This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2014-128751 and No. 2014-128752, both filed on Jun. 24, 2014, the contents of which are incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an electronic component mounting structure manufactured by mounting an electronic component such as Ball Grid Array (BGA) package on which a plurality of bumps is formed on a substrate, and a method of manufacturing the electronic component mounting structure.
2. Description of the Related Art
A method of mounting an electronic component such as a semiconductor device, a method of connecting the electronic component on a substrate by joining a plurality of bumps formed at a main surface of the electronic component to electrodes formed on the substrate through soldering has been widely used (for example, see JP-A-10-112478). In the related art described in JP-A-10-112478, in a configuration in which a BGA type semiconductor device is mounted on a substrate, four corner positions of outer edges of the BGA type semiconductor device are joined to the substrate by using adhesive. Thus, an effect of correcting warp deformation of the BGA type semiconductor device which arises in a heating process during reflow soldering is obtained.
Patent Document 1: JP-A-10-112478
Incidentally, in the manufacturing field of electronic devices, as portable devices represented by smart phones become small and thin, there is an increasing demand for space-saving and size reduction of an electronic component mounted on these devices. Particularly, among these demands, it is more important to manufacture the electronic component to be thin than in the related art. For this reason, as the electronic component and the substrate become thin and have low stiffness, warp deformation in an upward and downward direction (thickness direction) or positional deviation easily occurs in a heating process when the electronic component is joined to the substrate through soldering. As a result, defects arising from the warp deformation, such as a solder opening phenomenon in which the bumps of the electronic component are separated from the electrodes of the substrate without normally coming in contact with the electrodes or a bridge phenomenon in which the neighbor electrodes are connected each other through the solder by excessively pushing the bumps against the substrate, frequently occur. However, as in the related art described above, it is difficult to effectively prevent the warp deformation from occurring in the electronic component which is extremely thin and is easily bent.
Accordingly, a non-limited object of the present invention is to provide an electronic component mounting structure and a method of manufacturing an electronic component mounting structure which are capable of reducing defects arising from warp deformation even when an electronic component and a substrate which are thin and have low stiffness are used.
A first aspect of the present invention provides an electronic component mounting structure in which a plurality of bumps formed on an electronic component is joined to a plurality of electrodes formed on a substrate by way of joining portions formed with the bumps and solder, the structure including: bonding portions that bond the electronic component to the substrate in plurality of preset positions, wherein the bonding portions are formed by thermosetting materials obtained by curing thermosetting resins having a curing temperature which is lower than a melting point of the solder between the electronic component and the substrate, wherein the bonding portions include a bump bonding portion provided in a bump-forming region where the bumps are formed, and the thermosetting materials come in contact with a nearest-neighboring joining portion of the joining portions at least in the bump bonding portion.
A second aspect of the present invention provides a method of manufacturing an electronic component mounting structure in which a plurality of bumps formed on an electronic component is joined to a plurality of electrodes formed on a substrate by way of joining portions formed with the bumps and solder, the method including: supplying solder pastes to the electrodes; supplying thermosetting resins having a curing temperature which is lower than a melting point of the solder in preset resin supplying positions in order to bond the electronic component to the substrate in a plurality of positions on a component mounting surface of the substrate; mounting the electronic component on the substrate by disposing the plurality of bumps on the solder pastes supplied to the corresponding electrodes while bringing the electronic component into contact with the thermosetting resins; forming bonding portions that bond the electronic component to the substrate with thermosetting materials obtained by heating the substrate on which the electronic component is mounted at a temperature lower than the melting point of the solder and thermally curing the thermosetting resins between the electronic component and the substrate; joining the bumps to the electrodes through soldering by further heating the substrate and melting the solder; and solidifying the melted solder by cooling the substrate, wherein the resin supplying positions include a bump-region resin supplying position provided in a bump-forming region where the bumps are formed, and the resins are supplied such that the thermosetting materials come in contact with a nearest-neighboring joining portion at least in the bump-region resin supplying position at a timing at which cooling the substrate is completed.
A third aspect of the present invention provides an electronic component mounting structure in which a plurality of bumps formed on an electronic component is joined to a plurality of electrodes formed on a substrate by way of joining portions formed with the bumps and solder, the structure including: bonding portions that bond the electronic component to the substrate, wherein the bonding portions are formed of thermosetting materials obtained by curing thermosetting resins having a curing temperature which is lower than a melting point of the solder between the electronic component and the substrate, wherein the thermosetting materials come in contact with a nearest-neighboring joining portion in the bonding portions.
A fourth aspect of the present invention provides a method of manufacturing an electronic component mounting structure in which a plurality of bumps formed on an electronic component is joined to a plurality of electrodes formed on a substrate by way of joining portions formed with the bumps and solder, the method including: supplying solder pastes to the electrodes; supplying thermosetting resins having a curing temperature which is lower than a melting point of the solder on a component mounting surface of the substrate; mounting the electronic component on the substrate by disposing the plurality of bumps on the solder pastes supplied to the corresponding electrodes while bringing the electronic component into contact with the thermosetting resins; forming bonding portions that bond the electronic component to the substrate with thermosetting materials obtained by heating the substrate on which the electronic component is mounted at a temperature lower than the melting point of the solder and thermally curing the thermosetting resins between the electronic component and the substrate; joining the bumps to the electrodes through soldering by further heating the substrate and melting the solder; and solidifying the melted solder by cooling the substrate, wherein the resins are supplied such that the thermosetting materials come in contact with a nearest-neighboring joining portion at a timing at which cooling the substrate is completed.
According to any of the aspects of the present invention, it is possible to reduce defects arising from warp deformation even when an electronic component and a substrate which are thin and have low stiffness are used.
In the accompanying drawings:
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of an electronic component mounting structure 1 will first be described with reference to
In the electronic component mounting structure 1 in which the electronic component 3 has been mounted on the substrate 2, bump joining portions 4 formed by joining the bumps 4* to the electrodes 2b through soldering are formed. That is, the electronic component mounting structure 1 is manufactured by joining the plurality of bumps 4* formed on the electronic component 3 to the plurality of electrodes 2b formed on the substrate 2 by the joining portions (bump joining portions 4) formed by soldering the bumps 4*. In the illustrated example, the electronic component mounting structure 1 is a thin-type package used for a portable device, and both the substrate 2 and the electronic component 3 that are used are thin and have low stiffness.
In the electronic component mounting structure 1, outer edge bonding portions 5a and bump bonding portions 5b which are bonding portions for bonding the substrate 2 to the electronic component 3 are formed in a plurality of positions between the component mounting surface 2a of the substrate 2 and the lower surface 3b of the electronic component 3. Both the outer edge bonding portions 5a and the bump bonding portions 5b are formed of a thermosetting material obtained by curing a thermosetting resin, which has a curing temperature lower than the melting point of solder, between the electronic component 3 and the substrate 2. As a thermosetting resin, an epoxy resin, a phenol resin, and a melamine resin are used. The curing temperature of the thermosetting resin in the present embodiment is calculated as a peak temperature of a curve indicating the relationship between the temperature and heat flow obtained by differential scanning calorimetry (DSC).
Here, the body part 3a is divided into a bump-forming region R1 which is a region where the bumps 4* are formed and an outer-edge region R2 which is a region outside the bump-forming region R1. The forming positions of the outer edge bonding portions 5a correspond to the outer-edge region R2, and the forming positions of the bump bonding portions 5b correspond to the bump-forming region R1. That is, the outer edge bonding portions 5a are formed in two facing diagonal positions in the body part 3a, and the bump bonding portions 5b are set in a plurality of positions (here, four places) surrounding the bumps 4* positioned in the center of the bump-forming region R1.
In the electronic component mounting structure 1 having the above configuration, the thermosetting material of the thermosetting resin comes in contact with the surrounding nearest-neighboring bump joining portions 4 in the bump bonding portions 5b, which are formed in the bump-forming region R1, of the outer edge bonding portions 5a and the bump bonding portions 5b. That is, in the present embodiment, among the bonding portions, the thermosetting material of the thermosetting resin comes in contact with the nearest-neighboring bump joining portions 4 in at least the bump bonding portions 5b set in the bump-forming region R1.
Here, a guanidine-based activator including diphenylguanidine is contained in the thermosetting resin of the bump bonding portions 5b. Through the operation of this activator, a bonding effect due to the curing of the thermosetting resin in the heating process after the component is mounted is prompted, and it is possible to obtain an effect of further improving bonding properties by bringing the activator in the bump bonding portions 5b into contact with the metal surfaces of the surrounding bump joining portions 4.
Next, an electronic-component-mounting-structure manufacturing method of manufacturing the electronic component mounting structure 1 will be described with reference to
Subsequently, as shown in
In the present embodiment, the thermosetting resins 5a* and the thermosetting resins 5b* are respectively supplied to outer-edge-region resin supplying positions P1 and bump-region resin supplying positions P2 by using an application tool such as dispensers so as to correspond to the positions of the outer edge bonding portions 5a and the bump bonding portions 5b shown in
Here, although it has been described that all of the thermosetting resins 5a* and 5b* have the same composition, the compositions of the thermosetting resins 5a* applied to the outer-edge-region resin supplying positions P1 and the thermosetting resins 5b* applied to the bump-region resin supplying positions P2 may be different depending on the bonding characteristics of the outer edge bonding portions 5a and the bump bonding portions 5b. For example, the activator described above may be added only to the thermosetting resins 5b* applied to the bump-region resin supplying positions P2.
Subsequently, the electronic component 3 is mounted on the substrate 2 to which the resins have been supplied (mounting process). Here, as shown in
Thereafter, the substrate 2 on which the mounting process has been performed is sent to a reflow apparatus, and is heated according to a heating profile shown in
That is, the outer edge bonding portions 5a and the bump bonding portions 5b for bonding the electronic component 3 to the substrate 2 are formed by the thermosetting materials obtained by heating the substrate 2 on which the mounting process has been performed at a temperature which is lower than the melting point of the solder and thermally curing the thermosetting resins 5a* and 5b* between the electronic component 3 and the substrate 2 (thermal curing process). In general, in order to completely cure the thermosetting resins, it is necessary to heat the thermosetting resins at a temperature which is higher than the curing temperature for a predetermined time. However, it is not necessary to completely cure the thermosetting resins in the thermal curing process of the present embodiment, and the thermosetting resins may be in a semi-cured state obtained when the heating time is shortened.
Subsequently, a primary heating process is performed. That is, the melted bump joining portions 4 are formed by raising the temperature up to the temperature higher than the melting temperature of the solder by further heating the substrate 2 and melting solder compositions contained in the bumps 4* and the solder pastes 6 as shown in
The operation and function of the outer edge bonding portions 5a and the bump bonding portions 5b in the aforementioned thermal curing process will be described. As described above, both the substrate 2 and the electronic component 3 used in the electronic component mounting structure 1 are thin and have low stiffness, and also have characteristics that bending is easily caused therein due to thermal deformation. For this reason, in the heating process after the component is mounted, warp deformation occurs in the substrate 2 and the body part 3a of the electronic component 3, and defects arising from this warp deformation frequently occur. Even when the substrate 2 and the electronic component 3 which are thin and have low stiffness are used, the thermosetting resins 5a* and 5b* are thermally cured through the pre-heating before the solder joining is performed on the bumps 4* in the primary heating process in the present embodiment. Thus, it is possible to effectively prevent the warp deformation due to the effect of maintaining the fixation of the body part 3a to the substrate 2 through the outer edge bonding portions 5a and the bump bonding portions 5b.
In the above examples, as an arrangement example of the outer edge bonding portions 5a and the bump bonding portions 5b, it has been described that the outer edge bonding portions 5a are set to the two facing diagonal positions in the body part 3a and the bump bonding portions 5b are set to the plurality of positions surrounding the bumps 4* positioned in the center in the bump-forming region R1 as shown in
For example, in the example shown in
Although it has been described in the above embodiment that the bump joining portions 4 are formed by joining the bumps 4* formed through the soldering to the electrodes 2b through the solder pastes 6, the material of the bumps 4* is not limited to the solder, and may be metal such as gold (Au) having a higher melting point than that of the solder or may be solder metal having a higher melting point than that of the solder in the solder paste 6. When the bump joining portions 4 are joined through the soldering, the solder included in the solder pastes 6 that have been previously supplied to the electrodes 2b contribute to the joining thereof. However, when the material of the bumps 4* is solder, the solder in the bumps 4* contributes to the joining thereof.
It has been described in the above embodiment that the bump bonding portions 5b are arranged in the bump-forming region R1 and the outer edge bonding portions 5a are arranged in the diagonal positions of the outer-edge region R2, as the bonding portions for bonding the electronic component 3 to the substrate 2. However, the arrangement positions of the bonding portions having such functions are not limited those in the above example, and may be arbitrarily set depending on the shapes and sizes of the electronic component 3 and the substrate 2 which are targets.
Thereafter, the substrate 2 on which the electronic component 3 has been mounted is sent through the heating process, and is heated according to the heating profile shown in
As described above, in the present embodiment, when the electronic component mounting structure is manufactured by joining the plurality of bumps formed on the electronic component to the plurality of electrodes formed on the substrate by way of the joining portions formed with the bumps and solder, the bonding portions for bonding the electronic component to the substrate are formed in the plurality of preset positions by using the thermosetting materials obtained by thermally curing the thermosetting resins having a curing temperature which is lower than the melting point of the solder between the electronic component and the substrate, and the thermosetting materials come in contact with the nearest-neighboring joining portions in the bonding portions. Thus, it is possible to stably maintain the bonding of the electronic component to the substrate by using the bonding portions, and even when the electronic component and the substrate which are thin and have low stiffness are used, it is possible to reduce the defects arising from the warp deformation.
As described above, in the present embodiment, when the electronic component mounting structure is manufactured by joining the plurality of bumps formed on the electronic component to the plurality of electrodes formed on the substrate by way of the joining portions formed with the bumps and solder, the bonding portions for bonding the electronic component to the substrate are formed of the thermosetting materials obtained by thermally curing the thermosetting resins having a curing temperature which is lower than the melting point of the solder between the electronic component and the substrate, and the thermosetting materials come in contact with the nearest-neighboring joining portions in the bonding portions. Accordingly, it is possible to stably maintain the bonding of the electronic component to the substrate through the bonding portions, and even when the electronic component and the substrate which are thin and have low stiffness are used, it is possible to reduce the defects arising from the warp deformation.
The electronic component mounting structure and the method of manufacturing the electronic component mounting structure according to the embodiments of the present invention may exhibit an advantage capable of reducing the defects arising from the warp deformation even when the electronic component and the substrate which are thin and have low stiffness are used, and are useful in the manufacturing field of a semiconductor device on which semiconductor elements are mounted on a thin substrate.
Number | Date | Country | Kind |
---|---|---|---|
2014-128751 | Jun 2014 | JP | national |
2014-128752 | Jun 2014 | JP | national |