JP2009250761A - Substrate connection inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate connection inspection apparatus for inspecting in a short time connections between a semiconductor device and a mounting substrate mounted with the semiconductor device, and for detecting a defective article. <P>SOLUTION: The substrate connection inspection apparatus 1 includes a probe section 7 wherein probes 8 are arranged, an interface substrate 5, a TDR measuring instrument 10, and a personal computer 15. The plurality of probes 8 are simultaneously brought into contact with a plurality of lands 4 provided on the printed substrate 2 mounted with the semiconductor device 50. Along with inputting pulses generated in the TDR measuring instrument 10 from the probes to the lands, reflected waves reflected after being input are measured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate connection inspection apparatus, and more particularly to a substrate connection inspection apparatus for inspecting a connection portion between a mounting substrate on which a semiconductor device is mounted and a semiconductor device.

  One form of a semiconductor device package is a ball grid array. In the ball grid array, solder balls are arranged in a grid shape on the bottom surface of the package, and connection with a printed circuit board or the like is performed via the solder balls. The state of the solder ball mounted on the printed circuit board (mounting board) cannot be visually confirmed. For example, inspection by boundary scan or X-ray is performed. Here, the boundary scan refers to a function capable of observing and operating the terminal state of the semiconductor device.

  The boundary scan requires a scanning circuit inside the semiconductor device, which leads to an increase in the size of the semiconductor device and an increase in production cost. Further, boundary scan cannot be used in a high-frequency circuit. On the other hand, with X-rays, the scanning accuracy is rough, and it is extremely difficult to find a connection failure location due to a minute crack or the like of a solder ball to be actually inspected.

In addition to inspection by boundary scan and X-ray, for example, Patent Document 1 proposes a soldering inspection apparatus using TDR (Time Domain Reflectometry). According to this inspection apparatus, a dedicated pad for measurement is provided on the printed circuit board, and an electric pulse is input thereto, and the connection reliability of the solder ball is inspected by its reflection characteristics.
JP-A-9-61486

  However, the inspection apparatus described above has the following problems. In the conventional inspection apparatus, it takes about several minutes to measure at one place. Therefore, it takes a long time to inspect the mounting substrate on which the semiconductor device is mounted with many solder balls and the like, which is not suitable for mass production inspection. Further, complicated wiring is formed in the circuit of the semiconductor device connected to the solder balls. For this reason, even if an electric pulse is input to the solder ball and its reflection characteristics are measured, it is difficult to detect an abnormality of the solder ball because a simple disconnection does not cause an open or short circuit waveform. As a result, there is a problem that defective products cannot be easily detected.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to detect a defective product by inspecting a connection portion of a mounting substrate on which a semiconductor device is mounted with a semiconductor device in a short time. It is providing the board | substrate connection inspection apparatus which can be performed.

The board | substrate connection inspection apparatus which concerns on this invention is provided with the some probe and the determination part. The plurality of probes are simultaneously connected to the plurality of connection portions on the mounting substrate on which the semiconductor device is mounted. The determination unit selects a predetermined probe from the plurality of probes, outputs a predetermined pulse to the connection unit corresponding to the selected predetermined probe, measures the reflected wave that is reflected and returns, The reflected waveform is compared with a preset reference waveform to determine whether the mounting substrate for measurement is a good product or a defective product. It is not necessary to match the characteristic impedance to 50Ω as the plurality of probes, but there is no problem even if a probe matched to 50Ω is used.

  According to the substrate connection inspection apparatus of the present invention, a reflected waveform is measured by simultaneously connecting a predetermined probe selected from a plurality of probes to a plurality of connection portions on a mounting substrate on which a semiconductor device is mounted. By comparing with the reference waveform, it can be easily determined in a short time whether it is a non-defective product or a defective product.

  A substrate connection inspection apparatus according to an embodiment of the present invention will be described. As shown in FIG. 1, the board connection inspection apparatus 1 includes a probe unit 7 provided with a probe 8, an interface board 5, a TDR measuring instrument 10 for measuring electrical characteristics, and a personal computer 15 for analyzing a waveform. Is done. The probe 8 of the board connection inspection apparatus 1 comes into contact with the land 4 provided on the printed board 2 on which the semiconductor device 50 to be measured is mounted.

  The board connection inspection apparatus 1 will be described in more detail. As shown in FIG. 2, the probe 8 is disposed so as to penetrate the probe portion 7. One end of the probe 8 contacts the portion 4 b of the land 4, and the other end of the probe 8 contacts the interface substrate 5. The probe unit 7 and the interface substrate 5 can be separated.

  In a semiconductor device employing a ball grid array, the pitch of solder balls has regularity. Therefore, the probe portion 7 provided with the probe 8 connected to the solder ball 51 has versatility, and can be applied to various ball grid array type semiconductor devices 50. On the other hand, the interface substrate 5 is prepared for each type of the semiconductor device 50.

  On the other hand, the through-hole 3 is provided in the printed circuit board 2 on which the semiconductor device 50 to be measured is mounted, and the land 4 is disposed in the through-hole 3. A solder ball 51 of the semiconductor device 50 is connected to one portion 4 a of the land 4. The probe 8 comes into contact with the other part 4 b of the land 4.

  Further, as shown in FIG. 3, the interface board 5 is provided with a switch unit 9 such as a relay for connecting to the probe 8. The switch unit 9 is switched on and off by the personal computer 15. Each switch unit 9 is connected to the TDR measuring instrument 10 via the wiring connector 6. The TDR measuring instrument 10 includes a pulse transmitter 2 and an oscilloscope 11 (see FIG. 6). By switching the switch unit 9, the probes 8 connected to the TDR measuring device 10 are sequentially switched, and measurement is performed on all the solder balls 51. The personal computer 15 displays the measurement result.

  As shown in FIG. 4, a double-end movable probe whose both ends are expanded and contracted by the elastic force of a spring is applied as the probe 8. One end 8a of the probe 8 is a crown type so as to surely contact the portion 4b of the land 4 disposed on the printed circuit board 2. The other end 8 b of the probe 8 is a contact portion with the interface substrate 5.

  In general, as a probe for applying a high-speed pulse, a probe whose characteristic impedance is matched to 50Ω is used. However, in this board connection inspection apparatus 1, the probe 8 does not have such a high-frequency specification. It is not always necessary to match the characteristic impedance. This is because, when trying to match the characteristic impedance of the probe, the probe is required to have an accurate shape, and the probe is in a multi-pin manner to be brought into contact with a plurality of lands provided on a printed circuit board on which a semiconductor device is mounted. This is because there is a case where it is not suitable for the device, and it leads to an increase in the cost of the device itself.

  The circuit (line) provided on the interface substrate 5 is preferably a 50Ω distributed multiplier circuit such as a microstrip line because a high-frequency pulse flows. The impedance of the circuit (line) portion from the interface board 5 to the TDR measuring instrument 10 becomes constant, and the measurement accuracy can be improved.

  The personal computer 15 stores in advance data of a reflected waveform (normal reflected waveform) obtained by measuring a plurality of non-defective printed boards each having a semiconductor device mounted thereon. Based on the variation (deviation) of the shapes of the plurality of normal reflection waveforms, a predetermined threshold value is set as a reference for determining whether the product is a non-defective product or a defective product.

  Next, the operation (inspection procedure) of the board connection inspection apparatus 1 described above will be described. First, for example, as shown in FIG. 1, each of the plurality of probes 8 is simultaneously brought into contact with the land 4 connected to each of the plurality of solder balls 51. Next, as shown in FIG. 5, the TDR measuring instrument 10 generates a pulse (waveform) 20 of about 400 mV (= V1) for about 3 μs to 60 μs, for example. The generated pulse 20 is input to the solder ball 51 from the probe 8 through the land 4 via the interface substrate 5.

  The probe 8 simultaneously detects the voltage (reflected waveform) from which the pulse input to the solder ball 51 is reflected and returned. Based on the detected voltage, the reflected waveform 24 is obtained. This reflected waveform (entire waveform) is shown in a state including all the reflected waves that flow from the solder ball 51 to the inside of the semiconductor device 50 and are reflected, including the probe 8. In the personal computer 15, the obtained reflected waveform 24 is compared with the stored normal reflected waveform 23.

  In this board connection inspection device 1, when the value of the voltage deviation (voltage difference V2) between the measured reflection waveform 24 and the normal reflection waveform 23 exceeds a predetermined reference value (for example, about 50 mV) (Condition A), Even if the voltage divergence value does not satisfy the reference value, it is set to be judged as abnormal when such a voltage divergence continues for a predetermined reference time T2 (for example, about 200 pS to 400 pS) (condition B). Yes. Since the reference value is also expected to vary slightly from circuit to circuit, the reference value of the threshold value that is determined to be abnormal based on the deviation obtained from the reflected waveform data of multiple non-defective products during mass production. It is desirable to ask for

  As a result of comparing the measured reflection waveform 24 with the normal reflection waveform 23, if any of the condition A and the condition B is satisfied, it is determined as a defective product. On the other hand, if neither the condition A nor the condition B is satisfied, it is determined as a non-defective product.

  Thus, by observing the reflected waveform (whole waveform) observed between the start of pulse input and the stop of pulse input, and comparing it with a non-defective reflected waveform, the probe 8 to the semiconductor device 50 It is possible to determine whether or not there is a defect in the part leading to the inside, and it is possible to easily determine whether the printed circuit board 2 on which the semiconductor device 50 is mounted is good or bad. The determination of pass / fail is made in terms of whether or not there is a defect in the printed circuit board on which the semiconductor device is mounted, rather than in which part of the printed circuit board on which the semiconductor device is mounted.

Modifications Now, when a mass production board is actually assumed, it is not rare that several BGAs (Ball Grid Array) having several hundred pins or more are mounted on the board. Then, the number of pins of the BGA on the substrate becomes 1000 pins or more, and in order to inspect them in a time that can be applied for mass production, it is necessary to inspect in as short a time as possible. In that case, it takes too much time to evaluate the characteristics of the entire circuit including the reflected wave and compare it with a non-defective product, so it is necessary to pay attention to the waveform and voltage reflected only from the object to be inspected.

  Therefore, a case where only the solder ball portion is inspected as an inspection target will be described. As shown in FIG. 6, the solder ball is located in the vicinity of the probe 8 through the land 4. Therefore, as shown in FIG. 5, the reflected waveform measured by being reflected by the solder ball 51 is measured in a range of time (time T3) determined after the input pulse is applied, out of the entire waveform. Corresponds to the reflected waveform and voltage.

  Therefore, in order to measure a BGA having a large number of pins in a short time during mass production, it is only necessary to confirm the waveform of only the solder ball portion rather than comparing the entire waveforms. By comparing only the portion of the reflected waveform corresponding to the position of the solder ball with a reflected waveform or voltage of a good product, the inspection time can be greatly shortened.

  As shown in FIG. 6, when a crack 61 exists in the solder ball 51, when the pulse 20 (see FIG. 7) generated in the TDR measuring instrument 10 is input to the solder ball 51, the pulse 20 is reflected by the crack 61. Then, the probe 8 is returned. If there is an abnormality such as a crack in the solder ball, a change in voltage is recognized in the reflected waveform.

  At this time, as shown in FIG. 7, in the portion of the reflected waveform corresponding to the position of the solder ball, due to the crack 61 after the elapse of time (time T1) until the pulse 20 is input and returned. There is a tendency for the voltage to rise. By detecting this voltage change, it is possible to easily determine whether or not the solder ball 51 has a defect. In addition, it is only necessary to compare the reflected waveform of the portion corresponding to the position of the solder ball in the entire reflected waveform, and the determination can be made in a short time.

  Thus, by measuring the portion of the reflected waveform for a certain period of time in the entire reflected waveform, it is possible to inspect a specific portion such as a solder ball in a relatively short time.

  In the description of the operation of the board connection inspection apparatus 1 described above, in the reflected waveform 23 of the non-defective printed board shown in FIG. 5, the case where the voltage once decreases and then increases is described as an example. It is an example, and it is assumed that the voltage once rises. In addition, the case where the reflected waveform (voltage) 24 of the defective printed circuit board deviates toward the higher voltage with respect to the reflected waveform 23 of the non-defective printed circuit board has been described as an example. It is also envisaged.

  Further, as a manner of contact (connection) of the probe with the printed circuit board, one solder ball 51 or the like is connected to one probe 8, and a plurality of solder balls 51 or the like are connected to one probe 8. You may make it test | inspect as it is connected.

  And in the board | substrate connection inspection apparatus 1 mentioned above, by comparing with the reflected waveform of a good printed circuit board, the defect of the soldering part in other components other than the mounted semiconductor device, the disconnection of the wiring of a printed circuit board, etc. A defect can be easily detected in connection portions other than the solder balls.

  The reflected waveform is also affected by changes in impedance. From this, when a component such as a resistor or a capacitor is erroneously mounted, the erroneous mounting can be detected by capturing the change in the reflected waveform. Furthermore, the reflected waveform also changes due to changes in the physical properties of the insulation such as the wiring length, shape, and glass epoxy. For this reason, in LSI (Large Scale Integrated Circuit) and the like, it is possible to detect counterfeit products such as LSIs that are becoming a problem in recent years by capturing physical changes such as wire lengths and substrate materials as changes in reflected waveforms. be able to.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the scope described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure including a partial cross section which shows the structure of the board | substrate connection inspection apparatus which concerns on embodiment of this invention. FIG. 2 is a partial enlarged cross-sectional view of the substrate connection inspection apparatus shown in FIG. 1 in the same embodiment. FIG. 2 is a diagram showing a circuit configuration of the board connection inspection apparatus shown in FIG. 1 in the same embodiment. In the same embodiment, it is a partial expanded sectional view which shows the structure of a probe and its vicinity. In the same embodiment, it is a graph which shows the pulse for explaining operation of a substrate connection inspection device, and its reflected waveform. In the same embodiment, it is a figure including a partial cross section for demonstrating the test | inspection of the solder ball by a board | substrate connection inspection apparatus. FIG. 7 is a graph showing pulses and their reflected waveforms in the inspection shown in FIG. 6 in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Board | substrate connection inspection apparatus, 2 Printed circuit board, 3 Through hole, 4 Land, 4a Land part, 4b Land part, 5 Interface board, 6 Wiring connector, 7 Probe part, 8 Probe, 9 Switch part, 10 TDR measuring instrument 11 oscilloscope 12 pulse oscillator 15 personal computer 20 pulse 21 pulse waveform 22 measurement waveform 23 measurement waveform 24 measurement waveform 50 semiconductor device 51 solder ball 61 crack

Claims (4)

A plurality of probes simultaneously connected to a plurality of connecting portions on a mounting substrate on which a semiconductor device is mounted;
A predetermined probe is selected from the plurality of probes, a predetermined pulse is output to a connection portion corresponding to the selected predetermined probe, a reflected wave that is reflected and returned is measured, and the reflected wave is reflected. A board connection inspection apparatus comprising: a determination unit that compares a waveform with a preset reference waveform and determines whether a mounting board for measurement is a good product or a defective product.   The voltage of the reflected waveform is measured after a lapse of a predetermined time from the generation time of the pulse of the reflected wave, and the measured voltage is compared with the voltage after the lapse of the predetermined time from the generation time of the pulse of the reference waveform. The board connection inspection device according to 1.   The reference waveform is set based on a deviation of data of a plurality of reflected waveforms obtained by measuring a plurality of non-defective mounting boards, and used as a reference value for determination in the determination unit. Or the board | substrate connection test | inspection apparatus of 2. A pulse generator for generating the predetermined pulse;
The board | substrate connection inspection apparatus of Claim 1 or 2 provided with the signal switching part which switches the connection of each of the said several probe and the said pulse generation part.

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