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Solder Spheres

Tin-Lead and Lead-Free Solder Spheres


Solder Spheres

The evolution of Printed Circuit Boards and Semiconductors have also forced solder technology to evolve from through-hole and solder baths to surface mounted with solder paste, and now finally solder spheres for BGAs, and flip chips./> <caption>The evolution of Printed Circuit Boards and Semiconductors have also forced solder technology to evolve from through-hole and solder baths to surface mounted with solder paste, and now finally solder spheres for BGAs, and flip chips.</caption> </div><div class=

From old-school SN63PB37 wire to Pb-free Micron Size Solder Spheres for Flipchips: How solder has evolved!

Semiconductors and printed circuit board technology are relentlessly evolving industries. Their constant development has forced solder technolgy to change and evolve too. Solder technology, as a whole, has moved from Lead-based solder wire and seperately applied solder flux to solder spheres. The latest industry break-through being a move away from wire bonding to micron size solder spheres for flipchips. To understand how this happened let's start by breaking down SN63PB37 into something meaningful:

      SN = Tin
      63 = 63%
      PB = Lead
      37 = 37%

Alloys melt at different temperatures based on their composition or ratio of metals. SN63PB37 solder melts at 183°C: this was incredibly useful for circuit boards because it was high enough to melt the solder but low enough not to damage plastic components or the circuit board itself.

Solder wire needs flux. Flux removes oxidation.

Without flux the layer of oxidation acts as a barrier between the solder and the two conductive contact points thus preventing a clean and solid solder joint.

Solder Needs Flux. The technology of how flux and solder is applied has evolved and continues to develop./> <caption>Solder Needs Flux. The technology of how flux and solder is applied has evolved and continues to develop</caption> </div><div class=

Pre-coating parts in flux was, therefore, an essential extra step that cost more time and labor. So the next step in solder development was hollow solder wire filled with an internal flux. Further developments included multi-core wire with multiple hollows for better distribution of flux.

The industrial mass-produced Printed Circuit Board (PCB), as we know it, started out with through-hole technology. Semiconductor devices and chips had pins which were pushed through holes in the printed circuit board. The bottom side of the entire circuit board would then have flux applied in one go and then be dipped into a solder bath. This automated the soldering process and eliminated unnecessary extra steps. Which, in terms of mass production, saved millions of dollars in energy and material.

As semiconductor technology evolved over time so did soldering technology./> <caption>As semiconductor technology evolved over time so did soldering technology.</caption> </div><div class=

Evoling ICs – Pushing soldering technology to evolve

After through-hole technology PCBs evolved towards surface mounted technology: where solder paste was used. Solder paste is a suspension of powdered flux and powdered solder together. This allowed solder to be printed on circuit boards by a solder paste printer and then melted in one go in a solder reflow process: thereby allowing for much more complex and densely packed installations of semiconductors on the PCB.

Integrated circuits have been getting smaller and smaller and with larger and larger numbers of tiny transistors. This can be best seen in the evolution of Small Outline Integrated Circuits or SOIC: evolving at first by doubling the number of inputs and outputs or pinouts: from S08, on to SO16, SO32. Eventually for the sake efficiency, instead of two rows of pinouts, all four sides would be used in the Quad Flat Pack (QFP). This also meant that the legs got thinner and thinner and got packed closer and closer together.

Solder spheres or solder balls come microns wide and are used extensively in the semiconductor industry/> <caption>Solder spheres or solder balls come microns wide and are used extensively in the semiconductor industry</caption> </div><div class=

Micron size Solder Spheres: moving away from Wire Bonding

When you are using all four sides and even stacking wafers what can you do to further increase the number of inputs and outputs? The answer turned out to be: use the bottom of the chip as well. So, instead of many small thin legs, solder spheres would be placed directly on the bottom of the chip and would act as the connection between the Ball Grid Array (BGA) and the circuit board. This meant full encapsulation in an epoxy molding compound was no longer necessary and you could simply use an underfill.

250,000 solder spheres: sounds like a lot, but at mil sizes, that’s just enough for a heaped tablespoon full. Eventually, solder spheres got smaller and smaller so that they could pack even tighter grids of connection on the bottom of silica die. In these flip chips setups, tiny solder spheres are used instead of even 25-micron thick gold wire. Solder spheres are made in an amazing process with incredible accuracy and tight quality control.

A parallel evolution in material: from PB to PB-Free

Early in the 2000’s in Japan, Sony and other concerned companies started to push for lead-free solder. This was in response to a situation in which electronic devices were ending up in landfills, and these landfills were in turn exposed to rainwater which allowed the lead in the solder to contaminate the groundwater. In 2006 the EU Restriction of Hazard Substances Directive (RoHS) came into effect restricting the use of lead consumer electronics.

This led to SAC305 Lead-free solder replacing SnPB63/37 as the industrial standard: with 75% of companies using it. Here is what the name means:

      S = Tin
      A = Silver
      C = Copper
      3 = 3% Silver
      05 = 0.5% Copper

As a near eutectic solder it has adequate thermal fatigue properties, strength, and wettability. Another advantage of SAC solder is that it’s more resistant to gold-embrittlement and has substantially higher joint strength than PB solders.

Going Pb-free however means using silver instead of lead which means increases costs. For some applications SAC solders with less silver are suitable. These include SAC105, Bi57Sn42Ag1, as well as silver-free and lead-free solder , Bi58Sn42.

Using silver means that SAC solders have a 34°C higher melting point than Sn63Pb37 solder at between 217-220°C. This requires a higher solder reflow temperature of 235-245°C in order to achieve wetting and wicking. Some printed circuit components are susceptible to SAC assembly temperatures: including capacitors, optoelectronics etc.

Companies have since started offering 260°C compatible components to meet the high temperature required for SAC solder reflow. 260°C compatibility is fast becoming the new standard for semiconductor and component manufacturers.e.

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15 products

Product Selector Guide

Low volume flexibility, high volume pricing

CAPLINQ maintains an inventory of many sphere alloys and sizes, and we specialize in the fulfillment of small orders. CAPLINQ also offers volume breaks and discounts for our higher volume customers. A complete list of sphere diameters, packaging quantities, volume breaks and discounts can be seen by clicking on the product Alloy Type below.

Solder Sphere Selector Guide
% Metal Loading Melting Temperature Remarks
Top of Page
Product Overview of Tin-Lead and Pb-free Solder Spheres
Available from Caplinq Corporation
Tin/Lead (Sn63Pb37) Solder Spheres Tin-Lead 63 37 - - - - 183 - - Eutectic Tin-Lead
SAC105 Lead-Free Solder Spheres Pb-free 98.5 - - 1.0 0.5 - - 220 225 Lowest Silver Content
SAC125N Lead-Free Solder Spheres Pb-free 98.3 - - 1.2 0.5 - - 217 219 0.05% Nickel (Also called SAC125Ni)
SAC305 Lead-Free Solder Spheres Pb-free 96.5 - - 3.0 0.5 - - 217 221 Industry Standard Pb-free
SAC387 Lead-Free Solder Spheres Pb-free 95.5 - - 3.8 0.7 - - 217 219 Special Application Pb-free
SAC396 Lead-Free Solder Spheres Pb-free 95.5 - - 3.9 0.6 - - 217 221 Industry Standard Pb-free
SAC405 Lead-Free Solder Spheres Pb-free 95.5 - - 4.0 0.5 - - 217 225 Highest Silver Content
Sn96.5Ag3.5 Lead-Free Solder Spheres Pb-free 96.5 - - 3.5 - - 221 - - Eutectic Leadfree High Silver Sn96.5Ag3.5
Sn100 Lead-Free Solder Spheres Pb-free 99.9928% min - - - - - 232 - - 4N Pure Tin (>99.9928% Sn)
Bi58Sn42 Lead-Free Solder Spheres Pb-free 42 - 58 - - - 138 - - Eutectic Low-Temperature Bismuth-Tin Bi58Sn42
Bi57Sn42Ag1 Lead-Free Solder Spheres Pb-free 42 - 57 1.0 - - - 139 140 Near-Eutectic Low-Temperature Bismuth-Tin Bi57Sn42Ag1
In100 Pure Indium Solder Spheres Pb-free - - - - - 100 156.6 - - Pure Indium Solder Spheres In100

Learn More

Pb-Free Spheres SAC105, SAC125N SAC305, SAC387, SAC396, SAC405, SnAg or another alloy?

After many years of testing and debating, and with specific exceptions, the semiconductor industry has largely settled on the use of Tin (Sn), Silver(Ag), Copper(Cu) - or SAC - alloy for the assembly of lead free products. Although the SAC alloy has been settled, which SAC alloy to use is still up for debate. North American and Europe manufacturers favor SAC305 (Sn3.0Ag0.5Cu), while Asian manufacturers generally favor SAC405 (Sn3.8Ag0.8Cu).

SAC305 was first developed by Senju technology, who own the patents herefore. As such, manufacturers are required to pay a license to produce SAC305 which is built into the price charged to customers. SAC305 however has the benefit of being less expensive to produce than SAC405 owing to the lower silver content. This said, studies indicate that there is no significant reliability difference between SAC305 and SAC405, and so CAPLINQ continues to support both SAC305 and SAC405.

High Tech Tin

CAPLINQ is not only able to supply the alloys and purify the solder material, but it has an innovative diameter and spheroid selecting system of solder balls and an advanced anti-oxidation technology that actually dopes an anti-oxidation element into the alloy in addition to its OSP surface coating process.

Not only are our solder spheres High-Tech, but they are made from a unique uniform droplet spraying technology that far outperforms competitors in terms of productivity. This combination of high technology and high productivity allow CAPLINQ to offer its customers the best value for the best product.

Compare and Select the Solder Sphere you Need

Solder spheres or solder balls vary widely in their composition and application. Lead-free solder spheres may be the future, but Tin-Lead solder spheres are still widely in use today. Whether you are looking for lead-free solder spheres or Tin-Lead solder spheres, our Solder Sphere selector tool can help you choose the right solder sphere for your application.

View Technical Papers and Brochures

Solder Sphere Technical Papers, Solder Sphere Marketing Brochures, Solder Spheres Technical Data Sheets, Solder Sphere MSDS. If these are what you are looking for, then this is where you should be.

Read our Blog on Solder Spheres

Everyday, people just like you have questions about solder spheres. At CAPLINQ, we try to help people just like you by blogging about solder spheres. From solder sphere pricing to harmonization codes to product part numbers and leadtimes. We try to post as much information as we can on our blogs, to help you find more relevant information about solder spheres.