JP2007329303A - Carrier for transfer of thin printed wiring circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer carrier which can obtain suitable connection between a semiconductor chip and a thin printed wiring circuit board. <P>SOLUTION: The transfer carrier bonds and holds the thin printed wiring circuit board when a semiconductor chip is mounted on the board having a thickness of 0.5mm or less. The an adhesive layer is provided in a region for the semiconductor chip to be mounted thereon, and a non-adhesive layer is provided in a region outside of the chip mounting region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a carrier for transport suitable for use in a process of surface mounting an electronic component using a solder on a thin printed wiring board such as a flexible board.

  In order to mount an electronic component on a printed wiring board, a surface mounting method has been widely adopted as the electronic component becomes smaller and lighter. In a printed wiring board using a normal 1.6 mm thick glass cloth / epoxy resin laminate made of glass cloth impregnated with epoxy resin, the board itself is strong, so deformation such as warpage is unlikely to occur, There was no problem in alignment, and the surface mounting process could be fully automated.

  In recent years, in order to cope with further downsizing and weight reduction of electronic devices, electronic components are often mounted on a thin printed circuit board, and the strength of the board itself is low, and warping is likely to occur. It has become difficult.

  In general, thin printed wiring boards with a thickness of 0.5 mm or less are particularly low in strength, warp and twist, are difficult to align, and are used for surface mounting processes such as cream solder printing and electronic component automatics. Productivity in the work on the loading machine and the reflow process is reduced.

  Therefore, in order to solve the above-described problems, as a prior art, a carrier for transporting that can improve productivity in a surface mounting process on a thin printed wiring board as shown in Patent Document 1 and this carrier for transporting are used. A thin printed wiring board mounting method has been proposed.

  As shown in FIG. 3, this carrier 1 for transport is formed by forming a weak adhesive layer 2 for releasably attaching a thin printed wiring board 5 on the surface of a base substrate 3 made of a plate. Yes, when the thin printed wiring board 5 is attached to the surface of the carrier 1 for conveyance via the weak adhesive layer 2, the carrier 1 reinforces the thin printed wiring board 5 and the weak adhesive layer 2. Restricts warping and twisting of the thin printed wiring board 5 and fixes the position.

  As shown in FIG. 4, the thin printed wiring board mounting method using the carrier for carrier is as follows: (a) a weakly adhesive adhesive on the surface of the carrier 1 formed by forming the weakly adhesive layer 2. A thin printed wiring board 5 is stuck through the layer 2, and (b) a metal mask 11 with holes drilled at necessary locations is aligned with the surface of the thin printed wiring board 5 and polymerized, and then cream solder 12 (C) Next, after removing the metal mask, an electronic component such as a semiconductor chip 6 is mounted on the cream solder 12 remaining on the thin printed wiring board 5. Then, heating is performed using a reflow furnace or the like. (D) Thereafter, the carrier for transport is removed.

The weak adhesive layer is made of a weak adhesive resin that has high heat resistance and does not cause resin transfer even at room temperature or reflow, or has a very small transfer amount.
JP 2001-144430 A

  However, as shown in FIG. 5, when the thin printed wiring board is heated in a state where it is completely adhered to the carrier 1 as in the configuration of the prior art, the thin printed wiring board 5 is conveyed at a high temperature of 250 ° C. or higher. Due to the difference in the coefficient of linear expansion of the carrier 1, the phenomenon that the center of the thin printed wiring board 5 is deformed into a convex shape so as to follow the deformation of the weak adhesive layer 2 occurs near the center of the thin printed wiring board 5. In a configuration in which a large component such as the semiconductor chip 6 is mounted, this convex deformation causes a gap difference between the semiconductor chip 6 and the thin printed wiring board 5 to increase in a plane, thereby causing a connection failure. Occurred.

  As a method for countermeasures against warping at high temperatures, a method of increasing the adhesive strength of the carrier 1 for transportation and a method of bringing the linear expansion coefficient closer to that of the thin printed wiring board 5 can be easily considered. After that, there is a problem that the carrier 1 for transportation cannot be removed from the thin printed wiring board 5, and in the latter case, the linear expansion coefficient of the carrier 1 for transportation is very small as compared with the thin printed wiring board 5 such as a flexible substrate. When an electronic component such as a large semiconductor chip 6 is mounted, not only does the solder melt and harden at a high temperature and returns to room temperature, but also causes a large warp in the thin printed wiring board 5 due to the difference in linear expansion coefficient. Therefore, it is necessary to remake the carrier 1 for transportation in accordance with different linear expansion coefficients depending on substrate materials and pattern configurations of various thin printed circuit boards 5 There is a problem such as also lead to cost up.

  Accordingly, the present invention solves the above-described conventional problems, and the carrier for transporting is easy to remove because the warpage of the thin printed wiring board is small even during high temperatures such as a reflow process or after mounting a large part such as a semiconductor chip. The purpose is to provide.

  In order to solve the above-mentioned conventional problems, the present invention provides a carrier for holding the thin printed wiring board by adhesion when mounting a semiconductor chip on the thin printed wiring board having a thickness of 0.5 mm or less. A carrier for transporting a thin printed circuit board, comprising: an adhesive layer in a region of the mounting portion of the semiconductor chip; and a non-adhesive layer in a region outside the mounting portion of the semiconductor chip. Yes, by having a non-adhesive layer, the thin printed wiring board will have a part that does not adhere on the carrier, and the thin printed wiring board can be freely deformed by this non-adhesive layer, so the deformation of the adhesive layer Therefore, the central portion is not deformed so as to follow the above, and a good connection between the semiconductor and the substrate can be obtained.

  In the carrier for transportation according to the present invention, since the region outside the mounting portion of the semiconductor chip is a non-adhesive layer, the substrate can be freely deformed even in the heating process, so that the central portion of the substrate is deformed into a convex shape. Not only does this cause a connection failure, but also the removal of the substrate is easy because the bonding area of the substrate is small. In addition, by using a material lower than the linear expansion coefficient of the substrate for the base material, it is possible to suppress the elongation of the substrate in the semiconductor chip mounting part even in the heating process, and to approach the deformation of the semiconductor chip. It is possible to greatly reduce the warpage of the substrate.

(Embodiment 1)
Hereinafter, the thin printed wiring board carrying carrier according to the first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating a state in which a thin printed wiring board is attached to a carrier for conveyance in Embodiment 1 and a semiconductor chip is mounted.

  First, as shown in FIG. 1, the carrier for transport 21 in the present embodiment has an adhesive layer 22 made of a weak adhesive material in the region of the mounting portion 28 of the semiconductor chip 26 on the base substrate 23, The non-adhesive layer 24 is provided from the region having the adhesive layer 22 of the semiconductor chip mounting portion 28 to the outer region 29.

  Further, both the adhesive layer 22 and the non-adhesive layer 24 are made of a heat-resistant material that does not cause hardening or deformation even at 250 ° C. or higher, which is a condition for melting the lead flow solder.

  In this configuration, a thin printed wiring board 25 having a thickness of 0.5 mm or less is disposed on the adhesive layer 22 and the non-adhesive layer 24, and a semiconductor chip 26 is disposed at a location facing the adhesive layer 22.

  Thereafter, in order to mount the semiconductor chip 26 on the thin printed wiring board 25 as shown in FIG. 1, the carrier 21 for transporting is reflowed at a temperature of 250 ° C. or higher, which is a condition for melting the lead flow solder.

  Since the carrier 21 for conveyance of this Embodiment has the non-adhesion layer 24, since the thin printed wiring board 25 has the area | region which has not adhere | attached the conveyance carrier 21, lead flow solder melts. Even when heated by reflow at 250 ° C. or higher, which is a condition, the thin printed wiring board 25 can be freely deformed in a region facing the non-bonded portion 24.

  Therefore, unlike the prior art, the central portion of the thin printed wiring board 25 does not deform into a convex shape so as to follow the deformation of the adhesive layer 22, so that a gap difference between the semiconductor chip 26 and the thin printed wiring board 25 occurs. As a result, the solder bumps 27 melt and the semiconductor chip 26 can be mounted on the thin printed wiring board 25 with high accuracy. As a result, poor connection between the thin printed wiring board 25 and the semiconductor chip 26 is not caused, and a semiconductor component having good connection can be obtained.

  In the present invention, the distance 30 between the inner end of the region 29 outside the region of the non-adhesive layer 24, that is, the region having the adhesive layer 22 of the mounting portion 28 of the semiconductor chip 26 and the outer end of the mounting portion 28 is 5 mm or less. Is appropriate. If the interval 30 exceeds 5 mm, the phenomenon that the central portion of the thin printed circuit board 25 is deformed into a convex shape during reflowing, as in the case of a conventional carrier for transportation, will occur. You can't get it.

  Further, as compared with the conventional case, since the adhesion area between the thin printed wiring board 25 and the carrier for transport 21 is reduced, it is easy to remove.

  In addition, it is desirable to use a material having a linear expansion coefficient between the semiconductor chip 26 and the thin printed wiring board 25 as the base material of the carrier 21 for transportation, and it is preferable to use electronic components to be mounted, particularly large components such as the semiconductor chip 26. By approaching the linear expansion coefficient, the warpage of the substrate can be greatly reduced.

  In addition, although the form which mounts one semiconductor chip 26 was demonstrated in FIG. 1, it is also possible to mount the several semiconductor chip 26 arrange | positioned on the same surface simultaneously, and in this case, the semiconductor chip 26 is efficiently carried out. Can be implemented.

  As described above, according to the present embodiment, since the non-adhesive layer is provided in the outer region from the mounting portion of the semiconductor chip, the thin printed wiring board 25 can be heated even when heated by reflow at 250 ° C. or higher. Can be freely deformed, so that a poor connection between the thin printed wiring board 25 and the semiconductor chip 26 is not caused, and a semiconductor component having a good connection can be obtained.

(Embodiment 2)
Hereinafter, the thin printed wiring board carrying carrier according to Embodiment 2 of the present invention will be described with reference to the drawings. In addition, about the structure same as Embodiment 1, the same number is provided and the description is abbreviate | omitted.

  FIG. 2 is a cross-sectional view showing a state in which a thin printed wiring board is attached to the carrier for transportation according to the second embodiment and a semiconductor chip is mounted.

  As shown in FIG. 2, the feature of the present embodiment is that the heat-resistant film has an opening 31 at least at a location facing the mounting portion 28 of the semiconductor chip 26 on the adhesive layer 22 made of a weak adhesive. It is characterized in that the carrier 21 for conveyance with 32 attached is used.

  In the present embodiment, the heat-resistant film 32 is made of a material such as a polyimide film that can withstand a heating temperature of 250 ° C. or higher, which is a condition for melting the lead flow solder.

  Further, the distance 30 between the outer end of the mounting portion 28 of the semiconductor chip 26 and the inner end of the opening 31 is suitably 5 mm or less, as in the first embodiment.

  In the present embodiment, the heat-resistant film 32 has a function as a non-adhesive layer by attaching the heat-resistant film 32 having the opening 31 to the adhesive layer 22, so that the thin printed wiring is the same as in the first embodiment. The substrate 25 can be freely deformed in a region facing the heat resistant film 32, and the central portion of the thin printed wiring board 25 is not deformed into a convex shape so as to follow the deformation of the adhesive layer 22. A gap difference between the semiconductor chip 26 and the thin printed wiring board 25 does not occur, and the semiconductor chip 26 can be mounted on the thin printed wiring board 25 with high accuracy.

  Further, in this embodiment, since the entire surface of the carrier carrier 21 on the base substrate 23 is the adhesive layer 22 made of a weak adhesive, the carrier 21 for transportation is recreated even if the circuit pattern changes. Therefore, it is possible to respond by simply changing the shape of the heat-resistant film 32, and the effect can be exhibited in terms of cost reduction and design response.

  As described above, the carrier for transporting a thin printed circuit board according to the present invention is effective when a large-sized component such as a semiconductor chip is mounted on a thin printed circuit board having low rigidity and difficult to transport, such as a flexible substrate. Therefore, the present invention can be applied to applications related to the manufacture of module parts using semiconductor packages and semiconductor chips.

Sectional drawing which shows the carrier for conveyance in Embodiment 1 of this invention Sectional drawing which shows the carrier for conveyance in Embodiment 2 of this invention Sectional drawing which shows the state which stuck the thin printed wiring board on the conventional carrier for conveyance Process diagram showing mounting method to thin printed wiring board using conventional carrier for conveyance Sectional view showing problems with conventional carrier for conveyance

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Carrier for conveyance 22 Adhesive layer 23 Base base material 24 Non-adhesion layer 25 Thin printed wiring board 26 Semiconductor chip 27 Solder bump 28 Mounting part 29 The area | region outside a mounting part 30 Space | interval 31 Opening part 32 Heat resistant film

Claims (6)

A carrier for transporting and holding the thin printed wiring board when a semiconductor chip is mounted on a thin printed wiring board having a thickness of 0.5 mm or less, and an adhesive layer on the mounting portion of the semiconductor chip And a non-adhesive layer in a region outside the mounting portion of the semiconductor chip. The carrier for carrying a thin printed circuit board according to claim 1, wherein a distance between an inner end portion of the non-adhesive layer region and an outer end portion of the mounting portion of the semiconductor chip is 5 mm or less. The carrier for carrying a thin printed circuit board according to claim 1, wherein the adhesive layer and the non-adhesive layer have a heat resistance of 250 ° C. or higher. 2. A film having a heat resistance of 250 ° C. or higher and having an opening provided at least in a region of a mounting portion of a semiconductor chip on a carrier for conveyance having an adhesive layer on the entire surface. 2. A carrier for carrying a thin printed wiring board according to 1. The carrier for carrying a thin printed circuit board according to claim 4, wherein a distance between an outer end of the mounting portion of the semiconductor chip and an inner end of the opening is 5 mm or less. The carrier for carrying a thin printed wiring board according to claim 1 or 4, wherein the linear expansion coefficient of the base material used for the carrier has a numerical value between the semiconductor chip and the thin printed wiring board.

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