Plastics for IC test sockets and electronic testing fixtures

In the microchip and electronics manufacturing process, it is important to test the chips or electronic components under various conditions to ensure specific functionalities as well as durability. Different test socket designs are used to test electronic components, such as IC chips, printed circuit boards (PCB), flexible printed circuits (FPC), camera modules, and others. As several types of high-performance and engineering plastics are used to manufacture test sockets, the demand for plastic materials continues to grow rapidly. 
Similar basic material properties need to be provided by all variations of test sockets. High dimensional stability is critical for ensuring the micro structures to remain unchanged during fabrication and in usage, thus the material need a low level of water absorption, low thermal expansion, low internal stress level, and sufficient stiffness over a wide temperature range. Also, micro machinability of the material is key for realising the fine structures and tolerances, thus materials must provide minimal burr formation to lowering fabrication costs, low elongation for precise hole placement, and low internal stress to avoid warping during machining. Moreover, test sockets undergo continuous testing cycles, so the materials must provide sufficient wear resistance, mechanical strength, temperature resistance, and in case of problems with tribological charging, also anti-static properties. 
Additionally, the choice of material for test socket applications are based on operating temperature, hole and pitch sizes, electrical properties, and accordingly relative cost. 

Benefits of Ensinger materials for test sockets & electronic fixtures

  • Fiber-reinforced plastics, e.g., filled with glass fibers, provide improved rigidity and stiffness, which are advantageous properties for test socket contact plates or body parts. However, fiber-reinforced plastics are problematic when highly accurate hole placement is needed, as the fibers cause the drill bits to deflect, wear, or even break, and generate more heat during drilling. Ensinger's TECAPEEK CMF and TECAPEEK ESD are filled with nanoscale-sized additives that significantly enhance rigidity and stiffness, while keeping drill bit deflection to a significantly lower level than fiber-reinforced plastics and competitor products. Moreover, Ensinger's polyimide TECASINT 4111 provide outstanding stiffness without any additives, resulting in very high hole position accuracy even with very small pitches. 
  • Fiber reinforced plastics and injection molded plates tend to contain residual stresses that cause warpage and deformations while machining, thus making it difficult to realize small geometries with tight tolerances. The filler system and extrusion molding method of TECAPEEK CMF allows residual stresses to be significantly lower than fiber reinforced plastics or injection molded materials. For parts requiring higher temperature resistance, Ensinger's polyimide TECASINT are produced with compression molding, also offering very low level of residual stresses. Consequently, better dimensional stability and reduced deformation while machining enable smaller pitches and higher hole position accuracy. For parts besides the contact plate, such as body parts, where micro hole machining is not required, Ensinger’s glass fiber reinforced materials can be a cost-efficient option. 
    Material with high residual stress versus material with low residual stress level
    Example of machining down a 6 mm sheet to 2 mm thickness 
    The material properties also have an influence on the dimensional stability, as water absorption and thermal expansion can cause part deformations. Ensinger's TECATRON PPS, TECAPEEK, and TECAPEI plastics for test sockets offer low levels of water absorption, while materials with higher water absorption like PAI and PAI GF30 can cause issues in tight tolerance alignment. For higher temperature applications, the special polyimide type TECASINT 4011 and in particular TECASINT 4111 offer lower water absorption than industry standard polyimide, opening up new design possibilities for high temperature test sockets. 
    Plastics with glass fiber reinforcement
    Plastics without glass fiber reinforcement
    Plastics with glass fiber reinforcement
    Plastics without glass fiber reinforcement
  • Another important aspect for realizing precise hole placement is the material properties of the plastic material. Generally, a lower elongation material enables more precise hole placement, as plastics with higher flexibility provide more room for the drill bit to shift off target. Moreover, lower elongation and higher stiffness reduces burr deformation, enabling cost savings by eliminating additional deburring operations. However, materials with lower elongation will lead to cracking during machining, impacting machining yield and costs. TECAPEEK CMF, TECAPEEK ESD, TECASINT 4111, and TECASINT 4011 offer a low level of elongation, resulting in superior hole accuracy and reduced burr deformation, while keeping the risks of cracking to a minimum, and avoiding the disadvantages of fiber reinforced plastics such as drill bit deflection and warpage during machining.
  • While fiber-reinforced plastics cause drill bit deflections and drill bit wearing, frequent drill bit exchanges are common when machining micro-holes in the contact plates. The filler system of TECAPEEK CMF and TECAPEEK ESD enables comparably less drill bit deflection and wearing, resulting in significant reductions of drill bit exchanges. Also the polyimide type TECASINT 4011 and 4111 offer reduced drill bit deflection as no additives are used and residual stresses are kept to an minimum. In some cases, up to 4 times longer drill bit life could be achieved compared to similar competitor materials and other fiber-reinforced materials. 
  • Electrostatic discharge (ESD) induced failures are becoming a more significant problem, as devices become smaller, faster and sensitivity increases.  Test socket material interaction with the device substrate material causes tribo-charging, resulting in charge build up and ESD related device and tester failures. This issue can be resolved by replacing highly insulative socket materials, such as glass-fiber-reinforced plastics, to a resistive material with a surface resistivity of  106 –109 Ω/sq. Such ESD materials can slowly bleed away static electricity in a controlled manner and avoid charge buildup on the device. 
    Most ESD plastics are produced with compression molding, which is a cost intensive production method. Ensinger developed a cost-effective extruded PEEK ESD grade - TECAPEEK ESD that combines the advantages of high stiffness and superior micro-machinability with a surface resistivity of 106 –109 Ω/sq. For high-end test sockets that require higher temperature resistance, we also offer a polyimide ESD grade TECASINT 5501 ESD with a surface resistivity of 106 – 108  Ω/sq. 
  • For some automotive and other applications, integrated circuit testing conditions include temperature ranges between -55°C - 180 °C or even higher, requiring the testing equipment to consist of highly temperature resistant materials. Semi-crystalline plastics like PEEK show a decline of mechanical properties when exceeding the glass-transition temperature, which is 150 °C for PEEK. Reinforced materials like TECAPEEK CMF and TECAPEEK ESD show higher stiffness than unfilled PEEK also above 150 °C. For applications requiring even higher temperature resistance, Ensinger offers with TECASINT 4011 and TECASINT 4111 special polyimide types with superior dimensional stability, strength, and stiffness even above 260 °C.

Product portfolio

TECAPEEK natural
TECAPEEK SD black
TECAPEI GF30 natural
TECASINT 4111 natural
TECATRON natural
TECAPEI natural
TECASINT 4011 natural
TECAPAI CM XP403 green
TECAPEEK CMF white
TECAPEEK GF30 natural
TECASINT 5501 ESD light-brown
TECAPAI CM XP530 black-green

Case studies & Applications

FPC Connector Testing Fixture

made of TECAPEEK CMF white

Testing Fixture for Smartphone FPC Connectors
Flexible Printed Circuits (FPC) are becoming increasingly complex and miniaturized. With the pitch spacing of FPC connector contacts continually decreasing, functional testing fixtures must be fabricated with contact probes that have similarly small pitch spacing. The TECAPEEK CMF series has been engineered to provide excellent micro-hole machinability and dimensional stability, making it an ideal material for the next generation of FPC connector testing fixtures.

PCB Inspection Fixture

made of TECATRON natural

PCB Inspection Fixture
Printed Circuit Boards (PCBs) must undergo comprehensive testing during the manufacturing process to verify their proper functionality. The PCB inspection fixture consists of plastic sheets that include a fine-pitch array of nails that is pressed against the PCB. TECATRON SX natural is a commonly used material for the sheets due to its excellent dimensional stability, optical cleanliness, and micro-hole machinability.

IC Test Socket

made of TECASINT 4011

High Temperature IC Test Sockets
During the microchip manufacturing process, integrated circuits (ICs) undergo testing at multiple stages to verify their functionality in different environmental conditions. The testing equipment, including test sockets, must also withstand harsh testing conditions, including temperatures exceeding 200 °C. For such applications, the TECASINT 4000 series is an ideal choice, as it provides high dimensional and mechanical stability at high temperatures, as well as excellent micro-machinability.

IC Test Socket machined from TECAPEEK CMF white

  • Excellent machinability of micro holes
  • Less burr formation during machining
  • High machining accuracy of fine featues 
  • High dimensional stability
  • High rigidity and bending resistance

IC Test Socket machined from TECAPEEK ESD black

  • Consistent surface resistivity between 106 -109 Ohm
  • Less burr formation during machining
  • High machining accuracy of fine featues 
  • High dimensional stability
  • High rigidity and bending resistance

IC Test Socket machined from TECAPEI natural

  • High strength and ductility
  • Cost efficient
  • High dielectric strength 
  • High heat deflection temperature
  • Good machinability 

Contact

To request material samples or ask for a quotation please navigate through the product detail pages. If you are not sure what materials to use for your application, or if you have questions on technical details feel free to contact our technical support for advice.
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