Chip Quik, Inc.
. APRIL 2005 Feedback From The Rework Industry....
. The Chip Quik SMT Rework Newsletter

.
THE SMD REMOVAL KIT

Remove all SMD's Fast, Safe, Easy, and Affordable With Chip Quik and a Solder Iron. This Unique Rework Method Has Become Known Globally as The REWORK SOLUTION

SMD 16 Removal Alloy 16ft. in 6.5in. lengths

SMD 291 No Clean Paste Flux in 10cc syringe w/tip for solder and desolder

SMD 2000 Complete Solder Desolder Kit




PLEASE VISIT THE NEW CHIP QUIK ON-LINE STORE. WE SHIP DOMESTIC AND INTERNATIONAL DIRECT TO YOU. WATCH AS WE CONTINUE TO ADD NEW UNIQUE REWORK PRODUCTS.
HOW DO I INSTALL THE NEW SMD? THIS IS THE MOST FREQUENTLY ASKED QUESTION.

Chip Quik receives continuous feedback from e-mail inquiries, testimonials, phone calls, and questions asked while demonstrating Chip Quik at trade shows. The most frequent question asked is... "Now that I have successfully removed the SMD and the pads are perfectly clean, how do I install the new chip"? My answer is... With Chip Quik you have already solved the major challenge by safely removing the SMD without lifting a pad or damaging an adjacent component. Soldering on the new chip requires a careful selection of tools, equipment, and some practice in developing the necessary skills. I have found that many who attempt resoldering on the SMD are not successful because they are not prepared and are misinformed. LEARN TO SOLDER ON THE SMD!...YOU CAN DO IT!

PREPARE PADS BEFORE SOLDERING ON THE SMD
Before starting the resolder procedure it is important that all the pads are thoroughly clean and level in order to eliminate any coplanarity (height) problems. Clean pad surface with a good cleaner to remove oxidation. Inspect pads under magnification. You are now ready to install the new SMD.

SELECT A SOLDER IRON, TIP, SOLDER, AND FLUX


SOLDER IRON: A good solder iron is more important than most realize. The temperature must remain constant while applying the iron into the solder joint. This feature is called controlled heat delivery under varying thermal loads. In a quality solder iron this is accompished by having the temperature sensor located in the tip. This allows the closest possible monitering of extremely small temperature variations of the tip. When soldering or desoldering an SMD, the worst thing is to have to wait for the iron to return to its set temperature while applying heat. This can be the greatest cause of potential damage to pads and adjacent components. By using the correct iron you can effectively solder at a safe lower temperature of approximately 600deg F. When soldering with the new higher temperature no-lead solders, heat delivery becomes even more important. Your choice of a solder iron will determine the quality of your rework.

SOLDER TIP: The most common method of resoldering the SMD is called drag soldering. This is done with a slanted angle tip wide enough to cover the soldering area. A clean well tinned tip is important to provide good solder joint wetting and heat transfer. The most common cause of tip damage is high temperatures with certain fluxes. Another well known method uses a Mini-Wave Tip. This tip has a minature solder reservoir in the tip that holds a small amount of solder that is released upon demand. As you drag solder the tip rides on a mini-wave that rides over the pins as it releases solder. The tip actually never comes in contact with the pins. The tip is available in different sizes depending on the application. I use a different tip for solder and desolder.

SOLDER: Use 63/37 solid core tin lead solder called eutectic alloy. This means that it becomes molten and solid at the same temperature of 361F (180C). This eliminates the range (plastic range) that solders go through as they solidify. Also some rosin core solders do not fully activate when soldering. Solder paste is also used which consists of a mixture of lead tin granules with flux. Solder paste is used in manufacturing but it does have applications in rework that we will cover in future newsletters.

FLUX: Use a No Clean Paste Flux that is applied with a syringe and nozzle tip. The flux is non-conductive, non- corrosive and can easily be cleaned up with isopropyl alcohol. Use flux generously with all soldering. This is your key to good solder wetting. Also using a thick paste flux prevents the flux from running all over the board.

SOLDER IRON »

USEFUL TOOLS FOR SOLDER AND DESOLDER


Dental Pick & Tweezers: Both are very helpful for handling, placement, lead straightening, and prying off or lifting the SMD. Tweezers should be non-magnetic.

Vac-Pen: Used to pick and place SMD's accurately on pad. A must on micro-chip components. Should be ESD safe. Comes with different size suction tips for different size components. A great handling device for miniature components.

Magnification and Lighting: Both are very important for inspecting pads, placement, and the final solder joint. It is helpful to watch each pin pad solder joint as it is being formed. A magnifying head mask and a high intensity light works well. The most important need for light and magnification is to accurately place the chip on the center of the pads before soldering.

COMPLETE SOLDER DESOLDER KIT »

HOW TO SOLDER THE SURFACE MOUNT COMPONENT TO THE PCB


Now that you have carefully selected the recommended items we need for soldering, we are ready to resolder the SMD to the Circuit Board. Inspect all pads to make sure they are clean and equal in height. With syringe apply a thin bead of tack flux along all pads. With a Vac-Pen pick and place SMD on pads making sure the key for pin #1 is aligned with the correct pad. Use magnification with good lighting to make sure the pin pad alignment is perfectly centered on all sides of SMD. The tack flux helps to keep the SMD from moving out of place. Hold down SMD firmly with a dental pick so it will not move.

You are now ready to solder on the SMD. Set solder iron at 600Deg.F. Tin solder tip and carefully tack down 3-4 pin locations. Check pin pad alignment once more for this is your last chance to make a correction. Now drag solder by holding iron at a 45Deg. angle as you run along all pins on each side of SMD. Apply more solder as needed. If you create a solder bridge between pins, use solder braid to remove bridge. Clean area off with an acid brush and isopropal alcohol. Inspect work for perfection.

This is the most popular method used in the industry for low volume rework. With a little practice you can master the technique. The best part is you can do your own rework. The reward will be all the boards that you can prevent from entering the trash. HAPPY REWORK

CHIP QUIK ON-LINE STORE »

.    email: chipquik@aol.com
   voice: 1-508-477-2264
   web: http://www.chipquik.com
Chip Quik, Inc. · 195 Falmouth Road Bld. 1C · Mashpee · MA · 02649