JP2006514396A - Recovery method for encapsulated integrated circuit device - Google Patents

Abstract

A method of recovering an integrated circuit device in a sealed array of integrated circuit devices includes testing the array and applying a voltage signal to a pin that appears to be disconnected from an element in the array. including.

Description

  The present invention relates to integrated circuits, and more particularly to recovery of plastic encapsulated integrated circuit memory devices after exposure to high temperatures.

  Integrated circuit devices are widely used in a variety of electronic logic circuits and memory circuits, and are usually encapsulated with plastic materials to allow handling and protection from damage. As the device manufacturing technology and the circuit in which the device is used become more complex, the circuit density per sealing unit when sealing the apparatus is higher than ever. Since the design rules of integrated circuits have shifted to more precise ones, they are easily affected by surface charges and charges outside the encapsulation.

  Integrated circuit memory devices are typically used for large assemblies such as integrated circuit memories. An example of this memory is a crash protection memory used in an aircraft or the like. The crash protection memory is used to record data representing the state of a number of important devices and control levers and perform analysis after a crash. As aircraft equipment becomes more complex, more and more memory space is required to store data indicative of various critical device states for post-crash analysis. However, because the cost required to increase the physical size of the protective housing is high, it is desirable to use high density memory devices, such as commercially available plastic encapsulated electronic memory arrays, commonly referred to as PEM devices.

Plastic-encapsulated memory devices have the property of making them suitable for use in crash protection memory. The crash protection memory not only can withstand the impact of a crash, but also needs to withstand high temperatures, for example, a long time such as 1 hour at 300 ° C., or a high temperature such as 10 hours at + 260 ° C. However, it has been observed that the failure rate of devices in sealed circuit arrays such as electronic memory arrays tends to increase after exposure to high temperatures. This phenomenon is described, for example, in “THE EFFECTS OF MATERIALS AND POST-MOLD PROFILES ON ENCAPSULATED INTEGRATED CICUITS” (RD Mosbarger et al., 1994, IEEE). / RPS) is described in a publication (Non-patent Document 1) and the like. This publication describes various failure modes of these devices. It should be noted in this publication that the cause of the failure is a forward-biased enhancement-type parasitic field-effect transistor that accumulates charge, which results in an external electric field, resulting in an inoperable device after high temperature exposure. It has been found that Therefore, such a device may not be suitable for use in crash protection memory that must withstand temperatures as high as + 260 ° C.
"" THE EFFECTS OF MATERIALS AND POST-MOLD PROFILES ON ENCAPSULATED INTEGRATED CICUITS ", by RD Mosbarger, et al. 1994 IEEE / RPS"

  The present invention seeks to solve these and other problems in the prior art. That is, the method according to the present invention can recover a device with a fault in a sealed array, and thus can be adapted to applications where such devices are exposed to high temperatures. Methods for processing PEM devices and adapting such devices to applications exposed to high temperatures include testing the array, identifying faulty devices in the array, and identifying defective equipment. Applying a voltage signal of a predetermined level to the terminals of the connected sealing array.

  After applying a voltage signal according to the method of the present invention, advantageously, the plastic-encapsulated memory is again exposed to high temperatures and does not exhibit the above-mentioned problems.

A method for recovering data from an electronically programmable memory includes placing the memory device in a known and commercially available device programmer. As this programmer, for example, a device such as a universal device programmer BP-1400 sold by BP Microsystem can be used. The method further includes the following steps:
Use tweezers and isopropyl alcohol or similar equipment to straighten all the leads of the part and remove the dirt;
Placing the memory unit in a device programmer such as the well-known universal device programmer BP-1400; and executing a “read” command in the test equipment.

  When a read error occurs, the device programmer usually issues an error message indicating that the device cannot be read. This error message preferably identifies the connection pins of the device under test that are not considered properly connected inside the sealed device.

  The method of the present invention further includes applying a negative voltage signal to each of the connection pins determined to have no proper connection by the test apparatus. In one application of the invention, a -5 volt signal is applied to a specified pin through a resistor for a specified time. In a specific application, a current limited -5 volt signal is applied to the identified pin, preferably through a 100 kΩ resistor. This voltage is applied through a resistor for about 100 milliseconds.

  In addition, it is preferable that all the leads of the memory unit to be tested are cleaned with a clean solution such as isopropyl alcohol before the signal generator is connected to the pins.

  In one exemplary embodiment of the present invention, the apparatus for applying a signal to a pin of a device for a predetermined time is a series MT-3 curve trace system sold by Ultratest International, San Jose, California. Other preferred devices can be used to apply an appropriate voltage to the pin for an appropriate time.

  In addition, it is preferable that all the leads of the memory unit to be tested are cleaned with a clean solution such as isopropyl alcohol before the signal generator is connected to the pins.

  In a preferred embodiment of the invention, the method further comprises the step of placing the device again in the programmer under test after applying the appropriate signal to the identified pin and executing the “read” command again. This further step is preferably performed to determine whether all errors have been properly corrected. If further errors are found, the steps of the method described above are repeated.

Claims (7)

A method for recovering a faulty connection in an integrated circuit device having a plurality of memory circuit elements and a plurality of connection pins connected to the memory circuit elements, the method comprising a device read command using an integrated circuit programming device The stage of performing,
A method comprising: obtaining an error message from the programming device that identifies a connection pin that appears to be disconnected from a memory circuit element; and applying a voltage signal to the identified connection pin.   The method of claim 1, wherein the signal comprises a read command for reading from the memory device.   The method of claim 1, wherein the applying step comprises applying the signal to the connection pin identified via a resistor.   The method of claim 3, wherein the value of the signal is at least 5 volts.   The method of claim 4, wherein the value of the signal is −5 volts.   6. The method of claim 5, wherein the resistor value is 100 kilohms.   A method of recovering a faulty element in an integrated circuit device having at least one external connection pin, the method comprising applying a predetermined level voltage signal to the external connection pin.