![]() ![]() 1680: iPhone recommendations for seniors, unsticking iCloud Drive sync, iOS bug turns off devices at night, iOS 16 security fixes.#1681: Take Control Books 20th anniversary, USB-C Apple Pencil, Kini motion detector monitors access, topical social spaces.#1682: Apple’s “Scary Fast” announcement, X.1 updates to 2023 OS versions, Microsoft Word’s 40th anniversary, 5G wireless Internet.The first multilens array (LA1) splits the incident beam into multiple beamlets. The second multilens array (LA2), in combination with the Field Lens (FL), acts as an array of objective lenses that superimposes the images of each of the beamlets in the first array onto the homogenization plane FP, where the BGA to be soldered is located. E XPERIMENTAL S ETUP The four proposed optical setups for the FILSS were mounted on an optical table. The QTH lamp IR light source was used in all four setups, as well as a BGA with 35x35 mm dimensions. The length of the setups varied between 151 and 345.2 mm. Two cameras were used to measure the principal output parameters under study of the proposed optical setups for FILSS. For each optical setup, the output light spot at the location of the BGA was captured by means of a CCD camera. After recording the light spatial distribution image, the CCD camera is removed and the BGA is put in the soldering plane. Then the beam is applied to the BGA, and by means of a thermography camera ThermaCAM E25 from Flir TM systems, the thermal distribution in the BGA is obtained. The experimental setup mounted on an optical table is shown in figure 5. R ESULTS In order to confirm the theoretically calculated light spot horizontal and vertical lengths D FT at the BGA location in the proposed optical setups for FILSS, the light spots were captured by means of a CCD camera. The images that were captured are shown in figure 6. For figure 6(d), the center square of homogenized superimposed beamlets was calculated by means of Eq. (2), obtaining 15.38 x 11.53 mm horizontal and vertical D FT lengths, respectively, for the parameters of P LA1 = 4 (horizontal) x 3 (vertical) mm, f FL = 150 mm, f LA1 = f LA2 = 38.1 mm, and a 12 = 39 mm. The measured lengths of the light spot shown in figure 6(d) are 15.37 x 11.53 mm, which are in agreement with the theoretical calculation. The main results presented in this paper are the temperature distributions measured at the surface area of a 35x35 mm BGA, for each of the proposed optical setups for FILSS. In order to obtain these temperature distributions, the reflow soldering temperature profile was applied to the BGA for each of the proposed optical setups for FILSS. The captured thermal images are shown in figure 7.īy means of measuring the temperature distribution on the surface area of the BGA with an IR thermography camera, thermal images were captured at the peak temperature stage of the reflow soldering profile, in order to analyze the soldering capacity for each of the proposed optical setups for FILSS. The thermal images analysis gives a peak temperature of 241 ° C reached in the basic optical setup for FILSS, as can be seen in figure 7(a). This peak temperature is enough to melt lead free solder (~217 ° C for commonly used SnAgCu solder alloy), which is a main performance parameter to be obtained in the proposed optical setups for FILSS. ![]()
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