JP2022015730A - Inspection method for wiring net and wiring board - Google Patents

Abstract

To provide an inspection method capable of detecting disconnection even by the electrostatic capacity method in the electrical inspection of a wiring net and to provide a wiring board that makes it easy to detect disconnection.SOLUTION: Nondefective product determination is executed on a wiring net according to the time required until a voltage generated between the wiring net and an external electrode reaches a prescribed value in applying a DC voltage between the wiring net and the external electrode.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for inspecting a wiring board, and relates to a method for detecting disconnection of wiring and vias, and a wiring board having a structure that facilitates inspection.

The semiconductor package is assembled by electrically joining the semiconductor component and the wiring board via solder or the like. In recent years, semiconductor parts have become expensive due to the high functionality of semiconductor parts such as HBM (High Band Memory). Therefore, it is essential that the wiring board on which the semiconductor component is mounted is a good product, and the method of electrically inspecting the wiring net in the wiring board for ensuring the quality of the wiring board is very important.
Here, in the present specification, the "wiring net" refers to a series of net configurations of electrical connection including a wiring layer and vias from one electrode to another electrode. One or more wiring nets are formed on one wiring board.

Conventionally, the following two methods have been adopted as the electrical inspection method of the wiring board, and each method is used properly according to the situation.
As shown in FIG. 1, the first method is a wiring net in which one of the pair of continuity check probes 41a and 41b to which a certain DC voltage is applied is formed on the wiring board 42. In addition to contacting the electrode 44a on the 43, the other probe 41b is brought into contact with the electrode 44b on the other side of the wiring net 43. The first method is a method of determining the conduction state of the wiring net 43 based on whether a current flows between the probes 41a and 41b, and is called an IV method.

In the second method, as shown in FIG. 2, of the pair of continuity check probes 41a and 41b to which an AC voltage is applied, one of the probes 41a is placed on the wiring net 43 formed on the wiring board 42. It is brought into contact with a certain electrode 44a and the other probe 41b is brought into contact with an external electrode 45 provided outside the wiring board 42. The second method is a method of determining the conduction state of the wiring net 43 based on the capacitance generated between the wiring net 43 and the external electrode 45, and is called a capacitance method.

As a conventional technique using the capacitance method, for example, there is a technique described in Patent Document 1. In the method described in Patent Document 1, wiring is inspected by comparing the ratio of the voltage applied between a pair of continuity check probes and the voltage drop generated by the capacitance.

Japanese Unexamined Patent Publication No. 4-244976

In the IV method and the capacitance method, it is possible to detect a disconnection / short circuit of the wiring net 43.
Here, in a high-end semiconductor package using an expensive semiconductor component, the disconnection of the wiring net also greatly affects the quality. In the IV method, a method of comparing the resistance value calculated from the current and the voltage with a non-defective product is adopted in order to detect the disconnection of the wiring net.
On the other hand, the capacitance method has a problem that it is difficult to detect the disconnection because the capacitance does not easily change even if the disconnection occurs.

The present invention has been made in view of such a problem, and in the electrical inspection of the wiring net, an inspection method capable of detecting the disconnection even by the capacitance method, and a wiring board in which the disconnection can be easily detected. The purpose is to provide.

In order to solve the problem, one aspect of the present invention is a wiring substrate including a plurality of wiring layers laminated via an insulating layer and vias penetrating the insulating layer to electrically connect the wiring layers. This is an inspection method for inspecting the continuity of a wiring net composed of a wiring layer and a via from the electrostatic capacitance between the wiring net and an external electrode, and a voltage is applied between the wiring net and the external electrode. It is characterized in that a good product is determined for disconnection of the wiring net based on the time required for the voltage generated between the wiring net and the external electrode when applied to reach a preset value.

Further, another aspect of the present invention is a wiring net composed of a plurality of wiring layers laminated via an insulating layer and a plurality of vias penetrating the insulating layer and electrically connecting the plurality of wiring layers. The wiring board is provided, and the cross-sectional area of the wiring portion to be inspected for disconnection in the same wiring net is smaller than the cross-sectional area of other positions.

According to the aspect of the present invention, in the electrical inspection of the wiring net, it is possible to provide an inspection method capable of detecting the disconnection even by the capacitance method, and a wiring board in which the disconnection can be easily detected.

It is a schematic diagram explaining the electrical inspection method of the wiring board using the IV method. It is a schematic diagram explaining the electrical inspection method of the wiring board using the capacitance method. It is a schematic diagram of the electrical inspection method of the wiring board using the capacitance method which concerns on embodiment based on this invention. It is a figure explaining the wiring quality determination method of the electrical inspection method of the wiring board using the capacitance method which concerns on embodiment based on this invention. It is a figure explaining the detection accuracy improvement method of the electric inspection method of the wiring board using the capacitance method which concerns on embodiment based on this invention. It is sectional drawing of the modification 1 of the electric inspection method of the wiring board which used the capacitance method which concerns on embodiment based on this invention. It is sectional drawing of the modification 2 of the electric inspection method of the wiring board which used the capacitance method which concerns on embodiment based on this invention. It is sectional drawing of the modification 3 of the electric inspection method of the wiring board which used the capacitance method which concerns on embodiment based on this invention.

Hereinafter, embodiments of the invention will be described with reference to the drawings.
In each drawing, the same components may be designated by the same reference numerals and duplicate explanations may be omitted.

(Structure of wiring board)
First, the structure of the wiring board 42 according to the first embodiment will be described.
FIG. 3 is a schematic diagram illustrating an electrical inspection method of a wiring board according to the first embodiment, and is a diagram showing an outline of an inspection of wiring stakes according to the present invention.
Similar to the wiring board shown in FIG. 2, the wiring board 42 shown in FIG. 3 includes a plurality of wiring layers 52 laminated via an insulating layer 51 and vias penetrating the insulating layer 51 to electrically connect the wiring layers. , Equipped with. In the example of FIG. 3, the case of having two wiring layers is illustrated, but the present invention is not limited to this.

As shown in FIG. 3, the via of the present embodiment electrically connects the adjacent wiring layers and the upper wiring layer and the upper electrode 44a, and the lower wiring layer and the lower electrode 44b. The wiring net 43 is configured. In FIG. 3, one wiring net is illustrated.
Any layer such as another wiring layer, an insulating layer, via wiring, and a core layer can be formed on the upper layer of the insulating layer.
The lower layer of the insulating layer 51 may include a layer containing a resin as a main component, a layer containing silicon as a main component, a layer containing ceramic as a main component, and the like.

<Insulation layer>
Each insulating layer 51 (see FIG. 2) is formed of, for example, an insulating resin containing an epoxy resin or a polyimide resin as a main component. As the insulating resin, for example, a thermosetting insulating resin or a photosensitive insulating resin can be used.
The thickness of each insulating layer 51 can be, for example, about 3 to 35 μm. The insulating layer 51 may contain a filler such as silica (SiO ₂ ). The thickness of each of the laminated insulating layers is preferably equal.
The wiring board 42 may be composed of a build-up layer made of a thermosetting insulating resin or a photosensitive insulating resin in the upper layer of the insulating layer 51, or may be a thermosetting insulating layer. Both of the build-up layers of the sex resin or the photosensitive insulating resin may be present.

<Wiring layer>
The wiring layer 52 (see FIG. 2) is patterned in a predetermined planar shape on the upper layer of each insulating layer 51. As the material of the wiring layer 52, for example, copper (Cu) or the like can be used. The thickness of the wiring layer 52 can be, for example, about 1 to 15 μm. The wiring layer 52 is connected to a lower wiring layer via a via 53 or the like.

<Electrode>
The electrodes 44a and 44b (see FIG. 2) are formed with an insulating layer 51 located on the outermost side of the wiring board 42, and can be electrically connected to an electronic component such as a semiconductor chip.
The electrodes 44a and 44b may have a protruding shape, a flat shape, or a concave shape with respect to the surface of the insulating layer 51.
As the material of the electrodes 44a and 44b, for example, copper (Cu) can be used. Further, for the formation of the electrodes 44a and 44b, for example, a well-known semi-additive method can be used. Further, for the formation of the electrodes 44a and 44b, for example, a well-known subtractive method may be used.

<Wiring net inspection method>
In the inspection method of the present embodiment, as shown in FIG. 3, the wiring board 42 having the above configuration is installed on the external electrode 45. At this time, a gap is provided between the wiring net 43 and the external electrode 45, and both 42 and 45 are electrically insulated.
Then, in the inspection method of the present embodiment, as shown in FIG. 3, a pulse voltage Vin is applied between the electrode 44a and the external electrode 45. When the pulse voltage Vin is applied, the voltage Vout applied to the capacitive component Cout generated between the wiring net 43 and the external electrode 45 increases with time from the start of application.

The rise time of the voltage Vout applied to the capacitance component Cout is proportional to the product of the resistance value R of the wiring net 43 and the capacitance component Cout. The product of the resistance value R and the capacitance component Cout is called the time constant τ, and is a value representing the characteristics of the response speed of the element having a capacitance.
Here, when the wiring net 43 is about to be disconnected, the resistance value of the wiring net 43 increases from R and has the resistance value of R1. For example, when a part of the wiring net 43 is broken, the resistance value R of the wiring net 43 increases, so that the rising time of the voltage Vout increases proportionally as shown by the broken line in FIG.
By comparing this rise time with that of the normal part, it is possible to detect the disconnection.

In the inspection method of the present embodiment, based on the above findings, the voltage generated between the wiring net 43 and the external electrode 45 when a voltage is applied between the wiring net 43 and the external electrode 45 is set in advance. Based on the time required to reach the specified value, a good product is judged for the disconnection of the wiring net.
For example, the rise time to a predetermined voltage on a wiring net judged to be a non-defective product is obtained, and the rise time on the wiring net on the board to be inspected is set to a predetermined time or more by using the rise time as a reference time. If it is large, it is judged as a defective product.
The voltage Vin applied between the electrode 44a and the external electrode 45 may be repeated not only once but also a plurality of times. As shown in FIG. 5, the voltage Vin is applied as a continuous pulse voltage and the rise time is sampled a plurality of times. This makes it possible to detect the disconnection more accurately. That is, the inspection is continuously executed a plurality of times for one wiring net. Then, by performing statistical processing on the results of the plurality of inspections, it is possible to determine whether or not the wire is broken.

(Modification 1)
In order to improve the inspection accuracy of the inspection method of the present embodiment, it is desirable that the difference in the resistance value R1 of the wiring net 43 in which the disconnection is about to occur is larger than that of the resistance value R of the wiring net 43.
In order to realize this, in the first modification, the wiring net configured on the wiring board is configured to have vias having a diameter different from that of the other vias in a plurality of vias constituting the same wiring net. For example, in a plurality of vias constituting the same wiring net, the vias formed in the insulating layer for inspecting the disconnection of the vias are vias having different diameters, and the vias formed in the insulating layer for inspecting the disconnection of the vias. The diameter A1 is smaller than the diameter A2 of other vias in the same wiring net.

For example, as shown in FIG. 6, in the first modification, the vias 53a, 53b, and 53c constituting the wiring net 43 have vias 53b having different diameters in the same wiring net, and the vias have different diameters. The via diameter φ1 of the inspection target via 53b formed on the insulation layer to be inspected (the middle insulating layer in FIG. 6) and the via diameter φ2 of the other inspection accuracy improving vias 53a and 53c are φ1 <φ2. The structure.
In FIG. 6, the inspection target via 53b is formed on the second insulating layer from the top in the figure, but the present invention is not limited to this.

Although only one wiring net is shown in FIG. 6, for example, a plurality of wiring nets 43 having the same structure may be formed for all the insulating layers 51. That is, the via diameter A1 formed in the insulating layer for inspecting the disconnection of the via has a plurality of wiring nets smaller than the diameter A2 of other vias in the same wiring net, and each of the plurality of insulating layers has a smaller diameter A1. Vias having different diameters may be individually arranged, and each insulating layer may be an insulating layer for inspecting the disconnection of the vias.
In this modification 1, the resistance value r1 of the inspection target via 53b and the resistance value r2 of the inspection accuracy improving vias 53a and 53c are configured such that r1> r2, so that the inspection target via 53b is about to be disconnected. Since the change in the resistance value of the wiring net 43 can be highlighted, the inspection accuracy can be improved.

(Modification 2)
Modification 2 is a wiring board including a wiring net composed of a plurality of wiring layers laminated via an insulating layer and vias that penetrate the insulating layer and electrically connect the plurality of wiring layers. In the same wiring net, the number of vias electrically formed in parallel on one insulating layer and the number of vias formed electrically in parallel on another insulating layer are different.
For example, in the same wiring net, the number N1 of the vias in the insulating layer for inspecting the disconnection of the vias is smaller than the number N2 of the vias formed in the other insulating layer. At this time, for example, the number N1 of the vias in the insulating layer for inspecting the disconnection of the vias is set to one.

For example, in the second modification, as a method for improving the inspection accuracy of the inspection method, as shown in FIG. 7, the vias 53a, 53b, 53c constituting the same wiring net 43 are formed in the same insulating layer. The number N of vias has an insulating layer different from that of other insulating layers, and the number N1 of the vias 53b to be inspected formed on the insulating layer to be inspected (the insulating layer in the middle of FIG. 7) and the other insulating layers. The structure is such that the number N2 of the formed vias 53a and 53c is N1 <N2.
In FIG. 7, the via 53b to be inspected is formed on the second insulating layer from the top in the figure, but the present invention is not limited to this. A plurality of wiring nets 43 having the same structure may be formed for all the insulating layers 51.

Also in the second modification, when the resistance value r1 of the inspection target via 53b and the resistance value r2 of the inspection accuracy improving vias 53a and 53c are such that r1> r2, the inspection target via 53b is about to be disconnected. Since the change in the resistance value of the wiring net 43 can be highlighted, the inspection accuracy can be improved.

(Modification 3)
Modification 3 is a wiring board including a wiring net composed of a plurality of wiring layers laminated via an insulating layer and vias that penetrate the insulating layer and electrically connect the plurality of wiring layers. The configuration is such that wiring layers having different cross-sectional areas are provided in the same wiring net. For example, in the same wiring net, the cross-sectional area S1 of the wiring layer for inspecting the disconnection of the wiring is smaller than the cross-sectional area S2 of the other wiring layers.
In order to improve the inspection accuracy of the inspection method of the embodiment, it is desirable that the difference in the resistance value R1 of the wiring net 43 in which the disconnection is about to occur is larger than the resistance value R of the wiring net 43.

For example, in the third modification, in order to realize this, as shown in FIG. 8, among the wiring layers 54a and 54b constituting the same wiring net 43, the wiring layers 54b having different cross-sectional areas are provided and are to be inspected. The structure has a wiring layer 54a to be inspected and other wiring layers 54b for improving inspection accuracy formed in the wiring layer of the above, and the cross-sectional area S1 of the wiring layer 54a to be inspected and the cross-sectional area S2 of the wiring layer 54b are S1 <S2. Is adopted.
In FIG. 8, the wiring layer 54a to be inspected is formed on the second insulating layer from the top in the figure, but the present invention is not limited to this.

A plurality of wiring nets 43 having the same structure may be formed for all the insulating layers 51. Although only one wiring net is shown in FIG. 8, for example, the cross-sectional area S1 of the inspection wiring layer, which is a wiring layer for inspecting the disconnection of wiring in the same wiring net, is the cross-sectional area of another wiring layer. A plurality of wiring nets smaller than S2 may be provided, the inspection wiring layer may be individually arranged for each wiring layer, and each wiring layer may be a wiring layer for inspecting the wiring.
Also in the modified example 3, the resistance value r1 of the wiring layer to be inspected and the resistance value r2 of the wiring layer for improving inspection accuracy are configured to be r1> r2, so that the wiring when the wiring layer to be inspected is about to be disconnected. Since the change in the resistance value of the net 43 can be highlighted, the inspection accuracy can be improved.

<Others>
Here, the above-described embodiment and modification are not limited to this, but the structure is such that the resistance value r1 of the wiring layer 52a to be inspected and the resistance value r2 of the wiring layer 52b for improving inspection accuracy are r1> r2. It is desirable to do so, and the change in the resistance value of the wiring net 43 when the wire is about to be broken can be highlighted, so that the inspection accuracy can be improved.

(effect)
According to the wiring board inspection method and the wiring board of the embodiment according to the present invention, it is possible to detect the disconnection of the wiring by the capacitance method.

(1) In the present embodiment, the wiring layer and the vias in a wiring board including a plurality of wiring layers laminated via an insulating layer and vias penetrating the insulating layer to electrically connect the wiring layers. This is an inspection method for inspecting the continuity of a wiring net composed of the above from the capacitance between the wiring net and the external electrode, and when a voltage is applied between the wiring net and the external electrode, A good product is determined for disconnection of the wiring net based on the time required for the voltage generated between the wiring net and the external electrode to reach a preset value.
According to this configuration, even if the capacitance method is adopted, it is possible to detect the disconnection.

(2) The voltage applied between the wiring net and the external electrode is preferably a pulse voltage.
By setting the applied voltage as a pulse voltage, it is possible to keep the fluctuation of the rise time small.

(3) The voltage applied between the wiring net and the external electrode is preferably a continuous pulse voltage.
With this configuration, it is possible to improve the detection accuracy.

(4) The wiring board of the present embodiment is composed of, for example, a plurality of wiring layers laminated via an insulating layer and a plurality of vias penetrating the insulating layer and electrically connecting the plurality of wiring layers. It is preferable that the wiring board includes a wiring net and has a via having a diameter different from that of the other vias in a plurality of vias constituting the same wiring net.
According to this configuration, the electric resistance of the via having a relatively small via diameter is set high, and it becomes easy to detect the disconnection in the specific via.

(5) At this time, in the plurality of vias constituting the same wiring net, the vias formed in the insulating layer for inspecting the disconnection of the vias are vias having different diameters, and the insulating layer for inspecting the disconnection of the vias. It is preferable that the diameter A1 of the via formed in the above is smaller than the diameter A2 of other vias in the same wiring net.
According to this configuration, the detection accuracy can be improved by highlighting the change in the resistance value of the wiring net when the via to be inspected is about to be disconnected.

(6) Further, the via diameter A1 formed in the insulating layer for inspecting the disconnection of the via has a plurality of wiring nets smaller than the diameter A2 of other vias in the same wiring net, and the plurality of insulating layers have a plurality of wiring nets. On the other hand, it is preferable that vias having different diameters are individually arranged, and each insulating layer serves as an insulating layer for inspecting the disconnection of the via. The configuration of the plurality of wiring nets is preferably the same except for the detection via diameter.
According to this configuration, it is possible to improve the detection accuracy of the disconnection of the via formed in each insulating layer.

(7) In the present embodiment, the wiring board includes a wiring net composed of a plurality of wiring layers laminated via an insulating layer and vias that penetrate the insulating layer and electrically connect the plurality of wiring layers. Therefore, in the same wiring net, the number of vias electrically formed in parallel in one insulating layer may be different from the number of vias formed in parallel in another insulating layer.
According to this configuration, the electric resistance of the via having a relatively small via diameter is set high, and it becomes easy to detect the disconnection in the specific via.

(8) At this time, in the same wiring net, it is preferable to have a wiring net in which the number N1 of the vias in the insulating layer for inspecting the disconnection of the vias is smaller than the number N2 of the vias formed in the other insulating layer. For example, the number N1 of the vias in the insulating layer for inspecting the disconnection of the vias is one.
According to this configuration, the detection accuracy can be improved by highlighting the change in the resistance value of the wiring net when the via to be inspected is about to be disconnected.

(9) In the present embodiment, the wiring board includes a wiring net composed of a plurality of wiring layers laminated via an insulating layer and vias that penetrate the insulating layer and electrically connect the plurality of wiring layers. Therefore, a configuration may be configured in which wiring layers having different cross-sectional areas are provided in the same wiring net.
According to this configuration, the electric resistance of the wiring layer having a relatively small cross-sectional area is set high, and it becomes easy to detect the disconnection in the specific wiring layer.

(10) At this time, it is preferable that the cross-sectional area S1 of the wiring layer for inspecting the disconnection of the wiring is smaller than the cross-sectional area S2 of the other wiring layers in the same wiring net.
According to this configuration, the detection accuracy can be improved by highlighting the change in the resistance value of the wiring net when the wiring layer to be inspected is about to be disconnected.

(11) Further, in the same wiring net, the cross-sectional area S1 of the inspection wiring layer, which is a wiring layer for inspecting the disconnection of the wiring, has a plurality of wiring nets smaller than the cross-sectional area S2 of the other wiring layers, and each wiring. The inspection wiring layer may be individually arranged with respect to the layer, and each wiring layer may be a wiring layer for inspecting the wiring. The configuration of the plurality of wiring nets is preferably the same except for the cross-sectional area of the wiring layer.
According to this configuration, it is possible to improve the detection accuracy of the disconnection of the wiring layer formed in each insulating layer.

20 Wiring layer 41a, 41b Conduction check probe 42 Wiring board 43 Wiring net 44a, 44b Electrode 45 External electrode 51 Insulation layer 52, 54a, 54b Wiring layer 53 Via

Claims (12)

Continuity of a wiring net composed of the wiring layer and the via in a wiring board including a plurality of wiring layers laminated via an insulating layer and vias penetrating the insulating layer to electrically connect the wiring layers. Is an inspection method for inspecting from the capacitance between the wiring net and the external electrode.
When a voltage is applied between the wiring net and the external electrode, the wiring net is disconnected depending on the time required for the voltage generated between the wiring net and the external electrode to reach a preset value. A method of inspecting a wiring net, which is characterized by making a judgment on a non-defective product. The method for inspecting a wiring net according to claim 1, wherein the voltage applied between the wiring net and the external electrode is a pulse voltage. The method for inspecting a wiring net according to claim 1 or 2, wherein the voltage applied between the wiring net and the external electrode is a continuous pulse voltage. A wiring board provided with a wiring net composed of a plurality of wiring layers laminated via an insulating layer and a plurality of vias penetrating the insulating layer and electrically connecting the plurality of wiring layers.
A wiring board characterized by having vias having a diameter different from that of other vias in a plurality of vias constituting the same wiring net. In the plurality of vias constituting the same wiring net, the vias formed in the insulating layer for inspecting the disconnection of the vias are vias having different diameters.
The wiring board according to claim 4, wherein the diameter A1 of the via formed in the insulating layer for inspecting the disconnection of the via is smaller than the diameter A2 of another via in the same wiring net. The via diameter A1 formed in the insulating layer for inspecting the disconnection of the via has a plurality of wiring nets smaller than the diameter A2 of other vias in the same wiring net.
The wiring board according to claim 4, wherein vias having different diameters are individually arranged for each of the plurality of insulating layers, and each insulating layer serves as an insulating layer for inspecting the disconnection of the vias. A wiring board provided with a wiring net composed of a plurality of wiring layers laminated via an insulating layer and a via that electrically connects the plurality of wiring layers through the insulating layer.
A wiring board characterized in that the number of vias electrically formed in parallel on one insulating layer and the number of vias electrically formed in parallel on another insulating layer are different in the same wiring net. The wiring according to claim 7, wherein in the same wiring net, the number N1 of vias in the insulating layer for inspecting the disconnection of the vias has a wiring net smaller than the number N2 of vias formed in the other insulating layer. substrate. The wiring board according to claim 8, wherein the number N1 of the vias in the insulating layer for inspecting the disconnection of the vias is one. A wiring board provided with a wiring net composed of a plurality of wiring layers laminated via an insulating layer and a via that electrically connects the plurality of wiring layers through the insulating layer.
A wiring board characterized by having wiring layers having different cross-sectional areas in the same wiring net. The wiring board according to claim 10, wherein the cross-sectional area S1 of the wiring layer for inspecting the disconnection of the wiring in the same wiring net is smaller than the cross-sectional area S2 of the other wiring layers. In the same wiring net, the cross-sectional area S1 of the inspection wiring layer, which is a wiring layer for inspecting the disconnection of wiring, has a plurality of wiring nets smaller than the cross-sectional area S2 of other wiring layers.
The wiring board according to claim 11, wherein the inspection wiring layer is individually arranged for each of the plurality of wiring layers, and each wiring layer serves as a wiring layer for inspecting the wiring.

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