TWI650568B - Test system and method for testing an integrated circuit and a circuit board including the integrated circuit - Google Patents

Abstract

A test system includes a subtractor and a divider. The subtractor is configured to receive a first voltage of a circuit being tested and a second voltage of the circuit, and derive a difference between the first voltage and the second voltage. The divider is configured to receive the difference between the first voltage and the second voltage, and by dividing (i) the difference between the first voltage and the second voltage by (ii) applying A difference between a first current to the circuit and a second current applied to the circuit leads to a resistance of the circuit. The first voltage corresponds to the first current, and the second voltage corresponds to the second current.

Description

Test system and method for testing integrated circuit and circuit board including the integrated circuit

The present invention relates to a test system and a method for operating the test system, and more specifically to a test system for an integrated circuit and a method for operating the test system.

As the performance and complexity of integrated circuits (ICs) have increased over the years, the number of input / output (I / O) pins or the pin counts have also increased significantly. High density devices with high output pin counts can have a large number of output pins that can require output testing. A test system is needed to verify the functionality of the IC.

According to some embodiments of the present invention, a test system includes: (a) a subtractor configured to receive a first voltage of a circuit being tested and a second voltage of the circuit and derive the first voltage A difference from the second voltage; and (b) a divider configured to receive the difference between the first voltage and the second voltage and by (i) the first voltage The difference from the second voltage is divided by (ii) a difference between a first current applied to the circuit and a second current applied to the circuit to derive a resistance of the circuit, where the first A voltage corresponds to the first current, and the second voltage corresponds to the second current. According to some embodiments of the present invention, a method for testing an IC includes: (a) applying a first current to a pin of the IC; (b) measuring a first voltage at the pin of the IC (C) applying a second current to the pin of the IC; (d) measuring a second voltage at the pin of the IC; and (e) applying (i) the first voltage to the pin A difference between the second voltages is divided by (ii) a difference between the first current and the second current to derive a resistance of the IC, where a ratio of the second voltage to a second current is given The ratio of the first voltage to the first current is multiplied by β, and β is in a range of about 0.98 to about 1. According to some embodiments of the present invention, a method for testing a circuit board includes: (a) applying a first current to a conductive pad of the circuit board, the conductive pad being connected to a pin of an IC; (b) ) Measure a first voltage at the conductive pad of the circuit board; (c) Apply a second current to the conductive pad of the circuit board; (d) Measure the conductive pad of the circuit board (E) divide (i) a difference between the first voltage and the second voltage by (ii) a difference between the first current and the second current to derive a first a resistor (R _esd + R _pr); and (f) from the first by resistor (R _esd + R _pr) minus a third resistor (R _esd) deriving a second resistor (R _pr), said first Three resistors ( _Resd ) are associated with a circuit electrically connected to the pins of the IC.

Aspects, features, and advantages of example embodiments of the present invention will be better understood with reference to the following description in conjunction with the accompanying drawings. It should be apparent to those skilled in the art that the described embodiments of the invention provided herein are illustrative and non-limiting, and are presented by way of example. All features disclosed in this specification may be replaced by alternative features serving the same or similar purpose, unless expressly stated otherwise. Therefore, a number of other embodiments of its modifications are intended to be within the scope of the invention as defined herein and the equivalents thereof. In addition, the use of absolute terms (such as "must" and "must not") with respect to some example embodiments is not meant to limit the scope of the invention, as the embodiments disclosed herein are performed by way of example. In addition, as used in this specification and the scope of the accompanying patent application, the singular forms "a" and "the" include singular and plural references unless the context of their use clearly indicates otherwise. Thus, for example, a reference to "one" input includes multiple inputs and a single input, and a reference to "one output" includes a single output and multiple outputs and the like. FIG. 1 illustrates a block diagram of a test system 1 according to some embodiments of the invention. The test system 1 includes a circuit 10 to be tested, a current supplier 11 and a test module 12. The current supplier 11 is connected to the circuit 10 to be tested so as to apply a current to the circuit, and thus obtains a voltage corresponding to the applied current. In one embodiment, the current supply 11 is a constant current source. The test module 12 is configured to receive a voltage corresponding to an applied current. The test module 12 includes a buffer 121, a subtracter 122 and a divider 123. The buffer 121 is configured to delay the input signal received from the buffer 121 and transmit the delayed signal to the subtractor 122. The subtracter 122 has two inputs to receive two signals and performs subtraction of signals received from the two inputs. The subtracter 122 is connected to the divider 123 to provide a difference between the two signals to the divider 123. In some embodiments, the buffer 121 may be integrated into the subtractor 122. Other components of the test module 12 may be combined or integrated together, or may be further subdivided. During operation, a first current I _{m1 is} applied to the circuit 10 to be tested to obtain a first voltage V _m1 . The first voltage V _{m1 is} then sent to the buffer 121 of the test module 12. A second different current I _{m2 is} applied to the circuit 10 to be tested to obtain a second voltage V _m2 , and the second voltage V _{m2 is} sent to the subtractor 122 of the test module 12. In some embodiments, I _m1 and I _m2 are substantially continuous. That is, when satisfied I _m2 = I _m1 + ΔI, where β is in the range between about 0.98 and 1, and ΔI is in the range between about 50 μA and about 500 μA (for example, the expression between currents is absolute Value difference). The subtracter 122 is configured from the first to the second voltage minus the voltage V _m1 V _m2 to derive a difference between the first voltage and the second voltage V _m1 V _m2. The difference between the first voltage V _m1 and the second voltage V _m2 is then divided by the divider 123 by the difference between the first current I _m1 and the second current I _m2 to derive the total resistance RL of the circuit 10 to be tested. Whether the circuit 10 to be tested works normally can be checked by comparing the total resistance RL of the circuit 10 to be tested with a predetermined reference resistance value. If the total resistance RL of the circuit 10 to be tested is substantially equal to the reference resistance value, the circuit 10 is determined to be normal; otherwise, the circuit 10 may be further inspected or checked. Alternatively or in combination, the total resistance RL of the circuit 10 may be compared with a threshold reference resistance value, and if the resistance RL is between 0 and a threshold value, this may indicate that the circuit 10 is normal. As shown in FIG. 1, the comparator 124 is included to perform a comparison of the total resistance RL of the circuit 10 with a reference value, and may include a display unit to provide a comparison result and a visual indication that the circuit 10 is normal (or abnormal). Although shown separately from the test module 12, the comparator 124 may be integrated into the test module 12. In some embodiments, the components of the test module 12 may be implemented in hardware using a suitable circuit board. FIG. 2 illustrates a block diagram of a test system 2 according to some embodiments of the invention. The test system 2 includes an IC 20 to be tested, a current supply 21, a voltage meter (voltmeter) 22, and a test module 23. The IC 20 includes an internal circuit 20A and a protection circuit 20B. In some embodiments, the internal circuit 20A may be a digital circuit, an analog circuit, a radio frequency (RF) circuit, a microelectromechanical system (MEMS), a mixed signal circuit, or a combination thereof. The protection circuit 20B includes a plurality of diodes. In some embodiments, the protection circuit 20B may further include a passive component such as a current limiting resistor, an active component such as a metal oxide semiconductor field effect transistor (MOSFET) or a bipolar junction transistor (BJT), or the like A combination. The IC 20 further includes a plurality of pins 201, 202, and 203. In some embodiments, the pin 201 is electrically connected to an external power source, and the pin 203 is electrically connected to an external ground source. The current supply 21 is connected to a pin 202 of the IC 20 for supplying a current to the pin, and a voltage corresponding to the applied current is measured by a voltmeter 22. During operation, the first current I _{m1 is} applied to the pin 202 of the IC 20, and the first voltage V _m1 is measured by the voltmeter 22. The relationship between the first voltage V _m1 and the first current I _m1 is shown as the following equation, where V _esd1 is the voltage measured by the diode 20B1 when the first current I _{m1 is} applied to the pin 202 of the IC 20 , And _Resd is the total resistance of the protection circuit 20B: (1) If the first voltage V _m1 is 0, the protection circuit 20B electrically connected to the pin 202 of the IC 20 is determined as a short-circuit connection. If the first voltage V _{m1 is} substantially equal to the (non-zero) protection voltage of the current supplier 21, the protection circuit 20B electrically connected to the pin 202 of the IC 20 is determined to be open. If the first voltage V _m1 is not equal to 0 or the protection voltage of the current supply 21, the second current I _{m2 is} then applied to the pin 202 of the IC 20, and the second voltage V _m2 is measured by the voltmeter 22. The relationship between the second voltage V _m2 and the second current I _m2 is shown as the following equation, where V _esd2 is the voltage measured by the diode 20B1 when the second current I _{m2 is} applied to the pin 202 of the IC 20 : (2) The following equation can be derived by subtracting equation (2) from equation (1): (3) The relationship between the voltage V _{esd of the} diode 20B1 and the current I _m applied to the diode 20B1 is shown as the following equation, where I _s is the reverse bias saturation current, V _T is the thermal voltage, and n is the ideality factor: (4) In some embodiments, when applied for about 1 mA of current I _m, diode 20B1 of the voltage V _esd of about 0.53 V (for a silicon diode), or about 0.18 V (for the germanium diode) . Alternatively, when a current I _{m of} about 100 mA is applied, the voltage V _esd of the diode 20B1 is about 0.65 V (for a silicon diode) or about 0.30 V (for a germanium diode). Based on the above, due to the nature of the diode 20B1, the voltage V _{esd of the} diode 20B1 does not change significantly even if the current I _m changes to a relatively large extent. By selecting a second current I _m2 that is close to the first current I _m1 , the second voltage V _esd2 will be substantially equal to the first voltage V _esd1 . In some embodiments, the difference between the first current I _m1 and the second current I _m2 is greater than about 300 μA. In other embodiments, the ratio of the first current I _m1 to the first voltage V _m1 is greater than about 1. In other embodiments, the ratio of the second current I _m2 to the second voltage V _m2 is greater than about 1. Therefore, equation (3) can be simplified as follows: (5) The test module 23 is connected to the current supply 21 and the voltmeter 22 to receive the applied current and the measured voltage. The total resistance _{Resd of the} protection circuit 20B can be determined by the test module 23 based on the applied first current I _m1 and the second current I _m2 and the measured first voltage V _m1 and the second current V _m2 . For example, if the resistance _{Resd is} determined to be 0 by the test module 23, this may indicate that the protection circuit 20B electrically connected to the pin 202 of the IC 20 is connected by a short circuit. In other embodiments, if the first voltage V _m1 is 0, this may also indicate that the protection circuit 20B is connected via a short circuit. For another example, if the resistance _{Resd is} higher than the threshold reference value, this may indicate that the protection circuit 20B electrically connected to the pin 202 of the IC 20 is disconnected. In other embodiments, if the first voltage V _{m1 is} higher than a threshold value, this may indicate that the protection circuit 20B is turned off. As another example, if the resistance _Resd is between 0 and a threshold value, this may indicate that the protection circuit 20B electrically connected to the pin 202 of the IC is good or normal. In some embodiments, the test module 23 may be implemented similarly to the test module 12 shown in FIG. 1. In some embodiments, the voltmeter 22 may be integrated into the module 23. Other components of the test system 2 may be combined or integrated together, or may be further subdivided. In some embodiments, the IC can be tested by measuring the voltage at the pins of the IC without supplying power to the IC. Once the measured voltage is between 0 and a threshold value, the IC is considered as Good or normal. However, this test method can have a relatively large tolerance. The functionality of the pin 202 of the IC 20 is determined by both the measured voltage of the protection circuit 20B and the total resistance _Resd . The test system 2 in FIG. 2 is shown to obtain higher accuracy and reliability. In some embodiments, the IC is powered and tested by in-circuit-test (ICT) equipment, and at least two test terminals or pads are designated on the ICT equipment for testing. The test system 2 shown in FIG. 2 which can specify only one pin, one terminal or one pad for testing can save cost and time. In addition, compared with non-measured values of R _esd ICT equipment, the test system shown in FIG. 22 to obtain the high accuracy and precision. FIG. 3 illustrates a block diagram of a test system 3 according to some embodiments of the invention. The test system 3 includes an IC 30 to be tested, a current supply 31, a voltmeter 32, a test module 33, and a carrier 34. The carrier 34 is formed of, for example, a printed circuit board (PCB), such as a paper-based copper foil laminate, a composite copper foil laminate, or a polymer-impregnated glass fiber-based copper foil laminate. The carrier 34 may have an electrical interconnect (not shown), such as a redistribution layer (RDL). The IC 30 is located on a carrier 34. The IC 30 includes an internal circuit 30A and a protection circuit 30B. In some embodiments, the internal circuit 30A may be a digital circuit, an analog circuit, an RF circuit, a MEMS, a mixed signal circuit, or a combination thereof. The protection circuit 30B includes a plurality of diodes. In some embodiments, the protection circuit 30B may further include a passive component (such as a resistor), an active component (such as a MOSFET or BJT), or a combination thereof. The IC 30 further includes a plurality of pins 301, 302, and 303 electrically connected to a conductive pad on the carrier 34. In some embodiments, the equivalent impedance 34A (including components bonded to the carrier) between the pin 302 of the IC 30 and the conductive pad 342 of the carrier 34 can be expressed as a resistor as shown in FIG. A circuit formed by R _pr , capacitor C _pr and inductor L _pr . The current supply 31 is connected to the conductive pad 342 of the carrier 34 for applying a current to the conductive pad, and a voltage corresponding to the applied current is measured by a voltmeter 32. During operation, the first current I _m1 is applied to the pin 302 of the IC 30 via the conductive pad 342, and the first voltage V _m1 is measured by the voltmeter 32. The current supplier 31 can apply direct current (DC), so that the effects of the capacitor C _pr and the inductor L _pr can be ignored. Therefore, the relationship between the first voltage V _m1 and the first current I _m1 is shown as the following equation, where V _esd1 is a diode 30B1 measured when the first current I _{m1 is} applied to the conductive pad 342 of the carrier 34 Voltage, and _Resd is the total resistance of the protection circuit 30B: (6) If the measured first voltage V _m1 is 0, the equivalent impedance 34A or the protection circuit 30B or both can be determined to be connected via a short circuit. If the measured first voltage V _{m1 is} substantially equal to the protection voltage of the current supplier 31, the equivalent impedance 34A or the protection circuit 30B or both can be determined as disconnected. If the measured first voltage V _m1 is not equal to 0 or the protection voltage of the current supplier 31, the second current I _{m2 is} then applied to the conductive pad 342 of the carrier 34, and the second voltage V _{m2 is passed} through the voltmeter 32. To measure. The relationship between the second voltage V _m2 and the second current I _m2 is shown as the following equation, where V _esd2 is the voltage of the diode 30B1 at the second current I _m2 : (7) The following equation can be derived by subtracting equation (6) from equation (7): (8) The relationship between the voltage V _{esd of the} diode 30B1 and the current I _m applied to the diode 30B1 is expressed by the equation (4) shown above. In some embodiments, when a current I _{m of} about 1 mA is applied, the voltage V _esd of the diode 30B1 is about 0.53 V (for a silicon diode) or about 0.18 V (for a germanium diode). Alternatively, when a current I _{m of} about 100 mA is applied, the voltage V _esd of the diode 30B1 is about 0.65 V (for a silicon diode) or about 0.30 V (for a germanium diode). Based on the above, due to the nature of the diode 30B1, the voltage V _{esd of the} diode 30B1 does not change significantly even if the current I _m changes to a relatively large extent. By selecting a second current I _m2 that is close to the first current I _m1 , the second voltage V _esd2 will be substantially equal to the first voltage V _esd1 . In some embodiments, the difference between the first current I _m1 and the second current I _m2 is greater than about 300 μA. In other embodiments, the ratio of the first current I _m1 to the first voltage V _m1 is greater than about 1. In other embodiments, the ratio of the second current I _m2 to the second voltage V _m2 is greater than about 1. Therefore, equation (8) can be simplified as follows: (9) The test module 33 is connected to the current supplier 31 and the voltmeter 32 to receive the applied current and the measured voltage. The sum of the resistance R _{esd of the} protection circuit 30B and the resistance R _pr between the conductive pad 342 of the carrier 34 and the pin 302 can be determined by the test module 23 based on the applied first current I _m1 and the second current I _m2 and The measured first voltage V _m1 and second voltage V _m2 are calculated. Since the resistance R _{esd of the} protection circuit 30B can be calculated by the test system 2 shown in FIG. 2, the resistance R _pr can be obtained by subtracting the resistance R _esd from the sum of the resistance R _esd and the resistance R _pr . If the resistance R _{pr is} substantially equal to the predetermined reference value of the resistance of the carrier 34, the component on the carrier 34 (between the conductive pad 342 and the pin 302) can be judged as good or normal; otherwise, the component on the carrier 34 can be judged Is failed or pending further testing or replacement. In some embodiments, the test module 33 may be implemented similarly to the test module 12 shown in FIG. 1. In some embodiments, the voltmeter 32 may be integrated into the module 33. Other components of the test system 3 may be combined or integrated together, or may be further subdivided. In some embodiments, whether the components on the carrier 34 are functioning normally is determined by checking the measured voltage without calculating the resistance R _pr of the carrier 34. Compared with these embodiments, the test system 3 of the resistance R _pr of the comparison carrier 34 and the reference resistance shown in FIG. 3 obtains higher accuracy and reliability. In addition, it is unnecessary to switch on the IC 30 or power the IC for functional inspection by using the test system 3 shown in FIG. 3, which can reduce the time and cost for testing the carrier 34. In some embodiments, the resistance R _{pr of the} carrier 34 may be measured by an ICT device that specifies the connection to two nodes of the carrier 34 for measurement. Compared with using ICT, the test system 3 in FIG. 3 can obtain the resistance R _{pr of the} carrier 34 by connecting to only one node, which can reduce the time and cost for testing the carrier 34. FIG. 4 illustrates a flowchart of operations for testing an IC according to some embodiments of the invention. Referring to operation S41, a first current I _{m1 is} applied to the pins of the IC to be tested. In some embodiments, the first current I _m1 may be applied by a current supplier. Referring to operation S42, a first voltage V _m1 corresponding to the applied first current I _m1 is measured at the pins of the IC. In some embodiments, the first voltage V _m1 can be measured by a voltmeter. Referring to operation S43, the first voltage V _m1 is checked to determine whether the first voltage V _m1 is equal to 0 or the protection voltage of the current supplier. If the first voltage V _m1 is equal to 0, the circuit electrically connected to the pins of the IC is determined to be short-circuited. If the first voltage V _{m1 is} substantially equal to the protection voltage of the current supplier, the circuit electrically connected to the pins of the IC is determined to be open. Referring to operation S44, if the first voltage V _m1 is not equal to 0 or the protection voltage of the current supplier, a second current I _{m2 is} applied to the pins of the IC to obtain a second voltage V corresponding to the applied second current I _{m2 m2} . In some embodiments, the difference between the first current I _m1 and the second current I _m2 is greater than about 300 μA. In other embodiments, the ratio of the first current I _m1 to the first voltage V _m1 is greater than about 1. In other embodiments, the ratio of the second current I _m2 to the second voltage V _m2 is greater than about 1. Referring to operation S45, the resistance R _esd of the protection circuit of the IC is calculated by the equation (5) shown above. Referring to operation S46, the resistance _{Resd is} compared with a predetermined threshold to check the functionality of the pins of the IC. If the resistance _{Resd is} determined to be 0, the circuit electrically connected to the pins of the IC is determined to be short-circuited, and if the resistance _{Resd is} higher than a threshold value, the circuit electrically connected to the pins of the IC is determined to be open; Otherwise, the circuit of the pin of the IC to which it is electrically connected is judged to be normal. In other embodiments, if the first voltage V _m1 is 0, this may also indicate that the circuit electrically connected to the pins of the IC is connected via a short circuit, and if the first voltage V _{m1 is} higher than a threshold value, this may indicate The circuit was opened. In some embodiments, whether the pins of the IC are functioning properly is determined by checking the measured voltage without calculating the total resistance of the protection circuit. Compared with these embodiments, the functionality of the pins of the IC determined by both the measured voltage and the resistance R _{esd of the} protection circuit is shown in the test operation in FIG. 4 to provide higher accuracy and reliability. In addition, it may be unnecessary to turn on the IC or power the IC for a functional check, which can reduce the time and cost for testing the IC. FIG. 5 illustrates a flowchart of an operation for testing a circuit board (or other carrier) on which an IC is positioned according to some embodiments of the present invention. Referring to operation S51, a first current I _{m1 is} applied to a conductive pad of a circuit board connected to a pin of the IC. In some embodiments, the first current I _m1 may be applied by a current supplier. A first voltage V _m1 corresponding to the applied first current I _m1 is measured at the conductive pad of the circuit board. In some embodiments, the first voltage V _m1 can be measured by a voltmeter. Referring to operation S52, a second current I _{m2 is} applied to the conductive pad of the circuit board. A second voltage V _m2 corresponding to the applied second current I _m2 is measured at the conductive pad of the circuit board. Referring to operation S53, the total resistance R _pr between the conductive pad of the circuit board and the pins of the IC and the resistance R _esd of the protection circuit of the IC are calculated by the equation (9) shown above. Since the resistance R _esd of the protection circuit of the IC can be calculated by the operation shown in FIG. 4, the resistance R _pr can be obtained by subtracting the resistance R _esd from the sum of the resistance R _esd and the resistance R _pr . Referring to operation S54, the resistance R _{pr is} compared with a predetermined reference value of the resistance of the circuit board. If the resistance R _{pr is} substantially equal to the reference value of the resistance of the circuit board, the components on the circuit board are judged to be good or normal; otherwise, the components on the circuit board are judged to fail the test or will be further tested or replaced. In some embodiments, whether the conductive pad of the circuit board is functioning properly is determined by checking the measured voltage without calculating the total resistance of the circuit board. Compared with these embodiments, the calculated resistance of the comparison circuit board and the reference resistance are shown in the test operation in FIG. 5 to obtain higher accuracy and reliability. In addition, it may be unnecessary to turn on the IC or power the IC for functional testing by using the test operation shown in FIG. 5, which can reduce the time and cost for testing the circuit board. In some embodiments, the resistance R _{pr of the} circuit board can be measured by ICT equipment, which is assigned to the connection of two nodes of the circuit board for measurement. Compared with using ICT, the test operation in FIG. 5 can obtain the resistance R _{pr of the} circuit board by connecting to only one node, which can reduce the time and cost for testing the circuit board. As used herein, the terms "substantially", "substantially", "about" and "about" are used to describe and take into account small changes. When used in conjunction with an event or situation, the terms "substantially", "substantially", "approximately" and "approximately" may refer to situations in which the event or situation occurs precisely and situations in which the event or situation occurs approximately. For example, when used in conjunction with a numerical value, the term may cover a range of variation that is less than or equal to ± 10% of the value, such as less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± 3%, less than or A range of variation equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%. For example, when comparing the first value with the second reference value, if the first value is less than or equal to ± 10% of the second value, such as less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± Within the range of 3%, less than or equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%, the first value can be considered as "Substantially" is equal to or the same as the second value. In addition, quantities, ratios, and other numerical values are sometimes presented in a range format herein. Understandably, such a range format is for convenience and brevity, and should be flexibly understood not only to include values explicitly specified as range limits, but also to include all individual values or subranges covered by the range, as explicitly specified Each value and subrange is average. Although the invention has been described and illustrated with reference to specific embodiments thereof, these descriptions and illustrations do not limit the invention. Those skilled in the art will clearly understand that various changes can be made, and equivalent elements can be replaced in the embodiments without departing from the true spirit and scope of the present invention as defined by the scope of the attached patent application. Instructions need not be drawn to scale. Due to variables in the manufacturing process and the like, there may be a difference between the artistic reproduction in the present invention and the actual device. There may be other embodiments of the present invention that are not specifically described. This specification and drawings are to be regarded as illustrative rather than restrictive. Modifications may be made to adapt a particular situation, material, material composition, method, or process to the objectives, spirit, and scope of the present invention. All such modifications are intended to be within the scope of the patentable applications attached hereto. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it is understood that such operations may be combined, subdivided, or reordered to form an equivalent without departing from the teachings of the present invention method. Therefore, unless specifically indicated herein, the order and grouping of operations is not a limitation of the present invention.

1‧‧‧test system

2‧‧‧test system

3‧‧‧test system

10‧‧‧Circuit to be tested

11‧‧‧Current Supply

12‧‧‧test module

20‧‧‧Integrated Circuit (IC) to be tested

20A‧‧‧Internal circuit

20B‧‧‧Protection circuit

20B1‧‧‧Diode

21‧‧‧Current Supply

22‧‧‧Voltmeter

23‧‧‧test module

30‧‧‧Integrated Circuit (IC) to be tested

30A‧‧‧Internal circuit

30B‧‧‧Protection circuit

30B1‧‧‧diode

31‧‧‧Current Supply

32‧‧‧Voltmeter

33‧‧‧Test Module

34‧‧‧ carrier

34A‧‧‧ equivalent impedance

121‧‧‧Buffer

122‧‧‧Subtractor

123‧‧‧Divider

124‧‧‧ Comparator

201‧‧‧pin

202‧‧‧pin

203‧‧‧pin

301‧‧‧pin

302‧‧‧pin

303‧‧‧pin

342‧‧‧Conductive gasket

R _pr ‧‧‧ resistor

C _pr ‧‧‧capacitor

L _pr ‧‧‧ inductor

FIG. 1 illustrates a block diagram of a test system according to some embodiments of the invention. Figure 2 illustrates a test system according to some embodiments of the invention. Figure 3 illustrates a test system according to some embodiments of the invention. FIG. 4 illustrates a flowchart of operations for testing an IC according to some embodiments of the invention. FIG. 5 illustrates a flowchart for operation of a test circuit board according to some embodiments of the invention. Common reference numbers are used throughout the drawings and the embodiments to indicate the same or similar components. The invention will be more apparent from the following embodiments in conjunction with the accompanying drawings.

Claims (23)

A test system includes: a subtractor configured to receive a first voltage of a circuit being tested and a second voltage of the circuit, and derive a voltage between the first voltage and the second voltage A difference; and a divider configured to receive the difference between the first voltage and the second voltage, and by (i) the difference between the first voltage and the second voltage Divide by (ii) a difference between a first current applied to the circuit and a second current applied to the circuit to derive a resistance of the circuit, where the first voltage corresponds to the first current, and The second voltage corresponds to the second current. The test system of claim 1, further comprising a current source configured to apply the first current and the second current, and wherein a difference between the first current and the second current is It is in a range of about 50 μA to about 500 μA. The test system of claim 1, further comprising a current source configured to apply the first current and the second current, and wherein a ratio of the second voltage to the second current is given The ratio of one of the first voltage to the first current is multiplied by β, and β is in a range of about 0.98 and about 1. The test system of claim 1, further comprising a current source configured to apply the first current and the second current to a pin of an integrated circuit (IC) being tested, and wherein The first voltage corresponding to the first current is obtained at the pin of the IC, and the second voltage corresponding to the second current is obtained at the pin of the IC. The test system of claim 1, further comprising a comparator configured to determine that the circuit is short-circuited when the resistance is zero. The test system of claim 1, further comprising a comparator configured to determine that the circuit is disconnected if the resistance is above a threshold value. The test system of claim 1, further comprising a comparator configured to determine that the circuit is normal if the resistance is substantially equal to a reference value. The test system of claim 1, further comprising a current source configured to apply the first current and the second current to a conductive pad of a circuit board being tested, and which corresponds to The first voltage of the first current is obtained at the conductive pad of the circuit board, and the second voltage corresponding to the second current is obtained at the conductive pad of the circuit board. The test system of claim 1, wherein the circuit further includes a protection circuit, and the resistor is a resistance of the protection circuit. A method for testing an integrated circuit (IC), comprising: (a) applying a first current to a pin of the IC; (b) measuring a first voltage at the pin of the IC; ( c) applying a second current to the pin of the IC; (d) measuring a second voltage at the pin of the IC; and (e) combining (i) the first voltage and the second voltage A difference between is divided by (ii) a difference between the first current and the second current to derive a resistance of the IC, wherein a ratio of the second voltage to the second current is given as the first A ratio of a voltage to one of the first currents is multiplied by β, and β is in a range of about 0.98 to about 1. The method of claim 10, wherein a difference between the first current and the second current is in a range of about 50 μA to about 500 μA. The method of claim 10, wherein in operation (b), if the first voltage is 0, one of the pins electrically connected to the IC is determined to be short-circuited. The method as claimed in claim 10, wherein in operation (b), if the first voltage is substantially equal to a protection voltage of a current supplier to which the first current is applied, then one of the pins of the IC is electrically connected. The circuit is judged to be open. The method of claim 10, wherein in operation (e), if the resistance is 0, one of the pins electrically connected to the IC is determined to be short-circuited. The method of claim 10, wherein in operation (e), if the resistance is higher than a threshold value, a circuit electrically connected to the pin of the IC is determined to be disconnected. The method of claim 10, wherein the IC further includes a protection circuit, and the resistor is a resistance of the protection circuit. A method of testing a circuit board including an integrated circuit (IC) includes: (a) applying a first current to a conductive pad of the circuit board, the conductive pad being connected to a pin of the IC (B) measuring a first voltage at the conductive pad of the circuit board; (c) applying a second current to the conductive pad of the circuit board; (d) the conductive pad of the circuit board Measure a second voltage at the pad; (e) divide (i) a difference between the first voltage and the second voltage by (ii) a difference between the first current and the second current To derive a first resistance (R _esd + R _pr ); and (f) to derive a second resistance (R) by subtracting a third resistance (R _esd ) from the first resistance ( _Resd + R _pr ) _pr ), the third resistor ( _Resd ) is associated with a circuit electrically connected to the pin of the IC. The method of claim 17, wherein a ratio of the second voltage to the second current is given as a ratio of the first voltage to the first current multiplied by β, and β is between about 0.98 and about 1. Within range. The method of claim 17, further comprising deriving the third resistor by: (g) applying a third current to the pin of the IC; (h) measuring a pin at the pin of the IC A third voltage; (i) applying a fourth current to the pin of the IC; (j) measuring a fourth voltage at the pin of the IC; and (k) comparing the third voltage with the first voltage A difference between the four voltages is divided by a difference between the third current and the fourth current. The method of claim 19, wherein a difference between the third current and the fourth current is in a range between about 50 μA and about 500 μA. The method of claim 17, further comprising comparing the second resistor to a reference resistor of the circuit board. The method of claim 21, further comprising: if the second resistance is substantially equal to the reference resistance, determining that the circuit board is normal; otherwise, determining that the circuit board is abnormal. The method of claim 21, wherein the IC further includes a protection circuit, and the third resistor is a resistance of the protection circuit.