Frequently Asked Questions

• PariPoser® elastomeric materials
• PariProbe® pin interconnectors
• Complete test sockets and OEM connectors
• Development Kits

PariPoser® elastomeric material is an anisotropic electrical interconnect fabric made of a silicone-based matrix with a conductive particle filler.

• Elastomeric contacts are very short so the potential  bandwidth is very high.
• The unit cost per contact position can be lower than an array of spring pins.
• Unlike solder, a socket allows devices to be easily repaired or upgraded.

• The compression is less than a spring pin.
• Some elastomer contacts with a higher conductive filler percentage can take a set.
• Elastomeric interconnects are very different from spring pins AND are different from each other.

• PariPoser® material is thinner than most other elastomers, resulting in a higher bandwidth. 
• Most elastomer products have discrete pads that  have to be aligned to the interconnect locations; in contrast, PariPoser® elastomers are continuous flat sheets of anisotropic conductive material and do not need to be aligned.
• Paricon’s products have a very low metal/elastomer ratio, making them more resilient than some highly filled “elastomers.

PariPoser® material uses vertically oriented BallWire® conductive columns in an insulating silicone matrix. There are multiple BallWire® columns per pad, insuring redundancy in electrical continuity. The vertical conduction (through silver) provides low resistance, typically in the 5-50 milliohms range (depending on pad size); the lateral separation provides isolation, typically in the GigaOhm range. The multiple points of contact reduce inductance, typically below 0.1nH.

PariPoser® material is mostly elastomer, and compresses primarily by elastic deformation of the silicone matrix: the BallWire® conductive columns bend rather than crushing, allowing hundreds of thousands of cycles under good conditions. In contrast, highly filled materials typically compress by forcing the “elastomer” matrix between the conductive particles to tear, an irreversible process that reduces resilience.

PariPoser® material is made in large sheets and can be cut to most required shapes and sizes. Tightly toleranced or complex shapes are made with cutting dies, while loosely toleranced rectangles can be cut by hand.

1. A frame can be more convenient to handle than a loose piece of elastomer.
2. A frame can be used to both hold the material and align a device to the board below.
3. A frame can allow the PariPoser® material to operate at a higher temperature (e.g. 150C for burn-in) while loose material operates best below 100C.

The crown contact on the top of the PariProbe® pin makes the system more tolerant of ball diameter variations while protecting the PariPoser® material from excess forces that could be created by point contact at the bottom of an solder ball. A PariProbe® pin is much shorter than a conventional spring pin, only as tall as the pitch of the device pads. Instead of a coiled spring, the resilience comes from the layer of PariPoser® material below the array of PariProbe® pins, resulting in much shorter electrical path lengths and better electrical performance than spring pins typically provide.

It is a spring pin assembly that is placed on the PariPoser® elastomer material (the yellow area in the image below) to gain additional plunger travel when making contact with a target, in order to allow a large gap between a device and a board or between two boards.

PariPoser® material is available in the form of thin sheets ranging from 0.05mm (0.002”) to 0.38mm (0.016”) thick.
If the PariProbe® options are used, the contact length will increase to be roughly equal to the pitch of the pads being connected.

PariPoser® material has two characteristics that have a favorable impact on bandwidth results. First, the length of a PariPoser® interconnect is very short. Second, each contact position has multiple BallWire® conductive columns in the elastomer material: the multiple contact points lower the resistance and the contact’s self-inductance (typically to below 0.1nH).

The self-inductance of a contact is a simple indicator of potential bandwidth. The lowest self-inductance measurements (and highest bandwidth) come from PariPoser® material. If additional components are included in the contact path, the self-inductance value will increase and the potential bandwidth results will decrease.

In large quantities, simple elastomeric material costs pennies per contact. In low quantities, the costs are higher due to tooling, molds, and application engineering support.

Elastomeric interconnects are most cost effective when the number of contacts per assembly is high or the overall contact surface area is high.

Pitch is the distance from the middle of one contact pad to the middle of an adjacent pad.

These pads can be round, rectangular, or any shape, such as a metal lead on a device. Pads can be recessed, flush, or protruding.

Note: “pitch” refers to the pitch of the device contact pads with which the material is intended to be used, NOT the distance between the BallWire® columns (which is much finer). PariPoser® material has about 6-10 BallWire® conductive columns per contact pad.

PariPoser® sheets are available in pitches from 0.1mm to 1.27mm. PariProbes® are available for pitches down to 0.3mm.

Typically, each contact pad is separated by a non-conducting space. The suggested space is equal to 40% of the pitch.

PariPoser® material is formulated using the 60/40 rule for contact pads. This means that 60% of the pitch would be pad width, and 40% of the pitch would be space between the pad. The size of the PariPoser® material is selected based on this rule for applications (for example: if the pad size is smaller than 60% of the pitch, then a finer pitch PariPoser® material will be suggested for a particular application).

Typically, the contact pads protrude from the surface of the device or the PCB (for example: the thickness of the copper trace on the PCB). The space between the pads is used for the elastomer to squeeze into. The compression of the elastomer onto the contact pads, and the subsequent expansion of the elastomer into the non-conducting space is an important geometric consideration when using a PariPoser® sheet. When contacting pads on a PCB, there should be no solder mask in the interstitial spaces, because that limits the amount of space into which the elastomer can squeeze.

To get the optimal performance from PariPoser® material, the diameter of the BallWire® conductive columns has to scale down with the pitch: a smaller pitch requires smaller particles, and thus, thinner material. Since the pitches of devices vary greatly, there are numerous different PariPoser® materials to accommodate them.

The PariPoser® material is designed to have 6-10 columns per pad – as shown in the photo below. This is a top-down view of PariPoser® material on an array of circular targets.

When compressed, the elastomer moves like an incompressible fluid. The particles in the columns move along with the elastomer, remaining separated from the adjacent columns.  The uncompressed elastomer fills the interstitial voids between the pads. When an elastomer has no more space to fill, it cannot be compressed further.

PariPoser® material compresses by 20-40% of its thickness: as little as 0.025mm (0.001”) to as much as 0.2mm (0.008”), depending on pitch. For a 0.5mm pitch application, the compression is typically 0.05mm (0.002”). PariProbes® accommodate more BGA coplanarity variation than PariPoser® material by itself because the crowns make contact partway up the side of the balls.

Relatively little force per unit area is required to achieve good electrical contact; most of the compression exists to compensate for coplanarity variations of the device and/or the substrate.

The BallWire® conductive columns will conduct current almost immediately at the start of a compression cycle, then remain conductive for the full compression length.

At a compression of 20-40%, the CRES is typically 5 to 50mΩ, depending upon pad size.

The typical current carrying capacity per contact location for the 1.0mm pitch PariPoser® material is 10A of continuous current with a temperature rise of 40 °C. This measurement was done in a laboratory environment in open air. The actual CCC for each application will depend on the conditions of the test fixture or connector, and can be significantly higher with a good heat sink.

In general, PariPoser® material has good current carrying capacity compared to spring pins and stamped contacts, because the electrical and thermal resistance are very low.

When PariPoser® material is used as a DC interconnect, the rating for the 1.0mm pitch material is 30 A/mm2.

Elastomer contacts with a high metal content generally do not spring back to the original position (they typically take a set). In contrast, PariPoser® material is mostly elastomer, and is thus more resilient than typical heavily-filled elastomers.

Semiconductor spring pins typically compress 0.3mm – 0.5mm. Interface spring pins compress 2mm – 3mm, both of which allow more compression than an elastomer.

When the Hybrid PariPoser® option is employed, the compression values are about the same as a spring pin with an equal length.

In general, conductive elastomers (including the PariPoser® material) are rated from -50°C to + 100 °C. When the PariPoser® material is placed on a stretch frame, the rating goes up to 150°C.

Pre-stretching PariPoser® material on a frame compensates for the coefficient of thermal expansion (CTE) and therefore will allow the material to function at elevated temperatures.

Spring pins with gold plating and stainless steel compression springs are typically rated up to 150°C.

Pure elastomers (which are not conductive) are very resilient and can maintain their springiness for millions of cycles.

PariPoser® materials are mostly elastomer. Testing of Paricon’s materials have shown that mechanical and electrical properties are consistent for hundreds of thousands of test cycles and have remained consistent over 12 years of continuous compression.

PariPoser® material can elastically stretch over 400% of its length.

Most other conductive elastomers are made with a larger fraction of metal and a smaller fraction of silicone. These “elastomers” tend to take a set because they compress by allowing irreversible microtears of the matrix between adjacent metal particles, thus reducing their resilience and cycle life.

Competitor’s conductive elastomer made with a higher density of metal particles.

Conductive cylinders are placed in an insulating carrier to keep the cylinders separated. Unlike PariPoser® material, this competing material also needs to be aligned to the contact pads, adding another requirement.

Elastomeric contacts have a much smaller range of motion than spring pins.

Elastomeric contacts work best when the pads are flat. If the pads have unusual shapes (like gull-wing leads), or the devices are not flat, then some kind of a compensating mechanism should be used with the elastomer.