Micro-Usmd Rework These are very small BGA style components

Confidential and Proprietary to OK International. © OK International All rights reserved. What are Micro - Usmd  Used on most mobile products  Cell phones,tablets, IPods  Laptops  Game machines  Amplifier products,  Stereos high quality amplifiers 1 These are generally Audio Amplifiers

Confidential and Proprietary to OK International. © OK International All rights reserved. 2 Micro SMD Evolution

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Component views

Micro-Usmd sizes.05mm (2 Mill )stand off on.5mm+.4mm pitch Controlling flux quantity is essential or component will swim..1mm (4 mill)flux dip blocks should be used with gel flux

Confidential and Proprietary to OK International. © OK International All rights reserved. Equipment Requirements 6 Camera Fine Placement Head Accuracy 0.001” (.025mm) Standard Placement Head Accuracy 0.004” (0.1mm)

New Micro –Usmd Specifications

Process for rework With conduction tools or with convection(hot air)... Removal Clean with a hoof tip or with small tip and solder wick to remove old solder. vacuum desolder tool can also be used clean pads Options flux pcb pads this not a process Flux dip part half the thickness of solder ball. what type of flux Gel flux used for POP dipping or normal lead free gel flux should be used not liquid flux Flux new component Place and release without moving package, using snap off or puff off that will release part in controlled repeatable method Place component Camera with top to bottom view is essential for these components. Align component to pads Dip Micro-USD in dip block that has been manually screen printed to give consistent flux coating to balls Dip in gel flux This is where the how to present component to vacuum pick on machine. By hand can be done not practical but slow and inexpensive. Use tape feeders to pick part from tape as supplied by component manufacturer. Pick up parts Without moving adjacent components Reflow component back

Confidential and Proprietary to OK International. © OK International All rights reserved. Thermal tweezers will be quick and simple if Component spacing allows this Thermal Removal Is Easy and Safe with Metcal Tweezer. Tin removal from pads with mini-hoof tip using same solder station, MX500.

Removal with convection Hot air nozzle with vent holes to stop pressure moving components. Used for reflow and removal with vacuum cup inside for removal Hot air removal and Reflow tool

Confidential and Proprietary to OK International. © OK International All rights reserved. Tin level must be equal for replacement Tinned pads must be leveled with a hoof solder tip or can be cleaned by using solder wick Alignment with Camera top to bottom view is essential

Confidential and Proprietary to OK International. © OK International All rights reserved. Clean up solder wick with very fine tip 12 Various tips available the one shown is a SMTC 1174 Alternatively Ultra Fine are available from Metcal mx series UFTC 7CN04 (.1mm bent hoof ),UFTC7DR412(.1mm drag tip). 1.5mm square Micro-Usmd Tooth pick to reference size

Confidential and Proprietary to OK International. © OK International All rights reserved. 13 Picking components up from tape is the best solution

Confidential and Proprietary to OK International. © OK International All rights reserved. 14 Micro_SMD Pick up package from tape in tape feeder. Manual handling is that easy. Flux dip process is required. If excessive flux is brushed onto PCB it may cause the part to float off the pads.

Confidential and Proprietary to OK International. © OK International All rights reserved. Placing parts onto small pick up tube for small volume. 15 Close up of vacuum cup and reflow nozzle

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Confidential and Proprietary to OK International. © OK International All rights reserved. NEVER Liquid Flux √☺√☺

Confidential and Proprietary to OK International. © OK International All rights reserved. Leaded Flux Cannot be Used in PB Free Soldering LF flux Activation zone Lead flux activation Lead flux is virtually burnt off before Lead Free Flux has reached 30% of its Activation time

Flux dip Micro-Usmd components Component pitch.5mm pitch and.4 mm can use 4 and 3 mill dip blocks solder ball size is 8-6 mills.

Confidential and Proprietary to OK International. © OK International All rights reserved. Flux Dip with Gel Flux Dip half the thickness of solder ball height

Confidential and Proprietary to OK International. © OK International All rights reserved. Flux Dip with Gel Flux

Confidential and Proprietary to OK International. © OK International All rights reserved. Flux transfer complete, placement to PCB is next Flux Deposition On Bottom 1/3 Of Solder Ball Flux Dip with Gel Flux

Confidential and Proprietary to OK International. © OK International All rights reserved. Flux Dip with Gel Flux is good for BGA components as well 4 mil dip Block(.1mm)Gel Flux removed is uniform

Alignment and placement  Placement height is important to touch PCB so gel flux holds part to pads.  Gel flux is used to be active during reflow process liquid flux would dry up  Release time needs to be controlled we call it puff off time

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Alternative to flux dip is Paste dip This is a.2mm ball dipped in.1mm type 6 paste Indium 96.5Sn 3.0Ag 0.5Cu Ind256 flux same tools used as used for flux gel

Confidential and Proprietary to OK International. © OK International All rights reserved. Reflow Profile for Lead VS Lead-Free Key Flux activation time / area Ramp Rate in cooling Temperature ramp up in PB is slower Ramp down in PB

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Confidential and Proprietary to OK International. © OK International All rights reserved. 29 Convection Reflow Profile

Confidential and Proprietary to OK International. © OK International All rights reserved. X-Ray Inspection 8 ball x ray, if any ball is 25% smaller this is generally considered the maximum difference in size which is acceptable.This may vary from which type of x ray machine is used. 8 ball x ray which shows all joints are the same size

References  National semiconductor now TI Texas instruments for some technical specifications and photos  Indium for materials supply of POP materials Mario Scalzo  For more details contact Paul wood ok international