Main Article: “Sticker Shock” With Recent sac305 Prices?

Second Article:
Reliability Update For Sn100c

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“Sticker Shock” With Recent sac305 Prices?

by Jim Wertin, Technical Sales Manager of FCT Assembly, Inc.

Has “Sticker Shock” affected you with the huge increase in silver prices and its repercussion on SAC305 bar pricing? In fact, another major solder manufacturer recently announced the addition of a silver surcharge on their silver bearing solder paste products! The price of silver has almost doubled in the last 8 months (see chart below) and this is affecting the price of SAC305 to a point that many companies are looking for ways to replace it to reduce costs. At over $14/troy ounce ($204/lb), the “cost” of silver in a pound of SAC305 is now over $6.00/lb!

In order to assist our customers, FCT Assembly has a number of options available. To reduce the cost of dross, we offer our lead free AO2000 Antioxidant Pellets, which acts to reduce the amount of dross produced in a solder pot. To reduce the dross already formed on the surface of the pot, FCT offers our Drossx Powder, which is applied to the dross on the surface and acts chemically to reduce the dross back to usable solder. Samples of both products are available upon request.

Converting the SAC305 wave solder machine to SN100C is your best option to eliminate this increasingly costly lead free decision. The cost of SN100C bar is less than half the cost of SAC305 and the overall cost to run an SN100C production line is one third the cost of a SAC305 line. We have a program available to assist our customers in converting their SAC305 line by offering a trade of the SAC305 in the pot for SN100C and an additional 50% of the weight of recovered SAC305 alloy in SN100C bar  if the lead content is less than 0.1%.  As an example, if the pot holds 1000 lbs of SAC305 bar, the conversion would include 1500 lbs. of SN100C bar.

If you are interested in converting your wave solder machine from SAC305 to SN100C, please contact your FCT Assembly sales support (http://www.fctassembly.com/rep_maps.htm) or FCT Assembly directly at 970-346-8002.

Reliability Update For Sn100c

This report is the fifth of a five part series highlighting the results of recent reliability testing comparing the Nihon Superior SN100C nickel stabilized tin/copper alloy to tin/lead and SAC alloys. The full report is available by contacting Jim Wertin at jwertin@fctassembly.com.

With the transition to lead free in full swing now, there are many companies forced to have both a lead free and a leaded production process on the same manufacturing floor. A major concern is the possibility of mixing alloys and what effect this would have on reliability of the repaired joint. Nihon Superior undertook a set of tests to determine the reliability potential of mixing alloys in a repair operation. The alloys tested were 63/37, SN100C and SAC305. Test boards were wave soldered with one alloy and then joints were repaired with the other alloys. The boards were then subjected to temperature cycling (-40°C for 13 minutes and +125°C for 25 minutes) for 1000 cycles. Cross sections were taken after wave soldering, after hand solder repair, 500 and 1000 cycles.

As an example, the joint below was wave soldered with SAC305 and hand soldered with 63/37. It displays a crack and shows segregation of the lead within the joint.

The results are summarized below:

• When SN100C is reworked with SAC305 and vice versa there is no distinct separation into two microstructures.

• When SN100C is reworked with SAC305 and vice versa there is no cracking after 1000 cycles of -40+125°C.

• When SN100C or SAC305 is reworked with 63/37 and vice versa cracking occurs at the solder/pad interface.

• This cracking is thought to be associated with segregation of Pb to that interface.

The complete test results are available on cd by contacting Jim Wertin at jwertin@fctassembly.com.

SN100C has been patented by Nihon Superior and is offered worldwide through licensed manufacturers including FCT Assembly for North America. We offer SN100C for wave solder and lead tinning, reflow solder paste applications, SN100C wire for touch-up, and SN100CL for lead free hot air solder leveling (HASL) of P.C. Boards.

We will be including in future newsletters, many of the advantages our current customers have discovered in switching to SN100C as their lead free alloy of choice and we welcome your comments and questions. We look forward to working with you to make your transition to lead free as successful as possible. 

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