JP4835251B2 - Pressing piece of pressure device - Google Patents

Description

  The present invention relates to a pressing piece used in a precision mounting pressure device suitable for an electronic component crimping process or the like.

  Usually, a flexible wiring board for driving signal input is conductively bonded to a connection terminal of an electrode wiring drawn from each electrode of a liquid crystal display panel via a conductive member such as an anisotropic conductive adhesive. The anisotropic conductive adhesive is made by dispersing and mixing conductive particles in a thermosetting resin material such as epoxy resin. In the conductive bonding process, the connection terminal on the liquid crystal display panel side and the corresponding flexible wiring board side After connecting and superimposing the connecting terminals accurately with the anisotropic conductive adhesive interposed therebetween, the pressure is usually applied while heating from the flexible wiring board side.

  In recent high-definition liquid crystal display panels, the arrangement pitch of the connection terminals of the electrode wiring is highly fine, and the corresponding connection terminals on the flexible wiring board side are accurately and accurately connected to the connection terminals arranged in the fine pitch. In order to reliably conduct and bond, it is necessary to bring the entire pressing surface of the pressing head in the thermocompression bonding apparatus into close contact with the surface of the flexible wiring board as a workpiece during the above-described thermocompression bonding.

  That is, it is necessary to raise and lower the pressure head in a state where the pressure surface of the pressure head is held in parallel with high accuracy with an allowable error of about several μm with respect to the base surface on which the connection terminal portion of the liquid crystal display panel is placed. is there. For this reason, conventionally, an adjustment mechanism for adjusting the parallelism of the head pressing surface to the base surface has been provided in the pressing head.

As a pressurizing device provided with a parallelism adjusting mechanism, a support that supports a pressing head is provided with a screw adjusting type adjusting mechanism having a wedge structure or a slide block structure as shown in Patent Document 1. Are known.
JP-A-9-161935

  However, the adjustment mechanism of the above-described screw adjustment method has a large structure, and as a result, the entire pressurizing device is enlarged. Moreover, since it is a screw adjustment system, it becomes an operation | work while observing measuring instruments, such as a micrometer and a dial gauge, and an operation man-hour increases.

The object of the present invention is that the pressing surface can be automatically brought into contact with the surface of the flexible wiring board without any complicated adjustment work without gaps, which contributes to a reduction in work man-hours and a simplified structure. It is to provide a pressing piece of a pressing device.

The pressing piece of the pressing device of the present invention is a pressing piece of the pressing device that presses the surface of the flexible wiring board, and the pressing piece penetrates between a pair of surfaces along the pressing direction. A plurality of through-holes, wherein the plurality of through-holes are juxtaposed on the pair of surfaces along a first direction orthogonal to the direction of the pressing, and the first of the pair of surfaces Both end portions along the first direction of the width are formed at a higher density than the central portion of the width in the direction of 1, and at least some of the plurality of through holes are pressed with the pressing. It is characterized in that it can be deformed according to the stress applied to the piece .

According to the present invention, the pressing surface can be automatically brought into contact with the surface of the flexible wiring board without any complicated adjustment work, and the structure can be simplified while contributing to the reduction of work man-hours. A pressing piece of the pressing device can be provided.

FIG. 1 is a perspective view showing a pressing head in a thermocompression bonding apparatus as an embodiment of the present invention. FIGS. 2A and 2B show a thermocompression bonding process of a liquid crystal display panel and a flexible wiring board by the thermocompression bonding apparatus. a side view and a plan view showing a front view FIG. 3 (a) showing a partially omitted configuration of a heater chip mounted on the thermocompression bonding device, FIG. 3 (b) is its sectional view taken along line B-B It is.

  In FIG. 1, a heater chip 2 as a pressing piece is attached to a tip end portion of the pressing head 1 formed in a tapered manner that is moved up and down in the direction of the white arrow 1 </ b> A by a lifting mechanism (not shown). A bar heater 3 is embedded in the substantially longitudinal center of the pressing head 1 so as to extend in the longitudinal direction of the head.

  The heater chip 2 in the present embodiment is made of a metal material having elasticity such as stainless steel, is formed in an elongated strip having a rectangular cross section, and is detachably attached to the lower end portion of the pressing head 1. The dimensions of the length L, height H, and thickness T of the heater chip 2 are optimally set according to the workpiece to be pressed. As shown in FIGS. 2A and 2B, the thermocompression bonding apparatus of the present embodiment applies the anisotropic conductive adhesive 6 to the electrode terminals 51 of the liquid crystal display panel 5 placed on the base 4. The length L and the width (chip thickness) T of the heater chip pressing surface 21 to be brought into pressure contact with the flexible wiring board 7 are electrically connected to each other. The dimension is set so as to sufficiently cover each array portion of the connection terminals 71 and 51 to be connected.

  Incidentally, each dimension in the heater chip 2 of the present embodiment is such that the length L is 20 to 40 mm, the thickness T is 1 to 4 mm, and the height H is 3 to 5 mm. Each is optimally set according to the size of the array portion.

  A plurality of through holes 22 are formed in the heater chip 2 so as to penetrate in the thickness direction of the chip. As shown in FIG. 3 (a), these through holes 22 are arranged in a three-row staggered pattern at a position slightly closer to the pressing surface 21 side than the central portion of the heater chip 2 in the height direction 2H. Are arranged at equal intervals in parallel along the length direction 2L.

  Here, each through hole 22 has a diameter gradually increasing from both main surfaces 23 and 24 opened as shown in the cross-sectional view of FIG. 3B toward the center (back) of the chip thickness direction 2T. Is formed in a drum-shaped inclined hole. In this case, the inclination angle θ of the inclined side surface is preferably about 1.5 to 3.5 °.

  The opening diameter φ of each through hole 22 is optimally set in the range of 500 to 1000 μm according to the above-described outer size of the heater chip 2.

  Next, regarding the conductive bonding operation of the liquid crystal display panel and the flexible wiring board by the thermocompression bonding apparatus of the present embodiment including the heater chip 2 configured as described above, FIGS. 4 (a), 4 (b), and 5 (a). ) And (b).

  As shown in FIG. 4A, as the pressing head 1 is lowered, the pressing surface 21 of the heater chip 2 is inclined by an angle α in the length direction 2L with respect to the surface 71 of the flexible wiring board 7 as a pressing object. In the case of contact, when the pressing head 1 is lowered by a predetermined stroke length in this state, as shown in FIG. 4B, members around the through-hole 22 on the end face 25 side that comes into contact first are in the head ascending / descending direction. The shape of the through hole 22 is deformed from a perfect circle to an ellipse. The degree of compressive deformation of each through-hole 22 gradually decreases as the through-hole 22 is close to the opposite end face 26 in the length direction 2L of the heater chip 2.

  Thereby, although the parallelism with respect to the workpiece | work surface in the length direction 2L of the heater chip 2 has shifted | deviated, the substantially whole surface corresponding to the workpiece | work of the pressing surface 21 of the heater chip 2 is the surface of the flexible wiring board 3 which is a workpiece | work. As a result, all the corresponding connection terminals to be thermocompression-bonded are reliably connected to each other.

  That is, in the case of using a conventional heater chip that does not have a through-hole, the heater chip hardly deforms when it comes into contact with the parallelism with respect to the work surface being deviated. The portion of the flexible circuit board where one end of the heater chip pressing surface is in contact with the first end is excessively pressed and deformed, and the other end is not in contact with the chip pressing surface. Even if they are in contact with each other, they are in contact with each other and are hardly pressurized. As a result, the excessively pressed part of the flexible wiring board is damaged, or the part where the heater chip pressing surface is lifted is in a poor conduction state where the corresponding connection terminals are not securely connected to each other. Will occur.

  On the other hand, in the case of the heater chip 2 provided with the through hole 22 according to the present invention, as the pressing head 1 is lowered, the flexible part having the largest end portion that comes into contact with the surface of the flexible wiring board 7 of the heater chip 2 is the largest. In response to the reaction force from the wiring board 7, the member around the through hole 22 at the end thereof is most greatly compressed and deformed, and the reaction force from the flexible wiring board becomes closer to the member around the through hole 22 near the opposite end. Is reduced and the degree of compressive deformation is reduced, the inclination of the pressing surface 21 to the surface 71 of the flexible wiring board 7 (shift in parallelism) is automatically corrected, and the workpiece of the pressing surface 21 of the heater chip 2 is corrected. The corresponding substantially entire surface is in pressure contact with the surface of the flexible wiring board 3. The elastic force, that is, the pressure contact strength of the heater chip pressing surface 21 with respect to the flexible wiring board 3 in this pressure contact state becomes the largest as the end portion that comes into contact first becomes closer to the opposite end portion, but the flexible wiring substrate 7 that comes into contact with the pressure. The pressure contact strength within a range in which all connection terminals to be thermocompression-bonded can be sufficiently brought into conductive contact without being damaged.

  Further, as shown in FIG. 5A, when the parallelism with respect to the surface of the flexible wiring board 7 in the thickness direction 2T of the heater chip 2 is shifted, the lowering of the pressing head 1 in the pressing surface 21 causes the lowering first. The reaction force from the flexible wiring board 7 with respect to the abutting main surface 23 side end portion is the largest, and the reaction force received from the center portion of the thickness T toward the opposite end portion decreases. However, since each through hole 22 is formed as a drum-shaped inclined hole having the smallest diameter at the center, members around the through hole 22 at the center have the greatest resistance (elasticity) to compression deformation. For this reason, as shown in FIG. 5B, when the predetermined stroke length of the pressing head is finished, the opening on the main surface 23 side that contacts the tip of each through hole 22 is compressed most. The degree of compressive deformation gradually decreases as the reaction force that is deformed and gradually decreases toward the center, but the wiring is flexible because there is almost no compressive deformation in the center where resistance to compressive deformation is greatest. The substrate 7 side is recessed accordingly, and the degree of compressive deformation gradually decreases in response to the reaction force that gradually decreases from the central portion toward the opposite opening.

  Thus, by forming the through-hole 22 in a drum-shaped inclined hole, the degree of compression by the external force in the thickness direction 2T of the heater chip 2 is reduced from the opening on both main surfaces 23 and 24 side to the center (back). Part) gradually becomes smaller. That is, the elastic modulus in the thickness direction 2T of the heater chip gradually increases from both openings toward the back. As a result, each through hole 22 responds more flexibly to a deviation in parallelism in the thickness direction 2T, which is difficult to correct because the overall length is shorter than a deviation in parallelism in the length direction of the heater chip 2. As shown in FIG. 2 (b), the pressing surface 21 of the heater chip 2 can be brought into contact with the surface of the corresponding flexible wiring board 7 with a necessary and sufficient pressure as shown in FIG.

  As described above, according to the thermocompression bonding apparatus of the present embodiment, the plurality of through holes 22 extending in the thickness direction 2T are formed in the length direction on the heater chip 2 that is pressed against the work surface (the surface of the flexible wiring board 7). Since the holes are evenly drilled along 2L, the deviation of the parallelism with respect to the work surface in the length direction 2L of the heater chip 2 is automatically compressed by the corresponding through-holes 22 being compressed and deformed to a degree corresponding to the deviation. Will be corrected.

  In addition, since the through holes 22 are formed as drum-shaped inclined holes, each through hole 22 is individually extended in the extending direction even when the overall length of the heater chip 2 is short in the thickness direction 2T. By changing the degree of compressive deformation, it is possible to respond flexibly and the shift is automatically corrected.

  Therefore, even if the heater chip 2 is displaced with respect to the workpiece surface in both the length direction 2L and the thickness direction 2T, each of the through holes 22 is compressed and deformed corresponding to the displacement in the respective direction. The displacement of the direction is automatically corrected, and the workpiece surface is always surely ensured with a pressure sufficient to prevent the workpiece from being damaged even if the pressing surface 21 is brought into conductive contact regardless of the occurrence of the deviation in parallelism. Can be pressed against.

  As a result, it is possible to obtain a thermocompression bonding apparatus having a simple structure that can always be accurately performed with less man-hours even in a precision mounting operation such as a conductive connection process of a wiring board in a high-definition liquid crystal display panel.

Next, another embodiment of the present invention will be described with reference to FIGS. 6 (a) and 6 (b).
The heater chip 8 shown in FIG. 6A is obtained by changing the arrangement density of the same plurality of through holes 81. That is, a plurality of drum-shaped inclined through holes 81 similar to those in the above-described embodiment are arranged most densely at both ends with respect to the length direction 8L of the heater chip 8, and gradually become sparse toward the center. It is arranged.

  Further, in the heater chip 9 shown in FIG. 6B, the diameter of the plurality of through-holes 91 to be drilled is set to be the largest at both ends with respect to the length direction 9L of the heater chip 9, and the center part The diameter is gradually reduced toward the.

  According to the heater chips 8 and 9 configured as described above, since the degree of compressive deformation with respect to the external force at both ends is larger than that at the center, it is possible to prevent a slight shift in parallelism in the length directions 8L and 9L. However, it can be more flexibly compressed and deformed, and the desired full-surface pressure contact state with the workpiece surface can be obtained more stably.

  In addition, this invention is not limited to the said embodiment, For example, in the case of the pressurization apparatus which only pressurizes, as an elastic material which forms a press piece, resin materials etc. other than a metal are used suitably, for example. be able to. In the case of the resin material, the through hole can be formed at the same time as the pressing piece is formed, and the cost reduction of the pressing device is promoted.

  Further, the through hole is not limited to the drum-like inclined hole as in the above embodiment, and may be formed as a simple cylindrical hole having a constant diameter when the thickness of the pressing piece is large.

It is the perspective view which showed the press head in the thermocompression bonding apparatus as one Embodiment of this invention. (A) is explanatory drawing which showed the thermocompression bonding process of the liquid crystal display panel by the said thermocompression bonding apparatus, (b) is a top view which shows the joining state of the said liquid crystal display panel as a workpiece | work and a flexible wiring board. (A) is the elevation view which abbreviate | omitted and showed the heater chip used with the said thermocompression bonding apparatus, (b) is the BB sectional drawing. It is explanatory drawing which shows operation | movement when the parallelism of the heater chip | tip in the said thermocompression bonding apparatus has shifted | deviated in the length direction, (a) has shown the state before crimping, (b) has each shown the state at the time of crimping | compression-bonding. It is explanatory drawing which shows operation | movement when the parallelism of the heater chip | tip in the said thermocompression bonding apparatus has shifted | deviated in the thickness direction, (a) has shown the state before crimping, (b) has each shown the state at the time of crimping | compression-bonding. (A), (b) is an elevational view showing a heater chip as another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Press head 2, 8, 9 Heater chip 21 Press surface 22, 81, 91 Through-hole 3 Heater 4 Base 5 Liquid crystal display panel 6 Anisotropic conductive adhesive 7 Flexible wiring board

Claims (8)

A pressing piece of a pressing device that presses the surface of the flexible wiring board,
The pressing piece includes a plurality of through holes formed so as to penetrate between a pair of surfaces along the pressing direction,
The plurality of through holes are juxtaposed on the pair of surfaces along a first direction orthogonal to the direction of the pressing, and from a central portion of the width of the pair of surfaces in the first direction. Both ends of the width along the first direction are formed with higher density,
At least a part of the plurality of through holes is deformable in accordance with a stress applied to the pressing piece in accordance with the pressing. 2. The pressing piece of the pressurizing device according to claim 1, wherein the plurality of through holes are formed as a drum-shaped inclined hole in which each diameter gradually decreases between the pair of surfaces . The pressing piece of the pressing device according to claim 1 or 2, wherein the plurality of through holes are formed in a staggered arrangement on the pair of surfaces . The pressing piece includes a pressing surface that presses the surface of the flexible wiring board,
The plurality of through-holes are formed in the pair of surfaces on the pressing surface side with respect to a central portion of the height along the pressing direction . A pressing piece of a pressurizing device according to any one of claims. 5. The plurality of through-holes, wherein the both end portions of the width have a larger diameter than the central portion of the width on the pair of surfaces. The pressing piece of the pressurizing apparatus according to any one of the claims. The pressing piece of the pressurizing device according to any one of claims 1 to 5, wherein the pressing piece is formed of a metal material having elasticity. 2. The pressing piece of the pressurizing apparatus according to claim 1, wherein an opening diameter of the plurality of through holes is in a range of 500 μm or more and 1000 μm or less. The pressing piece of the pressurizing device according to claim 2, wherein an inclination angle of the drum-shaped inclined hole is in a range of 1.5 ° to 3.5 °.

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