CN114846336A

CN114846336A - Probe sheet and method for manufacturing probe sheet

Info

Publication number: CN114846336A
Application number: CN202080082481.9A
Authority: CN
Inventors: 石松朋之
Original assignee: Dexerials Corp
Current assignee: Dexerials Corp
Priority date: 2019-11-26
Filing date: 2020-11-19
Publication date: 2022-08-02
Also published as: JP2021086676A; KR20220082085A; TW202129280A; WO2021106754A1

Abstract

The invention provides a probe sheet and a method for manufacturing the probe sheet, wherein excellent anisotropy and durability can be obtained even for a terminal with a fine pitch. The probe sheet is provided with: a flexible sheet (10) having a plurality of through-holes; a first elastomer layer (20) disposed on one surface of the flexible sheet (10); a second elastomer layer (30) disposed on the other surface of the flexible sheet; and a locking section (40) formed by interlocking the conductive particles in the thickness direction from the surface of the first elastic body layer (20) to the surface of the second elastic body layer (30) through the through-hole.

Description

Probe sheet and method for manufacturing probe sheet

Technical Field

The present technology relates to a probe sheet for inspecting electrical characteristics of a wafer, a chip, a package, and the like, and a method for manufacturing the probe sheet. The present application claims priority based on japanese patent application No. japanese patent application 2019-213062, filed in japan on 11/26/2019, which is hereby incorporated by reference.

Background

Conventionally, in the evaluation of electrical characteristics of semiconductor devices such as bare chip (bare chip) and Package (PKG), a handler test (handler test) using a rubber connector has been performed. As a rubber connector serving as a probe sheet, for example, an anisotropic conductive sheet in which conductive particles oriented by a magnetic field are arranged to penetrate in the thickness direction of an elastomer sheet has been proposed (for example, see patent document 1).

However, for example, in the case of inspecting a BGA (ball grid array) package, the stroke of the probe sheet needs to be about 80 μm in order to cope with the height variation of the solder electrodes, and in the anisotropic conductive sheet in which the elastic layer is one layer, the thickness of the inspection sheet needs to be 400 μm or more in order to exhibit the stroke, and the limit of the pitch of the arrangement of the conductive particles is 300 μm. Further, when the conductive particles are oriented by a magnetic field, it is necessary to orient the conductive particles while keeping a certain degree of spacing due to the relationship of overlapping magnetic flux densities, and it is therefore difficult to cope with the recent fine pitch of the semiconductor chip.

In the anisotropic conductive sheet described in patent document 1, a frame is attached so as to surround the periphery for the purpose of improving durability, but an elastic body inside the frame expands and contracts due to heat history, and therefore, a defective inspection due to misalignment may occur.

Further, a three-layer sheet laminate in which conductive particles are oriented in the thickness direction in an elastic substance has also been proposed (for example, see patent document 2).

However, in the probe sheet described in patent document 2, since the intermediate layer is also made of an elastic material and the conductive particles are oriented by a magnetic field, the thicker the thickness of the elastic material layer is, the more easily the particles are connected to the adjacent electrodes, and short-circuiting is induced. Therefore, it is difficult to cope with fine pitches. On the other hand, when the elastic material layer is made thin, the stroke characteristics are degraded and the durability is also degraded. Further, the elastic material expands or contracts due to the thermal history, and thus an inspection failure due to misalignment may occur.

In recent years, PKG and semiconductor chips have been increasingly finer in pitch, and conventional probe sheets have come to the limit. In addition, in the actual case, inspection is not performed on some of the semiconductor chips, inspection and screening are performed on the PKGs after assembly, and as a result, the yield is extremely deteriorated and the price cannot be lowered. Therefore, there is a strong demand for a probe sheet capable of coping with further fine pitches.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-024580

Patent document 2: japanese laid-open patent publication No. 2015-501427

Disclosure of Invention

Problems to be solved by the invention

The present technology has been made in view of such circumstances, and provides a probe sheet and a method for manufacturing the probe sheet, which can obtain excellent anisotropy and durability even for a fine pitch terminal.

Means for solving the problems

In order to solve the above problem, a probe sheet according to the present technology includes: a flexible sheet having a plurality of through holes; a first elastomer layer disposed on one surface of the flexible sheet; a second elastomer layer disposed on the other surface of the flexible sheet; and an interlocking section formed by interlocking conductive particles in a thickness direction from the surface of the first elastic body layer to the surface of the second elastic body layer through the through-hole.

Further, a method for manufacturing a probe sheet according to the present technology includes: a disposing step of disposing a first uncured resin layer made of an elastomer uncured composition containing conductive particles on one surface of a flexible sheet having a plurality of through holes, and disposing a second uncured resin layer made of an elastomer uncured composition containing conductive particles on the other surface of the flexible sheet; an orientation step of applying a magnetic field or an electric field from the outside of the first uncured resin layer and the second uncured resin layer to orient the conductive particles in the thickness direction through the through-holes from the surface of the first uncured resin layer to the surface of the second uncured resin layer; and a curing step of curing the first uncured resin layer and the second uncured resin layer in a state in which the conductive particles are oriented, thereby forming an elastomer layer on both surfaces of the flexible sheet.

Effects of the invention

According to the present technology, excellent anisotropy and durability can be obtained even for a fine pitch terminal.

Drawings

Fig. 1 is a cross-sectional view showing an example of the structure of a probe sheet.

Fig. 2 is a sectional view schematically showing a state where both sides of a flexible sheet are coated with an elastomer uncured composition.

Fig. 3 is a cross-sectional view schematically showing a state in which conductive particles are oriented in the thickness direction through the through-holes from the surface of the first uncured layer to the surface of the second uncured resin layer.

Detailed Description

Hereinafter, embodiments of the present technology will be described in detail in the following order with reference to the drawings.

1. Probe sheet

2. Method for manufacturing probe sheet

3. Examples of the embodiments

< 1. Probe sheet >

The probe sheet of the present embodiment includes: a flexible sheet having a plurality of through holes; a first elastomer layer disposed on one surface of the flexible sheet; a second elastomer layer disposed on the other surface of the flexible sheet; and an interlocking section formed by interlocking the conductive particles in the thickness direction from the surface of the first elastic body layer to the surface of the second elastic body layer through the through-hole. The flexible sheet has a plurality of through holes, and the conductive particles are inserted through the through holes in a chain manner in the thickness direction to obtain anisotropy, and the flexible sheet can also cope with fine pitches of semiconductor chips. Further, by dividing the elastic body layer into two layers by the flexible sheet, more excellent durability can be obtained than a probe sheet in which the elastic body layer is one layer.

Fig. 1 is a cross-sectional view showing an example of the structure of a probe sheet. As shown in fig. 1, the probe sheet includes: flexible sheet 10, first elastomer layer 20, second elastomer layer 30, and interlocking portion 40.

The flexible sheet 10 has a through hole 11 at a predetermined position in a plan view. The through holes 11 may be arranged so as to correspond to the terminal positions of the PKG and the semiconductor chip to be inspected, or may be formed at regular fine pitches with a predetermined interval smaller than that of the terminals, so that the inspection can be performed without alignment (alignment free).

As the flexible sheet 10, one selected from the group of polyimide, polyamide, polyethylene naphthalate, and biaxially oriented polyethylene terephthalate is preferably used. These resins have a low thermal expansion coefficient and excellent heat resistance, and therefore can suppress the occurrence of expansion and contraction due to heat history, suppress the positional shift of conductive particles, and further cope with fine pitches.

The lower limit of the thickness of the flexible sheet 10 is preferably 5 μm, more preferably 10 μm, and further preferably 20 μm. The upper limit of the thickness of the flexible sheet 10 is preferably 100 μm, more preferably 80 μm, and still more preferably 60 μm. If the thickness of the flexible sheet 10 is too small, the durability is reduced, and if it is too large, the through-holes 11 are difficult to form.

The through-hole 11 is formed in the thickness direction of the flexible sheet 10. The size of the through-hole 11 is set according to the PKG to be inspected and the terminal of the semiconductor chip, and for example, the lower limit of the diameter of the through-hole 11 is preferably 5 μm, more preferably 10 μm, and further preferably 15 μm, and the upper limit of the diameter of the through-hole 11 is preferably 50 μm, more preferably 35 μm, and further preferably 25 μm.

When the through holes 11 are formed in a lattice shape, the pitch is preferably 2 times or more the average particle diameter of the conductive particles, more preferably 5 times or more the average particle diameter of the conductive particles, and still more preferably 8 times or more the average particle diameter of the conductive particles. This makes it possible to obtain an appropriate distance from the adjacent interlocking section 40 and excellent anisotropy.

The flexible sheet 10 may have a metal layer on one or both surfaces of the outer peripheral portion. By providing the metal layer on the outer peripheral portion, the base material can be reinforced, and thermal expansion can be reduced. Further, the first or second elastic layer is in contact with a part of the metal layer, whereby the strength can be further increased. Alternatively, the side surface of the through hole 11 may be chemically plated with a metal, and the metal layer may be provided on the side surface of the through hole 11. By forming the metal layer on the side surface of the through hole, the conductivity of the interlocking portion 40 can be improved, and the durability can be improved.

First elastomer layer 20 is disposed on one surface of flexible sheet 10, and in a plan view, a linkage portion 40 formed by linking conductive particles in the thickness direction from the point of passing through hole 11 to the surface is disposed at the position of through hole 11.

The material of the first elastomer layer 20 may be any material as long as it has rubber elasticity, and preferably has heat resistance. Examples of the material of the first elastomer layer 20 include: silicone resin, polyurethane resin, acrylic resin, and the like. Among them, silicone resin which is less likely to have residues adhering to PKG and semiconductor chips after inspection is preferably used.

The lower limit of the thickness of the first elastomer layer 20 is preferably 5 μm, more preferably 20 μm, and still more preferably 35 μm. The upper limit of the thickness of the first elastomer layer 20 is preferably 150 μm, more preferably 100 μm, and still more preferably 75 μm. If the thickness of the first elastomer layer 20 is too thin, the durability as a film is reduced, and if it is too thick, the number of particles linked to the conductive particles increases, and the contact resistance between the particles increases.

Preferably, the interlocking part 40 is in the following state: the conductive particles pass through the through-hole 11 and are linked from the surface of the first elastic layer to the surface of the second elastic layer, and the conductive particles at the endmost portion of the linkage are exposed from the surface. The interlocking section 40 may be an interlock in which the conductive particles are in a single layer (1), but in order to reduce the resistance value, it is preferable to form a plurality of interlocks in one through-hole 11.

As the conductive particles, metal particles such as Ni and Cu, or particles obtained by plating metal particles such as Au, Pd, Co, and Ag with metal such as resin cores and inorganic core particles can be used as long as they have conductivity. When the conductive particles are linked by a magnetic field, it is preferable to use a metal or alloy having magnetic properties such as Fe, Co, and Ni. Among them, from the viewpoint of low resistance, conductive particles in which an Au plating layer is applied to the surface of Ni particles or Ni alloy particles are preferably used.

The upper limit of the average particle diameter of the conductive particles is smaller than the size of the through-holes, and is preferably 50 μm or less, more preferably 20 μm or less, and further preferably 10 μm or less. The conductive particles are preferably spherical, polygonal, or spike (spike) shaped, and more preferably have protrusions on the surface thereof for the purpose of reducing contact resistance.

The second elastic layer 30 is disposed on the other surface of the flexible sheet 10, and similarly to the second elastic layer 20, an interlocking portion 40 is disposed at the position of the through hole 11 in a plan view, and the interlocking portion 40 is formed by interlocking the conductive particles in the thickness direction until the conductive particles pass through the through hole 11 to the surface. The material, conductive particles, and interlocking portions of the second elastic layer 30 are the same as the material, conductive particles, and interlocking portions of the first elastic layer 20, respectively, and therefore, description thereof is omitted here.

According to the probe sheet having such a configuration, highly reliable electrical conductivity can be achieved in the thickness direction, and insulation can be achieved in the surface direction between adjacent terminals. Further, by dividing the elastic body layer into two layers by the flexible sheet 10, the interlocking portions can be formed at a fine pitch and more excellent durability can be obtained as compared with a probe sheet in which the elastic body layer is one layer.

< 2. method for manufacturing Probe sheet

The method for manufacturing a probe sheet according to the present embodiment includes: a disposing step of disposing a first uncured resin layer made of an elastomer uncured composition containing conductive particles on one surface of a flexible sheet having a plurality of through holes, and disposing a second uncured resin layer made of an elastomer uncured composition containing conductive particles on the other surface of the flexible sheet; an orientation step of applying a magnetic field or an electric field from the outside of the first uncured resin layer and the second uncured resin layer to orient the conductive particles in the thickness direction through the through-holes from the surface of the first uncured resin layer to the surface of the second uncured resin layer; and a curing step of curing the first uncured resin layer and the second uncured resin layer in a state in which the conductive particles are oriented, thereby forming an elastomer layer on both surfaces of the flexible sheet. Thus, a probe sheet having excellent anisotropy and durability even for a fine pitch terminal can be obtained.

The above-described arrangement step, orientation step, and curing step will be described below.

[ disposing step ]

In the disposing step, a first uncured resin layer made of an elastomer uncured composition containing conductive particles is disposed on one surface of a flexible sheet having a plurality of through holes, and a second uncured resin layer made of an elastomer uncured composition containing conductive particles is disposed on the other surface of the flexible sheet.

Fig. 2 is a sectional view schematically showing a state where both sides of a flexible sheet are coated with an elastomer uncured composition. As shown in fig. 2, the first uncured resin layer and the second uncured resin layer can be disposed by pressing the elastomer uncured composition 50 coated on both sides of the flexible sheet 10. Further, the thicknesses of the first uncured resin layer and the second uncured resin layer may be controlled by disposing gap spacers on both surfaces of the flexible sheet 10.

The elastomer uncured composition 50 is configured by dispersing conductive particles 52 in an uncured resin 51. As the uncured resin 51, for example, an uncured material such as a silicone resin, a urethane resin, an acrylic resin, or the like can be used. Among them, from the viewpoint of heat resistance, two-pack liquid silicone is preferably used. The conductive particles 52 are the same as those described in the probe sheet, and therefore, the description thereof is omitted here.

[ orientation Process ]

Fig. 3 is a cross-sectional view schematically showing a state in which conductive particles are oriented in the thickness direction through the through-holes from the surface of the first uncured layer to the surface of the second uncured resin layer. For example, the first uncured resin layer and the second uncured resin layer are disposed by placing the gap spacer 63 on the first electromagnet 61, applying the elastomer uncured composition 50, disposing the flexible sheet 10 having the through-hole thereon, further placing the gap spacer 63 thereon, applying the elastomer uncured composition 50, and finally covering and pressing the second electromagnet 62. Next, by applying a magnetic field to the first electromagnet 61 and the second electromagnet 62 in a state of being pressed by the first electromagnet 61 and the second electromagnet 62, as shown in fig. 3, the interlocking section 40 can be formed in which the conductive particles 52 are interlocked in the thickness direction through the through-holes from the surface of the first uncured layer to the surface of the second uncured resin layer.

[ curing step ]

In the curing step, the first uncured resin layer and the second uncured resin layer are cured in a state in which the conductive particles 52 are oriented, and an elastomer layer is formed on both surfaces of the flexible sheet 10. The curing conditions in the case of using the two-pack liquid silicone in the elastomer uncured composition 50 are, for example, preferably 50 to 150 ℃ for 0.5 to 2 hours.

According to such a method for manufacturing a probe sheet, the plurality of through holes of the flexible sheet are filled with conductive particles, and the conductive particles are oriented in the thickness direction, whereby anisotropy can be obtained. Further, by dividing the elastic body layer into two layers by the flexible sheet 10, a probe sheet having excellent durability and coping with fine pitches of semiconductor chips can be obtained as compared with a probe sheet having one elastic body layer.

In the above-described method for manufacturing the probe sheet, the first electromagnet 61 and the second electromagnet 62 are used in the orientation step, but a mold in which a magnetic body is disposed at a position facing the through hole of the flexible sheet 10 may be used. In the alignment step, an electric field may be used instead of the magnetic field. When the alignment is performed by an electric field, electrodes may be disposed instead of the electromagnets, and an ac voltage may be applied.

Examples

< 3. example >

Hereinafter, examples of the present technology will be described. In the present example, a probe sheet a as an example and a probe sheet B as a conventional example were produced, and the electrical characteristics of the evaluation substrate were measured using the probe sheet A, B, and insulation evaluation and reliability evaluation were performed. The present technology is not limited to these examples.

[ production of Flexible sheet ]

A polyimide film (Kapton 200EN, manufactured by DU PONT-TORAY) having a thickness of 50 μm was subjected to laser processing to form through holes having a diameter of 20 μm at lattice intervals of 60 μmP, thereby producing a flexible sheet.

[ preparation of an elastomer uncured composition ]

Conductive particles were prepared by applying a gold plating layer to the surface of nickel particles (Type123, available from Vale) having an average particle diameter of 5 μm by displacement electroless plating. The conductive particles were mixed with an elastomer obtained by blending agent A and agent B in a ratio of 1: 1 in a two-pack type liquid silicone (KE-1204A/B, manufactured by shin-Etsu Silicone Co., Ltd.) to prepare an uncured elastomer composition.

< production of Probe sheet A >

A frame of a polytetrafluoroethylene sheet having a thickness of 50 μm as a gap spacer was placed on the electromagnet, the elastomer uncured composition prepared as described above was applied, a flexible sheet having a through hole was disposed thereon, the gap spacer was further placed thereon, the elastomer uncured composition was applied, and finally the electromagnet was covered. Subsequently, a magnetic field was applied by an electromagnet in a state of being pressed by the electromagnet, and silicone was cured in an oven at 100 ℃ for 1 hour to prepare a probe sheet a. The thickness of the elastomer layer was 50 μm for each of the upper and lower layers, and the total thickness of the probe sheet A was 150. mu.m.

< production of Probe sheet B >

A frame of a polytetrafluoroethylene sheet having a thickness of 150 μm as a gap spacer was placed on the electromagnet, and the elastomer uncured composition prepared as described above was applied to the frame, and the electromagnet was covered. Next, in a state of being pressed by an electromagnet, a magnetic field was applied by the electromagnet, and silicone was cured in an oven at 100 ℃ for 1 hour to produce a probe sheet B. The thickness of the probe sheet B was 150. mu.m.

< evaluation of insulation >

A5 mm square evaluation substrate (hereinafter referred to as "evaluation PKG (package)" 1 ") having a pitch of 200 μm P, a solder ball size of 110 μm φ, and a pin (pin) count of 484 was prepared. A6 mm square evaluation substrate (hereinafter referred to as "evaluation PKG (package)" 2 ") having a pitch of 500 μmP, a solder ball size of 300 μm φ, and a pin count of 64 was prepared.

A socket (socket) having electrode pads opposed to the solder balls of the evaluation PKG1 was prepared, and the probe chip a or the probe chip B was set in the socket, and the evaluation PKG1 was disposed thereon. Then, the insulation resistance value was measured when a voltage of 30V was applied to the adjacent electrode pad in a state where the evaluation PKG1 was pressed 30 μm from above by a pressing jig. In addition, for the evaluation of PKG2, the insulation resistance value was also measured in the same manner as for the evaluation of PKG 1.

The number of short circuits was counted by taking the case where the insulation resistance value between adjacent electrodes was 1 × 10E-6 Ω or more as short circuit (NG). The evaluation results of the insulation properties are shown in table 1.

< evaluation of reliability >

Using the above evaluation PKG2, voltage measurement was performed at a temperature of 100 ℃. The voltage V was monitored when the dc current of 10mA was applied constantly by repeatedly applying pressure while pressing the evaluation PKG2 for 30 μm for 5 seconds with a pressure jig.

The resistance value is obtained according to the following expression (1), a case where the resistance value R is 1 Ω or more is determined as NG, and the number of pressurization times at the time of NG determination is counted. The evaluation results of the insulation properties are shown in table 1.

R＝V/I (1)

[ Table 1]

As shown in table 1, in the probe sheet B, short circuit occurred between adjacent electrodes in the 200P evaluation PKG1 of the insulation evaluation, and the resistance value increased when the number of pressurization was 2 ten thousand in the durability evaluation. On the other hand, in the probe sheet a, no short circuit occurred between adjacent electrodes even in the 200P evaluation PKG1 of the insulation evaluation, and the number of times of pressurization for increasing the resistance value was 10 ten thousand or more in the durability evaluation, and excellent anisotropy and durability were obtained.

Description of the reference numerals

10: a flexible sheet; 11: a through hole; 20: a first elastomeric layer; 30: a second elastomeric layer; 40: an interlocking section; 50: an elastomeric uncured composition; 51: an uncured resin; 52: conductive particles.

Claims

1. A probe sheet is provided with:

a flexible sheet having a plurality of through holes;

a first elastomer layer disposed on one surface of the flexible sheet;

a second elastomer layer disposed on the other surface of the flexible sheet; and

and a locking portion formed by interlocking conductive particles in a thickness direction from the surface of the first elastic body layer to the surface of the second elastic body layer through the through hole.

2. The probe tile of claim 1,

the flexible sheet is one selected from the group consisting of polyimide, polyamide, polyethylene naphthalate, and biaxially oriented polyethylene terephthalate.

3. The probe tile according to claim 1 or 2,

the flexible sheet has the through-holes in a lattice shape.

4. The probe tile according to any one of claims 1 to 3,

the conductive particles are Ni particles or Ni alloy particles.

5. The probe tile according to any one of claims 1 to 4,

the first elastomer layer and the second elastomer layer each have a thickness of 5 μm to 150 μm.

6. A method of manufacturing a probe sheet, comprising:

a disposing step of disposing a first uncured resin layer made of an elastomer uncured composition containing conductive particles on one surface of a flexible sheet having a plurality of through holes, and disposing a second uncured resin layer made of an elastomer uncured composition containing conductive particles on the other surface of the flexible sheet;

an orientation step of applying a magnetic field or an electric field from the outside of the first uncured resin layer and the second uncured resin layer to orient the conductive particles in the thickness direction through the through-holes from the surface of the first uncured resin layer to the surface of the second uncured resin layer; and

and a curing step of curing the first uncured resin layer and the second uncured resin layer in a state in which the conductive particles are oriented, thereby forming an elastomer layer on both surfaces of the flexible sheet.