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SMT-Jun2017

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34 SMT Magazine • June 2017 AOI CAPABILITIES STUDY WITH 03015 COMPONENTS its infancy; more improvement and testing will be performed. We will continue to provide new test results from all suppliers. Introduction The printed circuit board assembly (PCBA) industry has long embraced the smaller, light- er, faster mantra for electronic devices, especial- ly in recent years 4-5 . With the increasing use of smaller components, more consideration is re- quired to study and implement changes; not only for SMT processes, but also for testing. There have been some studies conducted for SPI (solder paste inspection) with 03015 com- ponents 6-7 , however, there are very few recom- mended practices for AOI. The 03015 [0.3 mm x 0.15 mm] device is a mi- crochip component. For reference, please note that a human hair is approximately 0.1mm. To ensure a successful implementation of the 03015 components, besides for these three criti- cal areas—placement equipment, assembly ma- terials, and process control—the capabilities of machines used to test these component types is another critical consideration. Now, 3D SPI is more commonly used in the SMT process, and 3D AOI is quickly catching up. During the initial stage of our study, we first tested these five boards with 03015 components on our 2D AOI machine in our Milpitas manu- facturing site. Next, we provided the boards to the R&D labs of five AOI vendors who all have 3D AOI machines. Working with various R&D engineers, it was obvious this was a challenging task for their current AOI systems, especially for 3D AOI systems due to component reflection. Our test data and results showed that the 2D AOI machines have different capabilities in detecting defects for 03015, such as misalign- ment, tombstoning, and shorts. While the de- fect escape percentage decreased, false call PPM increased, therefore, optimized programming should be based on test data analysis. Experiments In total, we asked five AOI vendors (R&D en- gineers) to work on this project. We received four sets of test data—AOI System 3 data is to be provided later. The test procedure is the same for all machines with five boards. Test Vehicle Five boards with 03015 components were tested on the AOI machines. Figure 1 is our test vehicle, which has three areas for different pitch sizes. The pitch areas are indicated as different color arrows: red color (A – 100 µm), yellow col- or (B – 150 µm), and blue color (C – 200 µm). The 03015 component was a production resistor: 292 µm, 143 µm, and 100 µm corre- sponding to its length, width, and height, re- spectively, as shown in Figure 2, where area A is without fab mask. There are a total of 87, 81, and 78 components in areas A, B, and C, respec- tively. The pad size (length, width) is 150 µm by 150 µm on the PCB fab. Figure 3 shows pictures for area A (right column), area B (center col- umn), and area C (left column); after print (top row), after placement (center row), and after re- flow (bottom row). There are different colors for optical pictures due to 03015 component reflec- tion, which increased AOI testing difficulty. Attribute GR&R We used 78 components with a pitch of 200 µm on Board 4 for the Attribute GR&R study; the board was tested a total of nine times (three operators testing the test vehicle three times). Then, we used production statistical software for getting Attribute GR&R. The Attribute GR&R data results (Within Appraisers, and Appraiser versus Standard) of AOI 1, AOI 2, AOI 4, AOI 5 and AOI 6 are shown as in Figure 4. Figure 1: Company Miniaturized Test Vehicle.

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