JP2009123390A - Contact sheet for solder ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact sheet in which deterioration in quality of a solder ball caused by conduction failure and inspection is hard to occur. <P>SOLUTION: The contact sheet for the solder ball includes an insulating plate-like member 301 having elasticity and a plurality of ultraelastic wires 302a, 302b of which its one part is embedded in the plate-like member. The ultraelastic wires 302a, 302b are respectively embedded in a doughnut-like region to form 60 to 90% of a diameter of the solder ball having an abutting point of the solder ball 321 as the center. A contact wire length is 90 to 120% of the thickness in an unloaded state of the plate-like member, and when the solder ball contacts the plate-like member, the embedded parts of the contact wire are curved to be separated from each other, one end part of the contact wire turns to the center side of the solder ball and contacts the ball, and a wire diameter d (mm), Young's modulus E (MPa) of the contact wire, a thickness T (mm) of the plate-like member, and an internal stress Fr (N/mm<SP>2</SP>) of the plate-like member in the maximum curved part of the contact wire at the time of contact with the solder ball satisfy a formula (1): Fr>0.53×Ed<SP>4</SP>/T<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic component inspection jig for measuring and inspecting electrical characteristics of an electronic component such as an integrated circuit, and a manufacturing method thereof, and more particularly to a semiconductor device, particularly a semiconductor integrated circuit (hereinafter referred to as “IC”). The present invention relates to a contact sheet for solder balls used for inspection of electronic components such as

  When measuring the electrical characteristics of an electronic component such as an IC, the inspection circuit disposed on the inspection substrate and the terminals, solder balls, or bumps of the electronic component to be inspected are electrically connected by a contact sheet. This contact sheet is an elastic sheet having conductivity only in the thickness direction. For example, the contact sheet has a rubber cushioning property, and the conductive particle dispersion embedment method shown in FIG. 15 and the conductive wire inclined embedment shown in FIG. There is a contact sheet.

  In the conductive particle dispersion embedding method, the contact sheet 151 has a structure in which metal particles 153 are dispersed in the elastic member 152. In an unloaded state, the metal particles 153 are appropriately dispersed, and the upper and lower surfaces of the contact sheet 151 are electrically insulated. In this state, when the contact sheet 151 is pressed by the solder ball 155 included in the inspection target, for example, the IC 154, the elastic member 152 is compressed and deformed, and as a result, the metal particles 153 dispersed therein are brought into contact with each other and pressed. Conductivity is manifested between the upper and lower surfaces only in the portions that are formed.

  In the conductive wire inclined embedding method, the thin metal wires 163 are embedded obliquely inside the elastic member 162 of the contact sheet 161 so as not to contact each other. For this reason, the upper and lower surfaces of the contact sheet 161 are electrically connected independently by the thin metal wires 163. When the elastic member 162 is deformed by the pressing contact of the object to be inspected, the fine metal wires 163 are deformed so as to fall down obliquely, but do not contact each other. For this reason, the function of electrically conducting the upper and lower surfaces independently remains maintained.

  Such a contact sheet has elasticity in the film thickness direction, can conduct in the film thickness direction with a low compressive load, and can be elastically recovered and is suitable for frequent use. Is required. In particular, when a relatively soft solder ball comes into contact with the contact sheet, the tip of the solder ball is physically damaged during the inspection process and easily deforms locally. There is a possibility that the solder ball bondability is lowered and the reliability as a product is lowered. Therefore, a contact system capable of minimizing such damage at the solder ball tip is desired.

  However, to meet such demands, neither the conductive particle dispersion burying method nor the conductive wire inclined burying method can meet the demand.

  First, in the case of the conductive particle dispersion embedding method, the contact sheet is deformed in the thickness direction by the contact pressure of the solder ball, and the contact between the conductive particles dispersed inside is realized by the deformation. Is always needed. This contact pressure is generated by bringing the entire electronic component including the solder balls close to the contact sheet. Since there is a variation in the amount of protrusion of the solder ball tip from the electronic component main body, the variation in contact pressure is inevitably caused. It will occur. There may be a portion where electrical conduction does not occur due to the variation in the contact pressure. In addition, when the pitch is made finer, the solder balls having a relatively large amount of protrusion come into contact with the contact sheet, so that the thickness of the peripheral contact sheet is reduced. There is concern that no pressure is generated. In this case, there is a risk of poor conduction in the adjacent solder balls. Furthermore, since the contact pressure is relatively high, the tip of the solder ball serving as the contact portion is likely to be deformed, and the risk that the quality of the product is deteriorated by the inspection is relatively high.

  On the other hand, the conductive wire inclined burying method realizes electrical conduction at a lower contact pressure than the conductive particle dispersion burying method. For this reason, the problem of product quality degradation due to the inspection as described above is less likely to occur compared to the conductive particle dispersion embedding method, but a contact pressure that breaks through the oxide film is required at the contact portion with the solder ball. The conductive wire must be relatively rigid. Also, in order to avoid interference with adjacent conductive lines, it is necessary to increase the elastic coefficient of the conductive lines so that the bending amount does not vary greatly according to the contact pressure. Furthermore, since it is tilted in one direction, the contact state with respect to the solder balls is inevitably likely to vary, and there is still a possibility that partial conduction failure will occur.

Therefore, a contact sheet has been proposed in which through holes are provided in a plurality of locations of a base film made of an electrically insulating porous film, and a conductive metal made of plated particles is attached to the inner wall thereof (see, for example, Patent Document 1). ).
JP 2004-265844 A

  However, even with the above structure, it is still not sufficient from the viewpoint of stabilizing the contact state. However, if a contact sheet with this structure is to be manufactured, many processes including laborious processes such as a plating process are required. It is difficult to manufacture with high productivity. In the semiconductor field where demands for reducing product costs are particularly strict, how to realize basic performance with a simple structure is an important issue, and this contact sheet cannot meet such demands.

  An object of the present invention is to provide a contact sheet that has a simple structure but is less likely to cause poor conduction and a decrease in solder ball quality due to inspection.

A first invention provided to achieve the above object includes an insulating plate-like member having elasticity, and a plurality of superelastic wires partially embedded in the plate-like member, and a solder ball is provided. At least two wires are formed in each of the donut-shaped regions that form 60 to 90% of the diameter of the solder ball, centered on the contact point that the tip of the solder ball should contact when contacting the plate-like member. The plurality of super elastic wires are embedded so that the contact wires are arranged, and the length of the contact wires is the thickness T (mm) of the plate-like member in the unloaded state at the portion where the contact wires are embedded. 90% to 120% of the contact wire, when the solder ball contacts the plate member, each of the contact wires is curved so that the portions embedded in the plate member are separated from each other, and one end of the contact wire Is solder bo The wire diameter d (mm) and Young's modulus E (MPa) of the contact wire and the thickness T (mm) of the plate-like member in an unloaded state are the solder balls. This is a contact sheet for a solder ball that satisfies the internal stress Fr (N / mm ² ) of the plate-like member at the maximum bending portion of the contact wire and the following formula (1).
Fr> 0.53 × Ed ⁴ / T ² (1)

  Here, the “contact” state refers to a state in which the solder ball is close to the contact sheet and the tip of the solder ball is in contact with the contact sheet, and the “contact” state exceeds the contact state. The state where the solder ball is close to the contact sheet until the inspection can be started.

  In the above contact sheet, when the solder ball comes into contact with the plate member, the length of the contact wire is determined by the thickness T of the plate member in an unloaded state from the contact surface of the plate member with the solder ball. You may have a protrusion part which protrudes by 20% or less of (mm). In this case, it is unlikely that the contact wire is buried in the plate-like member and does not come into contact with the solder ball.

  Further, the rubber hardness of the plate-like member may be 40 to 60 degrees, the Young's modulus of the superelastic wire may be 50 to 70 MPa, and a positioning part for bringing the solder ball into contact with the contact point is provided. A frame body may be provided, and a plate-like member may be fixed to the frame body.

  According to the present invention, the wire embedded in the plate-like member comes into contact with the periphery of the tip of the solder ball when the solder ball contacts the contact point or the vicinity thereof. Then, the contact force applied to the plate-like member from the solder ball, the contact force applied to the wire from the protruding end of the wire, and the recovery force inside the plate-like member trying to return the wire deformed by these contact forces Are properly balanced and the wire bends so that its embedded center is away from the solder balls.

  For this reason, in the contact state, the wire is deformed so that the protruding portion is directed toward the center of the solder ball, and as a result, the contact pressure is maximized while minimizing the contact area, and the peripheral edge is not the tip of the solder ball. Will come into contact with the part. Therefore, poor conduction between the solder ball and the wire is unlikely to occur, and the contact portion is not the tip portion of the solder ball, so that deterioration of the solder ball quality due to inspection is unlikely to occur. That is, by using the contact sheet according to the present invention, it is possible to suppress deterioration in inspection quality and product quality.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a top view conceptually showing a solder ball contact sheet according to this embodiment, and FIG. 2 is a partially enlarged view of the plate-like member of FIG.

  As shown in FIG. 1, the solder ball contact sheet 0100 according to the present embodiment includes an insulating plate-like member 0101 having elasticity, a plurality of superelastic wires 0102 embedded in the plate-like member 0101, and The frame includes a positioning mark 0103 and a frame body 0104 for fixing the plate-like member 0101.

  “Superelastic wire” is a shape memory alloy wire that exhibits superelasticity in the operating temperature range by setting the shape recovery temperature lower than the operating temperature, and has a Young's modulus E of approximately 50 to 70 MPa. Say.

A typical material for the plate-like member is rubber, and in addition, an elastomer may be used. The physical characteristics are approximately 40 to 60 degrees when expressed in terms of rubber hardness.
In the contact sheet 0100 according to this embodiment, the superelastic wire 0102 and the plate-like member 0101 satisfy the following relationship.
Fr> 0.53 × Ed ⁴ / T ² (1)

Here, for the superelastic wire 0102,
d (mm): Wire diameter E (MPa): Young's modulus
For the plate-like member 0101,
T (mm): thickness in an unloaded state Fr (N / mm ² ): internal stress at the maximum bending portion of the wire at the time of contact with the solder ball (details will be described later)
It is.

  FIG. 2 conceptually shows an example of the arrangement of superelastic wires 0102 embedded in the plate-like member 0101. In FIG. 2, when the solder ball comes into contact with the plate-like member, the four super elastic wires 0202a to 0202d are embedded at equal intervals around the contact point 0201 where the tip of the solder ball should come into contact. It is shown. In the solder ball contact sheet according to the present embodiment, such super elastic wires are arranged at all contact points.

  Here, the number of super elastic wires per contact point may be two or more, and the larger the number, the more preferable from the viewpoint of the reliability of electrical contact. However, if this number is too large, there is a possibility that a problem of mutual interference with the adjacent superelastic wire may occur. Therefore, when the pitch of the solder balls is narrow, an upper limit is set. If these are considered comprehensively, the number of arrangement is preferably 3 to 5.

  Moreover, the relative arrangement | positioning relationship of the superelastic wire arrange | positioned at an adjacent contact point is not restrict | limited in particular. In FIG. 2, the arrangement relationship of the four superelastic wires arranged at each contact point, specifically, a cross line formed by connecting wires facing each other across the contact point (shown by dotted lines in FIG. 2). .) Is inclined by 30 degrees with respect to the arrangement axis of the solder balls. This arrangement is preferable from the viewpoint of manufacturing because the super elastic wires are arranged in a line at predetermined intervals. In addition, since the adjacent superelastic wires are arranged so that the bending directions do not oppose each other so that the influence from deformation (details will be described later) of the superelastic wires related to the adjacent contact points is minimized. Particularly preferred.

  Subsequently, the behavior when the contact sheet according to the present embodiment comes into contact with the solder ball will be described with reference to the drawings.

  FIG. 3 is a partial cross-sectional view conceptually showing a state (a) immediately before contact with the solder ball of the contact sheet according to the present embodiment and a state (b) in contact with the solder ball.

  As shown in FIG. 3A, the contact sheet 0300 is placed on the inspection circuit board 0310, and the super elastic wires 0302a and b embedded in the plate-like member 0301 in the contact sheet 0300 are substantially linear. The plate-like member 0301 is embedded substantially parallel to the thickness direction. The embedding interval D has a length of 80% of the diameter Db of the solder ball 0321, and the wires are arranged so as to be substantially equidistant from the contact point 0303.

  The embedding interval D preferably satisfies 0.6Db ≦ D ≦ 0.9Db. If it is less than 0.6 Db, the possibility that the superelastic wires 0302a and 0302b will come into contact with the tip of the solder ball 0321 increases, and there is a concern that the quality of the solder ball in the product after the inspection will be deteriorated. If it exceeds 0.9 Db, there is a high possibility that the contact state of the super elastic wires 0302a, 0302a and b with the solder ball 0321 will not be an appropriate contact state as described later.

  Note that the superelastic wires 0302a, b satisfy the burying interval D means that the superelastic wires 0302a, b are in a donut-shaped region centering on the contact point and forming 60 to 90% of the diameter of the solder ball 0321. It means to be buried.

  Further, the superelastic wires 0302a and 0302b protrude slightly from the solder ball facing surface of the plate-like member 0301. If the tips of the superelastic wires 0302a and 0302b are buried in the plate-like member 0301 in the initial state (no load state), it may cause a contact failure. Therefore, the tip protrudes from the plate-like member 0301. desirable. Moreover, when this protrusion length is large, the deformation amount of the wire can be increased with the same rubber compression amount. For this reason, even when the amount of rubber compression cannot be increased, the contact force at the time of contact can be ensured by setting the protrusion length to be large. However, if the protruding length is excessively large, the risk of the protruding portion deforming unrecoverably when the protruding portion comes into contact with the solder ball increases. Therefore, the upper limit of the “slight amount” is about 20%, preferably about 10% of the thickness of the plate-like member 0301 in the no-load state, and its typical length is the thickness of the plate-like member 0301 in the no-load state. Of about 5%. That is, in a typical example, the relationship between the unloaded thickness T of the plate-like member 0301 and the length L of the superelastic wires 0302a and b is L = 1.05 × T.

  However, it is not a necessary condition that the tips of the superelastic wires 0302a and b protrude from the plate-like member 0301 in an unloaded state. When the solder ball 0321 comes into a final contact state, it is possible to achieve connection so that the tips of the super elastic wires 0302a and 0302b can realize electrical connection to the peripheral portion other than the apex of the solder ball 0321. As long as it is necessary and can be achieved, the ends of the superelastic wires 0302a and 0302b may be embedded in the plate-like member 0301 in an unloaded state. Specifically, since the general compression rate of the plate-like member 0301 in the contact state is about 25% with respect to the thickness in the no-load state, 10% of the thickness of the plate-like member 0301 in the no-load state. As long as it is up to about 5%, preferably about 5%, it may be buried.

  As described above, the superelastic wires 0302a and 0302b are summarized in a range of approximately 90% to 120%, preferably approximately 95% with respect to the thickness of the plate-like member 0301 in the unloaded state in the portion where these wires are embedded. To 110%. Further, when the solder ball 0321 comes into contact with the plate-like member 0301, it is preferable to have a protrusion of about 20% or less of the thickness of the plate-like member 0301 in an unloaded state. %, And a typical example is 5%.

  When the contact sheet 0300 comes into contact with the solder ball 0321, the relative position of the inspection object 0320 including the solder ball 0321 with respect to the contact sheet 0300 is determined using the positioning mark included in the contact sheet 0300, and the center 0322 of the solder ball 0321 The contact 0303 is arranged on substantially the same axis in the thickness direction of the plate-like member 0301.

  In this state, the contact sheet 0300 and the inspection object 0320 are brought close to each other in the thickness direction of the plate-like member 0301, and the contact sheet 0300 and the inspection object 0320 are brought into contact so that the tip of the solder ball 0321 contacts the contact point 0303. This contact portion is not the tip of the solder ball 0321 but the peripheral portion, specifically, the region on the donut in the range of 60 to 90% of the diameter of the solder ball 0321 with the contact point as the center as described above. Therefore, even if the error of the solder ball arrangement process to the inspection object and the operation mistake in the contact process between the inspection object and the contact sheet are taken into consideration, the tip of the solder ball 0321 is moved by the contact of the superelastic wires 0352a and b. A situation of deformation in the inspection process is avoided.

  As shown in FIG. 3B, when the solder ball 0371 comes close to the plate-like member 0351, the solder ball 0371 comes into contact with the plate-like member 0351. When the solder ball 0371 comes closer, the solder ball of the superelastic wires 0352a and 0352b. The end portions 0353a and b on the side come into contact with the solder balls 0371. Even when the length of the superelastic wires 0352a and b is smaller than the thickness of the plate-like member 0351 in the no-load state, the plate-like member 0351 is compressed by contact with the solder ball 0371. The end portions 0353a and b come to protrude and can come into contact with the solder balls 0371. From the viewpoint of reliably realizing the protrusion of the end portions 0353a and b due to the compression deformation of the plate-like member 0351, in the present invention, the plate-like member 0351 in the portion where the super elastic wires 0352a and b contacting the solder balls 0371 are embedded. The lower limit of the length of the superelastic wires 0352a and b with respect to the thickness in the no-load state is approximately 90%.

  Thus, as the degree of contact of the solder ball 0371 increases, the contact surface with the solder ball 0371 of the plate-like member 0351 is deformed, and an internal stress that causes the superelastic wires 0352a and b to be separated from each other around the contact point. Fr is generated.

  Further, since both ends of the super elastic wires 0352a and b are in contact with the inspection circuit board 0360 and the solder balls 0371, the super elastic wires 0352a and b are compressed from the contact ends 0353a and b with the solder balls 0371. The power to make it.

  The superelastic wires 0352a and b are deformed inside the plate-like member 0351 by these forces. However, the superelastic wires 0352a and b and the plate-like member 0351 satisfy the above formula (1) between the internal stress Fr. Therefore, the superelastic wires 0352a and b have a curved shape as shown in FIG. 3B while resisting the repulsive force to return the deformation.

  Because of such bending, the contact ends 0353a and b of the superelastic wires 0352a and b with the solder balls 0371 are deformed so as to face the center side of the solder balls 0371. For this reason, the contact area with the solder ball 0371 can be minimized, and as a result, the contact pressure becomes higher compared to other contact states. Therefore, it is possible to improve the reliability of electrical contact without damaging the tip of the solder ball 0371 at all.

Hereinafter, the derivation process of the formula (1) will be described in detail.
(A) Force acting on superelastic wire in contact state i) Outline FIG. 4 conceptually shows the force acting on the superelastic wire when the test object comes into contact with the contact sheet. In FIG. 4 and subsequent figures, in order to facilitate understanding of the direction in which the force acts and each symbol, the hatched lines indicating that the plate-like member, the inspection target, and the inspection circuit board are cross sections are omitted.

  Now, in a state where the plate-like member and the wire are compressed, as shown in FIG. 4, the wire has a force A in which the solder ball pushes the tip of the wire, an internal stress B of the plate-like member, and a repulsion of the plate-like member against the deformation of the wire Three forces of force C (force to push back the wire) are acting. The repulsive force C of the plate-like member includes the internal stress of the plate-like member generated when the adjacent solder ball presses the plate-like member.

  In such a contact state, a force C that pushes back the wire acts on the wire, and this force generates a force that pushes back the solder ball at the contact end of the wire. For this reason, the contact end of the wire comes into contact with the solder ball with a contact force equal to or greater than the contact force due to the elasticity of the wire, and the contact end of the wire bites into the surface of the solder ball to achieve stable contact. Yes.

ii) Influence of internal stress C Here, in the process in which the plate member is compressed by the solder ball and the wire is deformed, as shown in FIG. Therefore, the internal stress C generated by the adjacent solder ball pressing the plate-like member in the vicinity of the wire is extremely small.

  As the contact state approaches, the deformation of the wire increases, the distance between the maximum bending portion of the wire and the adjacent solder ball decreases, and the internal stress C generated when the adjacent solder ball presses the plate-like member increases. (See FIG. 5 (c)).

  At this time, if the wire deforms along the deformation of the plate member by at least the internal stress B of the plate member, the internal stress C generated when the adjacent solder ball pushes the plate member is small. In the process (FIG. 5B), since the wire is deformed along with the deformation of the plate-like member, the contact end of the wire does not slide on the surface of the solder ball and jump out to the side surface of the solder ball. Further, as the internal stress C generated when the adjacent solder ball presses the plate member increases (FIG. 5C), the force with which the wire is pushed back by the internal stress C increases. The force with which the contact end comes into contact with the solder ball is also increased, and the contact end of the wire starts to bite into the solder ball and the contact is stabilized.

  That is, when the internal stress is small as shown in FIG. 5B, the influence can be ignored, and even if the internal stress increases as shown in FIG. 5C, this stabilizes the contact. Contributes to direction. Therefore, assuming that the internal stress C is zero in the contact state and using a wire that deforms in the same manner as the contact state only with the force of the internal stress B, the wire deforms along the deformation of the plate member in the process of deformation. Therefore, even when the internal stress C increases to a level that cannot be ignored, the above stable contact can be realized.

(B) Deformation characteristics required of wire Based on the above consideration, the characteristics required of the wire are the same force (Fr) as the internal stress B in free space, where δ is the deformation amount of the wire in the contact state. The wire is deformed by δ or more (see FIG. 6). Note that even a wire that deforms by δ or more in free space is not deformed by more than δ due to internal stress C inside the plate-like member.

  Therefore, in order to realize stable contact, a plate-like member that generates internal stress B in a contact state in which internal stress C is assumed to be zero is equal to or greater than δ with the same force Fr as internal stress B in free space. What is necessary is just to combine the wire to deform | transform.

(C) Preconditions for Deriving Internal Stress Fr A method for obtaining this combination will be described below.
First, a force corresponding to the internal stress of the plate-like member (hereinafter simply referred to as “internal stress”) Fr is obtained. Since the internal stress Fr of the plate-like member is obtained by FEM analysis, it is necessary to digitize parameters necessary for the analysis. Accordingly, the dimensions of the plate-like member, wire, and solder ball are defined as shown in FIG. 7, and the respective dimensions are set as follows as the preconditions.

i) Thickness T of the plate-like member in an unloaded state
Since the thickness T of the plate-like member in an unloaded state is usually substantially equal to the length of the wire, it is desirable that the plate-like member is also thin from the electrical characteristics of the wire. However, if the plate-like member is thin, the amount of compression inevitably decreases, and the contact becomes unstable. Therefore, the following three thicknesses are analyzed in the FEM analysis of the plate member as the thickness of the plate member generally used.
Thickness of plate-shaped member under no load T = 1.5mm, 1mm, 0.75mm (2)

ii) Compression amount Hr
Next, with regard to the amount of compression, a certain amount of compression is required to absorb variations in the height of the solder balls. However, if the amount of compression is large, the elastic limit of the wire will be exceeded. Set to about 25% of the thickness of the member. Therefore, in the FEM analysis, the compression amount of the plate-like member is set to the following value. The amount of compression actually used is about 20% to 30%.
Hr = 0.25T (3)

iii) Solder ball diameter Db
The diameter Db of the solder ball is determined by the semiconductor to be measured and is not a design value, but in order to analyze the internal stress of the plate member, the shape of the solder ball must be determined. In general semiconductors, the height of the solder ball is about 1/2 to 3/4 of the diameter, and the amount of compression of the plate-shaped member usually does not exceed the height of the solder ball. It is assumed that the following relationship holds between the thickness T in the unloaded state and the diameter Db of the solder ball.
0.25T = 0.5Db (4)

iv) Wire length L
The length L of the wire is adjusted in the range of 90% to 120% of the thickness T of the plate-like member in the no-load state as already described, but the contact end of the wire is buried in the plate-like member in the initial state. If this occurs, it may cause contact failure, so it is desirable that the contact end of the wire protrude slightly from the plate-like member. Since the typical example of the protruding length is about 5% of the thickness T of the plate-like member in the unloaded state as described above, the length L of the wire is usually set to the following value.
L = 1.05T (5)

v) Wire embedding interval D
As for the wire embedding interval D, if the wire deformation is large, the elastic limit of the wire may be exceeded. Therefore, the wire arrangement position should be as close to the outer periphery of the solder ball as possible to reduce the deformation amount of the wire during compression. Although it is desirable, it must be determined in consideration of misalignment of the solder balls.

  The positional deviation of the solder ball varies depending on the type of semiconductor and manufacturer, but is generally about 5% (± 2.5%) of the pitch of the solder ball. In general, since the diameter of the solder ball is about 50% of the pitch of the solder ball, the apex of the solder ball may cause a positional deviation of about 10% (± 5%) of the diameter of the solder ball.

  As for the position where the contact end of the wire comes into contact with the solder ball here, if the wire comes in contact with the vicinity of the top of the solder ball, the contact causes scratches and deformation, which may cause contact failure during semiconductor mounting. It is desirable not to contact the range of about 50% of the diameter centering on the center.

  On the other hand, even if the solder ball is at the outermost peripheral position where no force to push down the wire is generated, the force C that pushes back the wire acts on the wire, so that the contact end of the wire contacts toward the center of the solder ball, Stable contact can be obtained. Therefore, the range in which the wire can be contacted is 50% to 100% of the diameter of the solder ball as shown in FIG.

  Here, considering that the positional deviation of the solder ball is 10% of the diameter, in order for the contact end of the wire to be within the above-described contactable range even if the solder ball is displaced, the wire is shown in FIG. As shown in the figure, they may be arranged in the range of 60% to 90% of the diameter.

As described above, considering the elastic limit of the wire, it is desirable that the position where the wires are arranged be as close to the outer periphery of the solder ball as possible to reduce the deformation amount of the wire during compression. Accordingly, the wire arranging diameter is set to be close to 90% of the upper limit of the solder ball diameter, and the wire embedding interval D in the FEM analysis is set to the following value in consideration of manufacturing errors in arranging the wires.
D = 0.8Db (6)

vi) Coordinates (X, Y)
From the above values, the position coordinate (X, Y) of the maximum curved portion of the wire is obtained as a point for obtaining the internal stress.

In FIG.
r ² = (Db / 2) ² = x ² + (D / 2) ²
So
x = {(Db / 2) ^2- (D / 2) ² } ^1/2
It becomes.

Therefore,
y = r-x = Db / 2-{(Db / 2) ^2- (D / 2) ² } ^1/2
And
Hw = Hr + y = Hr + Db / 2-{(Db / 2) ^2- (D / 2) ² } ^1/2
Substituting the above equations (3), (4) and (5) here,
Hw = 0.85T (7)
It becomes.

Based on the above results, the arc width δ when a wire having a length L = 1.05T is compressed to a height of 0.85T as shown in FIG. 11 is as follows.
δ = 0.26T (8)
Accordingly, the coordinates (X, Y) have the following values.
X = D / 2 + δ = 0.46T (9-1)
Y = Hw / 2 = 0.425T (9-2)

  Based on the above results, the internal stress Fr of the plate-like member may be obtained as a horizontal stress value at coordinates (X, Y) in the state of FIG.

In order to obtain the stress value, the Young's modulus of the plate-like member is required. Usually, the elasticity of the plate-like member is specified by hardness. Since the hardness of a plate member that can be generally used and has appropriate elasticity is about 40 degrees to 60 degrees, the plate member is also analyzed for three types of hardness of 40 degrees, 50 degrees, and 60 degrees. The Young's modulus varies with temperature, etc., but the following values obtained by experiments by material manufacturers are used in the analysis.
Rubber hardness 40 degrees: Young's modulus 1.5Mpa (10-1)
Rubber hardness 50 degrees: Young's modulus 3.1Mpa (10-2)
Rubber hardness 60 degrees: Young's modulus 3.8Mpa (10-3)

(D) Derivation of internal stress Fr As a result of FEM analysis under the above conditions, the distribution of internal stress of the plate-like member was as shown in FIG. The figure below shows an FEM analysis result when the plate member has a thickness T = 1.0 mm in an unloaded state and the plate member has a Young's modulus of 3.1 Mpa as an example.

  Further, the internal stress in the horizontal direction at the coordinates (X, Y) is as shown in Table 1 below from this internal stress distribution diagram.

  Since the compression height Hr of the plate-like member and the coordinates (X, Y) for obtaining the stress are both directly proportional to the thickness T of the plate-like member in an unloaded state, the internal stress at the coordinates (X, Y) is the plate It is constant with respect to the thickness T of the member.

Accordingly, the internal stress has the following value regardless of the thickness of the plate member.
Hardness 40 degrees: 0.051 N / mm ² (11-1)
Hardness 50 degrees: 0.105 N / mm ² (11-2)
Hardness 60 degrees: 0.129 N / mm ² (11-3)
When this is graphed, FIG. 14 is obtained.

(E) Characteristics required for wire Subsequently, the elasticity of the wire is determined. According to the elastic mechanics of the metal, as shown in FIG. 15, the lateral force Fr necessary to deform the wire of length L by δ is obtained as (wire spring constant) × δ.

Here, when the diameter of the wire is d and the Young's modulus (longitudinal elastic modulus) is E, the spring constant of the wire can be obtained by the following equation.
Spring constant = (48E / L ³ ) X (πd ⁴ /64)=2.355Ed ⁴ / L ³ (12)

If the above formulas (5) and (8) are substituted here, the lateral force Fr for deforming the wire is as follows.
Fr = (2.355Ed ⁴ / L ³ ) × δ = 2.355d ⁴ /(1.05T) ³ × 0.26T = 0.529Ed ⁴ / T ² (13)

Accordingly, in order to deform the wire so that the curved portion is in the outer peripheral direction due to the internal stress of the plate-like member, which is the object of the present invention, and to bring the contact end of the wire into contact with the center of the solder ball from the side surface of the solder ball Reads the internal stress value with respect to the rubber hardness of the plate-like member used from FIG.
F> 0.53 × Ed ⁴ / T ² (14)

  Here, regarding the Young's modulus of the wire, it is assumed that a Ti-Ni alloy superelastic wire is used as the wire. The Young's modulus in the superelastic region (austenite phase) of this Ti—Ni alloy is 50 to 70 MPa. Therefore, when the Young's modulus E of the wire is set to 60 MPa and the diameter d of the wire satisfying the above formula (14) is obtained with respect to the thickness T of the plate-like member in an unloaded state, it is as shown in Table 2.

  Therefore, the normal design, that is, the length of the wire is almost the same as or slightly longer than the thickness of the plate-like member, and the diameter of the wires is slightly smaller than the diameter of the semiconductor solder ball to be measured. As a general Ti—Ni alloy wire, the wire is deformed by the internal stress of the plate-like member so that the curved portion is in the outer peripheral direction, and the contact end of the wire is moved from the side surface of the solder ball to the center of the solder ball. In order to make it contact toward a direction, the diameter of the wire used with respect to the thickness and rubber hardness of each plate-shaped member should just be made into the value of Table 2.

  When the thickness of the plate-like member and the rubber hardness are values other than those shown in Table 2, or when the Young's modulus of the wire is greatly different from 60 Mpa, the internal stress value with respect to the rubber hardness is read from FIG. What is necessary is just to obtain | require the diameter d of the wire which satisfy | fills said Formula (14).

1 is a perspective view conceptually showing one aspect of a contact sheet according to the present invention. 1 is a perspective view conceptually showing one aspect of a contact sheet according to the present invention. 1 is a perspective view conceptually showing one aspect of a contact sheet according to the present invention. It is a fragmentary sectional view which shows notionally the deformation state of the wire in a contact state, and the force applied to a wire at this time. It is a fragmentary sectional view which shows notionally a non-contact state, a contact start state, and a deformation state of a wire in a contact state. It is the figure which showed notionally the deformation | transformation of the wire by the external force Fr. It is a fragmentary sectional view for defining each dimension of a plate-shaped member, a wire, and a solder ball required for FEM analysis. It is a fragmentary sectional view which shows notionally the field which can contact a solder ball with a wire. It is a fragmentary sectional view which shows notionally position shift and shows the field which can contact with the wire of a solder ball. It is a fragmentary sectional view which shows the derivation | leading-out method of the position coordinate of the largest curved part in a wire. It is a fragmentary sectional view which shows notionally width delta of a wire in a wire. It is a figure which shows the coordinate data for performing FEM analysis. It is a figure which shows an example of a FEM analysis result. It is a graph which shows the rubber hardness dependence of the internal stress in a coordinate (X, Y). It is a fragmentary sectional view which shows notionally the contact sheet of the conductive particle dispersion embedding system concerning a prior art. It is a fragmentary sectional view which shows notionally the contact sheet of the conductive wire inclination embedding system concerning a prior art.

Explanation of symbols

0300 Contact sheet 0310 Inspection circuit board 0301 Plate member 0321 Solder ball 0302a, b Super elastic wire

Claims (4)

A contact sheet for a solder ball, comprising an insulating plate-like member having elasticity and a plurality of super-elastic wires partially embedded in the plate-like member,
At least 2 in each of the donut-shaped regions that form 60 to 90% of the diameter of the solder ball centered on the contact point with which the tip of the solder ball should contact when the solder ball contacts the plate-like member The plurality of superelastic wires are embedded so that a contact wire made of a wire is disposed,
The length of the contact wire is 90 to 120% of the thickness T (mm) of the plate-like member in the portion where the contact wire is embedded,
When the solder ball contacts the plate member,
Each of the contact wires is curved so that portions embedded in the plate-like member are separated from each other, one end of the contact wire faces the center side of the solder ball, and contacts the solder ball; and ,
The wire diameter d (mm) and Young's modulus E (MPa) of the contact wire and the thickness T (mm) of the plate-like member in an unloaded state are the maximum bending portion of the contact wire when in contact with the solder ball. A solder ball contact sheet characterized by satisfying the internal stress Fr (N / mm ² ) of the plate-like member and the following formula (1):
Fr> 0.53 × Ed ⁴ / T ² (1)   When the solder ball comes into contact with the plate-like member, the length of the contact wire is the thickness T (mm) of the plate-like member in an unloaded state from the contact surface of the plate-like member with the solder ball. The contact sheet for a solder ball according to claim 1, wherein the contact sheet has a protruding portion protruding at 20% or less.   The solder ball contact sheet according to claim 1 or 2, wherein the plate-like member has a rubber hardness of 40 to 60 degrees, and the superelastic wire has a Young's modulus of 50 to 70 MPa.   4. The solder ball contact according to claim 1, further comprising a frame having a positioning portion for bringing the solder ball into contact with the contact point, and a plate-like member fixed to the frame. 5. Sheet.

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