Burn-In Sockets

uwe electronic offers burn-in sockets from Wells-CTI and Sensata – two of the world's leading manufacturers of solder-free contacting solutions for semiconductor reliability testing. The portfolio covers nearly every common package type: from large-area BGA and LGA packages to fine-pitch CSP and FBGA packages, QFN and QFP packages, right down to discrete TO/SOT and SOP/SSOP/TSSOP/TSOP devices. Depending on the package and requirements, different contact principles are used – such as spring contacts (spring probe), buckle-beam contacts, or cantilever contacts – along with different latching types such as open-top, clamshell or compression mounting. All sockets are built for continuous use at high temperature, high cycle counts and – inside the burn-in oven – additionally high humidity, enabling solder-free, reusable contacting across hundreds to thousands of test cycles. Besides the classic burn-in test used to detect early failures, the same sockets are also excellent for device programming prior to soldering onto the PCB.

Series by Package Type

All series are available as PDF datasheets with precise technical data (pitch, pin count, dimensions, temperature range) available. Click an image to open the corresponding datasheet.

BGA – Ball Grid Array

A BGA package has a regular grid of solder balls on its underside that provides both the electrical and the mechanical connection to the PCB. Burn-in sockets for BGA press the device firmly onto a matching field of spring contacts so that every ball is reliably contacted without a soldering process – ideal for devices with a high pin count in a small footprint.

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Carrier – Burn-In Carrier Housing

The carrier is not a direct device socket but a housing with a lid that securely holds, mechanically fixes and contacts one or more devices throughout the entire burn-in process. Carriers enable simple, automated transport of the devices through the burn-in oven and into handling systems, without the sensitive leads having to be handled individually.

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CSP-BGA-QFN – Chip Scale Package / BGA / QFN

This series covers three closely related, particularly compact package types at once: Chip Scale Package (CSP), where the package footprint is barely larger than the die itself, classic BGA, and QFN (Quad Flat No-Leads) without protruding leads. The sockets are designed for very fine pitch dimensions and high contact density, as is typical for modern, space-saving semiconductor packages.

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CSP-FBGA – Chip Scale Package / Fine-Pitch BGA

CSP-FBGA is the fine-pitch variant of chip-scale BGA with an even tighter ball grid. This package type is mainly used for highly integrated memory and logic devices, where a very high pin count must be accommodated in the smallest possible space. Accordingly, it places high demands on the socket's positioning accuracy and planarity.

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PGA – Pin Grid Array

Instead of solder balls, a PGA package carries a grid of pins on its underside that plug into a matching socket matrix. PGA burn-in sockets receive the pins and establish the electrical contact through them – a proven solution for devices with a high pin count where a pluggable rather than a planar contact is preferred.

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QFN-LGA – Quad Flat No-Leads / Land Grid Array

QFN packages have no protruding leads, but flat contact pads on the sides of the package and often an additional thermal pad in the center. LGA packages are contacted purely on their underside, with no side leads at all. Both package types are especially flat and compact and are covered together by this socket series.

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QFP – Quad Flat Package

A QFP package has finely spaced, outward-projecting gull-wing leads on all four sides. This classic, widely used package type requires burn-in sockets with laterally arranged spring contacts that contact the delicate leads gently yet securely.

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TO-SOT – Transistor Outline / Small Outline Transistor

TO and SOT packages are classic designs for discrete semiconductors such as transistors, diodes or small ICs with only a few leads. Despite their simple construction, these devices are produced in very large volumes – accordingly, the matching burn-in sockets are built to be robust and suited to high throughput.

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XSOP – (Extended) Small Outline Package

XSOP is an extended variant of the small-outline package with two rows of leads on opposite sides and a higher pin count than a standard SOP. This package type is commonly found on memory devices and compact logic ICs with medium to high pin counts.

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What Is a Burn-In Test?

A burn-in test is a stress test in which electronic devices are exposed simultaneously to elevated temperature and electrical voltage (bias) over a defined period of time. It is based on the so-called bathtub curve of failure rate: newly manufactured semiconductor devices show an elevated probability of failure at the start of their life cycle, caused by latent manufacturing defects – such as oxide defects, weak bond wires, voids in the die-attach layer, or metal migration. The burn-in test accelerates exactly these defects, so that the affected devices can be identified and screened out as early failures ("infant mortality") before they are built into an end product – a key building block for reliable electronics in safety-critical applications.

A burn-in test socket provides the releasable electrical connection between the device under test (DUT) and the burn-in board or oven – entirely without soldering, so the device can be removed and processed further without any trouble after the test. Since a test run typically involves hundreds of devices mounted in parallel on a burn-in board, the socket must withstand not only stable contact quality but above all a high number of insertion and temperature cycles unscathed.

Internationally, the burn-in process is based on standards such as JEDEC JESD22-A108 (Temperature, Bias, and Operating Life) and MIL-STD-883, Method 1015. Typical test parameters for pure early-failure screening burn-in call for a junction temperature T_j of at least 125 °C and a supply voltage at or above the specified maximum, with a test duration of 48 to 168 hours. For further reliability qualification (High Temperature Operating Life, HTOL), the same standards call for test times of 500 to 1,000 hours at the same temperature. Just how much such high-temperature stress anticipates real-world field aging is illustrated by a calculation based on the Arrhenius equation: with a typical activation energy of 0.7 eV, a stress temperature of 125 °C versus an assumed field operating temperature of 55 °C yields an acceleration factor of roughly 78.6 – meaning a 1,000-hour burn-in stress corresponds, mathematically, to roughly nine years of real field use.

How Does a Burn-In Socket Work?

At its core, a burn-in socket consists of three elements: a housing that fixes the socket to the burn-in board and holds or latches the device; the actual contact elements, which electrically connect the device's leads to the board's traces; and a latching or pressure mechanism that presses the device onto the contacts with a defined force and holds it securely for the entire time in the oven.

Latching Types

• Open Top – the device is placed in openly from above and held down by a separate lid or by the burn-in board itself; a simple design, often used with automated placement.
• Clamshell – a hinged lid folds over the device and latches it in place; fast, tool-free loading and unloading by hand.
• Compression mount – the socket is bolted onto the board, and the contacts establish the connection purely through contact pressure; no separate solder joint for the socket itself is needed.

Contact Principles

Depending on the package type, pitch and pin count, different contact technologies are used:

• Spring probe – a classic, spring-loaded contact pin (pogo pin) that compensates for height tolerances and makes contact with a defined force; the standard solution for BGA, LGA and PGA devices.
• Buckle beam – a contact that flexes in a controlled manner when pressed; robust and space-saving, often used in very fine-pitch BGA/FBGA sockets.
• Cantilever (single- or dual-beam) – a spring arm fixed at one end that contacts leads protruding from the side; typical for QFP and QFN packages.
• Pinch contact – two opposing contact springs "clamp" the device from both sides; used among others in certain FBGA series.

Steps in the Burn-In Process

In the typical process flow, the device is placed into the socket and latched, and the loaded socket is permanently mounted on the burn-in board. Several hundred such loaded sockets are pushed together into the burn-in oven and operated there – depending on the test regime – for 48 to 168 hours at a junction temperature typically between 125 °C and 150 °C under electrical bias. Once the test time has elapsed, the board is removed, the devices are electrically retested, defective devices are screened out – and the socket is immediately ready for the next test cycle with new devices.

What Are the Advantages of Burn-In Sockets?

A pluggable burn-in socket is not the only way to contact a device during a burn-in test. In practice, it competes with several alternative contacting and test methods that each bring advantages and drawbacks depending on the application – from simple direct soldering to fundamentally different test philosophies such as system-level test. The comparison below positions the burn-in socket against these alternatives..

Comparison with Similar Contacting Technologies

Burn-in sockets compared with alternative contacting methods

Method	Reusability	Advantage over burn-in socket	Disadvantage vs. burn-in socket
Direct soldering of the DUT onto the burn-in board	None – board or device is desoldered or scrapped after the test	Lowest transition resistance and inductance, very close to real operating conditions – advantageous for high-frequency devices	Destructive; every test run requires new soldering/desoldering, significantly higher time and labor cost, no parallel use across changing batches
Soldered (solder-mount) socket	Limited – desoldering can deform the socket through thermal stress, solder residue on the contact pins hampers reuse	Tends to have lower upfront cost per socket	Socket replacement only possible via a soldering process, risk to neighboring sockets during reheating, shorter service life compared with solder-free compression mount
Elastomer contact	Limited – the silicone interposer is subject to mechanical wear	Very low contact force, shortest signal path, high bandwidth	Generally not designed for the high cycle counts of a burn-in regime (thousands of insertions at high temperature)
Wafer-Level Burn-In (WLBI)	Applies to the wafer, not to an individual-chip socket	Screening already occurs before singulation and packaging – defective die incur no packaging cost	Economical only for certain, typically simpler devices (e.g. memory) with sufficient parallelism; complex SoCs are still tested packaged, in a socket
System-Level Test (SLT)	Not comparable – a different test principle (functional test in a target-system context)	Covers failures that pure structural test or burn-in do not catch, e.g. hardware/software interactions	Does not replace the thermal-electrical stress screening of burn-in, which specifically provokes early failures

Core Advantages of the Burn-In Socket

• Solder-free reusability – especially with compression-mount sockets, thousands of devices can be contacted one after another without damaging or replacing the socket itself.
• High degree of parallelization – hundreds of sockets on a single burn-in board enable testing large batch sizes simultaneously at comparatively low cost per device.
• Non-destructive handling – the DUT is subjected to no thermal or mechanical stress from soldering or desoldering when it is loaded or removed.
• Package flexibility – the same board concept can be adapted to different packages (BGA, QFN, QFP, TO-SOT and others) simply by swapping the socket series.

Competing and Complementary Test Trends

Two developments are currently changing the extent to which classic, socket-based burn-in tests are used:

• System-Level Test (SLT) – for complex SoCs with very high transistor counts, structural test and burn-in alone can no longer achieve complete fault coverage; part of the test coverage therefore shifts to SLT in a simulated target system. In application fields where burn-in is required anyway (e.g. automotive), both methods are increasingly combined on the same, high-parallelism test infrastructure rather than replacing one another.
• Adaptive, data-driven test skipping – based on prediction models for the expected failure rate (DPPM) per wafer bin, the share of devices that must go through a full burn-in or SLT run can be significantly reduced for low-risk bins. For already mature, low-risk production lots, this can noticeably cut test effort, while devices from flagged bins continue to be fully tested.

For most packaged, medium- to high-complexity devices, however, the socket-based burn-in test remains the most economical method for detecting early failures, thanks to its combination of solder-free reusability, high parallelism and targeted thermal-electrical stress acceleration.

Application Areas

Quality Features of Wells-CTI and Sensata Sockets

Burn-in sockets from Wells-CTI and Sensata are characterized by very high durability – even under demanding ambient conditions such as sustained high temperature or high humidity, as typically found in burn-in ovens. This makes the sockets a robust choice for continuous use in production test setups:

• High cycle endurance – designed for a very large number of contact cycles without a significant rise in contact resistance.
• Temperature resistance – materials and contact springs are designed for continuous operation at elevated burn-in temperatures.
• Humidity resistance – stable contact quality even at high humidity inside the oven.
• Broad package portfolio – matching series for nearly every common package, from discrete TO devices to large BGAs.

Package Types at a Glance

Wells-CTI and Sensata offer matching burn-in socket series for every common package type. The table below gives a brief overview of the package types before the next section lists all available series per package type with datasheet.

Package types and how they are contacted in a burn-in socket

Package type	Full term	Typical contacting
BGA	Ball Grid Array	Grid of solder balls on the underside of the package
Carrier	Burn-in carrier housing	Holder for device(s) including lid, for oven transport
CSP-BGA-QFN	Chip Scale Package / BGA / QFN (combined)	Fine-pitch balls or contact pads at chip scale
CSP-FBGA	Chip Scale Package / Fine-Pitch BGA	Very tightly spaced ball grid
PGA	Pin Grid Array	Grid of pins
QFN-LGA	Quad Flat No-Leads / Land Grid Array	Flat contact pads with or without side leads
QFP	Quad Flat Package	Protruding gull-wing leads on all four sides
TO-SOT	Transistor Outline / Small Outline Transistor	A few leads brought out to the side
XSOP	(Extended) Small Outline Package	Two rows of side leads, extended pin count

Products on Request

Beyond the standard Wells-CTI range shown above, we can source additional, more specialized series for QFP as well as FBGA/CSP/BGA/LGA packages on request. These series are not part of the regular range shown on this page, but are available through uwe electronic on demand. If you're interested, please get in touch with us directly.

QFP Sockets – additional series on request

Additional QFP series, complementing the 680 Series – available on request

Series	Pitch	Max. package size / pins	Contact type
3000 Series	0.4–0.8 mm	28×28 mm, 32–208 pins	Open top, single-beam cantilever
680H Series	0.4–0.8 mm	28×28 mm, 48–176 pins	Top-loaded, dual-beam cantilever
680HA Series	0.4–0.8 mm	28×28 mm, 48–176 pins	Top-loaded, dual-beam cantilever
CQF Series	0.4–0.8 mm	24×24 mm, 64–176 pins	Side-loaded, dual-beam cantilever

FBGA / CSP / BGA / LGA Sockets – additional series on request/h3>

Additional series for FBGA, CSP, BGA and LGA packages – available on request

Series	Pitch	Contact type	Note
715P Series	0.4–1.27 mm	Spring probe	Compression mount
718P Series	0.4–1.27 mm	Spring probe	Compression mount
773 Series	0.4–1.27 mm	Buckle beam	–
892 Series	0.4–1.27 mm	Buckle beam	Clamshell
CBG Series	0.4–1.27 mm	Pinch	Through-hole mount
FBGA Series	0.4–1.27 mm	Pinch	Through-hole mount
Q118 / Q318 Series	0.4–1.27 mm	Spring probe	Clamshell
Q323 Series	0.4–1.27 mm	Spring probe	Clamshell
Q340 Series	0.4–1.27 mm	Spring probe	Clamshell
859 Series	0.4–1.27 mm	Buckle beam / spring probe	Clamshell, for large BGA/LGA (35×35–65×65 mm)
861 Series	0.4–1.27 mm	Buckle beam / spring probe	Clamshell, for large BGA/LGA (35×35–65×65 mm)
863 Series	0.4–1.27 mm	Buckle beam / spring probe	Clamshell, for large BGA/LGA (35×35–65×65 mm)
869 Series	0.4–1.27 mm	Buckle beam / spring probe	Clamshell, for large BGA/LGA (35×35–65×65 mm)

FAQ

 

Technical FAQ: Electrical, Mechanical, Thermal & Selection

The following questions are aimed at engineering and procurement teams and go deeper into electrical parameters, mechanical service life, thermal behavior, and how to choose the right series.

Electrical Properties

Mechanical & Service Life

Thermal

Compatibility & Selection

Procurement & Practice