A Closer Look at Clamshell Socket Lid Styles

When conducting reliability testing of semiconductor devices, there’s a wide range of mechanical, thermal, and electrical challenges. Knowing the options available with a clamshell socket will help address and solve these issues. In addition to the lid being the force delivery system, there are other functions the socket lid can provide.

Understanding clamshell sockets

Clamshell sockets derive their name from the way they open and close like a clam — a simple name for a tool in which so much is done. They are used for hand test, all reliability burn-in test methods, and in some cases, production burn-in. They’re needed because:

  • Most high-power devices require thermal management solutions
  • Fragile devices require unique force delivery options
  • Lower quantity usage of sockets requires an ergonomic and cost-effective solution

Plastronics has been an industry leader which has taken the responsibility to address these needs. Read more about why you should choose us, here.

When it comes to clamshell socket lids, you have options.

Clamshell socket lids can be segmented into basic categories of plastic, metal, and hybrids. Subcategories of these are solid or floating plunger, thermal management, and failure analysis. The type of lid you need for the socket depends completely on the package and the features of this package or device under test (DUT). There’s a big difference in the needs of a thick robust package versus a thin CSP, just as there’s a huge difference in low-power devices versus super hot 400W-800W graphics chips or ASICs. So don’t be in a hurry to explore the options available to you when it comes to the lid types.

Clamshell lid types and some of their features:

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Solid Lids

  • Most common low-cost lid design.
  • For robust DUTs, generally thicker than 0.6mm.
  • Pusher height fine-tuned to match a specific DUT thickness.
  • Contact pins lift DUT slightly off of the nest floor, DUT only sees pin force during the test.
  • A shorter pusher face will lighten pin force against DUT.


clamshell socket lids - floating plunger

Floating plunger

  • For robust DUTs, generally thicker than 0.6mm.
  • Pusher face presses DUT to seat on nest floor for full pin travel and force.
  • A floating plunger can absorb wide variations in DUT thickness.
  • Contains extra parts and labor versus a solid lid, so utilized as needed.

Plastronics-Clamshell Socket Lids-Blog Coupon Lid

Coupon Lid

  • Four-sided pusher presses on the outer edges of the coupon substrate.
  • Open gap in middle of plunger clears exposed die or package.
  • Vent or access hole from the top.
  • Plunger available as a two-sided window-frame shape.

clamshell socket lids - reverse shelf seating

Reverse Shelf Seating

  • The shelf on the upper floating lid plunger seats on top of the nest as hard stop (yellow surfaces)
  • DUT is gently lifted up to the plunger face via pin force. No other external forces can be applied.
  • Offers full protection for more fragile or sensitive DUTs with light pin force.
  • Plunger height fine-tuned to match a specific DUT thickness.
  • A shorter plunger face will lighten pin force against DUT.

clamshell socket lids - center floating plunger

Center Floating Plunger

  • Outer window-frame plunger applies pressure to the outside perimeter of DUT.
  • Center plunger floats via springs for balanced light force against exposed die at a different height than substrate.
  • Supports center of higher pin count DUTs from warpage.
  • Very useful to pull heat from exposed die if made as a heat sink, or center plunger can be plastic for low power applications.

Plastronics-Clamshell Socket Lids-Blog Heat Sink Lid

Heat Sink Lid

  • Finned top side of lid to dissipate DUT heat to ambient air.
  • Solid or floating style lid.
  • Material: anodized aluminum, or nickel-plated copper if needing maximum thermal dissipation.
  • May include Integrated Thermal Control (ITC) with thermistor, RTD, heater or fan wired to Molex connector.

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Feature Analysis Lid

  • Large lid opening to see the entire DUT for thermal imaging of hot spots.
  • Lid opening covered with sapphire glass that engages DUT into the nest.
  • Optional: open hole through lid for physical probing to center area on top of DUT.
  • Large lid opening to see the entire DUT for thermal imaging of hot spots.
  • Low profile lid <5mm to top of DUT to minimize reflections and improve imaging accuracy.

Plastronics-Clamshell Socket Lids-Blog Vertical Actuation Pliunger

Vertical Actuation Plunger

  • Allows for true vertical actuation of lid plunger or heat sink against package for safe balanced force.
  • Lid closes and locks without touching the package.
  • Secondary motion of handle presses lid plunger or heat sink with vertical motion against package.
  • Ideal for higher pin count and fragile packages or bare die.

The above is a breakdown of clamshell socket lids. There might be a case where some of the types are combined to better meet the specific requirement. By communicating with your socket supplier, they will help with your understanding of the wide range of lid types available.

Determine which socket would best fit your requirements.

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