Design Features

• Maximize Throughput with Highest Board Density
• Lowest Cost-per-Position for Volume Needs
• Availability of Input Isolation and Output Loading
• All Device Types and Package Styles
• Clean Dynamic Signals and Low Power Supply Noise

• Isolation/Support Frame – Protects boards from damage, high-temperature warpage or twisting. Guarantees accurate board alignment in the oven rack and allows easy storage. Protects personnel from exposure to the sharp solder joint on the underside of board.
• Long Finger Tab (2.75") – The correct length to allow easy access to the mating edgecard connector OUTSIDE the chamber environment. (“Short” finger tab boards require connector to be located INSIDE the chamber which could cause reliability problems and difficulty for maintenance.)
• Offset Finger Tab – Prevents operator from improperly installing board assembly in oven chamber.
• Optional Test Fingers – Spot check (setup) or continuously monitor (during burn-in) the bias supplies and dynamic signals at the farthest point from where they enter the board.
• Support Puller – An integral part of the assembly which allows easy insertion and removal of the board inside the test chamber.
• Wide Dimension (11”) – This width is the best tradeoff to get the lowest cost and maximum overall DUT socket density in a chamber. Permits additional customer cost savings as fewer board assemblies, edgecard connectors, and internal rack supports, need to be purchased to achieve the desired burn-in part throughput.

In production burn-in areas, the need exists to burn-in large quantities of certain devices or families of devices. Here the requirement of flexibility or versatility, important to Test Engineering, Quality Control or Failure Analysis Burn-In Departments, is overshadowed by maximum throughputs at the lowest possible cost. To meet this need, we manufacture thousands of “dedicated” board designs to customer satisfaction.

Dedicated boards, which achieve high device socket density because space is not required for programming hardware, can be made for all device families, package styles and board sizes for either static or dynamic burn-in. Resistors, capacitors and other discrete components for input isolation, output loading, and supply decoupling may be added to simulate the circuit the devices will actually experience in field use.

For customers experienced in burn-in, we will review burn-in schematics and provide quotations regardless of the burn-in system being used.

For customers just getting started in burn-in, we can recommend static or dynamic burn-in schematics and provide standard dedicated boards which will stress and exercise semiconductor devices to determine their reliability. As with all of our boards, these dedicated circuits are unique in the testing industry in that the design, manufacture, and assembly of both boards and the device sockets are done at Loranger.

Horizontal USD Burn-in Motherboard

Design Features

• Flexibility – The Horizontal USD concept consists of three parts: 1) the “mother burn-in board” with its common buses for signals, power and ground, 2) the SocketSavers which plug into the top side of the Motherboard, and 3) the program boards which plug into the underside of the Motherboard, it is obvious that the only section dedicated to a particular test schematic is the program board. Therefore, flexibility is achieved on the Motherboard because the signal, power and ground inputs can be reconfigured by the program board to feed a new test set to the SocketSaver. Likewise, since the SocketSaver is totally programmed by the program board, it is capable of being reprogrammed over and over again as new requirements emerge.
• Packaging Changes are Easy – Obviously the only element in the Horizontal USD method that is affected by packaging changes is the socket itself. Therefore, if there is a need to concurrently qualify a certain device in two or more package forms, the engineer simply utilizes a SocketSaver for each package style and a program board to setup an identical bias plan on each package.
• Board Obsolescence – Since the test schematic is the item that most often changes for different device functions over time, only a change in the program board is required once the Motherboard and the SocketSaver are purchased. Thus the Motherboards and SocketSavers are not obsolete with each change in function.
• Lowest Total Cost – Cost savings are achieved immediately when the first new program card is ordered. Since the Motherboard and SocketSaver remain the same, each new program board order divides the previous purchase up into smaller units.
• Inventory and Storage – In a well thought-out program, the Motherboards are presumably always in burn-in or loading for the next run so storage space is reduced for large board sizes. Furthermore, SocketSavers are typically in the same burn-in/load cycle so space for the SocketSavers is only required when packaging mixes change. This leaves the program boards which are stored and inventoried for each dedicated test program. However, storage typically consists of small cell sizes of less than 2-1/2" by 4" so control becomes an easier task.
• Quick Response – Since the new designs most often only require program boards for the change, once the initial investment is made, design time is reduced to the program board only. Furthermore, emergency changes can also be made by stocking our “vector type” program cards that can be hand wired by a technician.

Design Features

• Reduce Board Inventory
• Quickly Respond to New Device Requirements
• Pin-Programmability and Gross Loading by Board or Column within Board
• Elimination of Board Obsolescence Through Programming Features

Flexible bus burn-in boards, usually for static burn-in, permit the user to program any incoming bias power to any pin on every socket on the board.

To accomplish this, each equivalent pin on each socket is connected to all the equivalent pins on the remaining sockets via a trace on the burn-in board, i.e., all Pin 1s are connected together, all Pin 2s are connected together, etc. A trace is then run on the board from each pin to a programming station. The programming station may be a program card and edge connector pair, a program socket or other means of interconnection. The incoming bias power lines, which enter the burn-in board via edgeboard fingers or other means, also proceed to the programming station. The user can then connect each pin to the proper incoming bias power line using jumper wires, resistors or other passive components.

The flexible bus board should be used when the operation involves static burn-in of large quantities of different device types. The main disadvantage of using this flexible concept is that individual devices are not protected from the interaction with adjacent devices unless resistors are separately used at each socket.

A common modification of this idea is called "resistor isolation flexible bus," which is actually a dedicated PC board with resistors to locally protect each device. Another subject is to isolate by row or column only.

30.9" x 12.5" USD Burn-in Motherboard w/SocketSavers

High-Voltage Capacitor Test Board

Check our Board Accessories for all the various and sundry items you'll need with burn-in also.

Also available, are the Cleaning Recomendations for various types of Loranger burn-in boards, storage racks and system chambers.