JPH0374857A - Method and device for inspection of bonding state between lsi terminal and substrate - Google Patents

Abstract

PURPOSE:To clarify judgment standard and to perform judgment in a short time by measuring reaction operated between a contact and a terminal and the size of deformation of the terminal for judging whether bonding of the terminal is appropriate or not. CONSTITUTION:The tip of a contactor 5 is applied to the outer-side surface of the terminal which is vertical to a substrate 2 of a terminal 3 of an LSI and an up/down and left/right feed means of traveling means is adjusted so that the change in resistance of a strain gauge 7 reaches a value near the minimum value showing a positive bonding state. After that, a forward/backward traveling mechanism is used for traveling by the amount of pitch of the terminal 3, thus measuring the output corresponding to the resistance of the gauge 7 for each traveling. Being based on the result, it is possible to judge whether bonding state is appropriate or not. That is, if it is appropriate, the state of a cantilever appears and it can be easily bent as compared with rigidity for force from the side surface of a center lever.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for inspecting the bonding state between an LSI terminal and a substrate.

2. Description of the Related Art Recent LSIs have become more integrated, and the number of terminals (pins) has increased significantly. At the same time, the circuits on the boards to which they are attached are also complex and expensive. Furthermore, as automatic assembly is progressing, there is an increasing need for equipment that can accurately and quickly inspect whether LSIs are electrically and mechanically bonded to the substrate sufficiently.

As this type of inspection method, the following methods (,) to (d) are conventionally known.

(,) Method using an ultrasonic microscope (b) Method of image processing using an optical system (c) Method of inspecting electrical resistance (d) Method of checking operation Problems to be solved by the invention However, the above-mentioned ( , ) to (d) have the following problems.

(,) Method using an ultrasonic microscope It is possible to examine the condition of an object without destroying it by focusing the ultrasonic microscope on a certain depth inside an LSI, but it is possible to investigate the condition of an object without destroying it, but it is possible to examine the state of an object without destroying it, but it is possible to examine the state of an object without destroying it by focusing the ultrasonic microscope on a certain depth inside an LSI. When bonding is performed within a certain range in the horizontal direction, measurement 1
This process takes a long time, and the criteria for judgment are not clear.

(b) Method of image processing using an optical system The distance between an LSI terminal and surrounding components may be 1 to 21 mm, making it difficult to use a high-performance, thin optical probe. Image processing also takes time. Further, even if the terminal and the board are visually in contact with each other, the bonding may be defective.

(c) Method of testing electrical resistance The condition of contact between each terminal and the corresponding wiring on the board side can be checked by measuring the electrical resistance, but even if the bonding is poor, low resistance can be tested by connecting another terminal or wiring. This method is unsuitable.

(d) Method of checking operation Once one LSI is installed on a board, it is possible to check the operation of the board, including the circuits on the board, to find defects, but it is necessary to develop an operation check program for each board. There is a need. Mainly, there are a huge number of combinations of relationships between people and output, and it takes a long time to check them all.

The present invention aims to solve the above-mentioned problems by measuring the quantitative strength of each terminal of an LSI after bonding and determining whether the bonding is good or bad. .

First, the present invention will be explained in detail.

In Figure 2, which shows an enlarged view of the state of bonding between one of the LSI terminals and the board, 1 is the LSI main body, 2 is the board,
3 is a terminal of the LSI, and 4 is a hang for chemically and mechanically bonding the terminal and the board.

If the solder 4 is not sufficient in quantity or if it is not sufficiently bonded to the terminal 3 through a chemical reaction, the terminal 3 will have significantly different quantitative properties compared to when the bonding is complete. Become something.

FIG. 3 shows a simplified mechanical model of each terminal in good and bad bonding states. If the bonding is perfect, it can be regarded as a double-sided beam (,), and if it is defective, it can be regarded as a cantilever beam (b). The ratio of stiffness to side forces for double-sided and cantilever beams is 8 to 1 in the center of the beam, and terminals with poor bonding are mechanically much more prone to bending. The quality of the bonding is determined based on the difference between the two.

That is, the first invention of the present invention is an invention of a method, in which one or more contacts are brought into contact with the terminals of an LSI, either sequentially or simultaneously, and the reaction between the contacts and the terminals at that time is controlled. The quality of the bonding between the terminal and the substrate is determined by directly or indirectly measuring the magnitude of force or displacement of the terminal.

A second invention of the present invention relates to an apparatus for carrying out the method of the first invention, which comprises a contact and a sensor that detects reaction force or deformation of the contact.

Although the reaction force or deformation of the contactor itself is detected in the above description, the same effect can be achieved even if the sensor is omitted and the displacement of the LSI terminal itself is detected.

When a contact is brought into contact with an LSI terminal, action and reaction force and displacement occur on the contact according to the bonding state, and by detecting either of the action or reaction force or displacement with a sensor,
Based on the detection output, it is determined whether the bonding is good or not.

Further, the same effect can be obtained even if the displacement of the terminal of the LSI is detected instead of the reaction force or displacement of the contactor.

Embodiment In FIG. 1, the LSI main body 1, substrate 2, LSI terminal 3, and solder 4, which are given the same numbers as in FIG. 2, are the same as those in FIG. This is for inspecting the quality of the bonding state with the terminal 3, and is indicated by the number 10 in FIG. The inspection device 1
01, 5 is a rod-shaped contact having a convex portion at its tip, the base of which is fixed to a support 6, hangs down from above to the substrate 2, and is held substantially parallel to the terminal 3. ing. Reference numeral 7 denotes a strain gauge attached to the contact 5, and a resistance value that changes in accordance with the displacement of the contact 5 is converted into an electrical output and taken out via a processing section (not shown). The above is the inspection device 10, and its support body 6 is coupled to a moving means consisting of a vertical moving mechanism consisting of a small air cylinder (not shown) and a forward/backward (orthogonal to the paper plane) and left/right direction feeding mechanism using a ball screw. , can be moved forward, backward, left and right.

In the above configuration, the tip of the contact 5 comes into contact with the outer surface of the terminal 3 of the LSI, which is perpendicular to the substrate 2, and the resistance change of the strain gauge 7 reaches a predetermined value (near the minimum value indicating a reliable bonding state). ), the vertical and horizontal feeding mechanisms of the moving means are adjusted upward, and then the forward and backward moving mechanism moves the terminal 3 by the pitch, and each movement corresponds to the resistance value of the strain gauge. The output is measured, and based on the result, it is determined whether the bonding state is good or bad.

In the above embodiment, the case where one contactor 5 is used is illustrated, but it is also possible to use a plurality of contacts and simultaneously determine the bonding state of a plurality of terminals.

Further, the contactors 5 may be provided in the same number as the terminals on each of the four sides of the LSI so that they are brought into contact with each terminal at the same time by lowering the vertical movement mechanism.

In addition, in the above embodiment, a strain gauge was used to detect the reaction force and displacement of the contact, but
The same effect can be achieved by fixing the contact to the support portion via a force sensor (7-inch sensor), and any known sensor may be used as appropriate for this type of sensor.

Further, in the above embodiment, the reaction force and displacement of the contact are detected, but the same effect can be obtained by determining the displacement of the terminal itself due to the contact of the contact. Optical (for example, detecting changes in light-transmitting area due to terminal displacement, etc.), electrical, and mechanical methods may be used.

Further, in the above embodiments, the contactor is moved by a moving means, but the same effect can be achieved by moving the support side of the substrate, or the moving means may be omitted and the contactor may be moved manually.

The effects of the invention are as described above, and the present invention determines whether the bonding of a terminal is good or bad by directly or indirectly measuring the reaction force acting between a contactor and the terminal or the magnitude of deformation of the terminal. Therefore, the criteria for determination are clear and determination can be made in a short time.

Further, since a mechanical external force is applied to determine a state where the terminal and the board are in contact but not chemically bonded, this state can also be reliably detected as a contact failure.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is a front view showing a bonding state between an LSI terminal as an object to be inspected and a board, and FIG. 3 is a model diagram showing whether the bonding state is good or bad. 5: Contact 6: Support 7: Strain gauge second skin (α) (b)

Claims (1)

[Claims] 1. One or more contacts are brought into contact with the terminals of an LSI, either sequentially or simultaneously, and the reaction force acting between the contacts and the terminals at that time or the magnitude of the displacement of the terminals is directly measured. Further, there is a method for inspecting the bonding state between an LSI terminal and a board, which determines whether the bonding between the terminal and the board is good or bad by almost indirect measurement. 2. A device for inspecting the bonding state between an LSI terminal and a board, which comprises a contact and a sensor that detects reaction force or deformation of the contact. 3. A device for detecting the bonding state between an LSI terminal and a board, which comprises a contact and a means for detecting deformation of an LSI terminal that comes into contact with the contact.