Page 62


www.us- tech.com


July, 2019


Handling Risk Mitigation in Hand Soldering: Questions and Concerns


Continued from previous page


uidus state. However, in this stage, further intermetallic growth occurs from liquidus to reflow stage and temperature differences can range up to 104°F (40°C). Each joint also varies, not only in


pad and pin size, but also from the structure of the PCB. All of these vari- ables contribute to the time required to reach molten solder state. Different solder alloys reach a liquidus state at varying tempera-


Temperature


red LEDs may be providing incorrect results. Figure 1 shows joint tempera-


ture and thermal energy distribution during the hand soldering process. Based on operating modes of these types of hand soldering systems, there appears to be no functional capability to collect and process data in real time and then make the same real-time adjustments to account for all variables. For hand soldering systems to


Figure 1: Joint temperature and thermal energy distribution during hand soldering.


tures, but there is no clear under- standing that such differences have been incorporated into the system.


Step 3: These soldering systems do not appear to provide any form of verification that the analysis is cor- rect or documented at the stage when they signal to the operator by green LED that the solder joint is good and in the range of 0.25 to 4 µm or by red LED that the solder joint has fallen below 0.25 µm or risen above 4 µm. Since so many variables are not


controlled, or controllable, within the simulation process outlined in Steps 1 and 2, it is difficult to perceive how accurate the data is in regard to the correct formation of the intermetallic layer and equally the thickness of the IMC. On this basis, if the simulation process is not managing all the inputs or variables, the algorithm cannot be expected to provide an accurate output and the green and


be effective validation systems, con- siderable changes must be imple- mented in the hardware/software. Additionally, without closed-loop feedback and analysis, there is no communication link to the operator. In reality, these systems cannot directly measure the IMC, but can only indirectly attempt to detect and verify that each solder joint is within a certain IMC range. The period of detection and ver-


ification is from the point at which the tip touches the pad until the time it is removed. To use the thermal properties of Curie heat to explain the solder joint formation is not sci- entific, since no real data supports the simulation results. Contact: Thermaltronics USA,


Inc., 1 Barstow Road, Suite P19, Great Neck, NY 11021 % 631-472-7600 E-mail: mgouldsmith@thermaltronics.com Web: www.thermaltronics.com r


Production Lines Continued from page 59


solutions from the material selection to the implementation in the dosing process. The comprehensive consul- tation leads to a consistent develop- ment of a highly reproducible dosing application to increase production rates and process safety — with com- plete cost control. Important parameters deter-


mine the dosing process, including: short cycle operation, cyclic applica- tion or continuous operation, low to high viscosity, structurally sensitive, solids-laden fluids, tribological losses such as friction, leakage, wear, aging, and contact geometry. The suitable pump will take into account all known variables and be adjusted to the material.


Microdispensing for Semi- and Fully-Automated


In addition, chemical reactions


can occur which produce wear such as plastic deformation, abrasion, adhesive friction and fracture mechanics. The optimal design of the dosing components for abrasive or chemically aggressive fluids is often obtained from preliminary tests and defined qualification levels. Close collaboration with the customer is the best strategy to develop the ideal solution to a challenging dispensing application. Contact: ViscoTec Pumpen- u.


Dosiertechnik GmbH, Amperstrasse 13, D-84513, Töging a. Inn, Germany % +49-8631-9274 E-mail: melanie.hintereder@viscotec.de Web: www.viscotec.de r


See at SEMICON West, Booth 2065


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100