphics 2 Threshold setup without graphics 5 Final Socket setup 7 Socket setup process flow 8 Initial Socket setup Follow these steps to initially set up the Socket algorithm. 1 Set the following threshold values for all subtypes. LOCATOR SEARCH_DIST 0.50 SEARCH_DIST_ACROSS 0.50 SPC PAD_PROFILE_WIDTH 0.4 HEEL_SRCH_DIST 1.0 SHORT MIN_THICK_MILS_SIDE 3.0 USE_LEARNED_JOINT 1 IPD_REDUC 0.9 EXCLUDE_REGIONS 48 INSUFFICIENT PAD_RJT_PCT 35 HEEL_WIDTH_RJT_PCT 35 CENTER_RJT_PCT 1.0 TOE_RJT_PCT 1.0 OPEN MIN_OPEN_SIGNAL 0.7 MIN_LENGTH_REJ 50 Ver 1.0 Page 1 of 8

2 Initial Socket setup (continued) 2 Set up the AlgSlice NDF file. Comment out Socket Short during initial setup. This will reduce false-calls during initial testing. Comment out Socket Excess and Misalignment to permanently exclude them from the test. Joints that are truly misaligned or excess will be caught by Short. Socket Locator, SPC, Insufficient, and Open should be included in the test. SPC setup with graphics With SPC Graphics turned on, test each subtype and complete the following steps. 1 Verify the pad profile location. The light blue box representing the pad profile should be centered over the solder joint. If the pad profile is not centered, verify the CAD location. If the CAD location Then does not match the X- follow the procedures in the Agilent ray image of the joints 5DX Approved Programming matches the X-ray image of the joints Practices CheckCAD document. turn on graphics for Locator and verify the size of the double yellow box matches the length and width of the solder joint. Adjust EFFECTIVE_PAD_LEN to lengthen or shorten the box. Adjust EFFECTIVE_PAD_WIDTH to widen or narrow the box. Ver 1.0 Page 2 of 8

3 SPC setup with graphics (continued) 2 Verify the pad profile width. If any portion of the side fillet falls within the pad profile reduce the size of the PAD_PROFILE_WIDTH threshold. 3 Verify the heel location. Make sure that the blue bar is centered on the thickest part (the peak) of the joint. If it is not centered on the peak, increase the HEEL_SEARCH_DIST. Increasing this threshold too much will make it more difficult to detect open joints. The dark purple line indicating the end of the heel search distance should not extend much beyond the peak of the heel for normal joints. Note: Certain socket designs have bent leads such that the heel is not in line with the rest of the joint. If this is the case use the TWIST_HEEL_SHIFT threshold to position the heel accordingly. If the heel is twisted to the extent that a portion of the heel falls onto the Background Profile boxes, it will be necessary to shift the background boxes away from the heel. This is done by adjusting the TWIST_BKG_SHIFT. In this example, TWIST_HEEL_SHIFT has been set to 0.1 to account for the offset of the heel from the rest of the lead. No change was necessary for TWIST_BKG_SHIFT. Ver 1.0 Page 3 of 8

4 SPC setup with graphics (continued) 4 Verify the heel size. Make sure that the size of the blue bar is approximately the size of the heel peak. HEEL_TOE_REGION_SIZE sets the size of the blue, yellow, and green bars in the Pad Thickness Profile. Increase or decrease this threshold to adjust the size of the blue bar. Note: The blue, yellow, and green bars should not overlap. 5 Verify the toe location. Make sure that the green bar indicating the toe region is located on the toe. If the green bar is not falling on the toe, complete the following steps. a. Measure in mils the pin length in the Image Window using the red or green cursor. b. Position the cursor to measure from the center of the heel (blue box) to the center of the toe. c. Set PIN_LENGTH to this value in mils. d. Retest the subtype with graphics on to verify this that this measurement places the green box on the toe. If not, readjust the threshold value. Ver 1.0 Page 4 of 8

5 Threshold setup without graphics With SPC Graphics turned off, test each subtype and complete the following steps. 1 Set the nominals. a. Test the Socket joint type, and create a Summary Data Sheet of the SPC measurements in Review Measurements. b. Select Update Thresholds function to write the nominal solder thickness values for all subtypes. 2a Set the Open thresholds using an unloaded "opens" board. Note: It is strongly recommended to use an "opens" board for setting open thresholds. If an "opens" board is not available, follow the procedure in 2b. a. Chart the Open Signal using tests date from both the loaded and unloaded boards, sorted by run. There should be a clear gap between measurements taken on the loaded board (assuming all joints are good) and unloaded board. b. Set MIN_OPEN_SIGNAL so that it is above the values for the unloaded board and below the values for the good joints. If there is not complete separation between the open signal values for good and open joints, complete the following steps: a. Test with SPC graphics on again. b. Make sure that the heel is located properly and the heel search distance is not too large. c. Chart the fillet length. d. Set MAX_LENGTH_REJ so that it is above the values for the unloaded board and below the values for the good joints. Choose a value nearer to the values for the open joints. Note: Do not set the length thresholds too tight. Rely on the open signal as the primary measurement to detect opens. Ver 1.0 Page 5 of 8

6 Threshold setup without graphics (continued) 2b Set the Open thresholds without using an unloaded "opens" board. a. Create a Raw Data Sheet of the Open Diagnostic measurements for each subtype. b. Chart the open signal. Ignoring all extreme values, identify the lowest value. Note: Extreme values may represent defective solder joints or out of focus images. These can be confirmed by running a test with SPC graphics enabled. c. Set the MIN_OPEN_SIGNAL. If the minimum open signal measurement for the good solder joints is above 1.0, leave the MIN_OPEN_SIGNAL threshold at 0.7. If it is below 1.0, set MIN_OPEN_SIGNAL to half of the minimum value. Note: It is not recommended to set MIN_OPEN_SIGNAL below 0.2. d. Chart the fillet length. e. Set MAX_LENGTH_REJ. If there is a clear separation between the good and open joints, choose a MAX_LENGTH_REJ nearer the value for the open joints. If there is not a clear separation, set MAX_LENGTH_REJ to the maximum value for an acceptable joint plus 20. Note: Do not set MAX_LENGTH_REJ too tight. Rely on Open Signal as the primary measurement to detect opens. Note: It is not possible to eliminate all false calls due to voids in the heel while maintaining the ability to catch all opens. A certain number of false calls due to voids in the heel may have to be accepted. Ver 1.0 Page 6 of 8

7 Final Socket setup Use the following steps to complete the Socket setup. 1 Reduce false calls. When you are done setting up all subtypes, test the Socket joint type with SPC Graphics off to fine-tune for false calls. If there are repeated open calls for fillet length, verify that the calls are not real defects before changing any thresholds. If the open calls for fillet length are false, increase MAX_LENGTH_REJ or decrease MIN_LENGTH_REJ as needed. If there are repeated calls for MIN_OPEN_SIGNAL, test these joints with graphics ON to determine the cause. If it is voids in heels, ignore. If the x-ray image looks in focus, but there are false calls, turn graphics ON to verify that SPC is locking onto the correct regions of interest. If there are false calls due to shading, it may be necessary to create a new subtype in order to test these joints with different thresholds. Measurements should be significantly (20 percent or more) different than average before establishing a new subtype. Testing of multiple boards can be useful to determine if the variation seen is due to shading instead of normal process and measurement variation. If the shading affects the whole component, merely assign a new subtype to that component. If one or more pins on the component need to be subtyped instead of the whole component, see the Component Subtyping procedure for details. 2 Set up Short. a. Remove the comment from Socket Short in the AlgSlice NDF file. b. Turn on joint learning for Socket Short. c. Test the Socket joint type on one or more boards that do not have shorts. d. Turn off joint learning for Short. e. Retest the joint type and check for false calls. Note: To save setup time, joint learning for Short can be postponed until all algorithm families have been adjusted up to that point. Joint learning can then be done for the entire application. Ver 1.0 Page 7 of 8

8 Socket setup process flow 5 Ver 1.0 Page 8 of 8