Whether you are placing components for die attach or creating wire bonds (ball or wedge), a good quality connection requires that the substrate surfaces be held firmly in place. Particularly for wire bonding, if the substrate is allowed to move at all, the wire will most likely fail to bond or will be poorly attached. There are many ways to clamp parts, but the methods fall into one of two categories: vacuum clamping or mechanical clamping. Vacuum clamping is typically done using the bottom surface of the part (the side opposite the bond surface) and mechanical clamping is typically done by pushing down on the top (bond-side) surface. Both methods have advantages and disadvantages, and there are several points to consider when deciding which method is best to use for a particular application.Read More
Palomar has had successfully worked with the global contract manufacturer Fabrinet over the last several years, working with our mutual customers to provide equipment and developed processes to successfully transition into manufactured goods. Many of these products started as prototypes in Palomar Technologies' Assembly Services department where the designs were validated for functionality. These were then further refined through pilot builds to include DFM (designed for manufacturability) changes. We learn much about a product when we build the first ten; we learn much more when we build the next 100 to 1,000 pieces. This is the time that we start understanding how to tweak the design and processes to make it easier, quicker and cheaper to produce.Read More
SST Vacuum Reflow Systems designs and builds systems and processes that achieve low to void-free seals for die attach component parts. However, the choice of materials is critical in achieving the most positive results by allowing good wettability, thus creating a good solder joint. Void-free solder joints mean improved thermal performance and high reliability (e.g. mechanical strength) of the device package.Read More
The semiconductor industry saw the highest-ever annual sales in 2016, totaling $338.9 billion, according to the Semiconductor Industry Association. An article in Nasdaq.com states that “while the industry as a whole may appear sluggish, there are solid opportunities waiting to be picked”, providing hope and optimism within the industry. John Nueffer, the president and CEO of the Semiconductor Industry Association, stated: “Market growth was driven by macroeconomic factors, industry trends, and the ever increasing amount of semiconductor technology in devices the world depends on for working, communicating, manufacturing, treating illness, and countless other applications”.Read More
There are many different directions to go in when it comes to part presentation stages—from that simple part built by the thousands yearly, to complex parts with different sizes and shapes. When making a presentation stage decision, start with the product mix and the parts’ typical requirements. For high-volume automated lines, we can put together integrated lines that are designed for a specific part, or a handful of products that can be handled with minimal tooling changeovers. Additionally, there is the question of manual presentation methods. This can allow the customer to be prepared for almost any part that may come in the future.Read More
Selecting the right solder alloy for your application is crucial to the success of the project. If the right solder alloy is not selected and plating requirements are not defined, the selected process may not be capable of producing solderable deposits. Incomplete plating requirements often result in excessive rework and scrap.
With so many different alloy compositions of solder available, choosing the right alloy could be quite challenging.
The best approach is to consider:
1) What is the maximum temperature that the device(s) can be exposed to without damaging the device or device performance?
2) Consider that some alloys really need from 25°C to in some cases 100°C hotter (above the melting point) to flow well and wet the mating surfaces. Can the device tolerate this elevated solder temperature?
3) What are the die and substrate metallizations?
4) Do you have the correct metallizations for that selected solder alloy?
5) Is there a good history of successful good wetting and flow for that alloy?
6) Flux Less or with Flux?
7) Is there a lead free requirement?
For flux-less die attach and lid seal the workhorse solder alloy used by the majority of SST Vacuum Reflow Systems' customers is 80Au20Sn with a melting point of 278°C. This alloy can be used as received without the need for any surface oxide removal as compared to lead, tin, or indium based solder alloys where the native metal oxides would interfere with solder wetting and would require acid etching just prior to loading for soldering.Read More
Liquid flux (acidic base or inorganic based) has traditionally been the primary solution to allow soldering of metal parts with surface oxides for high quality wetting of the solder to these metals. However, there are significant flaws or issues with the use of flux in soldering.
Issue #1: Flux Residue. Flux residue is known to react with water vapor to create an acidic solution surface that will react with and corrode metal connections. This results in possible metal shorts and opens and reduces reliability and long term life of the electrical connection.
Issue #2: Voiding. Flux, whether in liquid form or as a constituent of solder paste, has liquid components that vaporize or outgas during the soldering reflow high temperature, resulting in trapped voids or bubbles in the solder joint. These gas voids can displace heat and electrical paths which can cause non-uniform patchy heat transfer and can concentrate heat in localized areas, resulting in stress and possible cracks.Read More
Wire bonding is a well-known process that has been around for many decades. It was all performed manually from the mid-1950s to the late 1970s. In the very early 1980s, semi-automatic and fully automatic wire bonders started to become available. Hughes Aircraft Company’s equipment group in Carlsbad launched the venerable Model 2460 in March of 1980. As of about 5 years ago, the very first unit was still in production in upstate New York, being used for rework wire bonding. That unit has seen some battles! From the mid-1950s until today, one of the fundamental requirements for good wire bonding results has always been part tooling and clamping.Read More