SST Blog

“Creating high value hermetically sealed devices, what are the consequences of experiencing high voids...”

Posted by Julia Picarelli on Jun 7, 2017 10:05:00 AM

“If you are creating high value hermetically sealed devices, what are the consequences of experiencing high voids in the package seal ring?”

High levels of voids in the package seal ring may cause leak failures, which in turn can decrease the reliability and performance of your device. It may result in a short device lifetime and /or premature failure, or may cause some unforeseen damage to the end use product. For the best product performance and longevity, a void free seal is highly desirable.

So, how can we minimize voids in package seal ring?

First, recall that the keys to a void free seal are:

  • The quality of raw materials used
  • Impurities in the preforms
  • Cleanliness of components
  • Prebake time
  • Outgassing of materials and/or organic epoxies inside the seal cavity.

SST’s systems create hermetically sealed MEMS packages, such as IR sensors, gyroscopes, bolometers and accelerometers. Packages are required to be hermetically sealed to protect from all types of environmental conditions. All packages must pass the Fine and Gross Bubble Test according to the MIL SPEC 883 Method 1014 to be considered hermetically sealed. A Fine Leak Test must be performed first prior to Gross Bubble Test per MIL SPEC.

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Topics: Process Development

Preventative Maintenance for SST Vacuum Furnace Tooling

Posted by Julia Picarelli on May 17, 2017 10:05:00 AM

The specialized semiconductor grade graphite tooling manufactured by SST Vacuum Reflow Systems can be used for many years with proper maintenance and procedures.

What kind of maintenance?
The following is a guideline to keep your tooling in the best shape possible.

Every day:
- Check fasteners for looseness. The heat cycling will naturally loosen the fasteners used, so they need to be tightened when loose for proper operation.

- Check for obvious damage to the tooling or electrodes.

Monthly or Yearly:
- Check retainers for flatness, burrs, and signs of arcing or burning. Dress with a flat stone as necessary to remove burrs and any areas that might be raised due to arcing. (arcing is usually caused by loose fasteners or weak contact springs)

- Check for cracked or broken graphite plates, replace as necessary.

- Clean the graphite parts when necessary using ultrasonic with D.I. water for up to 30 minutes, blow dry with dry nitrogen to remove excess water, and then bake out (preferably in a vacuum oven other than the reflow furnace) at 250 degrees Fahrenheit (120C) for 1-2 hours to remove residual moisture prior to using for any soldering activity.

- If there is anything that does not come off the graphite, use Methanol instead of D.I. water for the ultrasonic cleaning.

- If there is any residue that prevents the graphite plates from making full contact with each other, you can carefully scrape it off with a sharp-edged blade.

- Flux or epoxy residue may be impossible to remove as it usually is anchored in the pores of the graphite.

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Topics: Graphite


Posted by Julia Picarelli on May 3, 2017 10:05:00 AM

MEMS technology is everywhere we look.  The Biotech, Medical Device, Communications and Inertial Sensing segments are increasingly using MEMS devices as miniaturization allows new synergies. Micro-displays, ink jet print heads, IR detectors, blood pressure sensors, and accelerometers are a few of the MEMS devices being used today and it is inevitable that new applications will emerge.  Some applications require MEMS devices to be packaged in a high vacuum environment.  This means that the package is sealed under vacuum level below 10-06 torr. 

A certain level of packaging protection is required for all MEMS devices, however, IR Microbolometers, Accelerometers, Gyroscopes, Atomic Clocks and RF MEMS require an internal package vacuum or controlled atmosphere to prevent degradation over the life of the device.

The complexity of high vacuum MEMS sealing falls in few major categories.  

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Topics: MEMS Packaging

Why or When One Should Use a Vacuum/Pressure Reflow Oven System

Posted by Julia Picarelli on Apr 19, 2017 12:38:38 PM

Why or When One Should Use a Vacuum/Pressure Reflow Oven System as Opposed to Other Packaging Technology Systems

Today, in the majority of high production soldering of electronic component applications, belt furnaces are used.  The typical length of a belt furnace exceeds 20 feet. Some of these high volume production processes require <200 ppm oxygen level, a nitrogen flush (to achieve such a low ppm oxygen level) and constant “power on” that keeps the oven heated at all times. This process significantly increases the costs of operation as compared to a vacuum reflow oven system. In addition, belt furnaces are known to produce a significant amount of voids - as much as 40% - within the solder joint, which decreases long-term reliability of electronic components.

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Topics: Process Development


Posted by Julia Picarelli on Apr 5, 2017 10:32:00 AM

SST Vacuum Reflow Systems recently exhibited its systems and services at SEMICON China in Shanghai.At the show, we introduced a new product, Model 518, a mid-range, radiant heat single chamber system to create void free, flux free microelectronics packages. We had a lot of fun with a customer quiz/drawing, and we gave Bose Headphones away to some lucky winners!

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Topics: Tradeshows

Vacuum Reflow System Basic Processing Techniques

Posted by Julia Picarelli on Mar 8, 2017 10:05:00 AM

Typical applications for the family of SST Vacuum Reflow Systems are: Package Assembly, Lid Attach, Die Attach, Glass to Metal Seals, and Brazing. These process profiles share a common sequence.

Chamber Preparation
Most process cycles begin by removing as much of the ambient atmosphere as possible and diluting what remains with an inert gas. Vacuum is turned on until the chamber reaches a low pressure. Inert gas, usually dry nitrogen, is then introduced into the chamber. This vacuum/pressure step can be repeated to further increase the cleanliness of the sealing environment and reduce the overall moisture level.

Vacuum Pre-Bake
A vacuum pre-bake provides the following benefits:

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Topics: Creating Profile Shortcuts

Why Upgrade from a 2200 to a SST 3130?  From an Operator’s Perspective

Posted by Julia Picarelli on Feb 22, 2017 10:05:00 AM

In August last year, we discussed the life cycle cost savings that can be enjoyed by upgrading from old DAP 2200 series soldering furnaces. Saving money and having the peace of mind that comes from owning a reliable, well supported machine are important, but so are the performance enhancements you can use to support your customers’ requirements.

In this blog, we compare the specifications of the two system series so you can see the differences.

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Topics: System Upgrade

Why Process Development is Critical to Effective and Profitable Use of your Vacuum Reflow System

Posted by Julia Picarelli on Feb 22, 2017 8:47:00 AM

SST Vacuum Reflow Systems offers customers far more than just high performance vacuum/pressure soldering systems. When acquiring a system, customers should seriously consider taking advantage of the process consulting assistance that SST provides for the following reasons:

  • So your system is in production in the shortest possible time.
  • For immediate successful completion of a customer project.
  • Reducing the overall cost of using externally designed and fabricated tooling, process profiles, and deciding how to optimize the soldering profile by trial and error (which could take months of time).
  • SST has 50 years of experience developing and refining processes that create void-free, flux-free solder joints. Custom engineered tooling design with improvements learned over those years is combined with in house fabrication of tooling using specialized and custom machinery. Using only proprietary semiconductor grade graphite, our craftsmen create tooling to contain the parts
  • SST’s fully equipped application lab allows our process engineers to create, develop, test, and refine optimized profiles for customers, allowing them to quickly get to production level output.
  • Using our customers’ actual parts, SST engineers can demonstrate the success of the soldering process. They can verify low voiding in die attach applications by X-ray or CSAM tests, or verify lid sealing applications through fine helium leak testing and gross bubble testing as per Mil Spec 883.
  • SST’s Process Development Team has special expertise in the areas of mechanical design, metallurgy, thermodynamics and high vacuum technology—all relating directly to microelectronic package assembly. They are a team of experienced design and process engineers with the know-how to overcome process challenges and develop solutions that work.
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Topics: Process Development

SST Annual System Maintenance Recommendations

Posted by Julia Picarelli on Feb 15, 2017 10:05:00 AM

You’ve made an investment in your SST Vacuum Reflow System and want to keep it producing at a high level.

To ensure systems operate at peak performance without any production down-time, SST recommends owners follow an annual system maintenance plan, performed by an SST service technician. During an annual service call, as well as performing routine service, the technician checks vital components of the system that are usually not the most obvious areas of failure in the system.

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Topics: Strategic Service Plan

Void-Free Eutectic Die Attach Solutions

Posted by Julia Picarelli on Feb 8, 2017 10:29:21 AM

SST International was acquired by Palomar Technologies as a partner in providing our customers with total solutions. There are many areas where our different capabilities complement each other. One area that both SST and Palomar concentrate on is void-free die attach.

Void-free Die and Substrate Soldering
Also known as eutectic die attach, void-free die and substrate soldering is key to the reliability of many advanced microelectronic products. This assembly process is used when heat must be transferred away from the die or other critical components to avoid thermal failure. The presence of voids increases the die operating temperature by inhibiting efficient heat transfer through the thermal interface material (TIM). Voids may be created by flux residue, surface oxides, trapped gas, and poor wetting.

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Topics: eutectic die attach, Void Free Eutectic Die Attach, Pulsed Heat System

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