JP2007180062A - Printed circuit board manufacturing method and dispenser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat dissipation performance by efficiently increasing the surface area of a coated resin without significantly changing the conventional manufacturing process of a printed circuit board.
[Solution]
The underfill resin 2 is applied by the first needle 41a in the vicinity of the electrode of the printed wiring board 1 having at least one electrode 12 on the surface, and the circuit component 3 is interposed on at least a part of the upper portion of the electrode 12 via the solder bump 33. Is implemented. The underfill resin 2 is applied to the surface of the mounted circuit component 3 by the first needle 41a. The air 22 is radiated by the second needle 41b on the surface of the applied underfill resin 2 to form a plurality of holes 2a.
Then, by reflow heating the printed wiring board 1, the bonding of the solder bumps 33 and the resin sealing of the underfill resin 2 are performed together.
[Selection] Figure 6

Description

  The present invention relates to a method of manufacturing a printed circuit board, and more particularly to a method of manufacturing a printed circuit board that improves heat dissipation characteristics and a dispenser device used in the manufacturing method.

  As a mounting method of an electronic component in which a bump as a connection electrode is provided on a semiconductor element such as a flip chip, a method of soldering a bump to an electrode on a substrate is widely used. In this mounting method, an underfill which is a reinforcing resin is provided between the electronic component and the substrate for the purpose of reinforcing the solder joint between the bump and the substrate. This underfill is caused by heat that is caused by differences in the thermal expansion coefficient between the materials of the board and the electronic component that are interposed between the electronic component and the board, and the joint reinforcement function that reinforces the solder joint between the bump and the electrode. It has a stress relaxation function to relieve stress.

  On the other hand, when such an electronic component is incorporated in, for example, a hard disk drive (HDD), an overcoat process for covering the IC surface with resin may be added to prevent chipping of the bare IC.

  However, covering the IC surface with a resin significantly reduces the heat dissipation characteristics, and causes another problem that the performance of the component cannot be fully exhibited.

For example, Patent Document 1 proposes that heat radiation performance is improved by forming an uneven shape on the surface of a resin sealed on the surface of an IC chip.
Japanese Patent Laid-Open No. 11-330315 (page 7, FIG. 1)

  However, the technique disclosed in Patent Document 1 described above applies a member having irregularities on the surface of the sealing resin after the liquid sealing resin is coated on the printed circuit board and before the sealing resin is cured. Press. Then, after the sealing resin is cured, the member is removed to form an uneven shape on the surface of the sealing resin. Therefore, there is a problem that a member in which the unevenness is formed for each part must be prepared, and the process becomes complicated.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and has improved the heat dissipation performance by efficiently increasing the surface area of the coated resin without significantly changing the manufacturing process of the conventional printed circuit board. Another object of the present invention is to provide a printed circuit board manufacturing method and a dispenser device.

  In order to achieve the above object, a printed circuit board manufacturing method according to the present invention includes a first resin application step of applying a resin in the vicinity of the electrode of a printed wiring board having at least one electrode on the surface, and the electrode A circuit component mounting step for mounting a circuit component on at least a part of the upper portion of the circuit board via a solder bump, and a second resin application step for applying the resin to the surface of the circuit component mounted by the component mounting step. A hole forming step of forming a plurality of holes in the surface of the resin by radiating air to the surface of the resin applied in the first and second resin applying steps; and the hole forming step. It is characterized by comprising a reflow process in which the applied printed wiring board is reflow-heated to collectively bond the solder bumps and seal the resin with the resin.

  Further, another printed circuit board manufacturing method according to the present invention includes a circuit component mounting step for mounting a circuit component on the electrode of a printed wiring board having at least one electrode on its surface via a solder bump, and the component mounting. Between the printed wiring board on which the circuit components are mounted by the steps and the circuit components, a resin application step of applying a resin to the surface of the circuit components, and a surface of the resin applied by the resin application step A hole forming step for forming a plurality of holes on the surface of the resin by radiating air, and reflow heating the printed wiring board subjected to the hole forming step, thereby joining the solder bumps, And a reflow process for collectively performing resin sealing of the resin.

  The dispenser device according to the present invention has a first nozzle diameter, a resin application means for applying a resin to the printed wiring board from the first nozzle diameter, and the first nozzle diameter. It has the 2nd nozzle diameter which is a small diameter, and has an air radiation | emission means which radiates | emits air with respect to the said resin from this 2nd nozzle diameter, It is characterized by the above-mentioned.

  Heat dissipation performance can be enhanced by efficiently increasing the surface area of the coated resin without significantly changing the conventional printed circuit board manufacturing process.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing steps of a method for manufacturing a printed circuit board according to an embodiment of the present invention. As shown in FIG. 1, the printed circuit board manufacturing method according to the present invention includes a printed wiring board preparation step (step S0), a first resin coating step (step S1), a circuit component mounting step (step S2), the second resin coating process (step S3), the hole forming process (step S4), and the reflow process (step S5) are the main processes.

  Next, details of each step will be described.

  First, the printed wiring board preparation step (step S0) will be described. FIG. 2 is a diagram showing a printed wiring board preparation process. As shown in FIG. 2, the printed wiring board preparation step (step S <b> 0) is a step of preparing the printed wiring board 1 having the electrodes 12 on at least one surface of the substrate 11.

  The substrate 11 is subjected to a predetermined etching process on a wiring layer of a copper-clad laminate composed of an insulating layer and a wiring layer laminated on the insulating layer, and an electrode 12 and a wiring pattern (not shown) are formed. It is obtained by creating. Examples of the material for the insulating layer include glass epoxy, bismaleimide triazine (BT) resin, and ceramic. The substrate 11 may be laminated with a solder resist obtained by masking the upper portion of the electrode 12 by a technique such as masking or punching.

  The electrode 12 on the printed wiring board 1 is preferably precoated with solder by, for example, a plating method or a leveler method. In addition, this solder is obtained by uniformly mixing a solder powder and a paste-like flux containing a solvent. Examples of solder alloys that can be used in this embodiment include Sn—Pb alloys and Sn—Ag alloys. , And Sn—Zn based alloys. The printed wiring board 1 may be a multilayer printed wiring board composed of a plurality of wiring layers or plane layers.

  Next, the first resin application step (step S1) will be described. FIG. 3 is a diagram showing a first resin application step. As shown in FIG. 3, in the first resin application step (step S1), the resin 2 is applied to the vicinity (area α) of the electrode 12 of the printed wiring board 1 prepared in the printed wiring board preparation step (step S0). It is a process.

  As shown in FIG. 3, the resin 2 is applied using, for example, a dispenser 4 that is a dedicated application device, and the diameter and application time of a needle 41a that is a part of the dispenser 4 are controlled to apply the application amount and the application. Can be controlled.

  Here, the diameter of the needle 41a of the dispenser 4 may be arbitrarily changed between, for example, 0.1 mm to 1 mm in consideration of the target printed wiring board and other situations.

  The resin 2 is a so-called underfill resin, and the material thereof includes, for example, a liquid epoxy resin / aromatic amine-based curing agent or phenol resin curing agent and oleic acid, malic acid or the like as a flux component. The phenol resin curing agent also functions as a flux.

  Therefore, the underfill resin 2 having the flux function is applied before the circuit component 3 is mounted on the electrode 12 in a circuit component mounting step (step S2) described later.

  The underfill resin 2 having the flux function is one whose curing acceleration temperature is higher than the preheating temperature, higher than the melting temperature of the solder bumps 33, and can be cured at the heating peak temperature or lower. use. Thereby, the thermosetting of the underfill resin 2 having a flux function is promoted after the joining of the solder bump 33 and the electrode 12 is completed. Therefore, the thermosetting of the underfill resin 2 having a flux function is not completed before the solder bumps 33 are joined, and it is possible to prevent troubles in joining the solder bumps 33 and lowering of connection reliability.

  Next, the circuit component mounting step (step S2) will be described. FIG. 4 is a diagram showing a circuit component mounting process. As shown in FIG. 4, the circuit component mounting step (step S2) is a step of mounting the circuit component 3 on the printed wiring board 1 on which the first resin coating step (step S1) has been performed.

  However, in this circuit component mounting process, the circuit component 3 is only mounted on the electrode 12 via the solder bumps 33, and actual soldering is not performed. However, since the solder bump 33 has adhesiveness, the solder applied to the solder bump 33 or the electrode 12 until the mounted circuit component 3 is heated and bonded by a reflow process (step S5) described later. Can be fixed with paste.

  The circuit component 3 mounted here is not necessarily required to ensure the connection strength other than solder bonding, such as a semiconductor integrated circuit component or a package component. That is, for example, the component main body 31 is not only a relatively large circuit component of about 5 mm square plate, but also a component on a flexible substrate (FPC) of the HDD, and may be a relatively small circuit component of about 1 mm to 2 mm square. In addition, it is preferable that the electrode 32 is provided on one surface of the component main body 31 and the solder bump 33 is provided on the upper surface of the electrode 32. In addition, the electrode 12 of the printed wiring board 1 is provided in the position corresponding to this so that the electrode 32 of the circuit component 3 may be mounted.

  Further, the bonding temperature of the solder bump 33 is lower than the upper limit of the curing acceleration temperature of the underfill resin 2 having a flux function, that is, the thermosetting completion temperature. The bonding temperature may be higher than the lower limit temperature of the curing acceleration temperature, but is preferably equal to or lower than the curing acceleration temperature.

  In order to securely mount the circuit component 3 on the electrode 12 of the printed wiring board 1, for example, an electrode 32 of the component main body 31 of the circuit component 3 is provided by a dedicated mounting machine such as a mounter 5 for mounting the component. This is realized by adsorbing the opposite surface, moving the electrodes 32 and 12 to corresponding positions via the solder bumps 33, and mounting (mounting) vertically with a predetermined force (F).

Here, the load required for mounting is, for example, 50 gf per one solder bump 33 of the circuit component 3, and the time required for mounting varies depending on the size and shape of the circuit component 3 such as 100 msec to 2 sec.

  The circuit component 3 shown in FIG. 4 has only two electrodes 32, but may be arranged at intervals of about 200 μm, for example, depending on the type of the circuit component 3. The height of the solder bump 33 is, for example, approximately 10 μm and has a composition of Sn, Sn / Pb, Pb / In, Sn / Bi, Sn / Ag, or the like.

  Next, the second resin application step (step S3) will be described. FIG. 5 is a diagram showing a second resin application process. As shown in FIG. 5, the second resin application step (step S3) is a step of applying resin to the surface of the circuit component 3 on which the circuit component mounting step (step S2) has been performed.

  As shown in FIG. 5, the surface of the circuit component 3 is applied to the printed wiring board 1 on which the circuit component 3 is mounted using the same dispenser 4 as in step S <b> 2, and the needle 41 a which is a part of the dispenser 4 is applied. It is possible to control the application amount and the application area by controlling the diameter and application time. Here, since the diameter of the needle 41a of the dispenser 4 and the resin 2 are the same as those in the first resin application step described above, the description thereof is omitted.

  By performing the second resin application process in this way, the circuit component 3 is covered (overcoated) with the resin 2.

  Next, the hole forming step (step S4) will be described. FIG. 6 is a view showing the hole forming step. As shown in FIG. 6, in the hole forming step (step S4), a plurality of hole portions are formed on the surface of the resin by radiating air to the surface of the resin applied by the first and second resin applying steps. Is a step of forming.

  The air is emitted by using the dispenser 4 which is a dedicated application device shown in FIG. That is, the dispenser 4 has a second needle 41b that radiates air in addition to the first needle 41a that injects the resin 2, and controls the diameter and radiation time of the second needle 41b. It is possible to control the number, depth, etc. of the holes to 2.

  The second needle 41b for air injection can supply air from a branch air pipe from the existing sidefill dispenser nozzle, and the XYZ stage as an air radiation mechanism and the drive mechanism are also dispensers for resin coating. And can be shared.

  Here, the diameter of the needle 41b of the dispenser 4 may be arbitrarily changed between 20 μm and 50 μm, for example, in consideration of the target printed wiring board and other situations.

  Further, the number of holes in the resin applied on the circuit component 3 should be as large as possible. In particular, as shown in FIG. 7 to be described later, it is preferable to provide many holes in the underfill resin 2 applied to the surface of the circuit component 3 as a heat dissipation measure.

  Further, a plurality of holes may be similarly provided in the underfill resin 2 applied between the circuit component 3 and the substrate 11 by controlling the angle and position of the second needle 41b.

  Next, the reflow process (step S5) will be described. FIG. 7 is a diagram showing a reflow process. As shown in FIG. 7, the reflow process (step S5) is a reflow process with a predetermined temperature profile in the printed wiring board 1 in a state where a plurality of holes are ejected to a desired position through the hole forming process (step S4). In this step, the solder bonding between the electrode 12 and the solder bump 33 and the sealing of the underfill resin 2 having a flux function are collectively performed to obtain the printed circuit board 100.

  This reflow process (step S5) is performed in two process steps of a preheating process and a heating process, similarly to a general solder reflow temperature profile. That is, after performing the preheating process, the temperature is further raised and the heating process is performed, and not only the bonding of the solder bump 33 (the solder paste on the electrode 12 in some cases) but also the thermosetting of the underfill resin 2 having a flux function. I do.

  Details of the heating temperature in the reflow process (step S5) will be described with reference to FIG.

  FIG. 8 is a diagram showing an example of temperature characteristics in the reflow process. In FIG. 8, the vertical axis represents temperature and the horizontal axis represents time. Y1 is a preheating temperature, P0 is a curing acceleration lower limit temperature of the underfill resin 2 having a flux function, P1 is a peak temperature, T1 is a preheating temperature holding time, and T2 is a peak temperature holding time. Further, point A represents the preheating temperature rising end, point B represents the reflow heating temperature rising portion, and hatched portion C represents the curing range.

  As a first step of the reflow process (step S5), a preheating process for the printed circuit board 100 manufactured in the processes of S0 to S4 in FIG. 1 is performed. The preheating treatment is set to the temperature of the preheating temperature Y1, and is performed for the preheating temperature holding time T1.

  By performing this preheating treatment, the thermal shock of the circuit component 3 can be reduced. Further, when the solder paste is present, most of the volatile material in the solder paste is removed by evaporation, the solder is dried, and the solder powder and the metal surface to be soldered can be cleaned to some extent.

  Furthermore, by performing this preheating treatment, for example, if a small chip component is mounted on the printed wiring board 1 in addition to the circuit component 3, the rising phenomenon of the component, for example, Manhattan, Tombstone phenomenon, and solder absorption The rising phenomenon, for example, wicking can be prevented.

  The preheating temperature Y1 is lower than the peak temperature P1 (for example, 140 to 175 ° C.), and the preheating holding time T1 is 60 seconds or more.

  As a second step of the reflow process (step S5), further heating is performed, and the temperature is increased to the peak temperature P1 at once.

  Here, the solder paste and the solder bump 33 may have different temperature characteristics of the joint. However, since these junction temperatures are higher than the preheating temperature Y1 and lower than the peak temperature P1, the solder between the electrode 12 and the electrode 32 before the heating temperature reaches the peak temperature P1 from the preheating temperature Y1. Joining can be completed.

  Since the heating temperature passes through the curing acceleration lower limit temperature P0 of the underfill resin 2 having the flux function until the heating temperature reaches the peak temperature P1, the underfill resin 2 having the flux function from this passing point. Curing starts.

  As the final step of the reflow process (step S5), heat treatment is performed for the peak temperature holding time T2 while maintaining the temperature of the peak temperature P1.

  Here, as a specific example of the peak temperature P1 and the peak temperature holding time T2, when Sn—Pb alloy solder having a melting temperature of 183 ° C. is used in the solder bump 33, the peak temperature P1 is 200 ° C. to 230 ° C. In general, the peak temperature holding time T2 is about 20 to 60 sec.

  By performing the reflow process (step S5) including the preliminary heating process to the heating process, the curing of the underfill resin 2 having the flux function is completed.

  The printed circuit board 100 is completed through all the steps of the printed wiring board preparation step S0 to the reflow step S5 described above.

  According to the above manufacturing process, it is possible to provide fine holes in the underfill surface layer by radiating air to the resin portion. For this reason, the surface area of the resin-coated portion is significantly increased. For this reason, it is possible to remarkably improve the heat radiation characteristics of the bare IC and the IC overcoat portion, which have a tendency to generate higher heat.

The second needle 41b for air injection can supply air from a branch air pipe from an existing sidefill dispenser nozzle. Can be shared. Therefore, the present dispenser 4 can be realized at low cost. Therefore, the heat radiation performance can be enhanced by efficiently increasing the surface area of the coated resin without significantly changing the manufacturing process of the conventional printed circuit board.

  In addition, this invention is not limited to the said embodiment as it is, It can modify and implement each process in the implementation stage in the range which does not deviate from the summary. Further, various inventions can be formed by appropriately combining a plurality of steps disclosed in the embodiment. For example, the circuit component mounting process (step S2) is performed before the first resin coating process (step S1), and then the first resin coating process (step S1) and the second resin coating process (step S3). You may make it the structure which implements. Furthermore, the processes in different embodiments may be appropriately combined.

The figure which showed the process of the manufacturing method of the printed circuit board which concerns on embodiment of this invention. The figure which showed the printed wiring board preparation process. The figure which showed the 1st resin application | coating process. The figure which showed the circuit component mounting process. The figure which showed the 2nd resin application | coating process. The figure which showed the hole part formation process. The figure which showed the reflow process. The figure which showed an example of the temperature characteristic of a reflow process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed wiring board 11 Board | substrate 12 Electrode 2 Underfill resin 22 Filler 3 Circuit component 31 Component main body 32 Electrode 33 Solder bump 4 Dispenser 41a 1st needle 41b 2nd needle 5 Mounter 6 Filler injector 100 Printed circuit board

Claims (6)

A first resin application step of applying a resin in the vicinity of the electrode of the printed wiring board having at least one electrode on the surface;
A circuit component mounting step for mounting a circuit component on at least a part of the upper portion of the electrode via a solder bump;
A second resin coating step of coating the resin on the surface of the circuit component mounted by the component mounting step;
A hole forming step of forming a plurality of holes in the surface of the resin by radiating air to the surface of the resin applied by the first and second resin applying steps;
A printed circuit board that has been subjected to the hole forming step is subjected to reflow heating, and includes a reflow step in which the bonding of the solder bumps and the resin sealing of the resin are collectively performed. A method of manufacturing a circuit board. A circuit component mounting step of mounting a circuit component on the surface of the printed wiring board having at least one electrode via a solder bump;
Between the printed wiring board on which the circuit component is mounted by the component mounting step and the circuit component, and a resin application step of applying a resin to the surface of the circuit component,
A hole forming step of forming a plurality of holes on the surface of the resin by radiating air to the surface of the resin applied by the resin applying step;
A printed circuit board that has been subjected to the hole forming step is subjected to reflow heating, and includes a reflow step in which the bonding of the solder bumps and the resin sealing of the resin are collectively performed. A method of manufacturing a circuit board.   The dispenser has a first nozzle diameter and a second nozzle diameter smaller than the first nozzle diameter, the application of the resin is performed by the first nozzle diameter, and the radiation of the air is performed by the first nozzle diameter. The method for manufacturing a printed circuit board according to claim 1, wherein the method is performed with a nozzle diameter of 2.   4. The method of manufacturing a printed circuit board according to claim 1, wherein the resin application in the resin application step and the air emission in the hole forming step are performed by a dispenser. A resin application means having a first nozzle diameter and applying a resin to the printed wiring board from the first nozzle diameter;
A dispenser device comprising: a second nozzle diameter that is smaller than the first nozzle diameter; and air radiating means that radiates air to the resin from the second nozzle diameter.   The dispenser device according to claim 5, wherein the air radiating unit forms a plurality of hole shapes on the surface of the resin by radiating the air.

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