Patent Publication Number: US-2023163147-A1

Title: Method of manufacturing package unit, package unit, electronic module, and equipment

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 16/817,847, filed Mar. 13, 2020, which claims the benefit of Japanese Patent Application No. 2019-55107, filed on Mar. 22, 2019. Each of these prior applications is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a method of manufacturing a package unit, a package unit, an electronic module, and an equipment. 
     Description of the Related Art 
     In recent years, the number of pixels and frame rates of solid-state imaging elements have increased and, further, progress has been made in digitization of output. Accordingly, there is a greater need to increase transmission speeds of output signals of the solid-state imaging elements. To this end, high-speed serial transmission such as LVDS (Low Voltage Differential Signaling) and SLVS (Scalable Low Voltage Signaling) has become established practice. 
     Therefore, since handled signals have smaller amplitudes and higher rates, inductance of wiring of a package (a package unit), noise due to a power supply-GND loop transmission magnetic field, crosstalk, and the like are no longer negligible. Furthermore, since a high-speed transmission signal is transmitted with a small amplitude, transmission wiring must be impedance-matched wiring with low power loss. To this end, efforts are made to shorten wiring of a power supply or output of an image sensor by directly mounting an image sensing element to a circuit board mounted with electronic components, reduce impedance mismatches, and the like. 
     Against this backdrop, Japanese Patent Application Laid-open No. 2015-185763 discloses a technique for forming a frame-shaped mold portion that surrounds an outer periphery of a circuit board and forming a package capable of housing an electronic device. This method enables generation of dust from a circuit board end surface to be suppressed by molding the board end surface using resin and can be described as a promising technique. 
     However, in Japanese Patent Application Laid-open No. 2015-185763, since the circuit board is clamped with a mold when the circuit board is inserted thereinto, problems arise such as an occurrence of a crack in the circuit board in a portion where the mold and a circuit board surface come into contact with each other and deformation of internal wiring. 
     WO 2009/150820 discloses a technique for similarly inserting a circuit board into a mold and performing resin molding. The technique prevents the circuit board from sustaining damage by roundly chamfering corners of the mold in a boundary portion of a region where the mold and the circuit board come into contact with each other and providing a board surface with recesses in the boundary portion of the region. 
     However, while the method disclosed in WO 2009/150820 is capable of reducing damage to the circuit board in the boundary portion of the region where the mold and the circuit board come into contact with each other, there is a problem that a resin material of the circuit board is likely to sustain significant damage. In particular, when there is a variation in a thickness of the circuit board, pressure applied to the circuit board over an entire contact region between the circuit board and the mold increases and significant damage occurs in a conductor layer directly underneath the contact region or in the resin material of the circuit board. 
     SUMMARY OF THE INVENTION 
     In consideration of the circumstances described above, an object of the present invention is to provide a highly reliable package unit. 
     The first aspect of the disclosure is a method of manufacturing a package unit, comprising: preparing a circuit board having a first region, a second region which surrounds the first region, and a third region between the first region and the second region; preparing a mold having a frame-shaped protruding portion which surrounds a first cavity, the frame-shaped protruding portion partitioning the first cavity and a second cavity which surrounds the first cavity; arranging the circuit board and the mold such that the first region of the circuit board faces the first cavity, the second region of the circuit board faces the second cavity, and a gap which communicates the first cavity and the second cavity with each other is formed between the frame-shaped protruding portion and the third region of the circuit board; and forming a frame-shaped resin member on top of the second region of the circuit board by pouring a resin into the second cavity. 
     The second aspect of the disclosure is a method of manufacturing a package unit, comprising: preparing a circuit board having a first region, a second region which surrounds the first region, and a third region between the first region and the second region; preparing a mold having a frame-shaped protruding portion which surrounds a first cavity, the first cavity and a second cavity which surrounds the first cavity being partitioned by the frame-shaped protruding portion; arranging the circuit board and the mold such that the first region of the circuit board faces the first cavity, the second region of the circuit board faces the second cavity, and the frame-shaped protruding portion overlaps with the third region of the circuit board; and forming a frame-shaped resin member on top of the second region of the circuit board by pouring a resin into the second cavity, wherein a solder resist layer is arranged in the third region at a position which overlaps with the frame-shaped protruding portion, and the solder resist layer of the third region is positioned between a conductor layer arranged in the first region and a conductor layer arranged in the second region. 
     The third aspect of the disclosure is a package unit, comprising: a circuit board having a first region, a second region which surrounds the first region, and a third region between the first region and the second region; and a resin member which covers the circuit board so as to surround a space above the first region of the circuit board, wherein the resin member has (1) a first resin portion which is arranged above the second region of the circuit board and (2) a second resin portion which extends above the third region of the circuit board from the first resin portion and which has a thickness smaller than half of the first resin portion. 
     According to the present invention, a highly reliable package unit can be provided. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A to  1 H- 6    are diagrams illustrating a method of manufacturing a package unit according to a first embodiment; 
         FIGS.  2 A to  2 C  are diagrams illustrating a mold used in the method of manufacturing a package unit; 
         FIGS.  3 A to  3 F  are diagrams illustrating a method of manufacturing a package unit according to a second embodiment; 
         FIGS.  4 A to  4 G- 3    are diagrams illustrating the method of manufacturing a package unit according to the second embodiment; 
         FIGS.  5 A to  5 D  are diagrams illustrating the method of manufacturing a package unit according to the second embodiment; 
         FIGS.  6 A to  6 C  are diagrams illustrating a method of manufacturing a package unit according to a comparative mode; 
         FIGS.  7 A to  7 C  are diagrams illustrating an electronic module using a package unit; 
         FIGS.  8 A and  8 B  are diagrams illustrating a circuit board used in the method of manufacturing a package unit; and 
         FIG.  9    is a diagram illustrating an example of an equipment using an electronic module according to an embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     First Embodiment 
     A method of manufacturing a package unit according to a first embodiment of the present invention will be described.  FIGS.  1 A to  1 G  sequentially show each step of the method of manufacturing a package unit. 
       FIG.  1 A  shows a cross-sectional view of a stage where a circuit board  1  has been prepared. In this case, a coordinate system is assumed to be a coordinate system depicted by XYZ in the drawing. A plate-like substrate including a wiring conductor can be used as the circuit board  1 , and the circuit board  1  is typically a printed circuit board (PCB). While the circuit board  1  may be a substrate made of an inorganic material such as a silicon substrate, a ceramic substrate, a glass substrate, or a metal substrate, a resin substrate is preferable since a copper foil with low electric resistivity can be readily used as a circuit conductor. Among resin substrates, a composite material substrate containing a fibrous or granular filler in resin such as a glass-epoxy substrate is particularly preferable.  FIG.  1 A  is a cross-sectional view in a case where a resin substrate is used as the circuit board  1 . 
       FIG.  1 A- 1    is an enlarged cross-sectional view of section A showing details of a layered structure of the circuit board  1 . In this case, an example is shown where the circuit board  1  is a so-called 2-4-2 build-up substrate which has a core layer including four conductor layers  14  and two conductor layers  14  respectively provided as build-up layers on front and rear surfaces of the core layer. The conductor layers  14  are formed of, for example, copper foil. Each conductor layer  14  is patterned into a desired pattern by lithography. 
     The core layer and the build-up layers include a prepreg layer  18 . The prepreg layer  18  is configured such that fibers woven or knitted into a cloth pattern are impregnated with a resin. As the resin which the fibers are to be impregnated with, resins having epoxy or phenol as a main component can be widely used, and resins containing an insulating filler such as paper or glass can also be used. Furthermore, while glass fibers are generally used as the fibers, the fibers are not limited thereto as long as the fibers have an insulating property. 
     In addition, a solder resist layer  11  is provided on front and rear surfaces of the circuit board  1 . Mainly, there are two methods of forming the solder resist layer  11  as described below. A first method involves pasting a dry film to the front and rear surfaces of the circuit board  1  and performing patterning by lithography in order to provide an opening at a desired location. A second method involves applying a liquid resist using a roll coater or a spray coater and, after curing the liquid resist by UV or heat, performing patterning in a similar manner. 
     A front surface electrode  12  is an electrode for connecting wiring from an electronic device. A rear surface electrode  13  is an electrode for connecting electronic components. The front surface electrode  12  is a conductor layer  14  exposed to the front surface and the rear surface electrode  13  is a conductor layer  14  exposed to the rear surface. Conduction between the front surface electrode  12  and the rear surface electrode  13  is realized along a desired path via the conductor layers  14 , a laser via  16 , and a drilled via  15 . 
       FIG.  8 A  is a plan view of the front surface of the circuit board  1  and  FIG.  8 B  is a plan view of the rear surface of the circuit board  1 . 
     In  FIG.  8 A , a solid line A indicates a position of an end surface of the printed circuit board  1 . A region surrounded by a dotted line C is a central region (a first region)  23 . A region between the solid line A and a long dashed line B is a peripheral region (a second region)  25 . A region between the long dashed line B and the dotted line C or, in other words, a region between the peripheral region  25  and the central region  23  is an intermediate region (a third region)  24 . The peripheral region  25  surrounds the central region  23 , and the intermediate region  24  also surrounds the central region  23 . On a front surface-side of the circuit board  1 , a resin frame  41  is provided above the peripheral region  25 . On the front surface-side of the printed circuit board  1 , an electronic device is provided in a central portion on the central region  23 . Among the central region  23 , a region surrounded by a short dashed line D is a mounting region  21  where the electronic device is to be mounted. Among the central region  23 , a region between the dotted line C and the short dashed line D (a peripheral portion) is a connecting region  22  for connecting the electronic device to the printed circuit board  1 . A plurality of the front surface electrodes  12  are arranged in the connecting region  22 . In order to ensure that the electronic device can be stored in a package unit, a thickness (a height) of the electronic device is smaller than a thickness wh of a frame-shaped resin portion  40  and greater than a thickness h of an extended resin portion  42  to be described later. 
     As shown in  FIG.  8 B , an electronic component group  2  is provided on a rear surface side of the printed circuit board  1 . Electronic components that constitute the electronic component group  2  include a connector  221 , passive components  222  such as a resistor, a capacitor, and a diode, active components  223  such as a transistor, and an integrated circuit chip  224 . In the example shown in  FIG.  8 B , while the electronic component group  2  is only provided in the central region  23  and not provided in the peripheral region  25  on a rear surface-side of the circuit board  1 , alternatively, at least a part of the electronic components of the electronic component group  2  can be arranged in the peripheral region  25 . 
       FIG.  1 B  shows a step of mounting the electronic components  2  to the rear surface of the circuit board  1 . The electronic components  2  are soldered and connected to the rear surface of the circuit board  1  by a known surface mounting method. Specifically, first, the circuit board  1  is arranged so that the rear surface is an upper surface, and a print mask having an opening that matches an arrangement of the provided rear surface electrode  13  is prepared. Next, the print mask is brought into contact with the rear surface so that the opening and the rear surface electrode  13  match each other. In this state, a solder paste is arranged on the mask and the solder paste is printed on the rear surface of the circuit board  1  using a squeegee. 
     Next, using a known mounter, desired components are mounted to the rear surface of the circuit board  1  so that the rear surface electrode  13  and a terminal of each electronic component match each other. Finally, the circuit board  1  is passed through a reflow furnace in this state to complete solder bonding between the rear surface electrode  13  and the terminal of each electronic component. 
     When flux contained in the solder paste falls off from the circuit board  1  and adheres onto an electronic device in subsequent steps, the flux causes a decline in yield. Therefore, the flux is desirably cleaned using a known cleaner and a known cleaning solution. 
     It is preferable to mount electronic components for surface mounting. Examples of types of surface-mounting electronic components include a ceramic capacitor, an organic capacitor made of tantalum or the like, a chip resistor, a B-to-B connector, a regulator IC for a power supply, a common-mode connector coil, a temperature measurement IC, and an EPROM. 
       FIGS.  2 A to  2 C  exclusively illustrate a mold  3  used in the present embodiment. A coordinate system is indicated by XYZ in a similar manner to  FIG.  1 A . The mold  3  is constituted by an upper mold  31  and a lower mold  32 .  FIG.  2 A  shows a state where the mold  3  is opened and  FIG.  2 B  shows a state where the mold  3  is closed. In the state where the mold  3  is closed, a cavity is formed inside the mold. 
       FIG.  2 C  is a Z-direction plan view in which the mold  3  is viewed from a Z direction of the coordinate system shown in  FIG.  2 A  and, in the diagram, a dashed line represents a boundary line by which the cavity formed inside the mold  3  is divided into three portions. In this manner, the cavity is constituted by a central cavity (a first cavity)  33 , a frame-shaped narrow cavity  34  provided on an outer periphery of the central cavity  33 , and a frame-shaped cavity (a second cavity)  35  provided on an outer periphery of the frame-shaped narrow cavity  34 . 
     The lower mold  32  has a first bottom surface  32   a  in a central portion of a region corresponding to the central cavity  33  and a second bottom surface  32   b  in a region corresponding to a peripheral portion of the central cavity  33 , the frame-shaped narrow cavity  34 , and the frame-shaped cavity  35 . The first bottom surface  32   a  is positioned lower in the Z-direction than the second bottom surface  32   b  and is capable of avoiding interference with the electronic components  2  when the circuit board  1  is arranged on the second bottom surface  32   b.  The upper mold  31  has a first ceiling surface  31   a  in a region corresponding to the central cavity  33 , a second ceiling surface  31   b  in a region corresponding to the frame-shaped cavity  35 , and a frame-shaped protruding portion  39  between the first ceiling surface  31   a  and the second ceiling surface  31   b.  The frame-shaped narrow cavity  34  is formed directly underneath the frame-shaped protruding portion  39 , and the central cavity  33  and the frame-shaped cavity  35  are partitioned by the frame-shaped protruding portion  39 . A height in the Z-direction of a lower surface of the frame-shaped protruding portion  39  is lower than the first ceiling surface  31   a,  and a height in the z-direction of the first ceiling surface  31   a  is lower than the second ceiling surface  31   b.    
     In addition, the mold  3  is provided with a gate (not illustrated) for injecting resin in a direction indicated by an arrow  201  in  FIG.  2 B  and an air vent (not illustrated) for releasing air having been forced out by resin in a direction indicated by an arrow  202 . 
       FIG.  1 C  shows a state where the circuit board  1  is inserted into the mold  3 .  FIG.  1 C- 1    is a z-direction plan view of  FIG.  1 C , and  FIG.  1 C- 2    and  FIG.  1 C- 3    are each enlarged cross-sectional views of section C 1  and section C 2  in  FIG.  1 C . 
     As shown in  FIG.  1 C- 1   , an entire outer periphery  21  of the circuit board  1  is included inside the frame-shaped cavity  35  in this state. In addition, the central region  23  of the circuit board  1  is included in the central cavity  33 , the peripheral region  25  is included in the frame-shaped cavity  35 , and the intermediate region  24  is included in the frame-shaped narrow cavity  34  (the frame-shaped protruding portion  39 ). It should be noted that the entire intermediate region  24  and the frame-shaped protruding portion  39  need not oppose each other, and an end portion on a side of the central region  23  among the intermediate region  24  may be included in the central cavity  33 . Furthermore, as shown in  FIGS.  1 C- 2  and  1 C- 3   , a gap  36  is provided between a bottom surface of the frame-shaped protruding portion  39  and the front surface of the circuit board  1 . The central cavity  33  and the frame-shaped cavity  35  are communicated via the gap  36 . In this manner, in the first embodiment, the circuit board  1  is not clamped by the mold  3  in a state where the circuit board  1  is inserted into the mold  3 . Therefore, an occurrence of damages such as a crack in the circuit board  1  and a deformation or a fracture of the conductor layers  14  which have been problems in the past can be prevented. 
       FIGS.  1 D to  1 G  show respective steps of pouring resin into the frame-shaped cavity  35  via the gate (not illustrated), filling resin  41  while discharging excess air from the air vent (not illustrated), and completing molding while maintaining the state shown in  FIG.  1 C . Due to these steps, a resin mold that covers the outer periphery of the circuit board is molded. 
     As the resin  41 , a material having necessary strength and profile stability for the electronic module can be used. In addition, desirably, the resin  41  does not contain halogens that adversely affect the electronic device in a use environment of the electronic module and substances which dissolve into moisture over a long period of time and which condense and precipitate on a surface of a translucent LID that is a lid of the package unit. 
     Injection molding can be performed as a molding method. Examples of thermoplastic resins used in injection molding include polyethylene resin, polypropylene resin, ethylene-vinyl acetate, polystyrene, AS resin, ABS resin, acrylic resin, polyvinyl chloride, cellulosic resin, polyacetal, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, modified polyphenylene ether, polyphenylene sulfide, polyether ether ketone, liquid crystal polymer, polysulfone, polyether sulfone, polyarylate, polyamide-imide, polyetherimide, and polymethyl pentene. 
     However, a thermosetting resin is preferable in order to stably maintain strength and shape in a wide temperature range from −40° C. to 130° C. While phenolic resin, urea resin, melamine resin, diallyl phthalate resin, unsaturated polyester resin, polyimide resin, urethane resin, and the like can also be used as the thermosetting resin, resins having epoxy resin as a main component are preferable. In particular, favorable resin is based on bisphenol A or novolac glycidyl ether-type resin and compounded with an aromatic amine curing agent, a phenolic resin curing agent, or an acid anhydride curing agent, and a filler. As the filler, a filler containing approximately 70 to 85 percent by weight of silica powder, talc, or the like is preferable due to a dimensional variation after molding being small. In addition, including a releasing agent for enhancing releasability from the mold  3  and a fire retardant is also known. 
     In the case of the present embodiment, transfer molding capable of keeping fill pressure of the resin  41  relatively low is more preferable. In the case of transfer molding, a thermosetting resin is used. Resin materials with powder resin as a main component and including a curing agent, a releasing agent, a coupling agent, a flame retardant, and the like are shaped in advance into a cylindrical tablet and the resin tablet is placed inside a pot to be preheated. In a state where the resin has been melted by the preheating and viscosity has dropped to within 10 to 100 Pa·s, the resin  41  is extruded from the pot with a plunger and injected into the cavity via a cull, a runner, and a gate. It should be noted that, generally, the mold  3  is preheated in advance to a temperature ranging from 100° C. to 200° C. which is higher than a glass-transition temperature of the resin  41 . 
     From  FIG.  1 D  to  FIG.  1 E , the resin  41  injected from the gate advances so as to fill the frame-shaped cavity  35 . Air in the portions to which the resin enters is discharged from the air vent (not illustrated). At this stage, pressure of the resin  41  is relatively low. Once a stage shown in  FIG.  1 F  is reached, the pressure of the resin  41  starts to rise and, eventually, filling is completed in a stage shown in  FIG.  1 G  at pressure ranging from 5 to 80 MPa. In the stage shown in  FIG.  1 G , a part of the resin  41  penetrates into the gap  36  from the frame-shaped cavity  35 . 
     A height h of the gap  36  shown in an enlarged cross-sectional view of section E in  FIG.  1 E- 1    is defined by the front surface of the circuit board  1  and a top plane of the frame-shaped protruding portion  39  and a value thereof is approximately constant. The height h of the gap  36  is, for example, 0.5 μm or more and 500 μm or less and preferably ranges from 5 to 50 μm. In addition, a width w of the frame-shaped narrow cavity  34  shown in the enlarged cross-sectional view of section E in  FIG.  1 E- 1    preferably ranges from 0.1 to 1 mm. 
     As shown in an enlarged cross-sectional view of section G 1  in  FIG.  1 G- 1   , desirably, the resin  41  stays inside the gap  36  or, in other words, the resin  41  does not advance to the central cavity  33 . Under conditions of the resin viscosity and the gap shape according to the present embodiment, the resin  41  can be more or less kept inside the gap  36  by setting the pressure of the resin  41  in the stage shown in  FIG.  1 G  within a range of 5 to 80 MPa. This is because a flow resistance of the gap  36  with respect to the resin  41  is sufficiently high and, therefore, a flow rate of the resin  41  to the gap  36  is sufficiently slowed, and a curing reaction of the resin  41  can be advanced in a state where the resin  41  remains in the gap  36  to solidify the resin  41 . However, as shown in  FIG.  1 G- 2   , the resin  41  may protrude from the gap  36  and a tip resin portion (a third resin portion)  44  may be formed at a tip of the extended resin portion  42 . The tip resin portion  44  is communicated with the extended resin portion  42  and is positioned on an opposite side of the frame-shaped resin portion  40  with respect to the extended resin portion  42 . 
       FIG.  1 H  represents a finished product of the package unit according to the first embodiment.  FIG.  1 H- 1    is a Z-direction plan view,  FIG.  1 H- 2    is an enlarged plan view of section h 1 , and  FIG.  1 H- 3    is an enlarged plan view of section h 2 .  FIG.  1 H- 4    is an enlarged cross-sectional view of section H 1 ,  FIG.  1 H- 5    is an enlarged cross-sectional view of section H 2 , and  FIG.  1 H- 6    is an enlarged cross-sectional view of section H 3 . 
     The package unit is provided with the circuit board  1  and a resin member  4  which covers the circuit board  1  so as to surround a space above the central region  23  of the circuit board  1 . The resin member  4  includes the frame-shaped resin portion  40  (a first resin portion) which is arranged above the conductor layer  14  of the peripheral region  25  of the circuit board  1  and which surrounds an outer periphery of the circuit board  1  and the extended resin portion  42  (a second resin portion) which is adjacent to an inner side of the frame-shaped resin portion  40 . The extended resin portion  42  extends above the intermediate region  24  from the frame-shaped resin portion  40  toward a center of the circuit board  1 . In addition, since the extended resin portion  42  is molded by the resin penetrating into the gap  36 , a thickness (a height) thereof is approximately constant at the height h of the gap  36  and a value thereof is 0.5 μm or more and 500 μm or less and preferably ranges from 5 to 50 μm. The thickness of the extended resin portion  42  is, for example, less than half (½) of the thickness of the frame-shaped resin portion  40 , more preferably less than ¼ and even more preferably less than 1/10 of the thickness of the frame-shaped resin portion  40 . Since providing the extended resin portion  42  increases a contact area between the resin member  4  and the circuit board  1 , adhesiveness between the resin member  4  and the circuit board  1  increases. Since providing the extended resin portion  42  enables the extended resin portion  42  to prevent moisture and the like from penetrating between the frame-shaped resin portion  40  and the circuit board  1 , adhesiveness between the frame-shaped resin portion  40  and the circuit board  1  increases. By reducing the thickness of the extended resin portion  42 , weight reduction of the resin member  4  can be achieved and, since an amount of use of the resin  41  can be reduced, there is also an advantage in cost reduction. 
     The thickness h of the extended resin portion  42  may be greater than a thickness t of an uppermost conductor layer  141  so that a height of an upper surface of the extended resin portion  42  is not affected by the thickness of the conductor layer  141  (h&gt;t). The thickness h of the extended resin portion  42  may be two times or more of the thickness t of the uppermost conductor layer  141 . A height of the upper surface of the extended resin portion  42  from the uppermost conductor layer  141  may be greater than the thickness of the conductor layer  141  and may be two times or more of the thickness of the uppermost conductor layer  141 . For example, when a solder resist layer  11  with a thickness k is present under the extended resin portion  42 , the height of the upper surface of the extended resin portion  42  from the uppermost conductor layer  141  is h+k which may satisfy h+k&gt;t or, preferably, h+k&gt;2×t. The thickness k of the solder resist layer  11  may be smaller than at least one of the thickness h and the thickness t. In addition, as shown from  FIG.  1 H- 1    to  FIG.  1 H- 3   , an outer shape of an inner side of the extended resin portion  42  is an indeterminate shape or, in other words, a horizontal length w′ is indeterminate. However, a maximum value of the horizontal length w′ of the extended resin portion  42  is equal to or less than a width w of the gap  36  and, preferably, equal to or less than 1 mm. The horizontal length w′ may be considered a length in a direction from the peripheral region  25  toward the central region  23  of a portion where an approximately constant height h continues in the resin portion. While the horizontal length w′ of the portion is greater than the thickness h of the portion (w′&gt;h) in a typical portion of the extended resin portion  42 , the horizontal length w′ of another portion of the extended resin portion  42  may be less than the thickness h of the other portion (w′&lt;h). 
     As shown in the enlarged plan view of section h 1  in  FIG.  1 H- 2    and the enlarged plan view of section h 2  in  FIG.  1 H- 3   , bubbles  43  are sparsely present inside the extended resin portion  42  but no bubbles are observed inside the frame-shaped resin portion  40 . Bubbles are not present inside the frame-shaped resin portion  40  because, in the stage shown in  FIG.  1 G , pressure of 5 to 80 MPa is applied to the resin  41  inside the frame-shaped cavity  35  and gas contained inside the resin  41  dissolves into the resin  41 . On the other hand, a pressure gradient such that pressure drops from a side of the frame-shaped cavity  35  toward a side of the central cavity  33  is present in the resin  41  having penetrated into the gap  36  of the frame-shaped narrow cavity  34 . In the resin  41  having penetrated into the gap  36  of the frame-shaped narrow cavity  34 , a portion close to the frame-shaped cavity  35  is subjected to pressure close to 5 to 80 MPa and gas contained inside the resin  41  has more or less been dissolved into the resin  41 . However, the closer to the central cavity  33 , the pressure on the resin  41  drops and, accordingly, solubility of the gas contained inside the resin  41  declines and the bubbles  43  are created. Pressure applied to the resin  41  in the vicinity of the central cavity is almost close to pressure of air inside the central cavity  33  and is at approximately 1 atmospheric pressure. In this manner, since bubbles remain in the extended resin portion  42 , a surface on an opposite side to a surface of the extended resin portion  42  that comes into contact with the circuit board  1  has holes. Examples of the holes of the extended resin portion  42  include through-holes which penetrate the extended resin portion  42  and expose the circuit board  1  constituting a base and bottomed holes which are depressed with respect to a flat portion of the upper surface of the extended resin portion  42  and of which the extended resin portion  42  constitutes a bottom, and through-holes and bottomed holes may coexist. 
     The pressure gradient described above occurs because flow resistance with respect to the resin  41  flowing through the gap  36  is present within an appropriate range. Therefore, in order to advance a curing reaction of the resin  41  and solidify the resin  41  in a state where the resin  41  remains in the gap  36 , a residual ratio of bubbles of the resin  41  having penetrated into the gap  36  is preferably higher than a residual ratio of bubbles of the resin  41  which is present inside the frame-shaped cavity  35 . A preferable range is 30 times or higher. In addition, a residual ratio of bubbles contained in the extended resin portion  42  as shown in  FIG.  1 H  is desirably 30 times or higher of a residual ratio of bubbles contained in the frame-shaped resin portion  40 . Furthermore, desirably, the residual ratio of bubbles of the frame-shaped resin portion  40  is lower than 5%, more preferably lower than 3%, and even more preferably lower than 1% in order to increase a moisture-proof property of the package unit and to maintain mechanical strength of the package unit. 
     In this case, a residual ratio of bubbles is defined as an area ratio of bubbles in a cross-sectional surface or a side surface of a portion of which the residual ratio of bubbles is to be measured, raised to the 3/2 power. In order to measure a residual ratio of bubbles of a portion which contains a large amount of bubbles, it is defined that the area ratio described above is to be measured with respect to a surface where a considerable number of bubbles can be observed. 
     Next, a further desirable mode of the first embodiment will be described. 
     When the resin  41  deeply penetrates into the central cavity  33  at the stage shown in  FIG.  1 G  and overlaps with the front surface electrode  12 , since an electrical junction with the electronic device cannot be formed, the package ends up being defective. While such a defect may conceivably be avoided by arranging the front surface electrode  12  and the gap  36  with a greater distance therebetween, this ends up increasing a size of the package and is therefore not preferable. 
     In consideration thereof, as shown in the enlarged cross-sectional view of section C 1  in  FIG.  1 C- 2    and the enlarged cross-sectional view of section C 2  in  FIG.  1 C- 3   , a height ch of an upper surface  31   a  of the central cavity  33  from the surface of the circuit board  1  is preferably set to 10 times or more with respect to the height h of the gap  36 . Furthermore, the height ch is desirably smaller than a height wh (refer to  FIG.  1 H ) of an upper surface  33   b  of the frame-shaped cavity  35  from the surface of the circuit board  1 . Accordingly, even when the resin  41  does not remain in the gap  36  and penetrates into a part of the central cavity  33  and the tip resin portion  44  is formed, the possibility of the resin  41  reaching the front surface electrode  12  can be reduced. Therefore, the distance between the front surface electrode  12  and the gap  36  can be kept short and an effect of preventing the size of the package unit from increasing can be attained. 
     Furthermore, as shown in the enlarged cross-sectional view of section C 1  in  FIG.  1 C- 2    and the enlarged cross-sectional view of section C 2  in  FIG.  1 C- 3   , a depressed portion  17  is preferably formed on a surface of the intermediate region  24  of the circuit board  1 . The depressed portion  17  is formed at a position opposing the central cavity  33  among the surface of the intermediate region  24  of the circuit board  1  or, in other words, a frame-shaped region that is adjacent to the frame-shaped protruding portion  39  or the gap  36  in a state where the circuit board  1  is installed inside the mold  3 . A height (a Z-direction position) of the front surface of the circuit board  1  in the portion where the depressed portion  17  is provided is lower than portions where the depressed portion  17  is not provided. The depressed portion  17  shown in  FIGS.  1 C- 2  and  1 C- 3    represents an example in which the depressed portion  17  is formed by an opening provided in the solder resist layer  11 . By providing the depressed portion  17  described above, even when the resin  41  penetrates into the central cavity  33  and the tip resin portion  44  is formed as shown in  FIG.  1 G , the resin  41  pools in the depressed portion  17  and the possibility of the resin  41  reaching the front surface electrode  12  can be reduced. Therefore, the distance between the front surface electrode  12  and the gap  36  can be kept short and an effect of preventing the size of the package unit from increasing can be attained. 
     A distance between the depressed portion  17  and the gap  36  preferably ranges from 0.05 to 1 mm. When the distance is shorter than this range, a deviation of a position of the circuit board  1  inside the cavity of the mold  3  causes the depressed portion  17  and the gap  36  to interfere with each other and makes it difficult to properly maintain the height h of the gap  36 . In addition, when the distance is too long, the size of the package unit increases. In order to suppress a positional deviation of the circuit board  1  inside the cavity of the mold  3 , a round hole and a U-shaped hole may be opened on the circuit board  1  and a pin (a protrusion) which fits into the round hole and the U-shaped hole may be provided on the mold  3 . 
     Furthermore, a distance between the depressed portion  17  and the front surface electrode  12  also preferably ranges from 0.05 to 1 mm. When the distance is shorter than this range, depending on machining accuracy of the depressed portion  17 , the depressed portion  17  and the front surface electrode  12  interfere with each other and make it difficult to properly maintain the length of the front surface electrode  12 . For example, when the depressed portion  17  is a groove provided on the solder resist layer  11  by lithography, a positioning accuracy of a mask when performing the lithography is the machining accuracy of the depressed portion  17 . In addition, when the distance between the depressed portion  17  and front surface electrode  12  is longer than 1 mm, the size of the package unit increases. 
     It is also preferable to set the distance between the depressed portion  17  and the front surface electrode  12  shorter than the distance between the depressed portion  17  and the gap  36 . The distance between the depressed portion  17  and the gap  36  can be regarded as a distance between the depressed portion  17  and the extended resin portion  42  as well as a distance between the tip resin portion  44  and the extended resin portion  42 . Adopting such a configuration enables the resin  41  to remain in the depressed portion  17  and reduces the possibility of the resin  41  reaching the front surface electrode while suppressing an increase in package unit size. 
     Furthermore, a width of the depressed portion  17  preferably ranges from 0.1 to 1 mm. When the width is shorter than 0.1 mm, a space for pooling the resin  41  becomes insufficient. When the width is longer than 1 mm, the size of the package unit increases. 
     In addition, a height th of the tip resin portion  44  shown in the enlarged cross-sectional view of section H 2  in  FIG.  1 H- 5    from the front surface of the circuit board  1  is preferably greater than a height h of the extended resin portion  42  from the circuit board  1 . In other words, a thickness of the tip resin portion  44  is preferably greater than a thickness of the extended resin portion  42 . Furthermore, preferably, a lower end position of the tip resin portion  44  is lower than a lower end position of the extended resin portion  42 , and an upper end position of the tip resin portion  44  is higher than an upper end position of the extended resin portion  42 . Adopting such a configuration enables the height th of the tip resin portion  44  to be set greater than the height h of the extended resin portion  42 . The higher the height th of the tip resin portion  44 , the larger the amount of the resin  41  that pools in the depressed portion  17  even when the resin  41  penetrates into the central cavity  33  as shown in an enlarged cross-sectional view of section G 2  shown in  FIG.  1 G- 2   . This is preferable since the possibility that the resin  41  reaches the front surface electrode  12  can be reduced. 
     However, a situation where the height th of the tip resin portion  44  is higher than a height wh of the frame-shaped resin portion  40  shown in  FIG.  1 H  is not preferable from the perspective of the package unit. In order to prevent an occurrence of such a situation, a height ch of the central cavity  33  shown in  FIGS.  1 C- 2  and  1 C- 3    from the front surface of the circuit board  1  is preferably lower than the height wh of the frame-shaped cavity  35  from the front surface of the circuit board  1 . In other words, the thickness of the tip resin portion  44  is preferably smaller than a thickness of the frame-shaped resin portion  40 . 
     In addition, a filler may be added to the resin  41  as described earlier, and the filler preferably contains those of which a particle size is greater than the height h of the gap  36  shown in the enlarged cross-sectional view of section C 1  in  FIG.  1 C- 2    and the enlarged cross-sectional view of section C 2  in  FIG.  1 C- 3   . The filler is preferably a silica filler. In addition, a volumetric content of the silica filler is preferably 80% or higher. This is because, by having the silica filler fill the gap  36  in the stage shown in  FIG.  1 G , since flowability of the resin  41  in the gap  36  drops, an amount of the resin  41  that penetrates into the central cavity  33  can be reduced. Since the height h of the gap  36  is equal to the thickness of the extended resin portion  42 , the frame-shaped resin portion  40  has a filler of which a particle size is greater than the thickness of the extended resin portion  42 . 
     Second Embodiment 
     A method of manufacturing a package unit according to a second embodiment of the present invention will be described.  FIGS.  3 A to  3 F  represent an example of the method of manufacturing a package unit according to the second embodiment.  FIG.  3 A  is a diagram of a stage corresponding to  FIG.  1 C  illustrating the first embodiment and shows a state where the circuit board  1  has been inserted into the mold  3 . The mold  3  is the same as that of the first embodiment. 
       FIG.  3 B  is a Z-direction plan view (cross-sectional view) of the package unit, and  FIGS.  3 C to  3 F  are, respectively, enlarged cross-sectional views of sections A 1  to A 4 . 
     The circuit board  1  is the same as that of the first embodiment with the exception of a total thickness of the circuit board  1  being 10% thicker than that of the first embodiment. As shown in the enlarged cross-sectional views of sections A 1  to A 4  shown in  FIGS.  3 C to  3 F , the circuit board  1  has a plurality of conductor layers  14 . 
     The upper mold  31  of the mold  3  has the frame-shaped protruding portion  39  in a portion between the central cavity  33  and the frame-shaped cavity  35 . The circuit board  1  is sandwiched by a top frame-shaped plane  37  ( FIGS.  3 C and  3 D ) of the frame-shaped protruding portion  39  and an opposing plane  38  ( FIGS.  3 E and  3 F ) of the lower mold  32  that is provided so as to oppose the top frame-shaped plane  37 . 
       FIGS.  4 A to  4 D  show a creation stage of the circuit board  1  according to the second embodiment. These are diagrams showing enlargements of cross-sections taken at section D 2  in the Z-direction plan view shown in  FIG.  4 A- 1   . The circuit board  1  shown in the diagrams is a so-called 2-4-2 build-up substrate, and step a represents a stage where two build-up layers have been respectively formed on both surfaces of a core layer. 
       FIG.  4 B  shows a stage of step b. In step b, an uppermost conductor layer  141  formed in step a is patterned by lithography. The uppermost conductor layer  141  is a conductor layer  14  that comes into closest proximity to the top frame-shaped plane  37  in a state where the circuit board  1  is inserted into the mold  3  shown in  FIG.  3 A . 
       FIG.  4 B- 1    is a plan view of the circuit board  1  from the z direction in the stage of step b. As shown, the conductor layer  141  is provided with a frame-shaped opening  1411  in a portion sandwiched between two rectangular dashed lines. A region provided with the frame-shaped opening  1411  may be provided in the following step in a region including a position that overlaps with the frame-shaped protruding portion  39  and may be provided in, for example, the entire intermediate region  24  ( FIG.  8 A ) between the central region  23  and the peripheral region  25  on the circuit board  1 .  FIG.  4 B  also shows the frame-shaped opening  1411 . The frame-shaped opening  1411  is portion in which at least the uppermost conductor layer  141  has been removed in a frame shape by lithography. The frame-shaped opening  1411  can also be described as a frame-shaped depressed portion. As is apparent from a comparison between  FIG.  4 B  and  FIG.  3 D , the frame-shaped opening  1411  is provided in a portion where the top frame-shaped plane  37  of the mold  3  and the conductor layer  141  oppose each other. The frame-shaped opening  1411  is provided in this portion and a width kw thereof is greater than a width w of the top frame-shaped plane  37 . 
       FIG.  4 C  shows a stage of step c. In step c, the solder resist layer  11  is formed on a front surface of the circuit board  1 . The solder resist layer  11  is formed by applying a liquid resist using a known roll coater, spin coater, spray coater, or the like and solidifying the liquid resist by applying heat or UV. In the case of a liquid solder resist, even if a thickness of a portion where the conductor layer  141  is present and a thickness of a portion (the frame-shaped opening  1411 ) where the conductor layer  141  is not present are the same at a time point where the liquid resist is applied, thicknesses of the solder resist layer  11  after curing differ. Specifically, a thickness tk of an opening portion where the conductor layer  141  is not present becomes thicker by 10 to 30% than a thickness td of a portion where the conductor layer  141  is present. This is because, even when the thickness is the same at a time point where the liquid resist is applied, the liquid resist flows into the portion (the opening) where the conductor layer  141  is not present from the portion where the conductor layer  141  is present before solidifying and a leveling action takes place in which a liquid surface moves to even itself out. 
       FIG.  4 D  shows a stage of step d. In step d, exposure and a development process are performed on the cured solder resist layer  11  to open an opening in a desired portion of the circuit board  1 . As shown in  FIG.  4 D , the solder resist layer  11  remains in at least a part of the frame-shaped opening  1411 . As described later, the solder resist layer  11  is preferably formed in a portion that is sandwiched by the frame-shaped protruding portion  39  of the mold  3 . In addition, as shown in  FIG.  4 D , the solder resist layer  11  is formed so as to also remain in a portion other than the frame-shaped opening  1411  (other than the frame-shaped depressed portion) among the front surface of the circuit board  1 . 
       FIG.  4 E  is a state diagram which shows the circuit board  1  being inserted into the mold  3  and sandwiched by the top frame-shaped plane  37  and the opposing plane  38  and which is a same diagram as  FIG.  3 D . In the circuit board  1 , the central region  23  opposes the central cavity  33 , the peripheral region  25  opposes the frame-shaped cavity  35 , and the frame-shaped narrow cavity  34  (the frame-shaped protruding portion  39 ) opposes the intermediate region  24 . The frame-shaped protruding portion  39  comes into contact with (overlaps with) the solder resist layer  11  in the intermediate region  24  of the circuit board  1 . The solder resist layer  11  that overlaps with the frame-shaped protruding portion  39  is the solder resist layer provided in the frame-shaped opening  1411  or, in other words, the solder resist layer positioned between the conductor layer  14  of the central region  23  and the conductor layer  14  of the peripheral region  25 . 
     At this stage, the frame-shaped protruding portion  39  bites into the solder resist layer  11  and causes the solder resist layer  11  to deform and depress. In other words, a surface (a surface on an opposite side to the circuit board  1 ) of the solder resist layer  11  in the intermediate region  24  is a depressed surface. In addition, a slight depression has also occurred in the prepreg layer  18  in a portion indicated by an arrow  22 . However, the degree of depression can be kept within a range where the strength of a package does not become insufficient or moisture resistance of the package does not drop. This is because a thickness of the resist layer  11  being formed in the frame-shaped opening  1411  which is a contact region with the frame-shaped protruding portion  39  is set thicker by 10 to 30% than a portion that covers the conductor layer  14 . The resist layer  11  effectively absorbs stress applied from the frame-shaped protruding portion  39  and deforms, and prevents damage to the prepreg layer  18  and the conductor layer  14 . 
       FIG.  4 F  shows a stage where the resin  41  has flowed into a part of the cavity of the mold  3  or, in other words, the frame-shaped cavity  35 . 
       FIG.  4 G  is an overall completed view of a package according to the second embodiment.  FIG.  4 G- 1    is a Z-direction plan view thereof, and  FIG.  4 G- 2    and  FIG.  4 G- 3    are, respectively, enlarged cross-sectional views of section G 1  and section G 2  in  FIG.  4 G- 1   . 
     The completed package is constituted by the circuit board  1  including a plurality of conductor layers  14  and the frame-shaped resin portion  40  provided so as to surround an outer periphery of the circuit board  1 . The uppermost conductor layer  141  among the plurality of conductor layers  14  is removed along an entire inner periphery of the frame-shaped resin portion  40  to form the frame-shaped opening (the frame-shaped depressed portion)  1411 . In addition, the entire frame-shaped opening  1411  and at least a part of the uppermost conductor layer  141  are covered by the solder resist layer  11  having been created by curing a liquid resist. As described earlier, a central portion of the frame-shaped opening  1411  is sandwiched by the frame-shaped protruding portion  39  of the mold  3 . By being sandwiched, the solder resist layer  11  deforms and a thickness of a solder resist layer  11   a  in a portion being sandwiched by the frame-shaped protruding portion  39  (the central portion of the frame-shaped opening  1411 ) becomes thinner than a thickness of a solder resist layer  11   b  in a peripheral portion. A slight depression has also occurred in the prepreg layer  18  in the portion indicated by the arrow  22 . However, the degree of depression can be kept within a range where the strength of a package does not become insufficient or moisture resistance of the package does not drop. 
     Using a solder resist with a low modulus of elasticity is effective in also preventing an occurrence of a depression of the prepreg layer  18 . In particular, a solder resist having a modulus of elasticity of around 2 to 4 GPa is preferable. An example of a liquid resist with relatively low elasticity is PSR-4000 AUS308 manufactured by TAIYO INK MFG. CO., LTD. 
       FIGS.  5 A to  5 D  are diagrams showing a preferable example of the second embodiment.  FIGS.  5 A to  5 D  are enlarged cross-sectional views of section B 2  in a Z-direction plan view in  FIG.  5 A- 1   . Hereinafter, differences from the example shown in  FIGS.  4 A to  4 G  will be mainly described with reference to the drawings. 
     Processes up to step d are similar to those described above. As a step shown in  FIG.  5 A  following step d ( FIG.  4 D ), a solder resist layer  19  is once again formed on the circuit board  1 . 
     Next, as shown in  FIG.  5 B , the solder resist layer  19  is patterned by lithography and a solder resist layer  191  is formed on the frame-shaped opening  1411  created in the uppermost conductor layer  141 . In this manner, two solder resist layers  11  and  191  are formed in the frame-shaped opening  1411 . 
     Next, as shown in  FIG.  5 C , the circuit board  1  is inserted to a mold of which a height dh of the central cavity  33  differs from that of the mold  3  according to the first embodiment. The height dh of the central cavity  33  can be regarded as a length of the frame-shaped protruding portion  39 . In the present embodiment, the height dh of the central cavity  33  can be set 20 to 30 μm shorter than the height ch shown in  FIG.  1 C- 3   . Accordingly, an effect is produced in which, although the solder resist layer  11  and the solder resist layer  191  deform, the solder resist layer  11  and the solder resist layer  191  effectively absorb stress applied from the frame-shaped protruding portion  39  and prevent damage to the portion indicated by the arrow  22  of the prepreg layer  18  and to the conductor layer  14 . Finally, as shown in  FIG.  5 D , the resin  41  is poured into a part of the cavity of the mold  3  or, in other words, the frame-shaped cavity  35  to mold the tip resin portion  44 . 
     Comparative Mode 
     Next, a comparative mode will be described with reference to  FIGS.  6 A to  6 C . These are diagrams showing enlargements of cross-sections taken at section A 2  in the Z-direction plan view shown in  FIG.  6 A- 1   . 
     In the present comparative mode, instead of providing the frame-shaped opening  1411  on the uppermost conductor layer  141  of the circuit board  1  according to the second embodiment, a molding process is performed by sandwiching the circuit board  1  with the mold  3 .  FIG.  6 A  shows that an opening is not provided in the portion where the frame-shaped opening  1411  had been provided in the step shown in  FIG.  4 B . Furthermore, the solder resist layer  11  is formed in  FIG.  6 B . In this case, unlike in  FIG.  4 C , since the frame-shaped opening  1411  is absent, a leveling effect of a liquid solder resist is not produced and the solder resist layer  11  has a uniform thickness of td. 
     Furthermore,  FIG.  6 C  shows a state where the circuit board  1  is inserted into the same mold  3  as the first embodiment. As shown, in the present example, since insufficient thickness of the solder resist layer  11  and the absence of the frame-shaped opening  1411  on the uppermost conductor layer  141  causes stress applied from the frame-shaped protruding portion  39  to reach a lower part of the circuit board  1 , a crack  181  is likely to occur in the prepreg layer  18 . In addition, a crack  142  is also likely to occur in the uppermost conductor layer  141  and is therefore not preferable. 
     Third Embodiment 
     An electronic module using the package unit according to the first embodiment or the second embodiment will be described with reference to  FIGS.  7 A to  7 C . The electronic module is configured to include an electronic device mounted on a circuit board of a package and a lid portion that covers the package. When the electronic device is an imaging device, the electronic module is an imaging module, and when the electronic device is a display device, the electronic module is a display module. In order to ensure that the electronic device can be stored in the package unit, a thickness (a height) of the electronic device is smaller than a thickness wh of the frame-shaped resin portion  40  and greater than a thickness h of the extended resin portion  42 . By reducing the thickness of the extended resin portion  42 , a side surface of the resin member  4  (an inner surface of the frame-shaped resin portion  40 ) which faces a space surrounded by the resin member  4  can be separated from the electronic device  5 . When the electronic device is a display device or an imaging device, since reflection of light by the side surface of the resin member  4  can be suppressed, a decline in image quality due to the reflected light can be suppressed. By making the thickness of the extended resin portion  42  smaller than a thickness of the electronic device, an optical effect of the extended resin portion  42  on a surface (an upper surface) of the electronic device on an opposite side to the circuit board  1  can be reduced as much as possible. 
     A method of manufacturing the electronic module is as follows. First, as shown in  FIG.  7 A , a package unit  100  is fixed to a known suction stage  7  and the electronic device  5  such as an imaging device is bonded and fixed to a central portion of the package unit  100  via a known adhesive  6 . By reducing the thickness of the extended resin portion  42 , a volume of a space surrounded by the resin member  4  can be increased. Accordingly, since a work space can be widened when arranging the electronic device  5  in the space surrounded by the resin member  4 , the electronic device  5  can be readily arranged. Next, using a known wire  8  as shown in  FIG.  7 B , an electrode pad of the electronic device  5  and the front surface electrode  12  of the package unit  100  are connected to each other by a known wire-bonding method. A side surface of the resin member  4  (an inner surface of the frame-shaped resin portion  40 ) can be separated from the electronic device  5 . Accordingly, the resin member  4  can be prevented from interfering with a capillary when performing the wire-bonding. Finally, a known translucent lid  10  is bonded and fixed to the package unit  100  via a known adhesive to complete an imaging element module. A distance between the translucent lid  10  and the electronic device  5  can be controlled by a thickness of the frame-shaped resin portion  40 . At this point, by sufficiently reducing the thickness of the extended resin portion  42 , the extended resin portion  42  is prevented from unnecessarily affecting the distance between the translucent lid  10  and the electronic device  5 . 
     Such an electronic module can be applied to various equipment. While applicable equipment are not particularly limited, examples thereof include electronic information equipment (electronic equipment, information equipment) such as a smartphone, a camera, and a personal computer. Alternatively, examples of equipment to which the present invention can be applied include communication equipment for performing radio communication or the like, office equipment such as a copier and a scanner, and transportation equipment such as an automobile, a ship, and an aircraft. Alternatively, examples of equipment to which the present invention can be applied include industrial equipment such as a robot, analyzing equipment which use energy beams (light, electron beams, or radio waves), and medical equipment such as an endoscope and radiological equipment. In an equipment to which the present invention is applied, the circuit board of the electronic module according to the embodiment described above is connected to other parts of the equipment. While functions of the other parts of the equipment to which the circuit board is to be connected can be appropriately set depending on functions of the electronic module, examples of the parts include a part for controlling or driving the electronic module and a part for processing signals for communicating with the electronic module. Adopting the electronic module according to the present embodiment in an equipment is advantageous in terms of improving durability and reliability of the equipment as well as downsizing and weight reduction of the equipment. Examples of equipment to be mounted with an imaging module include various equipment such as a digital still camera, a digital camcorder, a monitoring camera, a copier, a facsimile, a mobile phone, a vehicle-mounted camera, an observation satellite, and a camera for medical use. Such equipment include an optical system, an electronic equipment, and a processing apparatus. An electronic equipment that is an imaging equipment photoelectrically converts an object image formed by the optical system and outputs the photoelectrically converted object image as an image signal or a focus detection signal. The processing apparatus performs image processing, an equipment control process, and the like on the basis of a signal output from the imaging equipment. Examples of equipment control include control of a moving body such as a vehicle, a ship, or an aircraft. 
       FIG.  9    illustrates a camera CMR as an example of an equipment to which an electronic module is applied. The camera CMR may include an imaging module IS, an electric module MB, and a display module DP. The electric module MB is a component for controlling or supplying power to the imaging module IS and/or the display module DP and a component for processing signals used to communicate with the imaging module IS and/or the display module DP. The electric module MB may be connected to a circuit board of the electric module via flexible wiring. In the camera CMR, the display module DP may constitute an electronic view finder (EVF) or may constitute a touch panel. In addition, the camera CMR may include a lens LNS that is attachable to and detachable from a camera body or a lens LNS that is fixed to the camera body. The camera CMR may include a machine module MCHN for moving the imaging module IS inside the camera body. Any of the electronic modules according to the embodiments described above may be any of the imaging module IS and the display module DP. The imaging module IS is connected to the electric module MB via a flexible printed wiring board FPC 1  which is connected to the imaging module IS. The display module DP is connected to the electric module MB via a flexible printed wiring board FPC 2  which is connected to the display module DP. The flexible printed wiring boards may be connected to the connector  221  shown in  FIGS.  8 A and  8 B . In the camera CMR, a camera shake prevention (anti-vibration) function can be realized by moving (displacing) the imaging module IS that corresponds to the electronic module by the machine module MCHN. Since the imaging module IS to which the electronic module according to the present embodiment is applied attains weight reduction, an increased movement speed of the imaging module IS and a reduced load on the machine module MCHN for movement can be realized. Since the electronic module according to the present embodiment has a highly reliable package unit, durability of an equipment that involves such movements of the electronic module can be increased. 
     First Example 
     Hereinafter, an example of the present invention will be described. The package unit  100  was fabricated by the method of manufacturing a package unit shown in  FIG.  1 A to  1 H  using the mold  3  shown in  FIG.  2 A . 
     A resin substrate was used as the circuit board  1  and configured as a so-called 2-4-2 build-up substrate. The conductor layer  14  was created using 18 μm-thick copper foil. 
     The core layer and the build-up layer include a prepreg layer  18 . The prepreg layer  18  is configured such that fibers woven or knitted into a cloth pattern are impregnated with a resin. Epoxy containing an insulating filler was used as the resin. 
     In addition, front and rear surfaces of the circuit board  1  were provided with the solder resist layer  11 . The solder resist layer  11  was formed by a method involving applying a liquid resist using a roll coater, curing the liquid resist by UV and heat, and subsequently performing patterning in a similar manner. 
     The electronic components  2  were soldered and connected to the rear surface of the circuit board  1  as shown in  FIG.  1 B  by a known surface mounting method. Flux cleaning was performed using a known cleaner and a known cleaning solution. 
     The used electronic components include a ceramic capacitor, an organic capacitor made of tantalum or the like, a chip resistor, a B-to-B connector, a regulator IC for a power supply, a common-mode connector coil, a temperature measurement IC, and an EPROM. 
       FIGS.  2 A to  2 C  exclusively illustrate the mold  3  used in the present example. The mold  3  is constituted by the upper mold  31  and the lower mold  32 .  FIG.  2 A  shows a state where the mold  3  is opened and  FIG.  2 B  shows a state where the mold  3  is closed. In the state where the mold  3  is closed, a cavity is prepared inside the mold. As shown in  FIG.  2 B , the cavity is constituted by the central cavity  33 , the frame-shaped narrow cavity  34  provided on an outer periphery of the central cavity  33 , and the frame-shaped cavity  35  provided on an outer periphery of the frame-shaped narrow cavity  34 . In addition, the mold  3  is provided with a gate (not illustrated) for injecting resin in a direction indicated by the arrow  201  in  FIG.  2 B  and an air vent (not illustrated) for releasing air having been forced out by resin in a direction indicated by the arrow  202 . 
       FIG.  1 C  shows a state where the circuit board  1  according to the present example is inserted into the mold  3 . As shown in the Z-direction plan view of  FIG.  1 C- 1   , the entire outer periphery  21  of the circuit board  1  is included inside the frame-shaped cavity  35  in this state. Furthermore, the gap  36  is provided between an inner surface of the frame-shaped narrow cavity  34  and the front surface of the circuit board  1 . In this manner, in the present example, the circuit board  1  is not clamped by the mold  3  in a state where the circuit board  1  is inserted into the mold  3 . Therefore, an occurrence of damages such as a crack in the circuit board  1  and a deformation or a fracture of the conductor layers  14  which have been problems in the past can be prevented. 
     Transfer molding is used in the present example. A thermosetting resin is used. Resin materials with powder resin as a main component and including a curing agent, a releasing agent, a coupling agent, and a flame retardant were shaped into a cylindrical tablet and the resin tablet was placed inside a pot to be preheated. In a state where the resin had been melted by the preheating and viscosity had dropped to 30 Pa·s, the resin  41  was extruded from the pot with a plunger and injected into the cavity via a cull, a runner, and a gate. The mold  3  was preheated in advance to a temperature of 145° C. which is higher than a glass-transition temperature of the resin  41  of 140° C. 
     From  FIG.  1 D  to  FIG.  1 E , conditions were selected such that the resin  41  injected from the gate advances so as to fill the frame-shaped cavity  35 . Air in the portions to which the resin enters was adjusted to be discharged from the air vent (not illustrated). At this stage, pressure of the resin  41  was relatively low at 4 MPa. Once the stage shown in  FIG.  1 F  arrived, the pressure of the resin  41  started to rise and, eventually, filling was completed in the stage shown in  FIG.  1 G  at pressure of 30 MPa. 
     The height h of the gap  36  shown in the enlarged cross-sectional view of section E in  FIG.  1 E- 1    was adjusted to 30 μm. In addition, the width w of the frame-shaped narrow cavity  34  shown in the enlarged cross-sectional view of section E in  FIG.  1 E- 1    was similarly set to 0.3 mm. By adopting such conditions, it was possible to more or less keep the resin  41  inside the gap  36  as shown in the enlarged cross-sectional view of section G 1  in  FIG.  1 G- 1    when viscosity of the resin  41  was 30 Pa·s as described earlier in the final stage shown in  FIG.  1 G . This is because a flow resistance of the gap  36  with respect to the resin  41  was sufficiently high and, therefore, a flow rate of the resin  41  to the gap  36  was sufficiently slowed, and it was possible to advance a curing reaction of the resin  41  in a state where the resin  41  remains in the gap  36  to solidify the resin  41 . 
       FIG.  1 H  represents a finished product of the package unit according to the present example. The finished product is provided with the circuit board  1 , the frame-shaped resin portion  40  which surrounds an outer periphery of the circuit board  1 , and the extended resin portion  42  which is adjacent to an inner side of the frame-shaped resin portion  40 . As shown from  FIG.  1 H- 1    to  FIG.  1 H- 3   , an outer shape of an inner side of the extended resin portion  42  is an indeterminate shape. In addition, a height h of a narrow resin mold portion shown in the enlarged cross-sectional views in  FIGS.  1 H- 4  to  1 H- 6    corresponds to the height h of the gap  36  shown in the enlarged cross-sectional view of section E shown in  FIG.  1 E- 1    and had a value of 30 μm. 
     As shown in the enlarged plan views in  FIGS.  1 H- 2  and  1 H- 3   , bubbles  43  are sparsely present inside the extended resin portion  42  but no bubbles are observed inside the frame-shaped resin portion  40 . Bubbles are not present inside the frame-shaped resin portion  40  because, in the stage shown in  FIG.  1 G , pressure of 30 MPa is applied to the resin  41  inside the frame-shaped cavity  35  and gas contained inside the resin  41  is dissolved in the resin  41 . On the other hand, a pressure gradient such that pressure drops from a side of the frame-shaped cavity  35  toward a side of the central cavity  33  is present in the resin  41  having penetrated into the gap  36  of the frame-shaped narrow cavity  34 . In the resin  41  having penetrated into the gap  36  of the frame-shaped narrow cavity  34 , a portion close to the frame-shaped cavity  35  is subjected to pressure close to 30 MPa and gas contained inside the resin  41  has more or less been dissolved in the resin  41 . However, the closer to the central cavity, the pressure on the resin  41  drops and, accordingly, solubility of the gas contained inside the resin  41  declines and the bubbles  43  are created. Pressure applied to the resin  41  in the vicinity of the central cavity was almost close to pressure of air inside the central cavity  33  and was at approximately 1 atmospheric pressure. 
     The pressure gradient described above occurs because flow resistance with respect to the resin  41  flowing through the gap  36  is present within an appropriate range. A comparison between a residual ratio of bubbles of the resin  41  having penetrated into the gap  36  and a residual ratio of bubbles of the resin  41  which is present inside the frame-shaped cavity  35  yielded a result of 55 times. Accordingly, it was possible to advance a curing reaction of the resin  41  in a state where the resin  41  remains in the gap  36  to solidify the resin  41 . In addition, a residual ratio of bubbles contained in the extended resin portion  42  as shown in  FIG.  1 H  was also 60 times or higher as compared to a residual ratio of bubbles contained in the frame-shaped resin portion  40 . Furthermore, the residual ratio of bubbles contained in the frame-shaped resin portion  40  was 0.1% and, accordingly, it was possible to sufficiently increase a moisture-proof property of the package and maintain mechanical strength of the package. 
     The effect of the present invention is apparent from the present example. 
     Second Example 
     A package manufacturing method according to a second example will be described. 
     As the circuit board  1 , a circuit board  1  with a total thickness being 10% thicker than that of the first example was used. 
     A difference from the first example is that the circuit board  1  is sandwiched by the top frame-shaped plane  37  of the frame-shaped protruding portion  39  of the mold  3  and the opposing plane  38  provided so as to oppose the top frame-shaped plane  37 . 
       FIGS.  4 A to  4 D  show a creation stage of the circuit board  1  according to the present example. These are diagrams showing enlargements of cross-sections taken at section D 2  in the Z-direction plan view shown in  FIG.  4 A- 1   . 
       FIG.  4 B  shows step b or, in other words, a stage in which the uppermost conductor layer  141  formed in step a is patterned by lithography. The conductor layer  141  is a conductor layer  14  that comes into closest proximity to the top frame-shaped plane  37  in a state where the circuit board  1  is inserted into the mold  3  shown in  FIG.  3 A . 
       FIG.  4 B- 1    is a plan view of the circuit board  1  from the z direction in the stage of step b. As shown, the conductor layer  141  is provided with the frame-shaped opening  1411  in a portion sandwiched between two rectangular dashed lines.  FIG.  4 B  also shows the frame-shaped opening  1411 . As is apparent from a comparison between  FIG.  4 B  and  FIG.  3 D , the frame-shaped opening  1411  is a portion where the top frame-shaped plane  37  of the mold  3  and the conductor layer  141  oppose each other. The frame-shaped opening  1411  is provided in this portion and a width kw thereof is greater than a width w of the top frame-shaped plane  37 . The width kw was set to 0.62 mm and the width w to 0.3 mm. 
       FIG.  4 C  is a diagram showing step c or, in other words, a stage in which the solder resist layer  11  is formed. The solder resist layer  11  was formed by applying a liquid resist using a known roll coater and solidifying the liquid resist by applying heat or UV. In the stage of applying the liquid resist, a portion of the conductor layer  141  where a pattern is present and the frame-shaped opening  1411  where the pattern is not present had a same thickness of 30 μm. However, after curing, a thickness tk of the opening portion where the pattern was not present was 35 μm and a thickness td of the portion where the pattern was present was 28 μm, indicating an increase in thickness of 25%. This is because, before the liquid resist solidifies, the liquid resist flowed into the portion where the pattern is not present from the portion where the pattern is present and a leveling action took place in which a liquid surface moves to even itself out. 
       FIG.  4 D  shows step d or, in other words, a stage where exposure and a development process are performed on the cured resist layer  11  and an opening is opened in a desired portion of the circuit board  1  to complete the circuit board  1 . 
       FIG.  4 E  is a state diagram which shows the circuit board  1  being inserted into the mold  3  and sandwiched by the top frame-shaped plane  37  and the opposing plane  38  and which is a same diagram as  FIG.  3 D . At this stage, the frame-shaped protruding portion  39  had bitten into the solder resist layer  11  and caused the solder resist layer  11  to deform. In addition, while a slight depression had also occurred in the prepreg layer  18  in the portion indicated by the arrow  22 , the strength of the package did not become insufficient and moisture resistance of the package did not decline. This is because the thickness of the resist layer  11  formed in the frame-shaped opening  1411  which is a contact region with the frame-shaped protruding portion  39  was set thicker by 25% than other portions. While the total thickness of the circuit board  1  is thicker by 10%, the resist layer  11  effectively absorbs stress applied from the frame-shaped protruding portion  39  and deforms, and prevents damage to the prepreg layer  18  and the conductor layer  14 . 
       FIG.  4 F  shows a stage where the resin  41  has flowed into the frame-shaped cavity  35  which is a part of the cavity of the mold  3 . A solder resist with a low modulus of elasticity was used. Specifically, a solder resist with a modulus of elasticity of 3.4 GPa was used. 
     The effect of the present invention is apparent from the present example. 
     Other Embodiments 
     Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as anon-transitory computer-readable storage medium&#39;) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.