Fujitsu s Experience with Bead Probe and Evaluation by a Flying Probe Tester

Transcription

1 Fujitsu s Experience with Bead Probe and Evaluation by a Flying Probe Tester September 16, 2008 The 2nd Annual Bead Probe User Group Meeting 2008 Shuichi Kameyama, Kazuhisa Tsunoi Fujitsu Limited

2 1. Fujitsu s Experience with Bead Probe Agenda Background Bead types and test vehicle Stencil aperture shape to Bead shape Contact resistance and error analysis Conclusion

3 Background Fujitsu made an agreement about Bead Probe with Agilent, then we received the Bead Probe Handbook. But, the Handbook does not include any specific data to design or implement BP on boards. Therefore we decided to use the following 2 step approach. STEP1: Feasible study of the BP with Fujitsu test vehicle STEP2: Investigate how to implement BP with our products We are now on STEP1 This presentation introduces our experience of the STEP1 2

4 Bead type variation for evaluation Trace width Solder mask hole width Solder mask hole length Stencil aperture 0.1mm (4mil) OpenMask >trace width Trace width x1.5 Circle 0.2mm (8mil) OverMask <trace width Trace width x2 Diamond 0.3mm (12mil) Trace width x3 Bead height 0.1 mm 0.3 mm 0.5 mm Trace angle 0 deg 45 deg 90 deg 0.4mm (16mil) Trace width x4 Solder mask hole Width Stencil aperture OpenMask OverMask Heig ht Trace length Circle diamond 3

5 Fujitsu test vehicle for Bead evaluation size:158mm x 289 mm # of Beads:1872(@single side) # of Bead types : 78 # of trace angles : 3 Stencil thickness : 120um

6 Stencil aperture shape to Bead shape Solder Paste Stencil Aperture Shape Aperture Size D < b Aperture Size D b Aperture Size D > b Circle W D b a a=0.2 b=0.4 D= a=0.2 b=0.4 D= a=0.2 b=0.4 D=0.5 Diamond W D b a a=0.2 b=0.4 D= a=0.2 b=0.4 D= a=0.2 b=0.4 D=0.64 D =Aperture Size, a / b =Solder mask Opening Size, W =Trace Unit:mm There is no difference between circle and diamond in externals

7 Contact resistance of Beads on test vehicle Number of measured beads : 3,744 Probe types (pitch/force) : 4 (100mil/200gf, 100mil/150gf, 50mil/150gf, 50mil/100gf) Probe tip style : serrated Measurement method : 4 wire Probe Max. Min. Average Measured BP Contact error 100mil/200gf 3,827.3mΩ 23.7mΩ 51.5mΩ mil/150gf 1,736.4mΩ 24.9mΩ 51.4mΩ mil/150gf 1,426.0mΩ 22.9mΩ 52.5mΩ mil/100gf 294.9mΩ 24.7mΩ 59.7mΩ (Ω) Probe 50mil-150g Max Min Ave Bead type 6

8 Contact open error Bead analysis Solder Paste Resist Aperture Size OpenMask a > W W D OverMask a < W b D a Contact error Bead a=0.2 b=0.3 D= No error Bead a=0.2 b=0.3 D=0.44 W=0.2 W b a a=0.1 b=0.3 D= a=0.1 b=0.3 D=0.44 Unit:mm Thin Beads (width<0.2mm) cause contact error using a serrated probe, because a serrated probe tips stride over a bead. But fat Beads (width>0.2mm) do NOT cause contact error. The relation between the Bead width and a serrated probe tip pitch is critical. The Bead width is related to the bead height design. 0.2mm 0.1mm

9 Conclusion for the experience of STEP1 Obtained basic knowledge about Bead Probe Confirmed manufacturability on our own process Next evaluation 75um(3mil) trace width trial Manufacturing stability at volume Long term reliability Contact error rate Probe tip style Repairs in tight area, etc We welcome your knowledge and suggestions!! 8

10 2. Evaluation by a Flying Probe Tester Agenda Basic evaluation with Agilent sample board Small Bead and longevity evaluation with Intel TV Conclusion This evaluation data was presented by Takaya Corporation Agilent and Intel offered sample boards

11 Basic evaluation with Agilent sample board(1) 3.5 Contact resistance of probing from oblique direction ( Probe: Takaya special, tip form: flat ) Agilent Bead Probe sample board : 5 mil trace width Bead Probing angle : 6.4 deg C ontact resistance ( Ω ) Contact speed : 400mm/s Contact speed : 150mm/s Increasing resistance on 400mm/s Takaya special flat tip probe Contact number of times 150mm/s 5 mil trace width, Flat face probe 1000 times probing on one Bead Probing speed : 400mm/s(normal), 150mm/s(slow) Increasing the contact resistance at over 500 times in high speed probing (400mm/s) with a flat tip probe. No problem at normal usage (<10 times) 10

12 Basic evaluation with Agilent sample board(2) Contact resistance of probing from oblique direction ( Probe: Takaya standard, tip form: small 4-crown ) 3.5 Same Agilent sample board Same probing Contact resistance ( Ω ) Contact speed : 400mm/s Contact speed : 150mm/s Contact number of times 5 mil trace width, Standard crown tip probe 1000 times probing on one Bead Probing speed : 400mm/s(normal), 150mm/s(slow) Takaya standard crown tip probe No increase of the contact resistance with a standard crown tip probe. Takaya plying probe tester with standard crown tip probe is available for Agilent Bead sample boards. 11

13 Small Bead and longevity evaluation with Intel TV (1) 3.5 Contact resistance of probing from oblique direction ( Probe: Takaya special probe for smal-bead, tip form: micro 4-crown ) Intel Test Vehicle board for Bead 3mil 6mil trace width 480 beads in a test block 85μm (3.4 mil ) Takaya special micro crown tip probe for 3mil Bead Contact resistance ( Ω ) Test - 1, Contact speed : 400mm/s Test - 2, Contact speed : 400mm/s Contact number of times ( 480 ) 3-6 mil trace width, Special micro crown tip probe 250,000 times probing on 480 Beads Probing speed : 400mm/s Tip after 250,000 contacts Bead after 550 contacts Takaya flying probe tester with special micro crown tip probe is available for 3 mil bead on Intel TV. The longevity of probe tip is 100,000 contacts. 12

14 Small Bead and longevity evaluation with Intel TV (2) 130 μm (5.1 mil ) Min. Bead 3mil 14 mil Minimum Bead dimension on TV 9 mil Contact resistance ( Ω ) Contact resistance of probing from oblique direction ( Probe: Takaya standard, tip form: small 4-crown ) Contact speed : 400mm/s Takaya standard crown tip probe Tip after 3,250,000 contacts Contact number of times ( 480 ) 3-6 mil trace width, Standard crown tip probe 3,250,000 times probing on 480 Beads Probing speed : 400mm/s Takaya flying probe tester with standard crown tip probe is available for 3 mil bead on Intel TV. The longevity of probe tip is over 1 million contacts. 13

15 Conclusion Takaya flying probe tester has a high possibility to test boards using Bead Probe without any specific enhancement. By using Takaya standard crown tip probe, it is possible to contact from 3mil to 6mil Beads on Agilent demo board or Intel TV board. The longevity of the Takaya standard crown tip probe for Beads is over 1 million times. Individual evaluations are necessary for testing other boards. 14

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