JP2001228191A - Lsi soldered joint structure, and lsi soldered part abnormal joint detecting method used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LSI soldered part abnormal joint detecting method allowing a soldered joint condition to be monitored in any time during operation of LSI and an abnormal joint to be detected in its early stages. SOLUTION: Joint checking solder balls 3, 4 are arranged in optional positions in the outermost circumference part of BGA 1, which is considered to have a short soldered joint lifetime theoretically because of application of the highest mechanical stress, and electrically connected to PWB 8 by means of solder. The joint checking solder ball 3 is electrically connected to the GND, and connected to the joint checking solder ball 4 via LSI internal wiring 2. The joint checking solder ball 4 is pulled up by means of a resistor 9 so as to be connected to one end (+) of a comparator 10. A reference power source Vref is connected to the other end (-) of the comparator 10. The output of the comparator 10 is connected to a soldered joint part monitoring part 11 detecting abnormal joint between the soldered joint parts 7a, 7b, and an output of the joint part monitoring part 11 is connected to a device control unit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LSI solder connection structure and a method of detecting an abnormal connection of an LSI soldering portion used in the structure, and more particularly to a BGA (Ball Grid Array).
y) etc. by soldering to PWB (Printed Wir
The present invention relates to a method of detecting a connection abnormality when connecting to an Internet connection (ing Board).

[0002]

2. Description of the Related Art Conventionally, the quality of soldering is determined by the appearance of a soldering state based on its appearance or by applying a low voltage as required, and the voltage drop. In addition, the inspection of the soldering condition is performed by visual inspection, which is one of the functional tests, and is performed using a limit sample or the like that indicates the soldering condition, and there is no special inspection device used for that purpose. .

Further, an inspection device for inspecting connection quality is
A simple device combining a dry cell and a voltmeter or ammeter is used. Methods for inspecting these soldering connection defects are disclosed in Japanese Patent Application Laid-Open No. 6-18463, etc., but these are all inspection methods immediately after production.

Generally, BGA or the like is soldered to PWB.
When connecting to a BGA, the soldering life is a factor in determining the life of the package on which the BGA is mounted. However, since the soldering life is a mechanical and structural life, the connection state is not continuously monitored during operation.

[0005]

In the above-described conventional method for detecting a connection abnormality of a soldered portion, the connection state is not continuously monitored during operation. When it is necessary to avoid device failure due to connection life (deterioration) as much as possible, it is not possible to respond before the failure occurs.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, to monitor a solder connection state at any time during LSI operation, and to detect an abnormal connection at an early stage. An object of the present invention is to provide an LSI soldering portion connection abnormality detection method to be used.

[0007]

An LSI solder connection structure according to the present invention is an LSI solder connection structure for electrically connecting a large-scale integrated circuit to a substrate, wherein the large-scale integrated circuit is connected to the substrate. A solder connecting member disposed at the outermost peripheral portion of the large-scale integrated circuit having the largest mechanical stress due to a difference in thermal expansion and detecting a connection abnormality at the outermost peripheral portion, and a connection abnormality of the solder connecting member. Is to be detected.

The method for detecting an abnormal connection of an LSI soldering portion according to the present invention is a method for detecting an abnormal connection of an LSI soldering portion in an LSI solder connection structure for electrically connecting a large-scale integrated circuit to a substrate. A solder connection member for detecting a connection abnormality at an outermost peripheral portion of the large-scale integrated circuit having the largest mechanical stress due to a difference in thermal expansion between the large-scale integrated circuit and the substrate is arranged at the outermost peripheral portion, and the solder The connection abnormality of the connection member is detected.

That is, the method for detecting an abnormal connection of an LSI soldering portion according to the present invention uses a solder connection pin (ball) for detecting an abnormal connection in a solder connection structure for electrically connecting an LSI (large-scale integrated circuit). When a connection abnormality is detected, the abnormality is reported to a higher-level control unit of the apparatus, the connection life is grasped, and the apparatus is prevented from malfunctioning.

More specifically, in the method for detecting an abnormality in connection of an LSI soldering portion of the present invention, the mechanical stress is the largest due to the difference in thermal expansion between the BGA and the PWB. The connection abnormality at the outermost peripheral portion is electrically regarded as a change in impedance, so that the solder connection state can be monitored at any time during the operation of the LSI, thereby enabling early detection of the connection abnormality.

In other words, since the connection failure detection point is located at the outermost periphery where the connection life is short, it is possible to predict the occurrence of soldering failure before the signal ball portion reaches the limit of the connection life. It is possible to take countermeasures before the interruption of the system operation due to.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a method for detecting an abnormal connection of an LSI soldering portion according to an embodiment of the present invention. In FIG. 1, the solder balls 3 and 4 for confirming connection have the largest mechanical stress due to the difference in thermal expansion between the BGA 1 and the PWB 8, and therefore, any part of the outermost periphery of the BGA 1 which is theoretically considered to have a short solder connection life. Is located at
It is electrically connected to the PWB 8 using solder (solder connection portions 7a and 7b).

The connection confirmation solder balls 3 are electrically GN
D (ground), and connected to the connection confirming solder ball 4 through the wiring 2 in the LSI. The connection confirmation solder ball 4 is pulled up by a resistor 9 and connected to one end (+) of a comparator 10. The other end (−) of the comparator 10 is connected to a reference power supply (Vref).

The output of the comparator 10 is connected to a solder connection monitor 11 for monitoring the output and detecting connection abnormalities (high impedance, open) of the solder connections 7a and 7b. Is a device control unit for requesting a component replacement request while maintaining the connection life of the signal solder balls 5, 6 having a longer connection life than the connection confirmation solder balls 3, 4 based on the detected connection abnormality information. 1
2 is connected.

FIG. 2 is a signal waveform diagram showing a signal waveform when an abnormality occurs in the comparator 10 of FIG. The operation of the LSI soldering portion connection abnormality detecting method according to one embodiment of the present invention will be described with reference to FIGS.

When no soldering failure has occurred, the (+) side input terminal of the comparator 10 is a connection confirmation solder ball 4, a solder connection portion 7b, an LSI wiring 2, a connection confirmation solder ball 3, and a solder connection portion 7a. , And the potential is 0V.

The (-) terminal side of the comparator 10 is set to a Vref voltage (Vcc> Vref).
As a result, the output of the comparator 10 is at the “L” level.

The solder connection abnormality is caused by the solder connection portions 7a and 7b.
, The impedance of the solder connection portions 7a and 7b gradually increases, so that the potential of the (+) side terminal of the comparator 10 also gradually increases.

When the potential of the (+) terminal of the comparator 10 exceeds the Vref value of the (-) terminal of the comparator 10, the output of the comparator 10 is inverted and the output level becomes "H". This signal level inversion is detected by the solder connection monitoring section 11, and the detection result is reported to the apparatus control section 12.

The device control unit 12 determines the connection life of the signal solder balls 5 and 6 having a longer connection life than the connection confirmation solder balls 3 and 4 based on the connection abnormality information detected by the connection monitoring unit 11. Request replacement of parts while they can be held.

As described above, the mechanical stress is the largest due to the difference in thermal expansion between the BGA 1 and the PWB 8, and the connection abnormality at the outermost peripheral portion, which is theoretically considered to have a short solder connection life, is regarded as an electrical impedance change. At any time during the operation of the LSI, the state of the solder connection can be monitored, and a connection abnormality can be found at an early stage.

Further, since the connection abnormality detection point is located at the outermost periphery where the connection life is short, the signal solder balls 5 and 5 are used.
Before the part 6 reaches the limit of the connection life, occurrence of soldering abnormality can be predicted, and measures can be taken before disconnection of the system operation due to disconnection of the signal connection.

FIG. 3 is a conceptual diagram showing a method for detecting an abnormal connection of an LSI soldering portion according to another embodiment of the present invention. FIG.
, The connection confirmation pins 15 and 16 are connected to PGA (Pin
The mechanical stress is the largest due to the difference in thermal expansion between the grid array (Grid Array) 13 and the PWB 8. Therefore, the PGA 8 is disposed at an arbitrary position on the outermost periphery of the PGA 13, which is theoretically considered to have a short solder connection life. And are electrically connected to each other (solder connection portions 7a and 7b).

The connection confirming pin 15 is electrically connected to GND (ground), and is connected to the connection confirming pin 16 through the LSI internal wiring 14. The connection check pin 16 is pulled up by the resistor 9 and is connected to one end (+) of the comparator 10. The other end (−) of the comparator 10 is connected to a reference power supply (Vref).

The output of the comparator 10 is connected to a solder connection monitor 11 for monitoring the output and detecting a connection abnormality (high impedance, open) of the solder connection 7a, 7b. From the detected connection abnormality information to the device control unit 12 that requests a component replacement while the connection life of the signal pins 17 and 18 having a longer connection life than the connection confirmation pins 15 and 16 can be maintained. It is connected.

In the soldering structure according to the embodiment of the present invention shown in FIG. 1, the solder balls 3 and 4 for confirming the connection of the BGA 1 are formed.
Is arranged at an arbitrary position on the outermost periphery of the BGA 1,
As shown in FIG. 3, a monitoring method similar to that of the embodiment of the present invention can be applied to the PGA 13 instead of the BGA 1.

FIG. 4 is a conceptual diagram showing a method for detecting an abnormal connection of an LSI soldering portion according to another embodiment of the present invention. FIG.
In the above, the solder balls 3 and 4 for connection confirmation have the largest mechanical stress due to the difference in thermal expansion between the BGA1 and the PWB8, and therefore, the solder balls 3 and 4 have an arbitrary location on the outermost periphery of the BGA1 which is theoretically considered to have a short solder connection life PWB8
Are electrically connected using solder (solder connection portions 7a and 7b).

The connection confirmation solder balls 3 are electrically GN
D (ground), and connected to the connection confirming solder ball 4 through the wiring 2 in the LSI. The connection confirmation solder ball 4 is pulled up by the resistor 21 and is connected to one end (−) of the comparator 22. The other end (+) of the comparator 22 is connected to a reference power supply (Vref).

The output of the comparator 22 is connected to a solder connection monitor 23 for monitoring the output and detecting an abnormal connection between the solder connections 7a and 7b.
Is an apparatus for requesting a component replacement request while maintaining the connection life of the signal solder balls 5 and 6 having a longer connection life than the connection confirmation solder balls 3 and 4 based on the detected connection abnormality information. It is connected to the control unit 24.

FIG. 5 is a signal waveform diagram showing a signal waveform when an abnormality occurs in the comparator 22 of FIG. Referring to FIGS. 4 and 5, an LSI according to another embodiment of the present invention will be described.
The operation of the soldering part connection abnormality detection method will be described.

If no soldering failure has occurred, the (-) side input terminal of the comparator 22 is a connection confirmation solder ball 4, a solder connection portion 7b, an LSI wiring 2, a connection confirmation solder ball 3, and a solder connection portion 7a. , And the potential is 0V.

The (+) terminal side of the comparator 22 is set to a Vref voltage (Vcc> Vref). As a result, the output of the comparator 22 is at the “H” level.

The solder connection abnormality is caused by the solder connection portions 7a and 7b.
Occurs, the impedance of the solder connection portions 7a and 7b gradually increases, so that the potential of the (-) side terminal of the comparator 22 also gradually increases.

When the potential of the (-) terminal of the comparator 22 exceeds the Vref value of the (+) terminal of the comparator 22, the output of the comparator 22 is inverted and the output level becomes "L". This signal level inversion is detected by the solder connection monitoring unit 23, and the detection result is reported to the device control unit 24 requesting a component replacement request.

Based on the connection abnormality information detected by the connection monitoring section 23, the device control section 24 determines the connection life of the signal solder balls 5, 6 having a longer connection life than the connection confirmation solder balls 3, 4. Request replacement of parts while they can be held.

Thus, L according to another embodiment of the present invention
Even when the (+) and (-) input terminals of the comparator 22 are exchanged as in the SI soldering part connection abnormality detecting method, the same effect as the LSI soldering part connection abnormality detecting method according to the embodiment of the present invention is obtained. Can be obtained.

[0037]

As described above, according to the present invention, an LSI for electrically connecting a large-scale integrated circuit to a substrate is provided.
In the solder connection structure, a solder connection member for detecting a connection abnormality at the outermost periphery of the large-scale integrated circuit having the largest mechanical stress due to a difference in thermal expansion between the large-scale integrated circuit and the substrate is arranged at the outermost periphery. Then, by detecting the connection abnormality of the solder connection member, it is possible to monitor the solder connection state at any time during the operation of the large-scale integrated circuit,
There is an effect that a connection abnormality can be detected at an early stage.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an LSI soldering portion connection abnormality detection method according to one embodiment of the present invention.

FIG. 2 is a signal waveform diagram showing a signal waveform when an abnormality occurs in the comparator of FIG. 1;

FIG. 3 is a conceptual diagram showing an LSI soldering portion connection abnormality detecting method according to another embodiment of the present invention.

FIG. 4 is a conceptual diagram showing an LSI soldering portion connection abnormality detecting method according to another embodiment of the present invention.

FIG. 5 is a signal waveform diagram showing a signal waveform when an abnormality occurs in the comparator of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 BGA 2,14 Wiring in LSI 3,4 Solder ball for connection check 5,6 Solder ball for signal 7a, 7b Solder connection part 8 PWB 9,21 Resistance 10,22 Comparator 11,23 Connection part monitoring part 12,24 Device Control unit 13 PGA 15, 16 Connection confirmation pin 17, 18 Signal pin

Claims (12)

[Claims] 1. An LSI solder connection structure for electrically connecting a large-scale integrated circuit to a substrate, wherein the mechanical stress is largest due to a difference in thermal expansion between the large-scale integrated circuit and the substrate. An LSI arranged at the outermost periphery of a large-scale integrated circuit and having a solder connection member for detecting a connection abnormality at the outermost periphery thereof, wherein the connection abnormality of the solder connection member is detected. Solder connection structure. 2. The L according to claim 1, wherein the solder connection member is formed of a solder ball for confirming connection.
SI solder connection structure. 3. The large-scale integrated circuit includes a BGA (Bal
3. The LSI solder connection structure according to claim 2, wherein the connection structure is formed of (1 Grid Array). 4. The LSI according to claim 1, wherein said solder connection member comprises a pin member for confirming connection.
Solder connection structure. 5. The large-scale integrated circuit includes a PGA (Pin)
5. The LSI solder connection structure according to claim 4, wherein the connection structure is formed of a grid array. 6. The LSI according to claim 1, wherein the connection abnormality of the solder connection member is electrically regarded as an impedance change.
Solder connection structure. 7. A method for detecting an abnormal connection of an LSI soldering portion in an LSI solder connection structure for electrically connecting a large-scale integrated circuit to a substrate, the method comprising detecting a thermal expansion difference between the large-scale integrated circuit and the substrate. The mechanical stress is the largest, the solder connection member for detecting a connection abnormality in the outermost peripheral portion of the large-scale integrated circuit is arranged in the outermost peripheral portion,
An abnormal connection detection method for an LSI soldering portion, wherein an abnormal connection of the solder connection member is detected. 8. The light emitting diode according to claim 7, wherein the solder connection member is formed of a solder ball for confirming connection.
SI soldering part connection abnormality detection method. 9. The large-scale integrated circuit includes a BGA (Bal
9. The method for detecting an abnormality in connection of an LSI soldering part according to claim 8, wherein the method comprises: (1 Grid Array). 10. The LS according to claim 7, wherein the solder connection member is formed of a pin member for confirming connection.
I Solder connection error detection method. 11. The large-scale integrated circuit includes a PGA (Pi
11. The method for detecting an abnormality in connection of an LSI soldering part according to claim 10, wherein the method comprises: n grid array). 12. The L according to claim 7, wherein the connection abnormality of the solder connection member is electrically regarded as a change in impedance.
SI soldering part connection abnormality detection method.