JP4251144B2 - Manufacturing method of laminated substrate - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer substrate used in portable electronic devices and the like that are required to be downsized.

  Hereinafter, a conventional method for manufacturing a laminated substrate will be described with reference to the drawings. FIG. 25 is a flowchart of manufacturing a conventional multilayer substrate, and FIGS. 26 to 30 are detailed views of each process in the conventional multilayer substrate manufacturing process.

  In FIG. 25, a conventional method for manufacturing a laminated substrate includes a cream solder printing process 3 for printing cream solder 2 on a substrate 1, a mounting process 5 for mounting an electronic component 4 after the cream solder printing process 3, and this A reflow process 6 provided after the mounting process 5, a semiconductor mounting process 8 for mounting the semiconductor element 7 after the reflow process 6, and an intermediate material injection process for injecting the intermediate material 9 after the semiconductor mounting process 8. 10, a drying step 11 provided after the intermediate material injection step 10, a prepreg laminating step 13 for laminating the prepreg 12 after the drying step 11, and heating / compression bonding provided after the prepreg laminating step 13 Step 14 was included.

  Now, these steps will be described in detail with reference to the drawings. FIG. 26 is a cross-sectional view of the mounting means in the mounting step 5 of the conventional method for manufacturing a laminated substrate. As shown in FIG. 26, the cream solder 2 was printed on the connection pattern 21 formed on the upper surface of the substrate 1 by screen printing. And the electronic component 4 was mounted | worn on this cream solder 2, and the electronic component 4 was connected to the board | substrate 1 by heating by the reflow process 6. FIG.

  FIG. 27 shows a conventional semiconductor element mounting process. In the semiconductor mounting process 8, the semiconductor element 7 is mounted on the substrate 1. FIG. 28 is a cross-sectional view of the intermediate material injection means in the intermediate material injection step of the conventional method for manufacturing a laminated substrate. As shown in FIG. 27, in the semiconductor mounting step 8, the semiconductor element 7 is mounted on the substrate 1 to which the electronic component 4 is connected. In the intermediate material injection step 10, the semiconductor element 7 and the substrate 1 are connected. In order to fill the gap 31 between the semiconductor element 7 and the substrate 1, the intermediate material 33 is injected between the semiconductor element 7 and the substrate 1 with a dispenser 32 or the like. In some cases, an intermediate material is also injected between the electronic component 4 and the substrate 1. Then, by drying these intermediate members 33 in the drying step 11, the bumps 34 formed on the semiconductor element 7 and the semiconductor element connection pattern 21a are electrically and mechanically connected.

  Next, in the prepreg lamination step 13, a thermosetting resin prepreg 41 and a copper foil 42 are laminated on the substrate 1 on which the semiconductor element 7 is fixed in the drying step 11. The prepreg 41 has a hole 43 provided at a position corresponding to the electronic component 4 and a hole 44 provided at a position corresponding to the semiconductor element 7.

  FIG. 29 is a cross-sectional view of heating / crimping means in the heating / crimping step of the conventional method for manufacturing a laminated substrate. As shown in FIG. 29, in the heating / crimping step 14, the substrate 1 and the prepreg 41 are sandwiched between the platens 45, heated with a substantially constant inclination, and compressed at a substantially constant speed. As a result, the prepreg 41 is softened and melted, and the resin in the prepreg flows into the holes 43 and 44.

In the conventional method for manufacturing a laminated substrate, the temperature of the platen 45 is increased with a substantially constant slope, and is maintained at a temperature of about 175 ° C. to 180 ° C. for about 90 to 120 minutes. After the temperature of the platen 45 is substantially stabilized, by applying a pressure of about 2 MPa to the platen 45, the platen 45 compresses the prepreg 41 at a substantially constant speed. Then, the movement of the platen 45 is stopped when the prepreg 41 reaches a specified thickness. The prepreg 41 made of a thermosetting resin is a plate-like body up to 85 ° C., can flow in a temperature range of 110 ° C. to 150 ° C., and is cured in a temperature range of 150 ° C. or higher.

  FIG. 30 is a cross-sectional view of a multilayer substrate manufactured by a conventional method for manufacturing a multilayer substrate. According to the above-described process, the prepreg 41 is compressed while being heated by the platen 45, so that the prepreg 41 flows into the holes 43 and 44 and further rises to a temperature at which the resin is cured.

For example, Patent Document 1, Patent Document 2, or Patent Document 3 is known as prior art document information related to the invention of this application.
JP 2002-93957 A JP 2003-289128 A JP 2003-86949 A

  However, in such a conventional method for manufacturing a laminated substrate, before the step of laminating a resin sheet on the substrate and integrating the resin sheet and the substrate, an intermediate material or the like is previously provided in the gap between the substrate and the electronic component. Was buried. Accordingly, there is a problem that a step of filling and drying the intermediate material is required.

  Therefore, the present invention solves this problem, and without filling the gap between the electronic component and the substrate in advance with an intermediate material or the like, the resin is surely put into the gap at the same time in the process of integrating the resin sheet and the substrate. An object of the present invention is to provide a method for manufacturing a laminated substrate that can be filled in the substrate.

In order to achieve this object, in the integration step in the method for manufacturing a laminated substrate of the present invention, the heating step for softening the resin, the sheet is compressed after the heating step, and the electronic component and the substrate are a forced inflow step of once flowing the resin into the formed with a gap and the gap between, and a curing step of curing the resin after the forced flow-in step, in the heating step, the sheet is heated And compressed at a first pressure. In the forced inflow step, the sheet is compressed at a speed of 300 mm or more in a state where the sheet is laminated on the substrate, and the temperature of the sheet and the resin does not melt the solder. In the forced inflow step, the resin is rapidly flowed in a short time to fill the gap with the resin, thereby preliminarily providing a gap between the electronic component and the substrate. To without filling such as an intermediate material, it is possible to reliably fill the resin into the gap simultaneously integrating step of the resin sheet and the substrate.

As described above, according to the present invention, in the integration step, a heating step for softening the resin, and a gap formed between the electronic component and the substrate by compressing the sheet after the heating step. And a forcible inflow step for allowing the resin to flow into the gap at once, and a curing step for curing the resin after the forcible inflow step. In the heating step, the sheet is heated and the first In the forced inflow step, the sheet is laminated at a speed of 300 mm / s or more in a state where the sheet is laminated on the substrate, and the temperature of the sheet and the resin is set to a temperature at which the solder does not melt. Accordingly, in the forced inflow process, the resin is rapidly flowed in a short time to fill the gap with the resin, and the resin is forced to flow into the gap and the gap between the electronic component and the substrate. Even if no material is used, the resin can be reliably filled between the electronic component and the substrate. Therefore, a method of manufacturing a laminated substrate that can reliably fill the gap simultaneously with the resin sheet and the substrate integration step without previously filling the gap between the electronic component and the substrate with an intermediate material or the like. Can be provided.

  In addition, a step of separately injecting the intermediate material is not required, and the intermediate material is not necessary, so that a low-price laminated substrate can be realized.

  Furthermore, since the forced inflow process is provided, the resin can be reliably filled into a narrow gap between the electronic component and the substrate. Therefore, voids are less likely to occur, and a highly reliable laminated substrate can be realized.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart of a method for manufacturing a multilayer substrate according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view of the multilayer substrate, and FIGS. 3 to 18 are multilayer substrates according to Embodiment 1. It is detail drawing of each process of this manufacturing method. In FIG. 1 to FIG. 18, the same reference numerals are used for the same parts as in the prior art, and the description thereof is simplified.

  First, the configuration of the multilayer substrate in the first embodiment will be described with reference to FIG. In FIG. 2, reference numeral 101 denotes a thermosetting resin substrate formed in multiple layers. In this layer, the upper and lower surfaces of each layer are connected by an inner via (not shown). Also, a copper foil pattern (not shown) is laid on the upper surface of each layer to form each electronic circuit.

  Land patterns 104a and 104b are formed on the upper surface of the substrate 101. Between the semiconductor element (used as an example of an electronic component) 105 placed on the upper surface of the substrate 101 and the land pattern 104a. The solder bumps 102 are connected, while the resistor 106 (used as an example of an electronic component) 106 and the land pattern 104b are connected by solder (used as an example of a connection fixing material) 107.

  The solder 107 is a lead-free solder using tin, silver, or copper. This is because it does not contain harmful substances and does not adversely affect the environment. Further, instead of this solder 107, a thermosetting conductive adhesive can be used. When a conductive adhesive is used, the melting temperature of this conductive adhesive is higher than that of solder. For example, the semiconductor element 105 and the resistor 106 are not detached from the substrate 101 even in a high temperature environment by soldering or the like nearby. Absent.

  A thermosetting resin 108 is sandwiched between the substrate 101 and the copper foil pattern 109 and covers the outer periphery of the semiconductor element 105 and the resistor 106 so that there is no gap.

  Next, each process in the manufacturing method of the laminated substrate in this Embodiment 1 is demonstrated using FIGS. 3-18 in order of the process shown in FIG. FIG. 1 is a manufacturing flowchart of the multilayer substrate in the first embodiment, and FIG. 3 is a cross-sectional view of the multilayer substrate in the flux application process. 1 and 3, reference numeral 111 denotes a flux application process. In the flux application step 111, the flux 112 is printed by a metal screen (not shown) on the land pattern 104a for mounting the semiconductor element 105 (shown in FIG. 5).

  FIG. 4 is a cross-sectional view of the multilayer substrate in the cream solder printing process according to the first embodiment. In FIGS. 1 and 4, reference numeral 113 denotes a cream solder printing process provided after the flux application process 111. In this cream solder printing step 113, the cream solder 2 (used as an example of the connection fixing material) is printed on the land pattern 104b for mounting the resistor 106 (shown in FIG. 5) using the screen 131. The screen uses a stainless steel metal screen, and the screen 131 is formed with a recess 126 at a position where the flux 112 is applied. The concave portion 126 prevents the flux 112 from adhering to the screen 131 when the cream solder 2 is printed.

  FIG. 5 is a cross-sectional view of the multilayer substrate in the electronic component mounting process of the first embodiment. 1 and 5, reference numeral 114 denotes an electronic component mounting process provided after the cream solder printing process. In this electronic component mounting process 114, the semiconductor element 105, the resistor 106, etc. Mounted in position. Note that a semiconductor element 105 having a plurality of solder bumps 102 formed on the lower surface 105a side is used.

  FIG. 6 is a cross-sectional view of the multilayer substrate in the reflow process of the first embodiment. In FIG. 1 and FIG. 6, 115 is a reflow process provided after the electronic component mounting process. In this reflow process 115, the cream solder 2 is melted by making the cream solder 2 higher than the melting point temperature. The resistor 106 and the land pattern 104b, and the bump 102 of the semiconductor element 105 and the land pattern 104a are fixed by soldering. In the first embodiment, the reflow process 115 is performed in a nitrogen atmosphere. Thereby, the oxidation of the surface of the substrate 101 can be suppressed, and the adhesion between the substrate 101 and the prepreg is improved.

The reflow process 115 is followed by a cleaning process (not shown) to clean the flux 112 residue and solder balls. Further, it is better to perform O ₂ asher treatment or silane coupling treatment. This is because the adhesion between the substrate 101 and the prepreg can be improved by these surface modification treatments.

  In the first embodiment, reflow soldering is used in order to perform high-quality and high-quality soldering. According to this reflow soldering, a component that is reflow-soldered by a self-alignment effect. Is fixed in place. Therefore, since the component is fixed with high accuracy, the length of the pattern line following the component is constant. That is, in the case where the pattern line is used as an inductor, the inductance value is constant and the electric performance is a predetermined value. This is particularly important in high frequency circuits.

  FIG. 7 is a cross-sectional view of the laminated substrate in the prepreg lamination step of the first embodiment. 1 and 7, reference numeral 116 denotes a prepreg lamination step provided after the reflow step. This prepreg laminating step 116 is a step of laminating a prepreg 141 with a hole (used as an example of a sheet) on the substrate 101, and the prepreg 141 with a hole is preliminarily formed on the prepreg 12 with the semiconductor element 105. The hole 146 into which the resistor 106 is inserted and the hole 142 into which the resistor 106 is inserted are processed. The prepreg 12 according to the first embodiment is obtained by impregnating a glass nonwoven fabric with a thermosetting resin and drying it. In Embodiment 1, an epoxy resin is used as the thermosetting resin. However, other thermosetting resins such as phenol may be used. Moreover, in this Embodiment 1, although the glass nonwoven fabric was used, this may be a glass woven fabric or the cloth by resin-type fibers, such as another aramid resin, etc. may be used.

  Here, a gap 143 is provided between the hole 146 and the semiconductor element 105. Therefore, the prepreg 141 with a hole can be easily laminated on the substrate 101 on which the semiconductor element 105 is mounted. Similarly, since the gap 144 is also provided between the hole 142 and the outer periphery of the resistor 106, the prepreg 141 with a hole can be easily laminated on the substrate 101 on which the resistor 106 is mounted.

In addition, since the semiconductor element 105 and the resistor 106 are mounted by reflow soldering, the semiconductor element 105 and the resistor 106 are mounted at predetermined positions with high positional accuracy by the self-alignment effect due to the melting of the cream solder 2. That is, since the positional accuracy of the semiconductor element 105 and the resistor 106 is good, the gaps 143 and 144 can be reduced. Accordingly, the epoxy resin 108 can easily flow into the gaps 156 and 157. In the first embodiment, the gap 143a in the side surface direction of the semiconductor element 105 in the gap 143 is about 0.4 mm. The gap 144a in the lateral direction of the resistor 106 in the gap 144 is about 0.2 mm. Accordingly, since the gaps 143a and 144a are provided, the prepreg can be easily stacked even if the mounting positions of the semiconductor element 105 and the resistor 106 are shifted from the predetermined positions.

  In the first embodiment, six prepregs 141 a to 141 f having a thickness of 0.2 mm are stacked in this order on the upper surface of the substrate 101. Among these, four sheets of prepregs 141a to 141d are laminated in this order on the upper surface of the substrate 101. With respect to these sheets, a hole 146 into which the semiconductor element 105 is inserted and a resistor 106 are inserted. Holes 142 are formed.

  Further, the prepreg 141e stacked on the upper surface of the prepreg 141d is provided with only the hole 142 into which the resistor 106 is inserted, and is not provided with the hole 146 into which the semiconductor element 105 is inserted. That is, a hole corresponding to the height of the electronic component is provided. In this case, the air gaps 143a and 144a are preferably provided above the semiconductor element 105 and the resistor 106. This is to prevent the semiconductor element 105 and the resistor 106 from being destroyed by the compression pressure applied in the integration step 118 described later. That is, this prevents the compression pressure from being applied to the semiconductor element 105 and the resistor 106 before the epoxy resin 108 is softened.

  In the first embodiment, only two types of electronic components, the semiconductor element 105 and the resistor 106, are mounted on the substrate 101. Therefore, the number of stacked prepregs is six. However, when various types of electronic components are mounted, there are various heights of the electronic components. Therefore, it is necessary to set the height of the gap according to the height of these various electronic components. Therefore, in such a case, the number of stacked layers may be increased by using a prepreg having a thinner thickness. For example, using a prepreg having a thickness of 0.1 mm, 12 sheets thereof may be laminated, or two or more kinds of prepregs may be mixed and laminated. However, in this case, the number of prepregs stacked increases, so it is desirable to reduce the number of stacked layers as much as possible within a range that can accommodate the difference in height of electronic components.

  A prepreg 141f in which neither of the holes 146 and 142 is formed is placed on the upper surface of the prepreg 141e, and a copper foil 145 is provided on the entire upper surface of the prepreg 141f.

  Reference numeral 118 (shown in FIG. 1) denotes an integration process in which the substrate 101, the prepreg 141, and the copper foil 145 laminated in the prepreg lamination process are heat-bonded at a temperature at which the solder 107 does not melt and integrated. Hereinafter, the integration step 118 will be described in the order shown in FIG.

  FIG. 8 is a cross-sectional view of the integration means in the integration process of the first embodiment. The integration means will be described in detail with reference to FIG.

  Reference numerals 151 and 152 denote platens (used as an example of compression means), and the substrate 101 is mounted on the platen 152 side. The platens 151 and 152 and the telescopic wall 153 constitute a sealed container 154 (used as an example of a sealing means). The sealed container 154 is connected to a suction machine (not shown) used as an example of a vacuuming means. In the first embodiment, the air in the sealed container 154 is sucked from the hole 155 provided in the vicinity of the outer peripheral portion of the platen 152.

  A heater 160 embedded in the platens 151 and 152 heats the prepreg 141 with this heater (used as an example of a heating unit).

  Reference numeral 162 denotes a servo motor (used as an example of a driving unit), which is used to drive the platen 152 with good responsiveness. Further, a speed reduction mechanism 163 is inserted between the servo motor 162 and the platen 152. The speed reduction mechanism 163 converts the rotational motion into a reciprocating motion and decelerates the rotation of the servo motor 162. It should be noted that a ball nut bearing is used for the speed reduction mechanism 163 in the first embodiment. Therefore, the position of the platen 152 can be precisely controlled.

  The platens 151 and 152 are provided with a temperature sensor, a pressure sensor, and a position sensor (not shown), and an output of these sensors and a memory (not shown) are controlled by a control circuit (not shown, driving means control). Circuit as well as the input of the heating means control circuit). The output of this control circuit is connected to the input of the servo motor 162, the input of the heater 160, and the vacuuming means to control their operation. The control circuit is connected to the output of the clock timer, and also manages the time in the integration step 118. In the first embodiment, since the viscosity of the epoxy resin 108 changes depending on the temperature, the viscosity of the epoxy resin 108 is managed by replacing it with the temperature. Further, the memory stores determination conditions for the sensor output in the integration process as data, and the control circuit compares and determines these data and the output from each sensor, and the heater 160, servo motor 162, or vacuuming means. Etc. are controlled.

  Next, an integration process using the integration means configured as described above will be described in detail. FIG. 9 is a cross-sectional view of the integration means in the vacuuming process of the first embodiment. 1, 8, and 9, reference numeral 119 denotes a vacuuming process provided after the prepreg lamination process. In this vacuuming step 119, the laminated substrate in which the prepreg 141 is laminated on the substrate 101 in the prepreg laminating step 116 is stored in a sealed container 154 constituted by the platens 151 and 152 and the stretchable wall 153. In the first embodiment, the platen 151 side is fixed and the platen 152 side is movable.

  Then, the air in the sealed container 154 is extracted from the hole 155 provided in the platen 152 by a suction machine, and the inside of the sealed container 154 is brought into a substantially vacuum state. At this time, it is important to make the inside of the holes 146 and 142 substantially vacuum. This is because the holes 146 and 142 are evacuated, and the epoxy resin 108 in the prepreg 141 is removed from the gaps 143 and 144 and the narrow gap between the substrate 101 and the semiconductor element 105 in the forced inflow step 122 described later. This is because it is surely filled into the narrow gap 157 between the substrate 101 and the resistor 106. The gap 156 in the first embodiment has a size of about 40 μm to about 350 μm, and the gap 157 is about 10 μm to about 40 μm, which is very small compared to the gap 143 and the gap 144.

  In the first embodiment, for convenience of explanation, a description is given using a semiconductor element 105 and only two resistors 106 mounted. However, more electronic components are actually mounted on the substrate 101. In consideration of the productivity of the laminated substrate, it is desirable that the size of the substrate 101 is larger. Therefore, in reality, the gaps 143 and 144 and the gaps 156 and 157 are provided in more places. Therefore, in the evacuation step 119, it is important to suck the air existing in the numerous gaps 143 and 144 and the gaps 156 and 157.

Accordingly, a plurality of prepregs 141 that are not viscous at room temperature are used in the first embodiment. Further, by providing the evacuation step 119 before the softening step 120, viscosity is generated in the prepreg 141 so that the prepregs 141 or between the prepreg 141 and the substrate 101 does not stick. That is, the vacuuming step 119 is completed before the prepreg 141 becomes viscous. Thereby, air can be extracted from between the prepregs 141 or between the prepreg 141 and the substrate 101, and the gaps 143, 144 and the gaps 156, 157 can be substantially vacuumed.

  In the present embodiment, as the pressure in the sealed container 154 decreases, the stretchable walls 153 and 153 contract, and the platen 152 is lifted in the direction of arrow A as shown in FIG. As shown in FIG. 9, the prepreg 141 and the copper foil 145 laminated with the substrate 101 are completely sandwiched and held between the platen 151 and the platen 152. By evacuating the sealed container 154 in this way, a negative pressure of about 0.2 MPa is applied to the prepreg 141.

  FIG. 10 is a cross-sectional view of the integration means in the softening process of the first embodiment. 1 and 10, reference numeral 120 denotes a softening process (used as an example of a first heating process) provided after the vacuuming process. In the softening step 120, the epoxy resin 108 impregnated in the prepreg 141 is softened by heating the heater 160. In the first embodiment, the temperature of the epoxy resin 108 is increased to about 110 ° C., and the viscosity is decreased to about 2100 ps. This viscosity is a viscosity at which the epoxy resin 108 starts to flow at the pressure (0.2 MPa) generated by the evacuation by the evacuation means in the first embodiment.

  Since the prepreg 141 is compressed with a minute pressure of 0.2 MPa by the platens 151 and 152, the platen can be brought into close contact with the surface of the copper foil 145. Therefore, the heat of the heater 160 can be reliably transmitted to the prepreg 141, and an energy efficient and energy saving heating means can be realized.

  FIG. 11 is a cross-sectional view of the integration means in the resin flow suppression step. In FIG. 1 and FIG. 11, 121 (shown in FIG. 1) is a resin flow suppression step provided after the softening step. Here, the heater 160 heats the epoxy resin 108 to a viscosity that can flow. This is because in the forced inflow process 122 described later, the viscosity of the resin 108 is likely to flow into the gaps 156 and 157 as much as possible.

  For this reason, the epoxy resin 108 flows out to the outside of the substrate 101, the gaps 143 and 144, and the gaps 156 and 157 even if the pressure is as low as 0.2 MPa. . For example, when the epoxy resin 108 flows out of the substrate 101, the amount of the epoxy resin 108 that flows in the forced inflow process 122, which will be described later, is reduced, so that it becomes difficult for the resin to flow into the gaps 156, 157 and the like. .

  Further, in the softening process 120, the platens 151 and 152 heat the substrate 101 and the prepreg 141 from above and below, so that a temperature difference between a place close to the heater 160 provided on the platens 151 and 152 and a place far from them. Is likely to occur. In general, the gaps 156 and 157 are formed at positions away from the platens 151 and 152. That is, the temperature of the gaps 156 and 157 is lower than the temperature of the epoxy resin 108. Therefore, if the epoxy resin 108 flows into the gaps 156 and 157 before the forced inflow step 122, the temperature of the epoxy resin 108a decreases. As a result, the viscosity of the epoxy resin 108 that has flowed into the gaps 156 and 157 increases, and the epoxy resin 108 does not flow into the gap any more during the forced inflow step 122, causing voids and the like.

  Therefore, in the first embodiment, the resin flow suppression process 121 is provided between the softening process 120 and the forced inflow process 122. In this resin flow suppression process, the compression pressure applied to the prepreg 141 by the platens 151 and 152 is relaxed so that the epoxy resin does not flow from the start of the flow of the epoxy resin 108 until the epoxy resin 108 is forced to flow. It is to make. As a result, the epoxy resin 108 is less likely to flow out. Further, the epoxy resin 108 becomes difficult to enter the gap, and the epoxy resin can be surely filled into the gap in the forced inflow process 122.

  In the first embodiment, the servo motor 162 connected to the platen 152 is also used as the compressed resin flow suppression means in order to relieve the compression pressure. That is, based on the signal from the temperature sensor, the servo motor relaxes the compression pressure applied to the epoxy resin 108 by expanding the platen 152 in the direction B in FIG. Since the viscosity of the epoxy resin 108 changes depending on the temperature, the viscosity of the epoxy resin 108 is managed by replacing it with the temperature. That is, the memory stores flow start temperature data at which the epoxy resin 108 starts to flow. The control circuit compares the signal detected by the temperature sensor with the flow start temperature data, and drives the servo motor when it is determined that the epoxy resin 108 has reached the flow start temperature. The control circuit inputs the pressure signal from the pressure sensor and controls the servo motor 162 so that the pressure of the platen 152 becomes a predetermined pressure.

  In order to suppress the flow of the epoxy resin 108, it is desirable that the platens 151 and 152, the substrate 101, and the prepreg 141 are held at a pressure as low as possible within a contactable range. Therefore, the pressure in the resin flow suppression step 121 of the first embodiment is about 0.1 MPa. As a result, it is possible to reduce the flow of the epoxy resin 108, and it is possible to reliably fill the gaps 156 and 157 with the epoxy resin 108 in the forced inflow process 122 described later.

  Next, FIG. 12 is a cross-sectional view of the integration means in the forced inflow process of the first embodiment. In FIG. 1 and FIG. 12, 122 is a forced inflow process provided after the resin flow suppression process. In this forced inflow process 122, the prepreg 141 is compressed to a thickness of approximately two thirds, and the epoxy resin 108 contained in the glass nonwoven fabric of the prepreg 141 flows out to fill the entire gaps 143, 144 and gaps 156, 157. Is done. That is, the platen 152 is moved at high speed in the direction of arrow C in FIG. 12, and the prepreg 141 is compressed at high speed. Thus, the softened epoxy resin 108 is caused to flow into the gaps 143, 143a, 144, 144a and the gaps 156, 157. By increasing the compression speed of the platen 152, the gaps 156, 157 can be shortened in a short time. This is for injecting resin.

  Here, since the gaps 156 and 157 are very small compared to the gaps 143 and 144, a large pressure loss occurs when the epoxy resin 108 flows into the gaps 156 and 157. Further, since the epoxy resin 108 is a viscous fluid, friction is generated on the contact surface with the substrate 101, the semiconductor element 105, and the resistor 106.

  Here, since the semiconductor element 105 has the bumps 102, the width of the passage through which the epoxy resin 108 flows is repeatedly reduced and enlarged by the bumps 102. Therefore, in particular, the pressure loss of the epoxy resin 108 in the gap 156 increases. Therefore, by increasing the flow rate of the epoxy resin 108, the flow is not stopped by pressure loss or frictional force until the filling of the gaps 156 and 157 of the epoxy resin 108 is completed.

Further, in the first embodiment, the heating is continuously performed by the heater 160 even during the forced inflow step 122. Accordingly, it is necessary to fill the gaps 143, 143a, 144, 144a and the gaps 156, 157 in a short time. This is because the temperature of the epoxy resin 108 rises due to the heating from the heater 160 and the prepreg 141 is a thermosetting resin, thereby preventing the prepreg 141 from being cured.

  Note that the platen 152 in the first embodiment is compressed at a high speed of about 300 mm / second or more. As a result, a flow is generated in the epoxy resin 108, and the epoxy resin 108 is injected into the gaps 143, 143a, 144, 144a and the gaps 156, 157 at once. In the first embodiment, since the servo motor 162 with good response is used for driving the platen 152, a rapid acceleration can be given to the platen 152. Then, the movement of the platen 152 is stopped by contacting the stopper 161.

  Here, since the periphery of the gaps 156 and 157 in the forced inflow step 122 is sealed with the epoxy resin 108 having a high viscosity, the vacuum in the gaps 156 and 157 is released even if the vacuum is released almost simultaneously with the forced inflow step 122. Is thought to be maintained. That is, if the vacuum is released in the forced inflow process, the prepreg 141 receives pressure in a direction in which it is compressed inward.

  Therefore, in the first embodiment, the vacuum state is released substantially simultaneously with the forced inflow step 122, and the pressure is returned to the substantially atmospheric pressure. As a result, in the forced inflow step 122, the epoxy resin 108 is compressed from the vertical direction by the platens 151, 152 and at the same time, pressure is applied from the side surface direction, so that the epoxy resin 108 easily flows into the gaps 156, 157. .

  Then, after filling the epoxy resin 108 into the gaps 156 and 157 in this way, the epoxy resin 108 is cured by a curing step 123 (shown in FIG. 1). In this curing step 123, a second heating step in which the fluidity of the prepreg 141 is lost by heating at a temperature lower than the liquidus temperature of the solder bump 102 and the solder 107, and after this second heating step, the prepreg 141 is removed. And a third heating step for complete curing.

  Here, in the second heating step, it is important that the prepreg 141 loses fluidity at a temperature lower than the liquidus temperature of the solder bump 102 and the solder 107. Here, since lead-free solder having a melting point of about 217 ° C. is used for the solder bump 102 and the solder 107, the temperature at which the epoxy resin 108 loses fluidity in the second heating step is at least about 200 ° C. or less. Is desirable. Therefore, in the first embodiment, the fluidity of the epoxy resin 108 is lost at about 150 ° C. Therefore, since the viscosity of the epoxy resin 108 at 150 ° C. is about 24000 ps, the pressure in the second heating step is set to about 4 MPa so as not to flow above this viscosity.

  Thus, the fluidity of the epoxy resin 108 is lost in the second heating step, and then the temperature of the epoxy resin 108 is raised to 180 ° C. in the third heating step, and the epoxy resin 108 is surely cured. Accordingly, in the second heating step, the epoxy resin 108 loses fluidity at about 150 ° C., so that the connection between the semiconductor element 105 and the substrate 101 or between the resistor 106 and the substrate 101 is disconnected. There is nothing.

  When the curing of the prepreg 141 is completed in this way, the process proceeds to the cooling step 124 (shown in FIG. 1). In this cooling step 124, cooling is performed with a slow gradient. Therefore, it cools slowly, controlling the temperature of the heater 160, with the state pinched | interposed into platen 151,152. This slow cooling is performed until the temperature reaches a glass transition point or lower (160 ° C. by TMA measurement method), and then the platens 151 and 152 are opened and naturally cooled. Thereby, the difference in the amount of shrinkage caused by the difference in linear expansion coefficient from the copper foil 145 and the epoxy resin 108 can be reduced, and the warpage of the multilayer substrate can be reduced. Further, peeling at the interface between the conductor on the substrate 101 and the epoxy resin 108 can be prevented.

  FIG. 13 is a cross-sectional view of the cutting means in the cutting step of the first embodiment. In FIGS. 1 and 13, reference numeral 125 denotes a cutting process in which the resin 172 that has flowed out of the substrate 101 by the forced inflow process 122 is excised. In this cutting step 125, reference numeral 171 denotes dicing teeth for cutting the laminated substrate. In this cutting step 125, the dicing teeth 171 are rotated to cut off unnecessary resin 172. In the first embodiment, not only the unnecessary resin 172 part is cut off, but both the substrate 101 and the resin 172 are cut. This is because the inner side of the end of the substrate 101 is cut so that the dimension of the laminated substrate becomes substantially constant regardless of the expansion and contraction of the substrate 101.

  As described above, in the integration step 118, the softening step 120 is heated to a flowable temperature, and in the heating / compression step 118 a, the temperature applied to the prepreg 141 and the substrate 101 and the pressure and speed of the platen 152 are changed. The substrate 101 and the prepreg 141 are integrated by heating and compressing while controlling according to the viscosity or temperature of the substrate, thereby completing the laminated substrate (shown in FIG. 2). In FIG. 2, the copper foil 145 provided on the uppermost layer is etched to form the wiring pattern 110. Therefore, using this pattern 110, an electric circuit, its wiring, a terminal, etc. can be formed in the uppermost layer. If the copper foil 109 is connected to the ground without etching, it can be used as a ground plane or a shield.

  Next, an operation in which the epoxy resin 108 is injected into the gaps 156 and 157 in the integration step 118 will be described. First, the relationship between the temperature of the epoxy resin 108, the pressure and the viscosity characteristics will be described with reference to the drawings. FIG. 14 is a characteristic diagram of the epoxy resin 108, where the horizontal axis 201 is temperature, the first vertical axis 202 is viscosity, and the second vertical axis 203 indicates compression pressure. In FIG. 14, 204 indicates the viscosity characteristic of the epoxy resin 108 contained in the prepreg, and 205 indicates the pressure (pressure of the platens 151 and 152) that the prepreg receives.

  First, the resin 108 does not have a viscosity at room temperature, but softens and decreases in viscosity as the temperature increases. At the temperature 206, the minimum viscosity is 207. At the temperature 206 or higher, the viscosity increases and curing is accelerated. The temperature 206 in the epoxy resin 108 in the first embodiment is about 133 ° C., and the minimum viscosity 207 at that time is about 1150 ps.

  It should be noted that pressure is always applied to the epoxy resin 108 during the integration step 118 described above. That is, the flow of the epoxy resin 108 is determined by the pressure applied to the epoxy resin 108 and the viscosity (temperature) of the epoxy resin 108.

  Then, next, when looking at the pressure characteristics of the platens 151 and 152 in the first embodiment, the pressure 208 is applied in the softening process 120, the pressure 209 is applied in the curing process 123, and the pressure in the forced inflow process 122. An instantaneous peak pressure 210 that is at least twice that of 209 is applied.

  The epoxy resin 108 has a flow start viscosity 212 that starts flowing at a temperature 211 at a pressure 208. That is, the epoxy resin 108 has a plate shape in the temperature region 213 (used as an example of the first temperature region) from the normal temperature to the temperature 211 and does not flow. Since the pressure 208 is 0.2 MPa in the first embodiment, the flow starting viscosity is 2100 ps, and the temperature 211 at that time is about 110 ° C.

  Next, when the temperature 211 is exceeded, the viscosity of the epoxy resin 108 decreases to the minimum viscosity 207 at the temperature 206. The forced inflow step 122 is performed in a temperature region 214 (used as an example of the second temperature range) between the temperature 211 and the temperature 206.

  When the forced inflow step 122 is completed, the epoxy resin 108 is cured in the curing step 123, and the pressure 209 is applied in the curing step 123. The epoxy resin 108 gradually cures when it reaches a temperature region 215 (used as an example of the third temperature range) of a temperature 206 or higher, and becomes a viscosity 217 that loses fluidity at a temperature 216 at a pressure 209. When the pressure 209 is 4 MPa, the temperature 216 is 150 ° C., and the viscosity 217 is 24000 ps.

  In the curing step 123 in the first embodiment, the epoxy resin 108 is raised to a temperature of about 180 ° C. and held at that temperature for 60 minutes. Then, it has a slow cooling process of gradually cooling at a rate of about 1 ° C./min while adjusting the temperature of the heater 160 while being sandwiched between the platens 151 and 152.

  By the above method, the forced inflow process 122 is provided between the temperature 211 (flow start viscosity 212) and the temperature 206 (minimum viscosity 207), and the pressure 210 is applied by the platen 152. As a result, a rapid acceleration is generated, and the epoxy resin 108 is forced to flow. It should be noted that the time from the start to the end of the movement of the platen is completed in a short time of about 1 second or less. When the temperature exceeds the temperature 206 at which the minimum viscosity 207 is reached, the addition polymerization reaction proceeds by further heating, and curing begins. When heated to a temperature of 216 or higher, the epoxy resin 108 does not substantially flow and is cured.

  FIG. 15 is an enlarged view of a main part of the semiconductor element 105 in the forced inflow process of the first embodiment. In FIG. 15, the epoxy resin 108 is compressed by the platen 152 as shown in FIG. 12, and the tip 108 a flows into the gap 156. At this time, the gap 156 is much smaller than the gap 143, and the epoxy resin 108a may be considered as a fluid that passes through the reduction tube. Accordingly, a vortex 261 is generated near the corner 105b of the semiconductor element 105, and a pressure loss is generated.

  The solder bump 102 may be considered as a fluid that passes through the expansion tube after the reduction tube. Therefore, since the reduced pipe and the enlarged pipe are passed, the epoxy resin 108 that passes through the solder bump 102 also generates a large pressure loss.

  Furthermore, the forced inflow process 122 is performed between the temperature 214 (flow start viscosity 212) and the temperature 206 (minimum viscosity 207). That is, since the viscosity of the epoxy resin 108 is about 2100 ps to 1150 ps, the epoxy resin 108 that flows into the gaps 156 and 157 is a viscous fluid. Accordingly, friction occurs between the epoxy resin 108a and the lower surface 105a of the semiconductor element 105. Therefore, the pressure 210 is applied to the platen 152 to cause the epoxy resin 108 to flow at a high speed so that the flow rate of the epoxy resin 108a does not become zero due to this pressure loss and frictional resistance.

  In order to increase the flow rate of the epoxy resin 108a as much as possible, it is desirable that the temperature of the epoxy resin 108 in the forced inflow process 122 is as close to the lowest viscosity as possible. However, the energy loss due to pressure loss and friction generates heat by conversion into thermal energy. That is, it is considered that the temperature of the epoxy resin 108 a becomes higher than the temperature of the epoxy resin 108 in the forced inflow process 122 due to this heat generation. Here, since the viscosity of the epoxy resin 108a exceeds the temperature 206, it is necessary to flow into the gaps 156 and 157 at a temperature equal to or lower than the temperature 206 (FIG. 14).

  As described above, in the forced inflow step 122, in order to prevent the epoxy resin 108 from being cured, the temperature (viscosity) of the prepreg 141 is increased due to the heat generation of the epoxy resin 108a with respect to the temperature 206 (viscosity 207) at which curing is started. The temperature is set to be as low as possible (high viscosity).

  Further, when the inflow rate of the epoxy resin 108a is high, the heat generation is also increased. Therefore, the moving speed of the platen 152 needs to be a speed at which the temperature of the epoxy resin 108a that rises due to frictional heat does not exceed the temperature 206.

  In addition, here, for convenience of explanation, one semiconductor element 105 and two resistors are provided, but in reality, a larger number of more types of components are mounted. In such a case, the timing of the time when the epoxy resin 108 flows into each gap is different. This is considered to be due to the temperature variation in the prepreg 141 generated due to the size of the gap 143 and the gap 144, the arrangement of the heater 160, and the like.

  For the above reasons, the forced inflow process 122 is performed at a temperature (100 ps higher viscosity) about 8 ° C. lower than the temperature 206 (viscosity 207) while increasing the speed of the platen 152. Thereby, in the forced inflow process 122, the temperature of the epoxy resin 108a flowing into the gaps 156 and 157 does not become higher than the temperature 206 even if it rises due to frictional heat or the like. Accordingly, the epoxy resin 108 easily flows into the gaps 156 and 157.

  Moreover, since the forced inflow process 122 is completed in a short time, the viscosity of the epoxy resin 108 at the start of the forced inflow process 122 can be lowered. Accordingly, the epoxy resin 108 can flow into the gaps 156 and 157.

  By using the manufacturing method of the laminated substrate as described above, the epoxy resin 108 can easily flow into the gaps 156 and 157 between the semiconductor element 105 and the resistor 106 and the substrate 101. Even if not, the epoxy resin 108 can be reliably filled between the semiconductor element 105 or the resistor 106 and the substrate 101. Accordingly, the gaps 156 and 157 between the semiconductor element 105 and the resistor 106 and the substrate 101 are previously filled with the intermediate material or the like, and the gaps 156 and 157 are simultaneously formed in the integration step 118 of the prepreg 141 and the substrate 101. It is possible to provide a method for manufacturing a laminated substrate that can be reliably filled with the epoxy resin 108.

  In addition, a step of separately injecting the intermediate material is not required, and the intermediate material is not necessary, so that a low-price laminated substrate can be realized.

  Furthermore, the epoxy resin 108 can be reliably filled into the narrow gaps 156 and 157 in the forced inflow step 122. Therefore, voids are less likely to occur, and a highly reliable laminated substrate can be realized.

  Below, a series of control regarding the manufacturing equipment of the laminated substrate in this Embodiment 1 is demonstrated using drawing. FIG. 16 is a timing chart for illustrating this control. 16A is a time chart of the platen pressure, FIG. 16B shows a change characteristic of thickness obtained by adding the substrate and the prepreg, and FIG. 16C is a time chart of the vacuuming means. is there. 16A, 16B, and 16C, the horizontal axis 271 indicates time, the vertical axis 272 in FIG. 16A indicates pressure, the vertical axis 273 in FIG. 16B indicates thickness, and FIG. The vertical axis 274 of (c) indicates atmospheric pressure.

  First, the resin flow suppression step 121 will be described. In FIG. 16, 275 indicates the pressure characteristic of the platen, 276 indicates the thickness characteristic, and 277 indicates the vacuum degree characteristic. In the evacuation step 119, the prepreg 141 receives a pressure of 0.2 MPa. And while receiving this pressure, it transfers to the softening process 120, a viscosity becomes small with a temperature rise, and reaches the temperature which flows at the temperature 211. Therefore, when pressure is applied as it is, the epoxy resin 108 flows to the outside of the substrate and the gaps 156 and 157. Therefore, when the control circuit detects that the epoxy resin 108 has reached the temperature 211 by a signal from the temperature sensor, the control circuit once reduces the pressure of the platen 152 to the pressure 278. At this time, the control circuit inputs a signal from the pressure sensor, detects that the pressure of the platen 152 has reached 278 by this signal, and stops the operation of the platen 152. Thereby, the pressure applied to the epoxy resin 108 is relieved, and the epoxy resin 108 is prevented from flowing.

  In the first embodiment, the pressure 278 is about 0.15 MPa. Thereby, in the forced inflow process 122, the amount of the epoxy resin 108 flowing into the gaps 143 and 144 can be increased. In addition, since the epoxy resin 108 is less likely to flow into the gaps 156 and 157 before the forced inflow step 122, the epoxy resin 108 can be maintained at a uniform temperature without a temperature drop. Therefore, the epoxy resin 108 can be surely filled into the gaps 156 and 157 in the forced inflow step 122.

  Next, the control in the forced inflow process 122 will be described. In the forced inflow step 122, the platen 152 is moved at a high speed, and the epoxy resin 108 is forced to flow into the gaps 156 and 157. At this time, the control circuit determines whether or not the platen 152 is moving at a predetermined speed based on the output from the position sensor and the signal from the clock timer. That is, the control circuit compares the position of the platen 152 at a certain time with predetermined position information to determine whether or not the moving speed is a specified speed.

  Then, by changing the width of the pulse signal supplied to the servo motor 162 (FIG. 12) according to the difference between these position information, the compression speed of the platen 152 is controlled, and the prepreg 141 is compressed at once. As a result, the moving speed of the prepreg 152 in the forced inflow process 122 is increased. Therefore, as shown in FIG. 16B, the thickness of the prepreg 141 is reduced from the thickness 283 to the thickness 284 in the forced inflow step 122. In the forced inflow process 122 in the first embodiment, the thickness of the prepreg 141 is reduced by about 0.4 mm.

  Further, a pressure information signal output from the pressure sensor is also input to the control circuit. Therefore, the control circuit monitors the pressure of the platen 152 so that the pressure does not exceed a specified value. This is because the epoxy resin 108 a flows in from the four sides of the gaps 156 and 157 and collides at the approximate center of the gaps 156 and 157. At that time, the flow rate of the epoxy resin 108 increases in accordance with the pressure of the platen 152, and the force at the time of collision in the gaps 156 and 157 increases. The force due to the collision is applied in a direction in which the semiconductor element 105 and the resistor 106 are peeled off from the substrate 101. Therefore, the control circuit monitors the pressure of the platen 152 in order to prevent destruction of the bump 102 connecting the semiconductor element 105 and the substrate 101 and the solder 2 connecting the resistor 106 and the substrate by the force due to the impact. The control circuit stops the servo motor so that the pressure becomes equal to or lower than a predetermined limit pressure 279.

  Here, since the time of this forced inflow process 122 is very short, the response time from when the pressure information signal is output from the pressure sensor to when the servo motor is driven becomes a problem. This is mainly due to the slow response of the ball nut bearing portion (large moment of inertia). That is, if the control circuit determines that the limit pressure 279 has been reached and then stops the servo motor, the pressure on the platen 152 exceeds the limit pressure 279 due to the inertial force of the bearing. Therefore, in the first embodiment, the control circuit predicts the time 280 when the pressure of the platen 152 reaches the limit pressure 279 by calculating the increase slope of the pressure curve 275 from the timing clock signal and the pressure information signal. Then, the servo motor is stopped at a time 282 before the response time 281 necessary for the control system to respond before this time 280.

  As a result, the control circuit controls the feedforward of the platen 152 based on the pressure information signal from the pressure sensor. Therefore, the bumps 102 and the solder 2 are not easily broken, and a highly reliable laminated substrate can be obtained. In addition, it is possible to realize a laminated substrate manufacturing apparatus with good responsiveness.

  In the first embodiment, in order to relieve the force caused by the collision applied to the semiconductor element 105 and the resistor 106, the pressure relieving step 122a (shown in FIG. 1) for reducing the compression pressure to the pressure 209 after reaching the limit pressure 210. Is provided. In this pressure relaxation step 122a, when the control circuit detects that the pressure signal from the pressure sensor has reached the limit pressure 210, the control circuit rotates the servo motor in the reverse direction. By reverse rotation of the servo motor, the platen 152 is moved in the opening direction to reduce the pressure.

  In the first embodiment, the vacuum state is released substantially simultaneously with the forced inflow step 122. As a result, the epoxy resin 108 is compressed in the vertical direction by the platen 152 and at the same time the pressure in the side surface direction is increased by the pressure increase due to the release of the vacuum, and the epoxy resin 108 easily flows into the gaps 156, 157 and the like. Become.

  Further, in the vacuuming step 119, when the air in the prepreg 141 is not completely removed and air bubbles remain in some places, the air bubbles expand due to the softening in the softening step 120, and bubbles ( Hereinafter referred to as a vacuum void). Therefore, the vacuum release is performed substantially simultaneously with the forced inflow step 122 to reduce the vacuum void, thereby preventing the generation of the vacuum void.

  This vacuum release is desirably performed at a temperature 206 or lower at which the resin 108 is cured. This is because even if atmospheric pressure is applied to the resin 108 by releasing the vacuum, the shrinkage of the vacuum voids does not occur after the resin 108 is cured. Therefore, in the first embodiment, the vacuum is released simultaneously with the forced inflow step 122.

  If this vacuum void occurs in the bump portion of the semiconductor element 105, when the bump is melted by heating such as reflow soldering, the melted bump is sucked by the vacuum void, and the semiconductor element 105 and the land pattern 104a The connection between the two is disconnected or the adjacent bumps are short-circuited. Further, when water droplets enter the vacuum void due to moisture absorption of the epoxy resin 108 or the like, the water droplets may cause a water vapor explosion due to reflow soldering and disconnection.

  Therefore, in the first embodiment, the generation of vacuum voids is prevented by releasing the vacuum substantially simultaneously with the forced inflow step 122. As a result, vacuum voids are less likely to be generated in the gaps 143, 143a, 144, 144a and the gaps 156, 157, and a highly reliable multilayer substrate that is less likely to cause bump disconnection or short-circuit in a reflow process or the like. Can be realized.

  As described above, in the first embodiment, the flow of the epoxy resin 108 is controlled by managing and controlling the compression pressure, the moving speed, and the temperature of the platen, and the epoxy resin 108 is put into the small gaps 156 and 157 as well. It can be filled. As a result, voids or the like can be hardly generated in the gaps 156 and 157, and a highly reliable laminated substrate can be realized.

  Since the prepreg 141 is a thermosetting resin, it does not return to a plastic state even if it is heated again after being once thermoset. Therefore, fixing of the semiconductor element 105 once sealed with the resin 108 is maintained. Further, the viscosity of the epoxy resin 108 gradually decreases to a temperature of about 150 ° C. Therefore, in this way, the resin 116 has a reduced viscosity, increased fluidity, and can be sufficiently filled into a narrow gap. In addition, since the glass nonwoven fabric is impregnated with an epoxy resin, the appearance as a substrate can be maintained even if the epoxy resin 108 is flowed in the softening step 120 or the forced inflow step 122, so that the dimensional accuracy is good. A multilayer substrate can be realized.

  Further, it is desirable that the atmosphere temperature of the solder 107 is set so that the internal temperature of the solder 107 is equal to or lower than the melting point of the solder 107 by this thermocompression bonding. Therefore, a solder having a melting point higher than the temperature of the curing step 123 is preferably used as the solder 107.

  Furthermore, since the holes 146 and 142 having the gap 143 are provided between the semiconductor element 105 and the resistor 106 in the prepreg 141, even if electronic components protruding from the substrate 101 are mounted, the prepreg 141 can be easily inserted loosely. Can be done and assembly is easy.

  Further, the temperature in this forced inflow process is integrated at a low temperature (150 ° C.) so that the solder for connecting and fixing the semiconductor element 105 and the resistor 106 does not melt, so that the connection fixing is not broken by this integration. The semiconductor element 105 and the resistor 106 can be kept firmly connected and fixed.

  Further, the narrow gaps 156 and 157 are filled with the resin 108 by the softening during the thermocompression bonding. Further, since the thermosetting prepreg 141 is used, even if heated after being thermoset, it does not return to the plastic state again, and a stable fixed state between the sealed semiconductor element 105 and the resistor 106 is maintained. .

  Furthermore, since the semiconductor element 105 and the resistor 106 are mounted on the substrate 101, inspection can be performed in the state of the substrate 101, and the yield rate after completion of the laminated substrate is improved.

  In the first embodiment, six prepregs 141 are used, but this may be one thick prepreg. In that case, the stacking step 116 can be performed in a short time, so that a low-cost stacked substrate can be obtained.

  Further, in the first embodiment, the vacuum state is released in the forced inflow step 122. This is because the viscosity of the epoxy resin 108 is increased and the epoxy resin 108 is at a temperature at which there is no gap between the prepregs 141. However, it may be between the temperature at which the fluid loses fluidity. This is because even if the vacuum is released within this temperature range, air does not enter the gaps 143 and 144 and the gaps 156 and 157, so that the vacuum is maintained in the forced inflow step 122. Accordingly, the epoxy resin 108 can surely flow into the gaps 156 and 157 in the forced inflow step 122.

  In the present embodiment, the holes 142 and 146 are provided for the semiconductor elements 105 and 106, respectively, but this may be a single hole for a plurality of electronic components. In this case, since the hole processing becomes easy, the productivity of the hole processing step 117 is improved.

(Embodiment 2)
Hereinafter, Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 17 is a flowchart of the method for manufacturing a laminated substrate in the second embodiment of the present invention. 18 to 20, the same components as those in FIGS. 1 to 13 are denoted by the same reference numerals, and the description thereof is simplified. In the first embodiment, six prepregs 141 are stacked on the substrate 101. However, in the second embodiment, one prepreg having a thickness of about 1 mm is stacked on the substrate 101.

  Now, details of each step will be described in the order of the steps in FIG. In the second embodiment, as in the first embodiment, a semiconductor element and a resistor 106 are mounted on the substrate 101 and soldered in a reflow process 115. Reference numeral 300 denotes a suspension process that is provided after the reflow process 115 and suspends a prepreg (used as an example of a sheet) on the substrate 101, and 301 is a pressure reduction / stacking process that is provided after the suspension process 300. Hereinafter, the suspension process 300 and the decompression / stacking process 301 will be described with reference to FIGS. FIG. 18 is a cross-sectional view of the suspension means in the suspension process in the second embodiment, and FIG. 19 is a cross-sectional view of the decompression / stacking means in the decompression / stacking process.

  First, the suspension process 300 (FIG. 17) will be described. In FIG. 18, a sealed container 311 (used as an example of a sealing means) is provided at a platen 152 (used as an example of a compression means), a guide 312 surrounding the side surface of the substrate 101, and an upper end portion of the guide 312. And an opening 314 is provided above the guide 312. The substrate 101 is inserted into the guide 312 of the sealed container 311 configured as described above. Here, the gap between the guide 312 and the substrate 101 is about 0.5 mm on one side, and the substrate 101 is positioned by the guide 312.

  Then, a prepreg (used as an example of a sheet) 302 is placed so as to cover the opening 314. At this time, the width 315 of the prepreg 302 is larger than the width 316 of the guide 312 and smaller than the opening dimension 313 a of the inclined portion 313. Thus, in the suspension process 300, the prepreg 302 is held in a suspended state by the inclined portion 313. A copper foil 145 is laminated on the prepreg 302. That is, in the second embodiment, the inclined portion 313 serves as a suspension unit that suspends the prepreg 302 so that a gap is formed between the prepreg 302 and the semiconductor element 105 or the resistor 106 so as not to contact each other.

  Note that the prepreg 302 in the second embodiment is made of an epoxy resin 317 having a viscosity at room temperature in order to reduce the heating as quickly as possible to reduce heating and to manufacture a laminated substrate with a small amount of energy. Used. Therefore, the end portion 302 a of the prepreg 302 is in close contact with the inclined portion 313. As a result, the platen 152, the guide 312, the inclined portion 313, and the prepreg 302 are sealed. That is, in the second embodiment, the prepreg 302 itself forms the lid of the sealed container 311.

  The vacuuming means (not shown) sucks air from the hole 318 provided in the guide 312 while being covered with the prepreg 302. By reducing the pressure, the inside of the sealed container 311 becomes negative pressure, and the prepreg 302 moves downward along the inclined portion 313 and the guide 312. In the second embodiment, the hole 318 is provided near the lower end of the guide 312. The hole 318 is desirably provided below the prepreg surface that descends due to the reduced pressure. Thereby, even if air is extracted from the hole 318, the prepreg 302 is not sucked and can be surely evacuated.

  FIG. 19 is a cross-sectional view of the decompression / laminating means in the decompression / lamination process of the second embodiment. As shown in FIG. 19, the prepreg 302 stops in contact with the upper surface of the semiconductor element 105 and the upper surface of the resistor 106, and the prepreg 302 is stacked on the substrate 101. In this state, the prepreg 302 is held in a state where a negative pressure is applied due to evacuation.

  Thereby, bubbles containing air do not remain between the semiconductor element 105 and the resistor 106 and the prepreg 302. Accordingly, adhesion between the prepreg 302 and the upper surface 105c of the semiconductor element 105 and the upper surface 106a of the resistor 106 can be improved, and a highly reliable laminated substrate can be obtained.

  FIG. 20 is a cross-sectional view of the integration means in the integration step 303. In FIG. 20, 303 is the integration process provided after the pressure reduction / lamination process. In the integration step 303, the upper platen 321 heats, compresses, and cools the prepreg 302 so that the gaps 156 and 157 are filled with the epoxy resin 317 and the substrate 101 and the prepreg 302 are integrated.

  In this integration step 303, 304 is a softening step provided after the pressure reduction / lamination step 301. In this softening step 304, the heaters 160 provided on the platen 152 and the upper platen 321 are heated and the prepreg 302 is heated. Is softened to a temperature at which it can flow. In addition, since the prepreg 302 in this Embodiment 2 uses what has a substantially fluid state at normal temperature, the supply of heat in the softening process can be reduced. Therefore, it is energy saving.

  Then, in the forced inflow step 305 provided after the softening step 304, the epoxy resin 317 is caused to flow at a rapid pressure (speed) as in the first embodiment. Therefore, the platen 321 is moved so that the epoxy resin 317 flowing into the gaps 156 and 157 does not exceed the temperature at which the curing starts due to a temperature rise due to frictional heat or pressure loss due to the inflow. As described above, when the temperature of the epoxy resin 317 is about 100 ° C., a sudden pressure (speed) is applied to force the flow into the gaps 156 and 157, so that an intermediate material is separately injected into the gaps 156 and 157. There is no need. In the second embodiment, the temperature at which the epoxy resin 317 starts to cure is about 110 ° C. to 150 ° C., and the epoxy resin 317 starts an additional load reaction when held at 110 ° C. to 150 ° C. for about 10 minutes. Is used.

  Note that a position sensor (not shown) is provided on the upper platen 321 of the second embodiment. The control circuit compares the signal from the position sensor with the position data of the upper platen 321 stored in advance in a memory (not shown), and determines that the upper platen 321 is at the specified position. A command to stop is sent to the servo motor connected to H.321.

  Here, since no hole is provided in the prepreg 302, the gap 331 formed around the semiconductor element 105 and the resistor 106 in the second embodiment is larger than the gaps 143 and 144 formed in the first embodiment. . Therefore, by setting the temperature of the forced inflow step 305 in Embodiment 2 to 100 ° C., the epoxy resin 317 can be reliably filled into the gap 331 and the gaps 156 and 157.

  Reference numeral 306 denotes a curing process provided after the forced inflow process 305. The epoxy resin 317 is completely cured by setting the temperature to 150 ° C. in the curing process 306. And after making it harden | cure completely in the hardening process 306, it cools gradually in the slow cooling process 124, and cut | disconnects in the cutting process 125 after that.

  As described above, since the decompression / stacking step 301 is provided before the integration step 303, bubbles containing air do not remain between the semiconductor element 105 and the resistor 106 and the prepreg 302. Accordingly, adhesion between the prepreg 302 and the upper surface 105c of the semiconductor element 105 and the upper surface 106a of the resistor 106 can be improved, and a highly reliable laminated substrate can be obtained.

  Further, as in the first embodiment, the prepreg 302 does not need to be provided with holes corresponding to the semiconductor element 105 and the resistor 106 in advance, so that the hole processing step 117 in the first embodiment is not necessary. Therefore, a low cost laminated substrate can be obtained.

  Further, in the second embodiment, since a hole corresponding to the height of the component is not necessary, the number of the prepreg 302 may be one. Therefore, it is only necessary to stack one prepreg 302, so that a low-price stacked substrate can be obtained.

  Furthermore, since the prepreg 302 only needs to be placed on the inclined portion 313, the laminating operation can be performed very easily. Therefore, a low-cost laminated substrate can be realized.

  Furthermore, since the hole 318 is provided in the guide 312, the gap between the substrate 101 and the guide 312 can be reduced. Therefore, the guide 312 positions the substrate 101 with high accuracy and prevents the prepreg 302 from flowing out. Therefore, since the epoxy resin 317 flows into the gap 331 and the gaps 156 and 157, no voids are generated, and the epoxy resin 317 can be reliably filled into the gaps 156 and 157.

(Embodiment 3)
The third embodiment is another example of the decompression / stacking means in the second embodiment. Each step in the third embodiment is the same as that in the second embodiment. Therefore, in the third embodiment, only the decompression / laminating means in the decompression / lamination process will be described. 21 and 22 are cross-sectional views of the pressure reduction / laminating means in the pressure reduction / lamination process of the third embodiment, and FIG. 23 is a cross-sectional view of the multilayer substrate in the forced inflow step. 21, 22, and 23, the same components as those in FIGS. 18 to 20 are denoted by the same reference numerals, and the description thereof is simplified.

  In FIG. 21, a sealed container 154 (used as an example of a sealing means) is formed by the platens 151 and 152 and the stretchable wall 153. Then, the substrate 101 on which electronic components such as the semiconductor element 105 and the resistor 106 are soldered in advance is mounted at a predetermined position of the platen 152.

  Reference numeral 401 denotes a holding claw rotatably connected to a support shaft 402 provided on the platen 151. The holding claw 401 is biased inward by a spring (not shown), and holds the prepreg 302 with the nip. At this time, the holding claw 401 and the platen 151 hold the prepreg 302 so that the prepreg 302 faces the substrate 101. The suspension means composed of the platen 151 and the holding claws 401 prevents the prepreg 302 from contacting the semiconductor element 105 and the resistor 106. As a result, a gap 403 is formed between the prepreg 302 and the semiconductor element 105 or the resistor 106. Then, air is extracted from the hole 155 by a suction machine (not shown), and the pressure in the sealed container 154 is reduced to a negative pressure by raising the pressure of the platen 152.

  FIG. 22 is a cross-sectional view of the decompression / laminating means in the decompression / lamination process of the second embodiment. As shown in FIG. 22, the prepreg 302 stops in contact with the upper surface of the semiconductor element 105 and the upper surface of the resistor 106 by vacuuming, and the prepreg 302 is stacked on the substrate 101. In this state, the prepreg 302 is held in a state where a negative pressure due to vacuuming is applied.

  Thereby, bubbles containing air do not remain between the semiconductor element 105 and the resistor 106 and the prepreg 302. Accordingly, adhesion between the prepreg 302 and the upper surface 105c of the semiconductor element 105 and the upper surface 106a of the resistor 106 can be improved, and a highly reliable laminated substrate can be obtained.

  FIG. 23 is a cross-sectional view of the integration means in the integration step 303. As shown in FIG. 23, in the integration step 303, the upper platen 321 heats, compresses, and cools the prepreg 302 so that the epoxy resin 317 is filled into the gaps 156 and 157, and the substrate 101 and the prepreg 302 are bonded. It is integrated.

  In this case, the front end 401 a of the holding claw 401 stops at a position where it contacts the platen 152. That is, the holding claw 401 also serves as the stopper 161 in the first embodiment.

  In the third embodiment, the holding claw 401 is provided so as to cover the entire circumference of the prepreg 302. Thus, in the integration step 303, the holding claws 401 prevent the epoxy resin 317 from flowing out when the epoxy resin 317 flows. Therefore, since the epoxy resin 317 flows into the gap 331 and the gaps 156 and 157, no voids are generated, and the epoxy resin 317 can be reliably filled into the gaps 156 and 157. Further, since the outflow to the outside of the prepreg 302 can be reduced, the prepreg can be reduced accordingly. Therefore, since the prepreg 302 to be used can be reduced, a low-cost laminated substrate can be obtained. Here, the thermosetting resin generally cannot be reused once cured. Therefore, reducing the amount of prepreg 302 used is also very important from an environmental point of view.

  When the integration step 303 is completed, the holding claw 401 is rotated outward (in the direction of the arrow in FIG. 23), and the prepreg 302 is opened. As a result, the platen 151 is opened upward, and the substrate 101 can be taken out.

  As described above, since the decompression / stacking step 301 is provided before the integration step 303, bubbles containing air do not remain between the semiconductor element 105 and the resistor 106 and the prepreg 302. Accordingly, adhesion between the prepreg 302 and the upper surface 105c of the semiconductor element 105 and the upper surface 106a of the resistor 106 can be improved, and a highly reliable laminated substrate can be obtained.

  Further, as in the first embodiment, the prepreg 302 does not need to be provided with holes corresponding to the semiconductor element 105 and the resistor 106 in advance, so that the hole processing step 117 in the first embodiment is not necessary. Therefore, a low cost laminated substrate can be obtained.

  Further, in the second embodiment, since a hole corresponding to the height of the component is not necessary, the number of the prepreg 302 may be one. Therefore, it is only necessary to stack one prepreg 302, so that a low-price stacked substrate can be obtained.

  Furthermore, since the prepreg 302 only needs to be sandwiched between the holding claws 401, the stacking operation can be performed very easily. Therefore, a low-cost laminated substrate can be realized.

  In the third embodiment, the prepreg 302 is suspended, but this may be suspended from the substrate 101 side, and the same effect can be achieved in this case.

(Embodiment 4)
The present embodiment shows another example of the heating / compression process 118a in the first embodiment, and the heating / compression process in the present embodiment is the heating / compression process in the first to third embodiments. You may use with respect to a process. Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 24A is a relationship diagram between the prepreg temperature and the viscosity in the heating / compression process in the present embodiment, FIG. 24B is a pressure diagram in the heating / compression process, and FIG. Similarly, the degree of vacuum in the heating / compression process is shown.

  As shown in FIG. 24B, in the heating / compression step 118a of the present embodiment, the pressure applied to the prepreg 141 is a constant value and is not changed. In the present embodiment, a pressure of 40 kg is applied per square centimeter. Furthermore, as shown in FIG. 24C, in this embodiment, the degree of vacuum is kept constant during the heating / compression step 118a. In this embodiment, it is about 40 Torr.

  In FIG. 24A, the horizontal axis 600 indicates time 601, the first vertical axis 602 indicates the temperature of the prepreg 141, and the second vertical axis 603 indicates the viscosity of the prepreg 141. A characteristic curve 604 indicates the temperature of the prepreg 141 in the heating / compression process 118a, and a characteristic curve 605 indicates the viscosity of the prepreg 141.

  Here, the prepreg 141 starts to flow at a viscosity of 601 or less. In this embodiment, a pressure of 40 kg is applied per square centimeter, and the viscosity 606 at which the resin flow starts is about 24000 Pa · s. The temperature 607 at the viscosity 606 at which this resin flow starts is about 90 ° C. On the other hand, when the temperature of the prepreg 141 becomes about 150 ° C., the viscosity of the prepreg 141 becomes a viscosity of about 24000 Pa · s and does not flow.

  In the heating step 608 in the present embodiment, the prepreg is heated to a temperature 606 or higher at which resin flow starts. Then, after being heated to the temperature 610 in the heating step 608, in the forced inflow step 609, the viscosity of the prepreg 141 is lowered to the minimum viscosity 611 by keeping the prepreg 141 at the temperature 610. In this embodiment, the minimum viscosity 611 is 1500 Pa · s. Moreover, the temperature of the forced inflow process 609 in this Embodiment is about 110 degreeC.

  And in the forced inflow process 609, the prepreg 141 will flow into the space | gap 143, the clearance gap 156, etc. by the applied pressure by hold | maintaining in the state which applied the pressure. In the forced inflow step 609, the heating step 613 is performed by raising the temperature after a predetermined time 612 has elapsed. In this heating step 613, the temperature is raised to 614 in order to completely cure the prepreg 141. In this embodiment, the temperature 614 is set to about 200 ° C. to completely cure the prepreg 141.

  As described above, in the forced inflow process 609 of the present embodiment, the pressure and the degree of vacuum are constant, and the prepreg 141 is forced to flow into the gap 156 and the gap 143 by controlling only the temperature of the prepreg 141. Accordingly, since complicated operation control of the platen is not required, the equipment is easy and the equipment is inexpensive.

  Here, it is important that the temperature gradient of the heating process 608 is larger than the temperature gradient of the forced inflow process 609. In the heating step 608, the temperature of the prepreg 141 is increased to a temperature 610 that is equal to or higher than the temperature 606 at which the resin flow starts. As described above, in the heating step 608, the temperature increase of the prepreg 141 is increased and the temperature of the prepreg 141 is increased to the temperature 610, so that the viscosity of the prepreg 141 is rapidly reduced and reaches the minimum viscosity 611 in a short time. On the other hand, when the temperature gradient in the forced inflow process 609 is reduced, the time during which the prepreg 141 has the minimum viscosity 611 can be lengthened. As a result, the time of the minimum viscosity 611 can be lengthened, so that the prepreg can be caused to flow into the gap 156, the gap 143, etc. without controlling the pressure and the degree of vacuum.

  As described above, in the present embodiment, by controlling the temperature of the prepreg 141, the time 614 at which the resin starts to flow is advanced, and the time interval from the time at which the resin starts to be cured 615 is lengthened. As a result, even if there is a difference in the timing at which the resin flows in many electronic components, the resin can be reliably poured into the gap 156 or the gap 143. Therefore, the process of pouring the resin with a dispenser or the like in advance becomes unnecessary.

  The manufacturing method of the laminated substrate according to the present invention reliably fills the gap simultaneously with the resin sheet and the substrate integration process without previously filling the gap between the electronic component and the substrate with an intermediate material or the like. In particular, it is useful when used for portable electronic devices and the like that need to be miniaturized.

Manufacturing flow chart of the manufacturing method of the laminated substrate in Embodiment 1 of the present invention Same as above, sectional view of laminated substrate Same as above, sectional view of laminated substrate in flux application process Same as above, cross-sectional view of multilayer substrate in cream solder printing process Same as above, cross-sectional view of multilayer substrate in electronic component mounting process Same as above, sectional view of laminated substrate in reflow process Same as above, sectional view of laminated substrate in prepreg lamination process Same as above, sectional view of laminated substrate in vacuum process Same as above, sectional view of laminated substrate in vacuum process Cross-sectional view of laminated substrate in softening process Same as above, sectional view of laminated substrate in resin flow suppression process Same as above, sectional view of laminated substrate in forced inflow process Same as above, sectional view of laminated substrate in cutting process Same as above, viscosity characteristics of epoxy resin and pressure characteristics of platen Same as above, enlarged view of gaps in semiconductor elements (A) Same as above, (b) Same as above, (b) Same as above, (b) Same as above, (b) Same as above, (c) Same as above. Manufacturing flowchart of laminated substrate in Embodiments 2 and 3 Sectional drawing of the pressure reduction / laminating means in Embodiment 2 Sectional drawing of the pressure reduction / laminating means in Embodiment 2 Sectional drawing of the multilayer substrate in the forced inflow process of Embodiment 2 Sectional drawing of pressure reduction / laminating means in embodiment 3 Sectional drawing of pressure reduction / laminating means in embodiment 3 Sectional drawing of the multilayer substrate in the forced inflow process of Embodiment 3 (A) Relationship diagram between prepreg temperature and viscosity in heating / compression process in Embodiment 4, (b) Pressure diagram in heating / compression process, (c) Characteristic indicating degree of vacuum in heating / compression process Figure Manufacturing flowchart for conventional multilayer substrates Same as above, cross-sectional view of multilayer substrate in electronic component mounting process Same as above, cross-sectional view of laminated substrate in semiconductor element mounting process Same as above, sectional view of laminated substrate in intermediate material injection process Same as above, sectional view of laminated substrate in heating / crimping process Same as above, sectional view of laminated substrate

Explanation of symbols

101 substrate 116 prepreg lamination process 118 integration process 120 softening process 122 forced inflow process 123 curing process

Claims (8)

A method of manufacturing a multilayer substrate in which a plurality of electronic components are embedded, wherein the method of manufacturing the multilayer substrate is a method in which a land provided on an upper surface and an electrode of an electronic component are connected and fixed by solder. A sheet is formed by forming a gap in the outer periphery of the electronic component, and a copper foil is placed on the sheet. After the layering process, the sheet and the substrate are integrated by thermocompression bonding. The sheet is a plate-like body in the first temperature range, and has heat fluidity in a temperature range higher than the first temperature range, and heat that cures in a higher temperature range. in the method for manufacturing a multilayer substrate using the curable resin, the integration step is sandwiched laminate of the sheet and the copper foil and the substrate by the platen, a heating step of softening the resin, after the heating step The sheet was heated and compressed by the platen, the a forced inflow step of once flowing the resin into the formed with a gap and the gap between the electronic component and the substrate, the resin after the forced flow-in step In the method of manufacturing a laminated substrate having a curing step of curing the sheet, the heating step compresses the platen with a pressure that is in close contact with the copper foil surface, and the forced inflow step laminates the sheet on the substrate. And the sheet and the resin are compressed to a temperature at which the solder does not melt. For the sheet, a plate-like body made of a woven or non-woven fabric and a resin impregnated with the woven or non-woven fabric is used, and an opening having a gap between the outer periphery of the electronic component at a position corresponding to the electronic component. The manufacturing method of the laminated substrate of Claim 1 which provided. The method for manufacturing a laminated substrate according to claim 1, wherein in the forced inflow step , the temperature of the sheet is lower than the lowest viscosity point temperature. The method for producing a laminated substrate according to claim 3 , wherein the temperature of the sheet in the forced inflow step is set to a temperature lower by at least the temperature rise of the resin due to inflow into the gap than the temperature at which the minimum viscosity is reached. The method for manufacturing a laminated substrate according to claim 4 , wherein the temperature of the resin when the resin is caused to flow into the gap is lower than the lowest viscosity point temperature in the forced inflow step. The manufacturing method of the multilayer substrate according to claim 4 , wherein the temperature of the sheet in the curing step is lower than the melting point temperature of the solder . In forced flow-in step, method for producing a laminated substrate according to claim 4 to reduce the viscosity of the resin in the heating due to flowing the said resin to the inter-gap. Between the pressurized heat step and forced flow-in step, the resin flow suppression step provided, compress the sheet at Do pressure smaller than pressure that is applied in the heating step in this resin flow suppression process 請 Motomeko 2. A method for producing a laminated substrate according to 1 .

Images