JPH09264918A - Method for inspecting package board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain efficient inspection in a short time by allowing a probe to be brought into contact with a second pad for inspection, short-circuiting first pads to each other in such a state for further inspection, and by inspecting patterns excluding for previous inspections while a probe is brought into contact with the first pad. SOLUTION: After a package board is set, respective probes mounted to inspection jigs are brought into contact with respective second pads 3 for ball grid array and land arid array, so as to measure their resistance values. After comparing the result with the absorption data of normal product, a first connection state among a pad 3, an inner layer pattern 5 and a first pad for flip chip and a second connection state among the pad 3, an inner pattern 5A and a pad 2 are inspected for insulation. In such a state, the pad 2 is retained entirely by a conductive rubber sheet to measure its resistance value, and the continuity of both connection states is inspected. Next, a pair of flying probes are selectively brought into contact with respective pads 2 and the continuity and insulation tests are performed every set of pad 2 connected to each other through the pattern 5. Thus the electrical can be carried out efficiently in a short time.

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example, a first pad for a flip chip on one surface and a second pad for a ball grid array (BGA) and a land grid array (LGA) on the other surface. The first pad and the second pad are related to an inspection method for performing an electrical inspection of a package substrate made of ceramic, resin, or the like, which is connected to each other through various patterns via an inner layer pattern. The present invention relates to a method of inspecting a package substrate, which can efficiently perform an electrical inspection in a short time in consideration of various connection modes existing therebetween.

[0002]

2. Description of the Related Art Conventionally, a flip-chip pad (referred to as a first pad for convenience) is provided on one surface, and a BGA or a pad is provided on the other surface.
In a package substrate provided with an LGA pad (referred to as a second pad for convenience), it is general that the first pad and the second pad are in one-to-one correspondence via an inner layer pattern. . In such a package substrate, the inner layer pattern does not have a net structure, and therefore, the electrical inspection of each of the first pad, the second pad, and the inner layer pattern can be performed relatively easily. Here, an electrical inspection method for the first pad, the second pad, and the inner layer pattern in the conventional package substrate will be described with reference to FIGS. FIG. 5 is an explanatory view for explaining an insulation test of a connection state in which a first pad and a second pad are connected in a one-to-one correspondence via an inner layer pattern in a conventional package substrate, and FIG. FIG. 5 is an explanatory diagram for describing a conduction test of a connection state in the package substrate shown in FIG.

FIGS. 5 and 6 show a package substrate 10.
Reference numeral 0 denotes a first pad 101 for mounting a flip chip on one surface (the lower surface in FIGS. 5 and 6), and a second pad for a BGA or LGA on the other surface (the upper surface in FIGS. 5 and 6). 1
02 is formed. Further, each of the first pads 101 and the second pads 102 are in a one-to-one relationship via the inner layer pattern 103.
Connected to correspond to

In order to conduct an electrical inspection of the package substrate 100 as described above, first, a probe 104 of an inspection device is brought into contact with each of the second pads 102, and a predetermined voltage is applied to the probe 104 so that the second pads 102 and Inner layer pattern 1
03 and the insulation test between the first pad 101. At this time, the insulation test is performed by measuring the resistance with each probe 104. Next, as described above, the probe 10
4 in contact with each second pad 102,
A conductive rubber sheet 105 is brought into contact with the entirety of the pad 101, a predetermined voltage is applied to the probe 104, and the second pad 1
02, a conduction test between the inner layer pattern 103 and the first pad 101 is performed. According to the inspection method as described above, since the structure of the package substrate 100 is simple, the first pad 10 can be quickly manufactured using an inexpensive inspection device and jig.
1. Electrical inspection between the inner layer pattern 103 and the second pad 102 can be performed.

[0005]

However, in recent years, multi-chip substrates have become the mainstream package substrates. In such a multi-chip substrate, the first pad for flip-chip mounting is provided on one surface, and the BGA or LGA is provided on the other surface.
A second pad for the GA is formed, and the first pad and the second pad are connected to each other via an inner layer pattern having a complicatedly branched and net structure. There are a plurality of types of connection states (aspects) between the pad, the second pad, and the inner layer pattern.

Therefore, the following problems exist when conducting an electrical inspection of the first pad, the second pad, and the inner layer pattern in the multi-chip substrate having the above-described configuration. That is, in the multi-chip substrate, the fineness of each of the first pad and the second pad is further promoted. In particular, the first pad, which is a flip-chip mounting pad, is formed at a narrow pitch, and the pad diameter is small. Is also small. Accordingly, the positional accuracy of the inspection jig in the inspection device is required, and therefore, the inspection jig becomes expensive.

For example, as described above, when the inspection is performed using the probe and the conductive rubber sheet,
Strict positional accuracy is required for the probe and the conductive rubber sheet, and strict accuracy is also required for the inspection jig and the inspection device. The diameter of the first pad is 10
The limit is 0 μm and the pitch is about 0.2 mm. Therefore, an inspection jig that can cope with such a limit becomes considerably expensive and has low durability.

In order to cope with the limit of the positional accuracy of the probe or the conductive rubber sheet as described above, it is conceivable to employ a so-called flying probe method. Although the inspection apparatus employing the flying probe method is expensive, it has a good position accuracy of the probe and can correspond to the first pad (pad diameter: 50 μm, pitch: 0.15 mm) having a considerably fine pitch. Also,
There is no need for expensive inspection jigs. However, in the flying probe method, since the inspection is performed using only a few flying probes, an inspection time is required. Therefore, an inspection tact for inspecting a large number of substrates becomes a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has a first pad for flip-chip mounting on a package substrate and a second pad for BGA or LGA.
In consideration of various connection states between the first pad and the second pad based on the inner layer pattern derived from the net structure and existing between the pads, even when using a low-cost inspection device or inspection jig, An object of the present invention is to provide a method of inspecting a package substrate, which can efficiently perform an electrical inspection in a short time.

[0010]

According to a first aspect of the present invention, there is provided an inspection method for electrically inspecting a package substrate having a plurality of first pads and a plurality of second pads. A step of outputting a detection signal to the probe while the fixture probe is in contact with the second pad and performing an inspection based on the detection signal detected via the probe; and applying the fixture probe to the second pad. A step of outputting a detection signal to the probe in a state where the first pads are in contact with each other and short-circuited to each other and inspecting based on the detection signal detected through the probe, and a pattern not to be inspected in each step Detection that outputs a detection signal to the flying probe with the flying probe in contact with the pad and is detected via the flying probe Characterized in test method of a package substrate comprising a step of performing an inspection on the basis of the issue. In the method of inspecting a package substrate according to claim 1, which is made of steel, three types of inspection are sequentially performed,
Accurately perform complicated inspection of patterns derived from net structure,
Moreover, it can be inspected in a short time.

In particular, in the inspection method according to claim 1, when inspecting in the order of the steps described, it is configured such that from the first step to the coarse inspection to the dense inspection, the three steps are performed. If a conduction failure or insulation failure is detected in the first step, it is possible to select a defective package substrate without performing the next step. This maintains high efficiency in selecting non-defective / non-defective package substrates, particularly when performing an electrical inspection of the package substrate, particularly since the inspection process using a flying probe takes the most time and is the rate-determining stage. Important above. In addition, the first two steps of the three steps can be performed by using an inspection device and an inspection jig having relatively low positional accuracy, and if only the last step is inspected by the flying probe. Since it is good, it is possible to efficiently perform the electrical inspection in a short time even when the inspection device and the inspection jig which are low in cost are used.

According to a second aspect of the present invention, in the inspection method of the first aspect, the first pad is a pad for mounting a semiconductor chip, and the second pad is a ball grid array or a land grid. It is characterized in that it is an array pad. As described above, when the second pad is a pad for a ball grid array or a land grid array, the diameter of these pads is relatively large, and the positional accuracy is not so required. The first two steps can be easily carried out by contacting with the above. Further, when the first pad is a semiconductor chip mounting pad, it is formed in a finer pattern, so that it is possible to cope with such fineness. The final step is performed by a flying probe.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for inspecting a package substrate according to the present invention will be described in detail based on an embodiment embodying the present invention with reference to the drawings. First, a configuration of a package substrate to be subjected to an electrical inspection will be described with reference to FIG. FIG. 1 is a partial cross-sectional view schematically showing a package substrate. In FIG. 1, a package substrate 1
Is a build-up multilayer wiring board in which wiring patterns are formed by a so-called full additive method over multiple layers (in FIG. 1, 10 layers). A first pad 2 for a plurality of flip chips is formed on one surface (the upper surface in FIG. 1) of the package substrate 1, and each first pad 2 is formed by a photo via. In the present embodiment, the first pad 2 has a diameter of 100 μm, a pitch of 0.25 mm, and a diameter of 150 μm.
0 is provided. For example, after the first pad 2 is supplied with solder via a solder supply device (there is also a connection method using a conductive resin) or the like, the first pad 2 is connected to the connection terminal of the flip chip by solder.

The other surface of the package substrate 1 (in FIG. 1,
A plurality of second pads 3 for LGA are formed on the lower surface), and are constituted by photovias like the first pad 2. In the present embodiment, the second pad 3 has a diameter of 600
There are provided 1,000 pieces with a pitch of 1.25 mm and μm. For example, after the solder is supplied to each second pad 3 via a solder supply device (may be attached by a socket) or the like, the second pad 3 is mounted on the motherboard by soldering.

The first pad 2 and the second pad 3 are basically connected via an inner layer pattern 5 formed of a photo via formed in each interlayer insulating layer 4 of the package substrate 1. Here, a connection mode among the first pads 2, the second pads 3, and the inner layer pattern 5 will be described.
A predetermined number of the first pads 2 (800 in this embodiment)
The first pads 2 are connected to the second pads 3 via the inner layer pattern 5 so as to correspond one-to-one. This connection state is referred to as a first connection state for convenience. For example, in FIG.
Among the first pads 2, the A pad (the first pad 2 at the upper left position in FIG. 1) is connected to the F pad (the lower left position at the lower left position in FIG. 1) of the second pad 3 through the inner layer pattern 5. 2), and this connection state corresponds to a first connection state.

Of the first pads 2, a predetermined number (600 in the present embodiment) of the first pads 2 are selectively connected to the second pads 3 via the net-shaped inner layer pattern 5A.
It is connected to the. This connection state is referred to as a second connection state for convenience. For example, in FIG. 1, among the first pads 2, a B pad (first pad 2 from the left on the upper surface in FIG. 1) and a C pad (third first pad from the left on the upper surface in FIG. 1) 2) is connected to the G pad (the second pad 3 on the lower surface in FIG. 1 from the left) of the second pads 3 via the net-shaped inner layer pattern 5A. This corresponds to two connection states.

Further, among the first pads 2, the specific 100 first pads 2 are connected to each other through the inner layer pattern 5. This connection state is referred to as a third connection state for convenience. For example, among the first pads 2 in FIG. 1, a D pad (the fourth first pad 2 from the left on the upper surface in FIG. 1) and an E pad (the fifth first pad from the left on the upper surface in FIG. 1) 2)
They are connected to each other via the inner layer pattern 5, and this connection state corresponds to a third connection state.

Next, an electrical inspection method of the package substrate 1 having the above-mentioned structure will be described with reference to FIGS. 2 to 4. Here, FIG. 2 is a partial cross-sectional view of the package substrate schematically showing a state where an insulation test is performed in the first connection state and the second connection state, and FIG. 3 is a continuity test in the first connection state and the second connection state. And FIG. 4 is a partial cross-sectional view of the package substrate schematically showing a state in which a continuity test and an insulation test in a third connection state are being performed. Although FIGS. 2 and 3 show only the first connection state, the second connection state is the same as that in FIG. The electrical inspection of the package substrate 1 includes first an insulation inspection in a first connection state and a second connection state, and then a continuity inspection in a first connection state and a second connection state.
Finally, the continuity test and the insulation test of the third connection state are performed.

In order to perform an electrical inspection of the package substrate 1, first, as shown in FIG. 2, the package substrate 1 is set in an inspection device, and each probe 6 provided on an inspection jig (fixture jig) is attached. It contacts each second pad 3. still,
FIG. 2 shows a state where the probe 6 is in contact with the inner pad F of the second pad 3. While the probe 6 is in contact with the second pad 3, a predetermined voltage is applied to each probe 6, and a resistance value is measured via each probe 6 and compared with the non-defective sampled data to determine the first connection state and Second
Conduct an insulation test on the connection. Incidentally, in this test, only the probe 6 is in contact with each second pad 3. Therefore, the first connection state to the second pad 3, the inner layer pattern 5, and the first pad 2 and the second connection state to the second pad 3, the inner layer pattern 5A, and the first pad 2 are in a good insulation state. When no short circuit occurred, it was found that the insulation matched with the conforming data of the non-defective product, and that the short circuit occurred due to insulation failure in the first connection state or the second connection state. In FIG. 5, it is found that the insulation does not match the non-defective data (the number of nets is increased) and the insulation is poor. Note that a continuity test of the pattern connected by the second pads 3 is also performed at the same time. Also, a leak test is performed simultaneously by the same method. The first inspection step is completed in about 10 seconds.

Next, as shown in FIG. 3, in the state where the probes 6 are in contact with the second pads 3 as described above, the silicon resin sheet 8 and the conductive rubber sheet are provided over the entire first pads 2. 7 After pressing with the stuck sheets, a predetermined voltage is applied to each probe 6, and the resistance value is measured and compared with non-defective product data to conduct a continuity test in the first connection state and the second connection state. Incidentally, in this test, each first pad 2 is short-circuited via the conductive rubber sheet 7. Therefore, the second pad 3, the inner layer pattern 5, the first connection state reaching the first pad 2, the second pad 3,
When the second connection state to the inner layer pattern 5A and the first pad 2 is in a good conduction state and no open occurs, the non-defective data and the number of nets match, indicating that the conduction is good. If an open state occurs due to a conduction failure in the first connection state or the second connection state, it does not match the non-defective data, indicating that the conduction is defective. In addition, the insulation and continuity inspection of the pattern in which the second pad 3 is not connected to the first pad 2 is also performed at the same time. The second inspection step is completed in about 10 seconds.

In the above-mentioned two inspection steps, if insulation failure or conduction failure in the first connection state or the second connection state is detected, it can be determined that the package substrate 1 is a defective product. It is possible to shift to the next inspection of the package substrate 1 without performing the inspection process. As described above, by selecting defective products in advance through the two inspection processes performed earlier, the number of package substrates 1 to be inspected is reduced while eliminating defective products at an early stage, and the package substrates are efficiently reduced. One test can be performed.

In the two inspection steps, the insulation failure of the first connection state and the second connection state of the package substrate 1
If no continuity defect is detected, the process proceeds to the next final inspection step using the flying probe. This inspection process
In each of the above-mentioned two inspection steps, the continuity inspection / insulation inspection of the third connection state, which is not the object of inspection, is performed. First,
As shown in FIG. 4, the package substrate 1 is set in an inspection device equipped with a flying probe 9, and the pair of flying probes 9 are selectively abutted against each first pad 2, and the inner layer pattern 5 is interposed therebetween. A continuity test and an insulation test are performed for each predetermined set of the connected first pads 2. In the electrical inspection in such an inspection process, a predetermined voltage is applied to each flying probe 9, and the measured value of the capacitor capacitance (CAPACITANCE) detected through the flying probe 9 is compared with the measured value of the capacitor capacitance of a normal package substrate. By doing so, the continuity inspection and insulation inspection between the first pads 2 are performed, and the electrical inspection of the package substrate 1 is completed. The third inspection step is completed in about 1 minute.

The time required for the above-mentioned three inspection processes is about 10 seconds for the first inspection process and 1 for the second inspection process.
0, the third inspection step is about 1 minute, and the total inspection time is about 1.5 minutes. Therefore, the inspection time required for performing all the inspection steps via the flying probe 9 is about 3 minutes. Compared with the above, the electrical inspection of the package substrate 1 can be performed in about half the inspection time. Further, the first inspection step, the second inspection step, and the third inspection step can be performed in parallel with each other, and in such a case, the inspection time can be further shortened.

As described above in detail, in the inspection method of the package substrate 1 according to the present embodiment, the first connection state formed between the first pad 2, the inner layer pattern 5 and the second pad 3, and the first pad 2, net-shaped inner layer pattern 5A,
The insulation test of the second connection state formed between the second pads 3 is performed through an inexpensive inspection jig in a state where the probe 6 is in contact with the second pad 3, and the first connection state and the second connection state are checked. For the continuity test of the connection state, the probe 6 is connected to the second pad 3.
And the conductive rubber sheet 7 is in contact with the entire first pad 2 through an inexpensive inspection jig, and is further formed between each first pad 2 and the inner layer pattern 5. Since the continuity inspection / insulation inspection of the third connection state is performed via the flying probe 9, the inspection by the flying probe 9 which requires an inspection time is minimized, and an inexpensive inspection device and inspection jig are used. Therefore, the electrical inspection of the package substrate 1 can be efficiently performed in a short time. It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various improvements and modifications can be made without departing from the gist of the present invention.

For example, in the above embodiment, the probe is directly contacted with the pad to perform the inspection.
After the solder bump is formed on the pad, the probe may be brought into contact with the bump to perform the inspection. This is to prevent a crack from occurring in, for example, a photo via pad when the probe comes into contact with the pad. Further, it is because the reliability can be assured by performing the inspection using the probe in the final step (a state close to the shipping state). After forming the solder bump on the pad and flattening the solder bump,
An inspection is performed with the probe abutting the flattened solder bump. Further, the fixture insulation test, the continuity test with the fixture and the conductive rubber, and the capacitor capacitance measurement test with the flying probe are performed when the pads have different shapes (for example, Au-plated pads without solder bumps, solder bumps are formed). Pad, a pad having solder bumps formed thereon and flattened), and the inspection sequence thereof can be freely determined.

[0026]

As described above, the method of inspecting a package substrate according to the present invention exists between the first pad for flip chip mounting and the second pad for BGA or LGA on the package substrate, and has a net structure. In consideration of various connection states between the first pad and the second pad based on the derived inner layer pattern, an electric test is efficiently performed in a short time even when a low-cost test device or test jig is used. It is possible to provide a method of inspecting a package substrate capable of performing the above. In addition, a multichip package (MCM) substrate as well as a single chip package can be efficiently inspected.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view schematically showing a package substrate.

FIG. 2 is a partial cross-sectional view of the package substrate schematically showing a state where an insulation test is being performed in a first connection state and a second connection state.

FIG. 3 is a partial cross-sectional view of the package substrate schematically showing a state in which a continuity test is performed in a first connection state and a second connection state.

FIG. 4 is a partial cross-sectional view of the package substrate schematically showing a state in which a continuity test and an insulation test in a third connection state are being performed;

FIG. 5 is an explanatory diagram for explaining an insulation test of a connection state in which a first pad and a second pad are connected in a one-to-one correspondence via an inner layer pattern in a conventional package substrate.

FIG. 6 is an explanatory diagram for explaining a continuity test of a connection state in the package substrate shown in FIG. 5;

[Explanation of symbols]

 1 Package Substrate 2 First Pad 3 Second Pad 4 Interlayer Insulation Layer 5 Inner Layer Pattern 5A Net Inner Layer Pattern 6 Probe 7 Conductive Rubber Sheet 9 Flying Probe

Claims (2)

[Claims] 1. An inspection method for electrically inspecting a package substrate having a plurality of first pads and a plurality of second pads formed thereon, wherein a detection signal is sent to the probe while the fixture probe is in contact with the second pad. And performing a test based on the detection signal detected through the probe, and outputting the detection signal to the probe with the fixture probe contacting the second pad and the first pads being short-circuited. A step of performing an inspection based on a detection signal detected through the probe, and outputting a detection signal to the flying probe in a state in which the flying probe is in contact with the first pad for a pattern that is not an inspection target in each step. And inspecting the package substrate based on a detection signal detected through the flying probe. 2. The inspection of a package substrate according to claim 1, wherein the first pad is a pad for mounting a semiconductor chip, and the second pad is a pad for a ball grid array or a land grid array. Method.