JP6037300B2 - Circuit member joint structure - Google Patents

Description

  The present invention relates to a circuit member bonding structure. More specifically, the present invention relates to a circuit member bonding structure in which electrodes of a substrate and electrodes of an electronic component, electrodes of a substrate, electrodes of an electronic component, and the like are bonded to each other.

  For example, there are two general methods of soldering when mounting electronic components on a printed circuit board. One is a flow method in which the solder is melted in advance and then adhered to one of the electrodes, and the other is a reflow method in which the solder is heated between the electrodes and then melted by heating. is there. With the progress of miniaturization and high-density mounting of electronic components, the reflow method is now mainstream and is being improved.

  As one of the joining methods by the reflow method, particulate solder is mixed with an adhesive made of a thermosetting resin and the mixture is mixed between each electrode to be joined and between the printed circuit board and the electronic component body. Research and practical application of a method for supplying the water to the liquid is progressing (see Patent Documents 1 and 2). According to this method, it is possible to simultaneously bond the electrodes and bond the printed circuit board and the electronic component body, thereby improving the production efficiency.

  In the reflow method of mounting electronic components on a substrate, solder having a low melting point is often used in order to reduce thermal damage to the electronic components.

  In addition, it is generally performed that an electronic component module obtained by mounting one or a plurality of electronic components on a relatively small substrate to be modularized is further mounted on another substrate such as a mother board. In this case, a multi-step soldering process is executed, and the second and subsequent soldering processes are often executed by the reflow method.

JP 2008-69316 A JP 2008-69317 A

  However, when the second and subsequent soldering steps are executed by the reflow method, the solder joints formed in the previous soldering steps are also heated together. For this reason, the reheated solder joint may be melted and connection reliability may be lowered, or the molten solder may come into contact with adjacent electrodes or wirings, resulting in a short circuit.

  For this reason, it can be said that it is preferable to prevent remelting by using a high melting point solder at least for the solder joint portion where reheating is scheduled. However, when such a high-melting-point solder is used, it is necessary to heat an electronic component or the like at a higher temperature for a longer time during soldering. As a result, it is conceivable that large heat damage occurs in the electronic component or the substrate. Furthermore, since the electric power required for soldering also increases, the amount of electric power required for manufacturing electronic devices and the like is increased.

  Therefore, the present invention provides a circuit member joint structure that can suppress the heating temperature when soldering each electrode and can suppress remelting when the solder joint is heated later. The purpose is to do.

One aspect of the present invention includes a first circuit member having a first connection electrode, a second circuit member having a second connection electrode corresponding to the first connection electrode, the first connection electrode, A solder joint that is interposed between the second connection electrode and electrically connects the first connection electrode and the second connection electrode, wherein the solder joint is a metal A first metal region containing a first metal element as a main component, and a second metal region containing as a main component a second metal element having a melting point higher than that of the first metal element. The first metal region joins the first connection electrode and the second connection electrode outside the solder joint portion, and the second metal region is the center side of the solder joint portion. bonding the said the first connection electrode second connection electrode, wherein the first metal element said two metal It is capable of forming an element alloy, and melting point of the alloy, rather lower than the melting point of the melting point and the second metal region of the first metal region, wherein the first metal region and said second metal region, either The present invention also relates to a circuit member bonded structure, which is a region generated by segregation of constituent elements of the alloy .

The circuit member bonded structure includes (i) a first circuit member having a first electrode, a second circuit member having a second electrode corresponding to the first electrode, and a paste containing a thermosetting resin. A process wherein at least one of the first electrode, the second electrode, and the paste comprises solder,
(Ii) supplying the paste to at least one of the first electrode and the second electrode;
(Iii) placing the first circuit member and the second circuit member in proximity so that the first electrode lands on the second electrode via the paste;
(Iv) In a state where the first electrode is landed on the second electrode, a bonding region including at least the first electrode, the second electrode, and the paste is formed at a temperature equal to or higher than the melting point of the solder. Heating while pressing the second electrode to melt the solder and curing the thermosetting resin,
(V) The bonding region can be manufactured by applying an electrode bonding method including a step of gradually cooling the bonding region from a temperature equal to or higher than the melting point of the solder.

The circuit member bonded structure includes a first circuit member having a first electrode and a second circuit member having a second electrode corresponding to the first electrode, between the first electrode and the second electrode. A paste including a thermosetting resin is bonded to the first electrode, the second electrode, and at least one of the paste is a circuit member bonding line including solder,
A paste supply device for supplying the paste to at least one of the first electrode and the second electrode;
The first circuit member and the second circuit member are disposed close to each other so that the first electrode lands on the second electrode via the paste, and is disposed downstream of the paste supply device. In a state where one electrode is landed on the second electrode, at least the joining region including the first electrode, the second electrode, and the paste is heated at a temperature equal to or higher than the melting point of the solder, and then gradually cooled. And a mounting unit that cures the thermosetting resin and joins the first electrode and the second electrode to each other.

  According to the present invention, a solder joint part that joins the first electrode and the second electrode is formed by slowly cooling the joint region containing the molten solder. At this time, by setting the slow cooling conditions appropriately according to the composition of the solder to be used, it becomes possible to form a solder joint having a higher melting point while suppressing a decrease in strength. Therefore, even if each electrode is joined using a relatively low melting point solder, a high melting point solder joint is formed. As a result, the heating temperature when soldering each electrode can be suppressed, and remelting when the solder joint is heated later can be suppressed.

It is a block diagram which shows schematic structure of the circuit member joining line which concerns on one Embodiment of this invention. It is a top view which shows schematic structure of an adhesive agent coating unit. It is a top view which shows schematic structure of a mounting unit. It is the partial cross section figure which looked at the electronic component and the board | substrate from the side, Comprising: Application | coating of an adhesive agent is complete | finished by the circuit member joining process, and is a figure which shows the state by which each electrode was positioned. It is a partial sectional view which looked at an electronic component and a substrate from the side, and is a figure showing the state where electrodes were contacted by circuit member joining processing. FIG. 3 is a partial cross-sectional view of an electronic component and a substrate as viewed from the side, and shows a state where the adhesive is cured and the solder is melted in the circuit member joining process. FIG. 3 is a partial cross-sectional view of an electronic component and a substrate as viewed from the side, and is a view showing a state in which molten solder is solidified by a circuit member joining process. FIG. 10 is a partial cross-sectional view of an electronic component and a substrate as viewed from the side, and shows a state where each electrode is positioned after application of an adhesive is completed in another circuit member bonding process. It is the partial cross section figure which looked at the electronic component and the board | substrate from the side, Comprising: It is a figure which shows the state by which the electrodes were connected through the solder by another circuit member joining process. It is the partial cross section figure which looked at an electronic component and a board | substrate from the side, Comprising: It is a figure which shows the state which the adhesive agent hardened | cured by other circuit member joining processing, and the solder fuse | melted. FIG. 5 is a partial cross-sectional view of an electronic component and a substrate as viewed from the side, and shows a state in which molten solder is solidified by another circuit member joining process. It is a block diagram which shows schematic structure of the circuit member joining line which concerns on other embodiment of this invention. It is a block diagram which shows schematic structure of the circuit member joining line which concerns on further another embodiment of this invention. It is a top view of a press stand which shows the state in which the some board | substrate was mounted in the press stand. It is the partial sectional view which looked at a plurality of electronic parts and a board from the side, and is a figure showing the state where application of adhesives was completed by other circuit member joining processing, and each electrode was positioned.

  The electrode joining method according to the present invention relates to an electrode joining method for joining a first electrode of a first circuit member and a second electrode of a second circuit member by soldering. More specifically, in this joining method, (i) a first circuit member having a first electrode, a second circuit member having a second electrode corresponding to the first electrode, and a paste containing a thermosetting resin And are prepared. Here, the solder used for joining may be included in the first electrode, may be included in the second electrode, or may be included in the paste.

  The bonding method further includes (ii) supplying the paste to at least one of the first electrode and the second electrode, and (iii) so that the first electrode lands on the second electrode via the paste. A step of arranging the first circuit member and the second circuit member close to each other, (iv) in a state where the first electrode is landed on the second electrode, a bonding region including at least the first electrode, the second electrode and the paste is soldered Heating the first electrode against the second electrode at a temperature equal to or higher than the melting point of the solder to melt the solder and curing the thermosetting resin, and (v) the bonding area of the solder melting point A step of slow cooling from the above temperature.

  As described above, in this bonding method, the solder is melted by heating the bonding region to a temperature equal to or higher than the melting point of the solder. Thereafter, by cooling the joining region, the molten solder is solidified and a solder joint is formed. At this time, by gradually cooling the joining region, it becomes possible to form a solder joint having a higher melting point than in a normal case where the joining region is not gradually cooled.

  As a result, even when a solder having a relatively low melting point is used, a solder joint having a higher melting point than usual can be formed, so that it is not necessary to use a solder having a particularly high melting point. As a result, the heating temperature of the first circuit member and the second circuit member when soldering by the reflow method can be lowered. Therefore, it is possible to prevent each circuit member from being greatly damaged by heat.

  Solder can be included in either the first electrode or the second electrode as a so-called solder bump or solder cap. Alternatively, the solder can be included in either the first electrode or the second electrode by applying a so-called cream solder containing solder fine particles to the first electrode or the second electrode. Furthermore, for example, solder can be supplied between electrodes by including solder in a paste containing a thermosetting resin for sealing a solder joint.

  The reason why a high melting point solder joint can be formed by slowly cooling the joint region containing the molten solder is not necessarily clear. However, since the cooling rate of the molten solder is related to segregation, the above reason can be estimated as follows.

  In general, it is known that when a solder joint is formed by melting after melting the solder, an alloy contained in the solder is segregated at the joint. It is believed that when the segregation of the solder joint becomes significant, the strength of the solder joint decreases. For this reason, in order to suppress segregation, generally, an operation for cooling the joining region in as short a time as possible using a cooling device such as a cooling fan is performed.

  On the other hand, the inventors of the present invention do not pose a significant problem in strength reduction of the solder joint even when the alloy is segregated by gradually cooling the joint region, and a solder having a higher melting point than in a normal case. It has been found that joints can be formed. The reason for this is that if the segregation occurring in the solder joints is of an appropriate degree, the adverse effects (decrease in strength) due to segregation can be suppressed, and the composition of each region of the solder joints is different from the normal case. It is considered that a solder joint having a higher melting point could be formed. In this method, since the joining of the first electrode and the second electrode by the solder joint is reinforced by the cured resin, the strength reduction of the solder joint itself is a big problem as in other cases. Must not.

  Here, if the solder includes a first metal element having a first melting point and a second metal element having a second melting point higher than the first melting point, the temperature of the bonding region is set to It is preferable that the bonding region is gradually cooled so as to remain in a temperature range TR of not less than a melting point and not more than a predetermined temperature lower than the second melting point for 3 to 60 seconds. Thereby, it is possible to increase the melting point of the solder joint more reliably while suppressing the strength reduction of the solder joint. The above time range is more preferably 4.5 to 40 seconds, and further preferably 6 to 20 seconds. The temperature range TR is more preferably a temperature range TR that is not lower than a melting point of the solder and not higher than a predetermined temperature lower than the first melting point.

  On the other hand, the cooling rate of the joining region in the above-described slow cooling step is more preferably 0.1 to 10 ° C./second from the viewpoint of increasing the melting point while suppressing the strength reduction of the solder joint. The cooling rate of the joining region is more preferably 0.5 to 7 ° C./second, and further preferably 1 to 4 ° C./second. It should be noted that the above-described conditions relating to the cooling rate need only be satisfied for at least the average cooling rate in the temperature range TR. That is, in the temperature range TR, the cooling rate may instantaneously deviate from the above range. Further, for example, in a temperature range higher than the above temperature range TR, the average cooling rate or the instantaneous cooling rate may exceed an upper limit (for example, 10 ° C./second), or may be higher than the above temperature range TR. In the low temperature region, the average cooling rate or the instantaneous cooling rate may be lower than the lower limit (for example, 0.1 ° C./second).

  Here, a solder in which the first metal element is Sn and the second metal element is Bi (hereinafter referred to as Sn-Bi solder) is particularly preferable because a low melting point can be easily obtained. At this time, by setting the temperature range TR to 138 to 200 ° C., it is possible to more reliably realize a solder joint having a higher melting point than usual and suppressing a decrease in strength. Note that a general Sn—Bi solder has a melting point of 138 ° C., Sn has a melting point of 232 ° C., and Bi has a melting point of 271 ° C. Therefore, when Sn and Bi are segregated, the heat resistance of the solder joint is improved.

  When the solder is included in the thermosetting resin paste, the content of the solder is preferably 4 to 30% by mass. Although a thermosetting resin is not specifically limited, An epoxy resin, a phenol resin, a melamine resin, a urethane resin etc. can be used. The thermosetting resin may contain a curing agent, a curing accelerator, and the like. As the curing agent, an acid anhydride, an aliphatic or aromatic amine, imidazole or a derivative thereof is preferably used, and examples of the curing accelerator include dicyandiamide. The thermosetting resin may further contain a filler such as a reactive diluent, carbon black, and inorganic ceramic particles. You may control the viscosity of a thermosetting resin by changing content of a reactive diluent or an inorganic ceramic particle, for example. Components such as an activator included in the flux may be included in the thermosetting resin. Thereby, even when the thermosetting resin penetrates between the electrodes of the circuit member, the wettability between the molten solder and the electrodes is more reliably ensured.

  Here, in the electrode joining method according to the present invention, for example, when mounting a plurality of first circuit members on at least one second circuit member, one mounting of the plurality of first circuit members including slow cooling is performed. Each form can be completed. In this case, the flow (X) including the step (iii), the step (iv), and the step (v) is performed by sequentially bringing a plurality of first circuit members close to at least one second circuit member. It arrange | positions and it can carry out by the process of heating and pressing down a joining area | region for every 1st circuit member.

  In addition, in the electrode joining method according to the present invention, for example, when mounting a plurality of first circuit members on at least one second circuit member, a plurality of first circuit members are attached to at least one second circuit member. Temporary mounting can be performed sequentially, and the solder joints formed thereby can be reheated and gradually cooled. In this case, the flow (Y) including the step (iii) and the step (iv) includes a plurality of first circuit members arranged sequentially in proximity to at least one second circuit member. It is the process of heating while pressing the joining area for each circuit member. After this heating, the bonding region may be quenched. On the other hand, the step (v) may be performed by a step of reheating and gradually cooling the plurality of joining regions corresponding to the plurality of first circuit members after the flow (Y) until the solder is melted at the same time. it can. Thereby, since the mounting time per one 1st circuit member is shortened, the improvement of production efficiency can be aimed at.

  Furthermore, in the electrode joining method according to the present invention, for example, when a plurality of first circuit members are mounted on at least one second circuit member, all the first circuit members are mounted at once, including annealing. And can be implemented. In this case, in the step (iii), a plurality of first circuit members are sequentially arranged in proximity to at least one second circuit member, and a bonding region corresponding to all of the plurality of first circuit members. Is a step of forming. On the other hand, the flow (Z) including the step (iv) and the step (v) is a step of heating and gradually cooling the bonding regions corresponding to all of the plurality of first circuit members while pressing them simultaneously. As a result, the production efficiency can be further improved. In addition, after repeating said process (iii) with respect to each of several 2nd circuit members, said flow (Z) can be performed collectively with respect to all the 2nd circuit members. . As a result, the mounting of the first circuit member on the plurality of second circuit members can be performed simultaneously in a lump, and the production efficiency can be greatly improved.

  As an example, the first circuit member may be a semiconductor bare chip. At this time, the second circuit member may be an interposer substrate. As another example, both the first circuit member and the second circuit member may be semiconductor bare chips. As yet another example, the first circuit member may be an electronic component module. At this time, the second circuit member may be a mother board. As yet another example, the first circuit member may be a BGA (Ball Grid Array) package. At this time, the second circuit member may be a mother board.

  On the other hand, the circuit member joining line according to the present invention comprises a first circuit member having a first electrode, a second circuit member having a second electrode corresponding to the first electrode, a first electrode and a second electrode. The present invention relates to a circuit member joining line for joining with a paste containing a thermosetting resin interposed therebetween. As described above, the solder is contained in at least one of the first electrode, the second electrode, and the paste. The circuit member joining line includes a paste supply device and a mounting unit.

  The paste supply device supplies paste to at least one of the first electrode and the second electrode. The mounting unit is disposed downstream of the paste supply device, and the first circuit member and the second circuit member are disposed close to each other so that the first electrode lands on the second electrode via the paste, and the first electrode is In a state where it is landed on the second electrode, at least the first electrode, the second electrode, and the bonding region including the paste are heated at a temperature equal to or higher than the melting point of the solder, and then gradually cooled to cure the thermosetting resin. At the same time, the first electrode and the second electrode are joined.

  In the circuit member joining line according to the present invention, the mounting unit sequentially arranges a plurality of first circuit members with respect to at least one second circuit member, and presses the joining region for each first circuit member. While being heated and gradually cooled, the circuit member mounting-joining device may be included. At this time, two or more first circuit members among the plurality of first circuit members can be disposed close to the second circuit member at a time. And after heating them, pressing them toward the second circuit member at the same time, they are gradually cooled together. In other words, in this embodiment, one or two or more first circuit members among the plurality of first circuit members are arranged close to the second circuit member, and each time a process of pressurization / heating and slow cooling is performed. Done.

  In the circuit member joining line according to the present invention, the mounting unit sequentially arranges a plurality of first circuit members with respect to at least one second circuit member, and presses the joining region for each first circuit member. Circuit member mounting-joining device to be heated while being placed downstream of the circuit member mounting-joining device, and rejoining the joint region corresponding to all of the plurality of first circuit members at the same time until the solder melts, And a heating device that gradually cools. In this case, the circuit member mounting-joining apparatus can include means (for example, a cooling fan) for rapidly cooling the joining region after the joining region is heated to melt the solder. In the circuit member mounting-joining device, two or more first circuit members among the plurality of first circuit members may be disposed close to the second circuit member at a time.

  In the circuit member joining line according to the present invention, the mounting unit sequentially arranges the plurality of first circuit members adjacent to at least one second circuit member, and corresponds to all of the plurality of first circuit members. A circuit member mounting device that forms a bonding region, and a heating-bonding that is arranged downstream of the circuit member mounting device and that simultaneously heats and gradually cools the bonding region corresponding to all of the plurality of first circuit members. And a device. In the circuit member mounting apparatus, two or more first circuit members among the plurality of first circuit members may be disposed close to the second circuit member at a time.

  The circuit member joining line according to the present invention includes a first circuit member holding unit that holds the first circuit member and a second circuit member holding unit that holds the second circuit member when the mounting unit gradually cools the joining region. Can take the form of At this time, it is preferable that at least one of the first circuit member holding unit and the second circuit member holding unit contains ceramic. The ceramic is in surface contact with the first circuit member and / or the second circuit member so as to separate the first circuit member and / or the second circuit member from the good heat conductor (for example, metal). preferable. Thereby, the heat retention of the first circuit member and / or the second circuit member is facilitated, and it is easy to gradually cool the joining region under appropriate conditions.

  For the reason described above, when the solder includes the first metal element having the first melting point and the second metal element having the second melting point higher than the first melting point, the mounting unit has the temperature of the joining region. It is preferable that the bonding region is gradually cooled so as to remain in the temperature range TR not lower than a predetermined temperature and not higher than the second melting point for 3 to 60 seconds. As described above, the cooling rate when the mounting unit gradually cools the bonding region is preferably 0.1 to 10 ° C./second. The temperature range TR is preferably 138 to 200 ° C. when Sn—Bi solder is used. However, this temperature range TR may be appropriately set according to the composition of the solder.

  According to the electrode joining method or the circuit member joining line according to the present invention, a first circuit member having a first connection electrode, a second circuit member having a second connection electrode corresponding to the first connection electrode, In a circuit member bonding structure including a first connection electrode and a solder joint that electrically connects the second connection electrode, the first metal element is mainly contained in the metal portion included in the solder joint. A first metal region containing the component and a second metal region containing the second metal element as the main component can be generated. Here, the first metal element can form an alloy (solder) with the bimetallic element, and the melting point of the alloy is lower than the melting point of the first metal region and the melting point of the second metal region. The first metal region can include a second metal element, but is less than the content of the second metal element in the second metal region, and the second metal region can include the first metal element, but the first metal region Less than the content of the first metal element. Therefore, the melting point of the first metal region is different from the melting point of the second metal region.

  The metal portion of the solder joint may, of course, include a solder alloy region having a lower melting point than the first metal region and the second metal region. However, in order to sufficiently obtain the effect of improving the heat resistance of the solder joint by the higher melting point first metal region and second metal region, the total ratio of the first metal region and the second metal region in the metal part Is preferably 80% by mass or more, more preferably 90% by mass or more and 98% by mass or less.

  The first metal region and the second metal region are both regions generated by segregation of the constituent elements of the solder alloy, and each may be a region composed of only the first metal element or the second metal element, Each of the regions may contain a metal element other than the first metal element or the second metal element. However, in order for the first metal region to have a high melting point, for example, in the case of Sn-Bi solder, it is preferable to contain 47 mass% or more of the first metal element, and the second metal region has a high melting point. It is preferable that 63 mass% or more of 2nd metal elements are included. At least one of the first metal region and the second metal region may be an alloy of the first metal element and the second metal element or an intermetallic compound.

  The maximum diameter of the region (segregation phase) generated by segregation may be, for example, 5 μm or more, and it is preferable to grow the maximum diameter to 10 μm or more. However, from the viewpoint of ensuring the strength of the solder joint, the maximum diameter of the segregation phase is preferably 50 μm or less.

  As described above, the melting point of the solder used for mounting the circuit member is desirably low, for example, 150 ° C. or less, from the viewpoint of reducing the thermal shock applied to the circuit member. In this case, the temperature at which the circuit member bonded structure is reheated (reflow) is assumed to be around 200 ° C. Therefore, the melting point of the first metal region and the melting point of the second metal region must be over 220 ° C., respectively. For example, the effect of solder segregation is considered to be increased.

  When Sn is selected as the first metal element, Bi, Ag, Cu, Sb, In, Zn, Ni, Al, etc. can be selected as the second metal element, or any combination of a plurality of types can be selected. . For example, when the first metal element includes at least Sn and the second metal element includes at least Bi, the first metal region and the second metal region each having a melting point higher than 220 ° C. may be generated. it can.

  Specific examples of solder include Sn—Bi alloy, Sn—Ag—Cu alloy, Sn—Bi—Ag alloy, Sn—Cu alloy, Sn—Sb alloy, Sn—Ag alloy, Sn—Ag—Cu—Bi alloy, Sn-Ag-Bi-In alloy, Sn-Ag-Cu-Sb alloy, Sn-Zn alloy, Sn-Zn-Bi alloy and the like can be mentioned, but are not particularly limited. Other than the solder using Sn as a base material, for example, gold solder may be used.

  The solder joint may further include a resin portion that seals the metal portion. The resin portion is a region generated from a paste containing a thermosetting resin. Therefore, the resin portion is generally obtained as a cured product of a thermosetting resin. The resin portion not only seals the metal portion but also has a role of reinforcing the adhesive strength between the circuit members.

In the solder joint portion, the ratio of the resin portion in the total of the metal portion and the resin portion may be, for example, 60 to 98% by mass from the viewpoint of sufficiently obtaining the above-described sealing and adhesion strength improving effects.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
In FIG. 1, the circuit member joining line which concerns on one Embodiment of this invention is shown with the simplified block diagram. FIG. 2 is a top view showing a schematic configuration of the adhesive application unit. FIG. 3 is a top view showing a schematic configuration of the mounting unit.

  A circuit member joining line (hereinafter simply referred to as a line) 1 in the illustrated example is a line for mounting a plurality of electronic components 14 (for example, semiconductor bare chips) on a substrate 12 (for example, an interposer substrate). In addition, the circuit member joining line of this invention may be a line for joining the electrodes of electronic components (for example, semiconductor bare chips). Or the circuit member joining line of this invention may be a line for joining the electrode of board | substrates, for example, the electrode of an electronic component module or a BGA package, and the electrode of another board | substrate (for example, motherboard). This also applies to the embodiments described later.

  More specifically, the line 1 in the illustrated example includes an input unit 2, a cleaner 3, an adhesive application unit 4, a mounting unit (bonder) 5, and a recovery unit 6. Further, the line 1 includes a conveyor 7 for transporting the substrate 12 from the charging unit 2 to the recovery unit 6 through the cleaner 3, the adhesive application unit 4, and the mounting unit 5.

  A stage 7 a that holds the substrate 12 is attached to the conveyor 7. The conveyor 7 conveys the substrate 12 by moving the stage 7 a holding the substrate 12. The cleaning process in the cleaner 3, the adhesive application process in the adhesive application unit 4, the mounting process in the mounting unit 5, etc. may be performed using the stage 7 a as it is, It may be transferred to a dedicated stage of the process and executed.

  The stage 7a or the dedicated stage in the mounting process preferably includes ceramic. At this time, it is preferable that the surface on which the substrate 12 such as the stage 7a is placed (the upper surface of the stage 7a or the like) is formed of ceramic. Thereby, when the ceramic is in surface contact with the substrate 12, it is possible to separate the substrate 12 from the good thermal conductor and to prevent the substrate 12 from being rapidly cooled. Therefore, in the slow cooling step described later, it is easy to keep the solder joint region including the molten solder, and it is easy to cool the solder joint region under appropriate conditions.

  The input unit 2 includes a known vacuum loader or the like for placing the substrate 12 supplied in a state stored in a magazine rack or the like on the stage 7a. On the other hand, the collection unit 6 includes an unloader for storing the substrate 12 on which the electronic component 14 is mounted in a rack or the like.

  When the electrode of the substrate 12 contains, for example, Cu, the cleaner 3 performs plasma processing so as to remove an oxide film or the like on the electrode surface. More specifically, the cleaner 3 includes a plasma processing head (not shown) that generates, for example, atmospheric-pressure plasma, and irradiates the electrode with the atmospheric pressure plasma generated thereby. Remove the oxide film from the surface. As a result, even when the substrate electrode is a relatively inexpensive Cu electrode, the reliability of bonding between the electrodes can be maintained at a level close to the bonding between the Au electrodes. Therefore, a high quality electrode junction structure can be realized at low cost.

  As shown in FIG. 2, the adhesive application unit 4 includes an application head (dispenser) 16 for applying and supplying an adhesive containing a thermosetting resin to the substrate 12, and a triaxial moving mechanism (not shown). . The operations of the coating head 16 and the triaxial moving mechanism are controlled by the control unit 4a.

  The three-axis moving mechanism of the adhesive application unit 4 controls the application head 16 to move in the X-axis direction (direction along the line 1), Y-axis direction (direction perpendicular to the line 1), and Z-axis by positioning control of the control unit 4a. Move in three axial directions (up and down direction). The coating head 16 applies a predetermined amount of adhesive to each electronic component mounting position MP on the substrate 12 on which the electronic component is mounted in a later process, under the control of the control unit 4a. Thereby, the adhesive is supplied to the electrode of the substrate 12.

  The coating head 16 can be included in the mounting unit 5 described below. As a result, the electronic component 14 can be mounted on the board 12 at the same position immediately after the adhesive is supplied onto the board 12 in the mounting unit 5. Therefore, the production efficiency can be improved.

  In the mounting unit 5, there are an electrode joining process for joining the electrode of the substrate 12 and the electrode of the electronic component 14 by soldering, and a component adhesion process for adhering the electronic component 14 to the substrate 12 while sealing the solder joint. Run in parallel.

  More specifically, as shown in FIG. 3, the mounting unit 5 includes a component supply stage 18 on which a plurality of electronic components 14 are mounted, and a mounting so as to supply the electronic components 14 mounted on the substrate 12. A head 20, a three-axis movement mechanism (not shown), and a control unit 5a are provided. The mounting head 20 has holding means such as a suction nozzle for holding the electronic component 14. The operations of the mounting head 20 and the triaxial moving mechanism are controlled by the control unit 5a.

  The three-axis moving mechanism of the mounting unit 5 moves the mounting head 20 in the three-axis directions of the X-axis direction, the Y-axis direction, and the Z-axis direction by positioning control of the control unit 5a. The mounting head 20 picks up the electronic component 14 on the component supply stage 18 under the control of the control unit 5a. In this state, the mounting head 20 is moved above the electronic component mounting position MP corresponding to the electronic component 14 by the three-axis moving mechanism, so that each electrode of the electronic component 14 is corresponding to each corresponding substrate electrode. Opposed.

  In this state, the electronic component 14 is pressed toward the substrate 12 by the operation of the three-axis moving mechanism and / or the electronic component lifting / lowering operation of the mounting head 20 itself. At this time, the adhesive has already been applied by the adhesive application unit 4 to the corresponding electronic component mounting position MP. Hereinafter, the operation of the mounting unit 5 will be described with respect to the solder supply mode.

(When the electrodes of electronic parts contain solder)
As shown in FIG. 4A, the solder 22 can be included in the electrode 14a by forming a solder cap at the tip of the electrode 14a or forming the electrode 14a as a so-called solder bump. However, the solder cap is a solder layer (for example, Sn) provided on the electrode base when, for example, a columnar electrode base (for example, a Cu base) is provided in an electrode forming portion of an electronic component or the like. -10Ag or Sn-3.5Ag solder layer).

  The mounting head 20 includes a pressurizing actuator (not shown) (for example, a hydraulic cylinder or an air cylinder) and heating means (for example, a heater or an induction heating device). Alternatively, the triaxial moving mechanism itself that moves the mounting head 20 may include the above-described pressurizing actuator.

  As shown in FIG. 4A, the substrate 12 held by the stage 7a (or a dedicated stage) is positioned so that each electrode 12a and each corresponding electrode 14a face each other. While pressing the electronic component 14 against the substrate 12 by the pressure actuator, the solder 22 and the adhesive 24 are heated via the electronic component 14 by the heating means. In addition, you may assist the heating of the solder 22 and the adhesive agent 24 by including a heating means in the stage 7a (or a dedicated stage). FIG. 4B shows a state in which the solder 22 is pressed against the electrode 12a and heated.

  As the heating of the solder 22 and the adhesive 24 proceeds, as shown in FIG. 4C, the solder 22 is melted, and the molten solder 22a wets and spreads on the electrodes 14a and 12a. When the heating further proceeds, the adhesive 24 is cured, and the joint between the electronic component 14 and the substrate 12 is sealed by the cured resin 24a.

  Here, the composition of the solder 22 is not particularly limited. However, from the viewpoint of enabling soldering at a low temperature and reducing thermal damage to the electronic component 14 and the like, it is preferable to use a solder having a melting point as low as possible. For example, it is preferable to use Sn—Bi based solder (for example, Sn—Bi58 solder, Sn-57Bi-1Ag solder) containing an alloy of Sn (melting point: 232 ° C.) and Bi (melting point: 271 ° C.). In addition, Sn—Zn solder is also preferable in that it has a relatively low melting point.

  Thereafter, the mounting unit 5 starts to gradually cool the joining region including the molten solder 22a. Thereby, as shown to FIG. 4D, the molten solder 22a solidifies and the solder joint part 26 is formed. At this time, when the joining region is gradually cooled under an appropriate condition according to the composition of the solder 22, the solder joint portion 26 having two regions AR1 and AR2 is formed.

  At this time, the region AR1 on the center side of the solder joint portion 26 contains, for example, Sn, which is a Sn-Bi solder, contains a large amount of Bi, which is an element having a higher melting point than the original solder 22, due to segregation. It will be. On the other hand, the area AR2 outside the solder joint portion 26 contains a large amount of Sn, which is an element having a lower melting point than the original solder 22, due to segregation, for example, in the case of Sn-Bi solder. become.

  In the above example, since Bi is a highly brittle metal, if the amount of Bi in the area AR1 is too large, the strength of the entire solder joint 26 may be reduced. However, it is possible to appropriately adjust the degree of segregation by setting the conditions for slowly cooling the joining region, and the strength reduction of the solder joint portion 26 can be suppressed. Moreover, even if the strength of the solder joint portion 26 is reduced, the reduced amount can be compensated for by the joining force of the cured resin.

  On the other hand, since the regions AR1 and AR2 contain Bi having a concentration different from the concentration of the original solder 22, each region has a higher melting point than a normal solder joint formed when the joint region is not gradually cooled. It becomes. Thereby, for example, it is possible to form the solder joint portion 26 having a high melting point of 232 ° C. or higher and 271 ° C. or lower and sufficient strength.

  As a result of the above, for example, even when an electronic component module manufactured by mounting the electronic component 14 on the substrate 12 is remounted on another substrate or the like by the reflow method, the reliability of the solder joint portion 26 is reduced. Can be prevented.

(When the electrode on the board contains solder)
Even when the electrode 12a of the substrate 12 includes solder, the solder joint portion 26 may be formed between the electrode 12a and the electrode 14a in the same process as when the electrode 14a of the electronic component 14 includes solder. it can. As a result, as in the above case, the solder joint portion 26 having a higher melting point than that of a normal solder joint portion can be formed. In addition, when the solder 12 is included in the electrode 12a by applying cream solder to the electrode 12a, a screen printing device or the like can be added to the line 1.

(When the adhesive contains solder)
As shown in FIG. 5A, the solder 22 can be supplied to the electrode 12a and the electrode 14a by including solder in the adhesive 24 as solder particles 22b and using the paste as a paste. The melting point of such solder particles 22b is, for example, 138 ° C. in the case of the Sn—Bi solder described above. Content of the solder particle 22b contained in the said paste can be 4-30 mass%, for example. The average particle size of the solder particles is, for example, 2 to 10 μm, but is not particularly limited.

  Then, by pressing the electronic component 14 toward the substrate 12 by the same pressing and heating processes as described above, the solder particles 22b are sandwiched between the electrodes 12a and 14a as shown in FIG. 5B. And heated. When the solder particles 22b are melted by heating, the molten solder 22a wets and spreads on the electrodes 12a and 14a as shown in FIG. 5C. When the heating further proceeds, the adhesive 24 is cured, and the electronic component 14 is bonded to the substrate 12 by the cured resin 24a. Note that the adhesive 24 can contain an activator having an action of removing the oxide film of solder or electrodes.

  Thereafter, the slow cooling of the molten solder 22a is started, whereby the solder joint portion 26 having the area AR1 and the area AR2 is formed in the same process as described above. Thereby, it becomes possible to form the solder joint portion 26 having sufficient strength and a higher melting point than usual.

  Thus, in the form in which the solder particles 22b are included in the adhesive 24, there is no need to add a special mechanism (for example, a screen printing apparatus) for supplying low melting point solder such as cream solder to the line 1. Thereby, the line 1 can be constructed at a lower cost. Moreover, since the application | coating processes, such as cream solder, can be skipped, it becomes easy to improve production efficiency further.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 6 is a block diagram showing a schematic configuration of a circuit member joining line according to the present embodiment.

  The line 1 </ b> A in the illustrated example is configured as a line for mounting the electronic component 14 on the substrate 12, similarly to the line 1 in FIG. 1. More specifically, the line 1A includes a loading unit 2, a cleaner 3, an adhesive application unit 4, a mounting machine 5A, a collection unit 6, and a conveyor 7, which are the same as the line 1 in FIG. And an oven (or reflow furnace) 8 disposed between the storage unit 6 and the recovery unit 6. In the line 1 </ b> A, the combination of the mounting machine 5 </ b> A and the oven 8 functions as a mounting unit that executes a mounting process of the electronic component 14 on the substrate 12. Hereinafter, the points where the line 1A is different from the line 1 of FIG. 1 will be mainly described.

  In the line 1A, the mounting machine 5A includes a cooling device such as a cooling fan (not shown). In the mounting machine 5A, the process (process shown by FIGS. 4A to 4C or FIGS. 5A to 5C) until the molten solder 22a is formed between the electrode 12a and the electrode 14a is the same as the process in the line 1 of FIG. is there. In the line 1A, the joining region including the molten solder 22a is not gradually cooled, but is rapidly cooled by the above cooling device.

  Through the above processing, the electrode 12a and the electrode 14a are joined by a normal solder joint, and the electronic component 14 is temporarily mounted on the substrate 12. At this time, since the process so far does not include a slow cooling process, all the electronic components 14 are temporarily mounted on the substrate 12 in a shorter time compared to the mounting in the mounting unit 5 of FIG. .

  The oven 8 heats the substrate 12 on which the electronic component 14 is temporarily mounted (hereinafter, the substrate in such a state is also referred to as an electronic component bonded substrate) until the solder joint is melted again. Thereby, the electronic component bonding substrate is again in the same state as shown in FIG. 4C or 5C. The bonding region of the electronic component bonding substrate is slowly cooled under the same conditions as those in line 1 of FIG. This makes it possible to form a solder joint 26 having a high melting point and sufficient strength, similar to the line 1 in FIG.

  In the line 1 </ b> A, the slow cooling process can be collectively performed on all the electronic components 14 mounted on the substrate 12. As a result, when the number of electronic components 14 mounted on one substrate 12 is large, the time required for manufacturing the electronic component bonded substrate can be significantly reduced.

(Embodiment 3)
Next, Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 7 is a block diagram showing a schematic configuration of a circuit member joining line according to the present embodiment. FIG. 8 is a top view of the press stand of the press machine. FIG. 9 is an explanatory view for explaining the operation of the press machine, and is a side view of the press machine.

  The line 1B in the illustrated example is configured as a line for mounting a plurality of electronic components 14 on the substrate 12 in the same manner as the line 1 in FIG. More specifically, the line 1B includes the input unit 2, the cleaner 3, the adhesive application unit 4, the recovery unit 6, and the conveyor 7, which are the same as the line 1 in FIG. In the line 1 </ b> B, a temporary placement machine 9 and a press machine 10 are further arranged between the adhesive application unit 4 and the recovery unit 6. In the line 1B, the combination of the temporary placement machine 9 and the press machine 10 functions as a mounting unit that executes a mounting process of the electronic component 14 on the substrate 12. Hereinafter, the points of the line 1B different from the line 1 of FIG. 1 and the line 1A of FIG.

  The temporary placement machine 9 is disposed downstream of the adhesive application unit 4. Similarly to the mounting unit 5 shown in FIG. 3, the temporary placement machine 9 also includes a component supply stage 18 on which a plurality of electronic components 14 are placed, a three-axis moving mechanism (not shown), and a control unit 9a. . The temporary mounting machine 9 is different from the mounting unit 5 in that a temporary placement head 28 is provided instead of the mounting head 20. Unlike the mounting head 20, the temporary placement head 28 does not have a heating unit as an essential component. The operations of the temporary placement head 28 and the triaxial moving mechanism are controlled by the control unit 9a.

  The triaxial movement mechanism of the temporary placement machine 9 is controlled by the positioning control of the control unit 9a, whereby the temporary placement head 28 is moved in the three axial directions of the X axis direction, the Y axis direction, and the Z axis direction, The point that the electronic component 14 on the component supply stage 18 is picked up by the temporary placement head 28 under the control of the control unit 9a is the same as that of the mounting unit 5. Further, the temporary placement head 28 holding the electronic component 14 is moved above the electronic component mounting position MP corresponding to the electronic component 14 by the three-axis moving mechanism, and at the electronic component mounting position MP, each electrode is moved. Similarly, the electronic component 14 is pressed toward the substrate 12 with the electrodes 14a facing the corresponding electrodes 12a. At this time, the adhesive is already applied to the electronic component mounting position MP by the adhesive application unit 4.

  The temporary placement machine 9 is different from the mounting unit 5 in the temporary placement machine 9 in that the temporary placement head 28 presses the electronic component 14 toward the substrate 12 from above the adhesive. 12 is not operated only by placing on 12, and does not operate to join the electrodes together. For this reason, the processing time per substrate 12 in the temporary placement machine 9 is much shorter than that of the mounting unit 5.

  As shown in FIG. 8, the press machine 10 arranged downstream of the temporary placement machine 9 has a press table 30 for placing a plurality of substrates 12 on which a plurality of electronic components 14 are temporarily placed. ing. Each substrate 12 processed by the temporary placement machine 9 is sequentially placed on the press table 30.

  As shown in FIG. 9, the press machine 10 further includes a press plate 32 for simultaneously pressing the plurality of electronic components 14 placed on each substrate 12 toward the substrate 12. The press plate 32 may be provided independently for each substrate 12, or one press plate 32 may be provided for the plurality of substrates 12.

  At least one of the press plate 32 and the press table 30 can include a heating means for heating the solder 22 (in the example of FIG. 9, solder particles 22b) and the adhesive 24. Each electronic component 14 is pressed against the substrate 12 by the press plate 32 while being heated by these heating means. Thereby, as shown in FIG. 4C or FIG. 5C, the molten solder 22a in which the solder 22 is melted spreads between each electrode 14a and each corresponding electrode 12a, and each electronic component 14 and the substrate 12 Is sealed with the cured resin 24a.

  Thereafter, the joint region of each electronic component 14 is collectively cooled under the same conditions as in each of the above embodiments, so that each solder joint 26 having the same high melting point and sufficient strength as in each of the above embodiments is used. It becomes possible to join each electrode 14a corresponding to the electrode 12a. In addition, heat retention may be improved by forming at least one of the lower surface of the press plate 32 and the upper surface of the press table 30 from ceramic.

  As described above, by performing the slow cooling process on the plurality of substrates 12 at once, it becomes possible to bond the plurality of electronic components 14 to each of the plurality of substrates 12 and greatly improve the production efficiency. be able to.

Next, examples of the present invention will be described. In addition, this invention is not limited to a following example.
Example 1
As the adhesive, a resin composition containing an epoxy resin, a curing agent, a thixotropic agent, a pigment, and a coupling agent was used. A solder particle-containing adhesive (paste) was prepared by mixing only 20% by weight of Sn—Bi solder (Sn-58Bi solder) fine particles (average particle diameter: 4.8 μm, melting point: 138 ° C.). .

  A test substrate having a Cu electrode was prepared. Test electronic components each having 184 electrodes corresponding to each Cu electrode of the test substrate were prepared. Each Cu electrode of the test substrate was subjected to plasma treatment using a plasma processing apparatus manufactured by Panasonic Factory Solutions Co., Ltd. Thereafter, an appropriate amount of the above solder particle-containing adhesive was applied to the electronic component mounting position MP by an adhesive application unit manufactured by Iwashita Engineering Co., Ltd. A mounting device manufactured by Panasonic Factory Solutions Co., Ltd. having a configuration similar to that of the mounting unit 5 in FIG. 1 is used to mount a test electronic component on a substrate, and between each electrode of the component and each corresponding substrate electrode, After forming the molten solder, the joint region containing the molten solder was gradually cooled. The mounting conditions are as follows.

Mounting head temperature: 218 ° C
Load by mounting head: 0.1N per electrode
Heating time: 15 seconds Time when the bonding region is estimated to remain in the temperature region of 138 to 200 ° C. (hereinafter referred to as slow cooling time): 20 seconds Cooling rate: 3 ° C./second (temperature range TR of 138 to 200 ° C. Average cooling rate)

  Under the above conditions, ten electronic components were mounted one by one on one test substrate.

(Example 2)
Ten test electronic components were mounted on one test substrate in the same manner as in Example 1 except that the following conditions were different.
Cooling rate: 10 ° C./second Slow cooling time: 6 seconds

Example 3
Ten test electronic components were mounted on one test substrate in the same manner as in Example 1 except that the following conditions were different.
Cooling rate: 1 ° C / second Annealing time: 60 seconds

Example 4
Ten test electronic components were temporarily placed on one test substrate in the same process as in the third embodiment. By repeating this six times, six test substrates (referred to as component temporary placement substrates) on which ten test electronic components were temporarily placed were obtained. In order to mount each test electronic component of the six component temporary placement substrates on each test substrate under the same conditions as in Example 1, pressurization and heating were performed using a press machine manufactured by NP System Co., Ltd. After performing the process, the bonded area was slowly cooled.

(Comparative Example 1)
As shown in the following conditions, the test electronic component was mounted on the test substrate in the same manner as in Example 1 except that the bonding region was rapidly cooled by a cooling device and not slowly cooled.

Cooling rate: 25 ° C./second Estimated time that the bonding region remained in the temperature region of 138 to 200 ° C .: 2.5 seconds

  The electronic component mounting substrates produced in Examples 1 to 4 and Comparative Example 1 were reheated at 260 ° C., and the connection resistance values of the electronic components including the wiring resistance of the substrate were measured. When the temperature which rose 20% from the initial connection resistance value was confirmed, each temperature of Examples 1-4 was 197 degreeC, 183 degreeC, 211 degreeC, and 195 degreeC, respectively. On the other hand, the temperature of Comparative Example 1 was 146 ° C. On the other hand, the intensity | strength per piece of the solder joint part of Examples 1-4 was 0.51, 0.50, 0.54, and 0.50N, respectively. On the other hand, the strength per solder joint of Comparative Example 1 was 0.49N.

  From the above results, it can be seen that in Examples 1 to 4, the solder joints have higher melting points than Comparative Example 1. And it turns out that the intensity | strength per one of the solder joint part of Examples 1-4 is over the desirable intensity | strength (0.10N). In Examples 1 to 4, the strength of the solder joint is rather higher than that of Comparative Example 1, although it is slightly higher. This is because the bonding region was gradually cooled in Examples 1 to 4, and as a result, the heating time of the thermosetting resin became longer, and as a result, the resin curing reaction proceeded more than in Comparative Example 1. It is done. As a result, it is considered that the joining by the solder joint portion could be reinforced more effectively.

  Furthermore, in Example 4, the time required to mount the test electronic components on all six test substrates was 78 seconds. In contrast, in Example 1, the time required to mount the test electronic components on all six test substrates was 393 seconds. From this result, it is understood that according to Example 4, the production efficiency can be remarkably improved.

  According to the present invention, a solder joint having a high melting point and sufficient strength can be formed by soldering at a relatively low temperature. Therefore, the present invention is intended for various circuit member joint structures, in particular, re-reflow. This is useful in a structure including an electronic component module.

1, 1A, 1B ... line,
3 ... Cleaner,
4 ... Adhesive application unit,
5 ... Mounting unit,
5A ... Mounting machine,
7 ... conveyor,
7a ... stage,
8 ... Oven,
9 ... Temporary loading machine,
10 ... Press machine,
12 ... substrate
12a ... electrodes,
14 ... electronic components,
14a ... electrodes,
16 ... coating head,
18 ... parts supply stage,
22a ... Molten solder,
20: Mounting head,
22b ... solder particles,
24. Adhesive,
24a ... cured resin,
26: Solder joint,
28 ... Temporary placement head,
30 ... Press stand,
32 ... press plate,

Claims (12)

A first circuit member having a first connection electrode;
A second circuit member having a second connection electrode facing the first connection electrode;
A solder joint interposed between the first connection electrode and the second connection electrode and electrically connecting the first connection electrode and the second connection electrode; ,
The solder joint includes a metal portion;
The metal portion includes a first metal region containing a first metal element as a main component, and a second metal region containing a second metal element having a melting point higher than that of the first metal element as a main component,
The first metal region joins the first connection electrode and the second connection electrode outside the solder joint,
The second metal region joins the first connection electrode and the second connection electrode on the center side of the solder joint,
The first metal element may be formed of the second metal elements and alloys, and the melting point of the alloy, rather lower than the melting point of the melting point and the second metal region of the first metal region,
Both said 1st metal area | region and said 2nd metal area | region are the area | regions produced | generated by segregation of the constituent element of the said alloy .   The circuit member joint structure according to claim 1, wherein the metal portion further includes the alloy.   The circuit member joining structure according to claim 1 or 2, wherein a ratio of the first metal region and the second metal region in the metal part to the metal part is 80% by mass or more. The first metal element is Sn, and the second metal element is at least one selected from the group consisting of Bi, Ag, Cu, Sb, In, Zn, Ni, and Al. circuit member connection structure according to any one of 3. Melting point of the alloy is at 0.99 ° C. or less, the melting point of the melting point and the second metal region of the first metal region, respectively 220 ° C. greater than the circuit according to any one of claims 1-4 Member bonded structure. The circuit member bonding structure according to claim 5, wherein the first metal element includes at least Sn, and the second metal region includes at least Bi. It said solder joint further includes a resin portion for sealing the metal portion, the circuit member connection structure according to any one of claims 1-6. The circuit member joint structure according to claim 7, wherein a ratio of the resin part in a total of the metal part and the resin part in the solder joint part is 60 % by mass or more and 98% by mass or less . It said first circuit member and the second circuit board are both a semiconductor bare chip, circuit member connection structure according to any one of claims 1-8. The circuit member joint structure according to any one of claims 1 to 8 , wherein the first circuit member is a semiconductor bare chip, and the second circuit member is an interposer. It said first circuit member is an electronic component module, the second circuit member is a motherboard, the circuit member connection structure according to any one of claims 1-8. It said first circuit member is a BGA package, the second circuit member is a motherboard, the circuit member connection structure according to any one of claims 1-8.

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