KR100285624B1 - How to measure connection resistance of conductive balls - Google Patents

Abstract

The present invention relates to a method for measuring the connection resistance of a conductive ball that can accurately measure the connection resistance of the conductive ball.

The method of measuring connection resistance of a conductive ball according to an exemplary embodiment of the present invention includes forming a dummy pad on a lower plate glass to be connected to a first pattern, and a tape carrier package connected to the second pattern to be connected to a second pattern. Forming a contact hole on the wiring, and measuring a connection resistance between the first pattern and the second pattern connected with the anisotropic conductive film interposed between the dummy pad and the contact hole.

Accordingly, the method of measuring the connection resistance of the conductive ball according to the present invention ensures the reliability of the conductive ball crimping state and shortens the connection resistance measurement time.

Description

How to measure connection resistance of conductive balls

The present invention relates to a connection resistance measurement method, and more particularly to a connection resistance measurement method of a conductive ball that can accurately measure the connection resistance of the conductive ball.

In recent years, liquid crystal display panels (hereinafter referred to as "LCDs") have been improved in quality due to improvements in liquid crystal materials and development of fine pixel processing technology, along with features such as light weight, thinness, and low power consumption. In addition, the application range is gradually increasing. On the other hand, the LCD is composed of a liquid crystal panel and a driving circuit portion for driving the liquid crystal panel. The liquid crystal panel is arranged in a matrix form between two glass substrates (ie, upper glass and lower glass), but switch elements (ie TFT arrays) for switching between the liquid crystal cells and the signals supplied to these liquid crystal cells, respectively. It consists of. The driving circuit unit is mounted on a printed circuit board (hereinafter referred to as "PCB") to drive the liquid crystal panel. At this time, TCP (Tape Carrier Package) is used for signal transmission between the liquid crystal panel and PCB, and anisotropic conductive film (hereinafter referred to as `` PCB '') is used for the bottom glass and the printed circuit board (hereinafter referred to as `` PCB ''). Anisotropic Conductive Film (hereinafter referred to as " ACF ") may be directly attached using a conductive resin. In this case, a conductive ball having conductivity is incorporated in the ACF. When the TCP is pressed at a predetermined pressure so as to be attached to the attachment site (ie, the contact plate between the TCP and the bottom glass or the TCP and the PCB), the conductive ball embedded in the ACF is pressed to maintain the conductivity at the attachment site. At this time, since the resistance value changes according to the state in which the conductive ball is pressed, the conductive ball determines the crimped state of the attachment part by measuring the resistance value.

Referring to FIG. 1, there is shown a diagram for explaining a method of measuring a connection resistance of a conductive ball according to the prior art. The contact resistance of the conductive ball is measured by measuring the resistance between the first pattern 8a formed in the pad region of the lower plate glass 2 and the second and third patterns 8b and 8c formed in the TCP 12. . At this time, between the first pattern 8a and the second pattern 8b, the conductive balls 14 are pressed and attached as shown in FIG. 3. When two probes connected to the micro ohmmeter 18 are connected to the fourth and fifth patterns 8d and 8e and the resistance value is measured, the first pattern 8a is a metal resistor. RM ″, and the second and third patterns 8b and 8c have a TCP resistance (hereinafter referred to as “RT”). In addition, an ACF resistor (hereinafter referred to as "RA") has a value between the first and second patterns 8a and 8b and between the first and third patterns 8a and 8c.

The first pattern 8a and the conductive ball 14 will be described with reference to FIG. 3 (a) and FIG. 3 (b).

A transparent electrode (Indium Tin Oxide (hereinafter referred to as " ITO " or less) " ITO ")) is coated on the first pattern 8a. The conductive ball 14 is positioned on the transparent electrode 16 to compress the conductivity. Have.

Such connection patterns on the patterns 8b and 8c on the TCP and the bottom glass 2 may be represented by an equivalent circuit as shown in FIG. In the micro ohmmeter 18, the resistance value RT of the second pattern 8b, the resistance value RA of the conductive ball, the resistance value RM of the first pattern 8a, and the resistance value of the conductive ball 14 are shown. The series resistance value of the resistance value RT of the RA and the third pattern 8c is represented. In practice, the resistance value measured in the micro ohmmeter 18 is expressed by Equation 1 below. At this time, when the resistance value of the first pattern 8a is measured, the resistance value of the ITO 16 is actually measured.

[Equation 1]

Here, RT means TCP resistance value, RA means ACF resistance value, RM means metal resistance value, and RA means resistance value of the conductive ball 14 built in ACF. As can be seen from Equation 1, not only the connection resistance of the first pattern 8a can be determined from the total resistance measured by the micro ohmmeter 18, but also the accurate connection resistance of the conductive balls 14 can be measured. Since it becomes impossible, it is difficult to evaluate an exact crimp state, and it is difficult to trust a crimp state.

In addition, since the connection resistance is measured while the liquid crystal panel is turned upside down, it is difficult to cope with the increase in size of the liquid crystal panel, and the measurement port cannot be easily found, thereby increasing the connection resistance measurement time.

Accordingly, it is an object of the present invention to provide a method for measuring the connection resistance of a conductive ball that can accurately measure the connection resistance of the conductive ball.

1 is a view for explaining a method for measuring the connection resistance of the conductive ball according to the prior art.

2 shows the equivalent circuit of FIG.

FIG. 3 (a) is an enlarged plan view of a portion where the first pattern is located in FIG.

FIG. 3 (b) is a cross-sectional view taken along the line BB ′ of FIG. 3 (a).

4 is a view for explaining a method of measuring the connection resistance of the conductive ball according to an embodiment of the present invention.

FIG. 5 shows an equivalent circuit of FIG. 4. FIG.

6 is a view for explaining a method of measuring the connection resistance of the conductive ball according to another embodiment of the present invention.

FIG. 7 shows an equivalent circuit of FIG. 6. FIG.

* Explanation of symbols for main parts of the drawings

2,22: Lower glass 6,26: Upper glass

8: pad 10,30: wiring

12,32: TCP 36: Contact hole

In order to achieve the above object, the connection resistance measurement method of the conductive ball according to an embodiment of the present invention is to form a dummy pad on the lower plate glass to be connected to the first pattern, and the second pattern to be connected to the second pattern Forming a contact hole on the wiring of the tape carrier package connected to the pattern, and measuring a connection resistance between the first pattern and the second pattern connected with the anisotropic conductive film interposed between the dummy pad and the contact hole It includes.

In addition, the method of measuring the connection resistance of the conductive ball according to another embodiment of the present invention is the step of forming the first and second dummy pad on the bottom glass to be connected to the first pattern, and the second to be connected to the second pattern Forming a first and a second contact hole in each of the wires of the tape carrier package connected to the pattern, applying a current signal to the first dummy pad and the first contact hole, as well as the second dummy pad and the second contact hole. And applying a voltage signal thereto to measure a connection resistance between the first pattern and the second pattern connected with the anisotropic conductive film therebetween.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

A preferred embodiment of the present invention will be described with reference to FIGS. 4 to 7.

Referring to FIG. 4, there is shown a diagram for explaining a method of measuring a connection resistance of a conductive ball according to an embodiment of the present invention. In order to measure the connection resistance of the conductive ball, a first pattern 28a and a dummy pad 38 connected to the first pattern 28a are formed in the pad region of the lower glass 22, and the TCP 32 The second pattern 28b and the contact hole 36 connected to the second pattern 28b are formed. At this time, the conductive ball 14 is pressed and attached between the first pattern 28a and the second pattern 28b. Here, two probes connected to the micro ohmmeter 18 are connected to the contact pads 36 connected to the dummy pad 38 and the second pattern 28b as shown in FIG. 5 to measure resistance values. When the first pattern 28a has a resistance value RM, the second pattern has a resistance value RT. In addition, the conductive balls compressed between the first and second patterns 28a and 28b have a resistance value RA.

In the micro ohmmeter 18, as shown in FIG. 5, the resistance value RT of the second pattern, the resistance value RA of the conductive ball, and the resistance value RM of the first pattern are represented as series resistance values. The resistance value measured by the micro ohmmeter 18 is shown in equation (2).

[Equation 2]

In this case, since the metal resistance value RM and the TCP resistance RT of the first pattern 28a can be known in advance, the RA value can be known by inputting a known resistance value in the overall connection resistance. As a result, it is possible to accurately obtain the resistance value of the conductive ball only to know the crimped state of the lower plate glass 22 and the TCP 32, thereby ensuring the reliability of the crimped state. If the resistance RA of the conductive ball 14 is known in advance, the TCP resistance RT is usually less than 1 Ω, so that the metal resistance value RM of the first pattern 28a can be known. In addition, according to the method of measuring the connection resistance of the conductive ball according to the present invention, by forming the dummy pad 38 and the contact hole 36, the connection resistance can be measured from the upper portion of the liquid crystal panel, thereby coping with the enlargement of the liquid crystal panel. In addition, the contact resistance can be easily measured, and the measurement port can be easily found, thereby reducing the measurement time.

Referring to FIG. 6, there is shown a diagram for explaining a method of measuring connection resistance of a conductive ball according to another exemplary embodiment of the present invention. In order to measure the connection resistance of the conductive balls 14, the pad region of the lower glass 22 has a first pattern 28a and first and second dummy pads 38a and 38b connected to the first pattern 28a. The second pattern 28b and the first and second contact holes 36a and 36b connected to the second pattern 28b are formed in the TCP 32. At this time, the conductive ball 14 is pressed and attached between the first pattern 28a and the second pattern 28b. Here, of the four probes connected to the micro ohmmeter 18, two probes to which voltage and current are respectively supplied are connected to the first and second dummy pads 38a and 38b, respectively, and the remaining voltage The connection resistance is measured by connecting two probes supplied with overcurrent to the first and second contact holes 36a and 36b, respectively. The equivalent circuit at this time is shown in FIG.

The equivalent circuit of FIG. 6 includes a resistor RT connected between the current source I and the first node n1, a resistor RT connected between the first node n1 and the voltage source V, and a current source ( A resistor RM connected between I) and the second node n2, a resistor RM connected between the voltage source V and the second node n1, a first node n1 and a second node. It consists of a resistor RM connected between (n2). As can be seen from this equivalent circuit, the resistance value measured by the micro ohmmeter 18 appears to be equal to the ACF resistance value RA of the conductive ball 14.

[Equation 3]

Therefore, since the measured value indicated by the micro ohmmeter 18 accurately knows the resistance of the conductive ball 14, that is, the ACF resistance value RA, the compressed state between the lower pane 22 and the TCP 32 or You can see the connection status. In addition, by forming the dummy pad 38 and the contact hole 36, the connection resistance can be measured from the upper portion of the liquid crystal panel, so that the connection resistance can be easily measured and easily measured in response to the enlargement of the liquid crystal panel. The port can be found, reducing the measurement time.

As described above, the method of measuring the connection resistance of the conductive ball according to the present invention has the advantage of accurately measuring the connection resistance of the conductive ball to ensure the reliability of the crimped state and to facilitate the measurement of the connection resistance. have.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (2)

A resistance of a liquid crystal display device comprising a tape carrier package having a lower plate glass on which a first pattern having a metal resistance is formed and a second pattern connected to the first pattern on the lower plate glass with an anisotropic conductive film including a conductive ball therebetween. In the measuring method, forming a dummy pad on the lower glass to be connected to the first pattern, and a contact hole on the wiring of the tape carrier package connected to the second pattern to be connected to the second pattern And measuring connection resistance between the first pattern and the second pattern connected with the anisotropic conductive film interposed between the dummy pad and the contact hole. How to measure connection resistance A resistance of a liquid crystal display device comprising a tape carrier package having a lower plate glass on which a first pattern having a metal resistance is formed and a second pattern connected to the first pattern on the lower plate glass with an anisotropic conductive film including a conductive ball therebetween. A measuring method, comprising: forming first and second dummy pads on the lower glass to be connected to the first pattern, and forming the tape carrier package connected to the second pattern to be connected to the second pattern. Forming first and second contact holes in each of the wirings, applying a current signal to the first dummy pad and the first contact hole, and applying a voltage signal to the second dummy pad and the second contact hole, respectively. Measuring connection resistance between the first pattern and the second pattern connected with the anisotropic conductive film interposed therebetween.