This extensive how-to consists of 9 paragraphs. You can use the table of contents on the right to navigate between sections.<\/p>\n
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<\/p>\n Tweezer pull is performing a pull test using tweezers. Tweezers are micro grippers that allow complete force control during opening and closing.<\/p>\n The tweezer holds a wire, a ribbon, or some other feature on the sample, then applies an upward force and effectively pulls away from the substrate. In some cases, it is necessary to prepare the sample before testing.<\/p>\n A peel test is essentially the same, but in addition to the vertical movement, the XY stage also performs a controlled lateral movement. The purpose is to maintain perpendicular force on the ribbon or wire being pulled off the substrate.<\/p>\n <\/p>\n There are 3 types of\u00a0Tweezers<\/a>:<\/p>\n <\/p>\n <\/p>\n There are many types of jaws to suit a wide range of applications. The most common are plain, serrated, hook, and cavity jaws.<\/p>\n <\/p>\n There are 3 types of closing functions to suit all applications:<\/p>\n <\/p>\n <\/p>\n Increasing grip force as the pull force increases is typically used when gripping hard and parallel parts. This way, the grip is maintained as the pull force increases. A constant grip force, regardless of the increasing pull force, is useful when gripping soft parts, where the sample can be deformed to obtain a grip but squashed too much if the grip force gets too high. A fixed closing distance (or: closing position) is used when the part already has a feature that the jaws can “hook” under. You can use the following chart to select the type of hook your application requires.<\/p>\n Use the following chart to select the type of hook the application requires:<\/p>\n <\/p>\n The most common material for jaws is tough steel, i.e., tool steel. Hard material jaws are essential when the jaws require small detail and precise tolerances because smaller detail can be machined into these materials. The disadvantage of harder materials is that it makes the jaws brittle and fragile.<\/p>\n Damaged or worn jaws can influence the test. The amount of acceptable wear depends on the application. Any jaw damage is acceptable if:<\/p>\n <\/p>\n When the tips of the jaws close, they should align closely with each other. The same guidelines for acceptability exist for jaw alignment as for jaw damage. However, as a general guide, misalignment should be at most 5% of the jaw width.<\/p>\n Having precise control over the grip force of the tweezers is highly important to do a correct test on one bond tester and to maintain a correlation between tests on multiple machines.<\/p>\n Choose electric (USB) tweezers with intelligent jaws<\/a> and built-in closed-loop force control to obtain consistent settings between multiple systems.<\/p>\n USB tweezer maximum clamping force is 8 kgf, This tweezer type is for use on pull\/peel tests at or below 10 kgf of load.<\/p>\n <\/p>\n Tweezer jaws tips can be fragile. To avoid damage, handle them with care and always store them in their cases when not being used.<\/p>\n USB Tweezers come in a safe case in a bracket. The bracket enables the operator to place the tips in the USB Tweezer and tighten the fixation screw without touching the fragile tips by hand.<\/p>\n Clean the tips with extreme care in case of contamination. Using a contactless\u00a0CBP Jaw Cleaner<\/a> to eliminate the risk of damage when cleaning the cavities is best.<\/p>\n <\/p>\n Precise tool alignment<\/a> is essential.\u00a0Align the tweezer jaws centrally to the sample and engage the jaw features like serrations, hooks, or cavities correctly in the vertical axis to get the best results. Sigma bond testers have vision technology for automatic alignment to minimize handling errors.<\/p>\n <\/p>\n Here we list the most common failure modes for gold wire tweezer pull. We also refer to our\u00a0grading library<\/a>, where you can\u00a0download result codes.<\/p>\n Tweezers are a possible solution for ribbon pull<\/a> because the tweezer jaws distribute the load evenly under the ribbon loop. However, a pull test with a flat or offset hook will also effectively keep the pull force on the center of the bond.<\/p>\n Ribbon loop heights are often very low, and a hook of sufficient strength may not fit. Special hooks can help, but the tweezer solution is often a good way to overcome loop clearance limitations.<\/p>\n The principle of a peel test<\/a> is to move 2 axes at the same time. This is typically the Z axis and either the X or Y axis. Therefore, the best tool to perform peel tests is tweezers.<\/p>\n The following schematic outlines how this works when the objective is to keep the angle of the pull force perpendicular to the sample. The result is a 90 degree peel test.<\/p>\n Less common are angled peels. The movement shown in the X is not equal to the upward movement. Backward peeling decreases the lifting force on the sample and can be useful testing thin substrates that tend to bend upwards.<\/p>\n The results from a peel test often require more analysis than a simple pull or shear test. The useful data in the force\/displacement graph can consist of the maximum (peak) force, the average force, the minimum force, or the energy. A bond tester with a good SPC package gives all these results directly after a test.<\/p>\n <\/p>\n There are multiple ways to test copper pillars<\/a>. The best method depends on the failure mode of interest and the construction of the sample.<\/p>\n It depends on the shape of the construction whether a Cold Bump Pull<\/a>\u00a0 (CBP) type test or a shear test is feasible to qualify the process.<\/p>\n <\/p>\n <\/p>\n Below is the test sequence for the Cold Bump Pull test:<\/p>\n Choosing either a closing distance or constant closing force on the tweezer jaws depends on which method produces the most failure modes of interest or the highest force. The failure modes are:<\/p>\n Copper-to-substrate breaks are a common failure mode. The copper’s bond strength and failure mode to the substrate pad are known when this happens. Copper solder break is not so common and probably indicates a non-wet. Copper extrusions indicate strong bonds.<\/p>\n Below is the test sequence for the shear test:<\/p>\n![\"How-to-Tweezer-Pull-TP\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/How-to-Tweezer-Pull-TP-1.jpg\")
<\/a><\/p>\nWhat is Tweezer Pull\/Peel<\/h2>\n
![\"Lead-pull\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Lead-pull.jpg\")
<\/a><\/p>\nTweezer design<\/h2>\n
Manual and automatic<\/h3>\n
\n
![\"Tweezers\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Tweezers-2.jpg\")
<\/a><\/p>\nTypes of jaws<\/h3>\n
![\"Type-of-Tweezer-jaws\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Type-of-Tweezer-jaws.jpg\")
<\/a><\/p>\nClosing function<\/h3>\n
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\n<\/strong>For gripping hard and parallel parts to maintain the grip as the pull force increases.<\/li>\n
\n<\/strong>Operators can input a defined grip force. This is ideal for gripping delicate parts to minimize sample deformation.<\/li>\n
\n<\/strong>Jaw movement is defined by a prescribed open\/close distance rather than a contact force.<\/li>\n<\/ol>\n![](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Closing-position-3-1-word-1.jpg\")
<\/p>\n![\"Choose-your-tweezer-jaw-design-table\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Choose-your-tweezer-jaw-design-table-1.jpg\")
<\/a><\/p>\nMaterial<\/h3>\n
![\"Tweezer-jaw-quality\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Tweezer-jaw-quality.jpg\")
<\/a><\/p>\nQuality<\/h3>\n
\n
![\"Alignment-jaws\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Alignment-jaws.jpg\")
<\/a><\/p>\nForce control<\/h3>\n
Handle tips with care<\/h3>\n
Alignment<\/h2>\n
![\"Tweezer-pull-alignment\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Tweezer-pull-alignment.jpg\")
<\/a><\/p>\nGold wire Tweezer Pull failure modes<\/h2>\n
![](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Gold-wire-tweezer-pull-failure-modes-1.jpg\")
<\/p>\nRibbon pull<\/h2>\n
![](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Ribbon-pull-by-tweezers.jpg\")
<\/p>\n![](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Ribbon-pull-by-hook.jpg\")
<\/p>\nPeel testing<\/h2>\n
Perpendicular<\/h3>\n
![\"Schematic-overview-peel-test\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Schematic-overview-peel-test.jpg\")
<\/a><\/p>\nAngled peels<\/h3>\n
![\"Backward-peeling-forward-peeling\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Backward-peeling-forward-peeling.jpg\")
<\/a><\/p>\nResults<\/h3>\n
![\"peel-test-force-displacement-graph\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/peel-test-force-displacement-graph.jpg\")
<\/a><\/p>\nCopper pillar<\/h2>\n
Solder to copper<\/h3>\n
![\"copper-pillar-difficult-to-test\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/copper-pillar-difficult-to-test.jpg\")
<\/a><\/p>\n![\"copper-pillar-test-sequence-for-solder-interconnect\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/copper-pillar-test-sequence-for-solder-interconnect.jpg\")
<\/a><\/p>\n![\"copper-pillar-failure-modes-cbp\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/copper-pillar-failure-modes-cbp.jpg\")
<\/a><\/p>\n![\"copper-pillar-top-landing-test-sequence-mid\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/copper-pillar-top-landing-test-sequence-mid.jpg\")
<\/a><\/p>\n
![\"Copper_Pillar_failure_mode_P1\"](\"https:\/\/www.xyztec.com\/wp-content\/uploads\/2023\/06\/Copper_Pillar_failure_mode_P1.jpg\")
<\/a><\/p>\n