reflow soldering guidelines for rohs * compliant vcos and synthesizers rev. - ANI-010 ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 1 visit www.macomtech.com for additional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or inform ation contained herein without notice. introduction this application note describes recommended prac- tices and guidelines for the successful assembly of m/a-com vcos and synthesizers using automated solder reflow techniques. incorrect handling, storage, reflow and cleaning may damage the components. handling and storage precautions m/a-com vcos and synthesizers are static and mois- ture sensitive and are packaged accordingly. appropriate handling precautions should be observed. the typical shelf life of these components once re- moved from the protective reel bag is 168hrs. exposure to static electricit y or over voltage may cause defects in the product or degrade it?s reliability. components should also be stored in such a way so as to avoid exposure to corrosive, salty or dusty at- mospheres, high humidity, direct sunlight and strong electric fields. solder pad layout each vco and synthesizer data sheet recommends a solder pad layout based on ipc standards. deviation from these recommended layouts can adversely effect the solder joint strength and integrity. component construction all m/a-com vcos and synthesizers are designed to withstand solder reflow conditions, as recommended in this application note. the table below details the construction of m/a-com vcos and synthesizers. component construction substrate type plating construction cover material fr-4 leadless electroless nickel immersion gold enig brass (nickel plated) solder selection when selecting solder paste, parameters such as flux type, particle size and metal content should also be considered. the solder paste should be carefully se- lected to suit all of the relevant process parameters being used. m/a-com vcos and synthesizers are designed to work with most recommended reflow profiles for the sac305/sac405 type solders, and are fully compatible with the standard reflow profiles used for the sn60, sn62 and sn63 solder pastes, including no-clean pastes. solder screen guidelines a solder screen or stencil is required to screen the minimum amount of solder paste onto the pads of the footprint. this amount or thickness will directly affect the quality of the solder joint. the optimum thickness is 0.18 mm to 0.25 mm (0.007 inch to 0.010 inch). * restrictions on hazardous substanc es, european union directive 2002/95/ec. silk screen techniques can control paste thickness well enough to keep it in the optimum range; the thickness being a function of the screen mesh, emul- sion thickness and printer set up parameters. a stencil technique can also achieve similar results by using a stencil made of 0.2 mm (0.008 inch) thick brass or stainless steel. the stencil or screen opening should be the same size as the pads on the footprint (1:1 registration), excluding any solder resist mask areas. component placement m/a-com vcos and synthesizers are designed for placement using automatic pick and place equip- ment. component placement is critical to negate shorts caused by solder bridging.
reflow soldering guidelines for rohs * compliant vcos and synthesizers rev. - ANI-010 ? north america tel: 800.366.2266 ? europe tel: +353.21.244.6400 ? india tel: +91.80.43537383 ? china tel: +86.21.2407.1588 2 visit www.macomtech.com for additional data sheets and product information. m/a-com technology solutions inc. and its affiliates reserve the right to make changes to the product(s) or inform ation contained herein without notice. general soldering precautions: lead-free soldering process relation of qualification profile and actual produc- tion profile the profiles listed in this document are not production reflow profiles, but are related to those profiles with an added margin of safety to account for oven variation, temperature drift, and product variation and process robustness. the actual profile used in production will be dictated primarily by the solder composition selected. process requirements to minimize the thermal stress to which these compo- nets are subjected. always preheat the printed circuit board (failure to do so can ca use excessive thermal shock and stress that can result in damage to the component). the ovens used should be 100% convection reflow. we recommended 90 seconds above 217c with a maximum temperature not to exceed 260c. condition average ramp-up rate (30c to 217c) > 100c > 150c > 217c peak temperature cool-down rate (peak to 50c) time from 30c to 255c all temperatures shown are +5/-0c exposure less than 3c / second between 360-600 seconds at least 240 seconds at least 90 seconds 255c at least 15 seconds less than 6c / second no greater than 360 seconds
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