JP2006100492A - Fixing method of electronic component onto support plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent air bubbles from being formed in a brazing material for fixing a support plate and an electronic component. <P>SOLUTION: A linear brazing material 3 is heated in a feeder 4 to a temperature lower than the melting temperature of the brazing material 3 but higher than ordinary temperature, and is further heated to a temperature higher than the melting temperature of the brazing material 3 and is brought into contact with the support plate 1 disposed below the feeder 4. Then, the lower end of the brazing material 3 is melted with heat of the support plate 1 and is dropped with its self weight, and further the electronic component 2 is made to adhere onto the brazing material 3. Thereafter, the support plate 1 is cooled to fix the electronic component 2 onto the support plate 1. The solder material 3 has been heated beforehand and is prevented from being melted in the feeder 4 until it makes contact with the support plate 1, so that the molten solder of a predetermined amount can be securely supplied and air bubbles can be prevented from being entrained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of fixing an electronic component on a support plate that prevents bubbles from forming in the brazing material and securely fixes the electronic component to the support plate.

  A method of manufacturing a semiconductor device such as a transistor or an IC, in which a lead frame for connecting a plurality of support plates and lead terminals to each other by a tie bar (connection strip) is prepared and a semiconductor chip is fixed to the main surface of the support plate using a die bonder Is known. As shown in FIG. 2, when the semiconductor chip is fixed on the support plate (1), soldering including a transfer device (10), a feeder (solder supply device) (14), and a die bonder (electronic component mounting device) is provided. The device is used. The transport device (10) includes a metal rail (6) extending in the longitudinal direction of the lead frame (11), a heater (not shown) that heats the rail (6) to a melting temperature of the solder material (3), a rail (6) A driving device (not shown) that conveys the lead frame (11) disposed on the lead frame (11) in the longitudinal direction of the lead frame (11) along the rail (6). The cover (5) surrounding the transport device (10) is filled with a forming gas such as nitrogen that prevents oxidation of the lead frame (11) or the solder material (3) supplied thereon. The rail (6) and the lead frame (11) exposed to the forming gas atmosphere in the cover (5) do not touch the outside air during the soldering process and are not oxidized.

  The feeder (14) for supplying the solder material (3) formed in a linear or thread shape onto the lead frame (11) is installed above the conveying device (10). The feeder (14) includes a feeding device (not shown) that feeds the linear solder material (3) from the nozzle (19) at the tip of the feeder (14) by roller feeding or crank feeding, and a cover (5) of the conveying device (10). And a feeder driving device (not shown) that moves the feeder (14) in the vertical direction so as to be able to advance and retreat with respect to the rail (6) through the opening (16) formed in the inner surface. A die bonder (not shown) includes a collet that holds the semiconductor chip and places the semiconductor chip on the support plate (1) of the lead frame (11), and an opening (16) formed in the cover (5) of the transfer device (10). ) Through which the collet is moved vertically with respect to the rail (6), and a vacuum suction device that holds the semiconductor chip by vacuum suction to the collet.

  When soldering a semiconductor chip using the soldering apparatus shown in FIG. 2, the rail (6) is first heated to a temperature equal to or higher than the melting temperature of the solder material (3) with a heater, and the rail (6) is heated. The lead frame (11) is placed on. Next, the support plate to which the lead frame (11) is transported in the longitudinal direction of the lead frame (11) at a predetermined pitch interval along the rail (6) of the transport device (10) and the solder material (3) is supplied. (1) is placed below the feeder (14) and stopped. Subsequently, as shown in FIG. 2, the feeder (14) is lowered by the feeder driving device while a predetermined amount of the linear solder material (3) in the feeder (14) is fed from the nozzle (19) by the feeding device. Let When the feeder (14) in which the tip of the linear solder material (3) moves so as to be movable forward and backward with respect to the upper surface of the lead frame (11) is lowered toward the lead frame (11), it is fed out from the feeder (14). The linear solder material (3) contacts the lead frame (11). The solder material (3) in contact with the lead frame (11) is already heated to a temperature equal to or higher than the melting temperature of the solder material (3) by the heater via the rail (6). As shown in FIG. 2, it melts on the support plate (1). At this time, a predetermined amount of the solder material (3) fed out from the nozzle (19) is melted and dropped by its own weight and adheres to the support plate (1). Thereafter, the feeder (14) rises to the initial position above and is held at the initial position until the next support plate (1) is conveyed downward.

  Next, the lead frame (11) is conveyed again in the longitudinal direction of the lead frame (11) at a predetermined pitch interval, and the support plate (1) to which the molten solder is attached is disposed below the die bonder and stopped. Subsequently, the collet that vacuum-sucks the semiconductor chip is lowered, and the semiconductor chip is placed on the molten solder. With the lower surface of the semiconductor chip held by the collet attached to the upper surface of the support plate (1) via the molten solder, when the collet is repeatedly moved parallel to the support plate (1), the molten solder is moved to the semiconductor chip. Can be spread over the entire lower surface of the. Thereafter, if the solder material (3) is cooled and hardened, the semiconductor chip can be fixed on the support plate (1). In this fixing method, since the linear solder material (3) is brought into contact with the heated support plate (1) and melted, the amount of the solder material (3) fed out from the feeder (14) is adjusted, and the support plate ( 1) There is an advantage that the amount of the solder material (3) supplied on the top can be controlled relatively well.

  However, the conventional fixing method has a drawback that bubbles are easily enclosed in the molten solder supplied on the support plate (1). When bubbles are included in the molten solder, the thermal conductivity of the solder layer is impaired by the bubbles between the semiconductor chip and the support plate (1), and the mechanical adhesion strength of the semiconductor chip to the support plate (1) Also decreases. In particular, when a heat cycle test is performed, there is a risk that the expansion and contraction of the bubbles are repeated, resulting in poor electrical connection between the support plate (1) and the semiconductor chip. The reason why bubbles are generated in the molten solder is not necessarily clear, but is considered to be due to insufficient heating of the solder material (3). That is, when a linear solder material (3) that is not sufficiently heated is supplied from the feeder (14) and comes into contact with the support plate (1), as shown in FIG. The temperature of the central surface (18) of 1) is partially and significantly lower than the outer surface (20) around the central surface (18). The molten solder (13) spreads rapidly from the central surface (18) toward the outer surface (20) having a higher surface temperature than the central surface (18). When the molten solder (13) spreads rapidly to the surrounding high temperature region, surrounding gas is entrained to enclose bubbles in the molten solder (13). Further, due to the movement of the molten solder (13) to the outer surface (20), the amount of the solder material (3) at the central surface (18) is relatively reduced, and the surface of the molten solder (13) is uneven. Even when the semiconductor chip is disposed, bubbles are formed at the interface between the molten solder (13) and the semiconductor chip.

  On the other hand, Patent Document 1 below discloses a semiconductor chip fixing device having an inclined member that slides a molten solder material fed from a feeder onto a lower support plate. The solder material that slides down on the inclined member improves the wettability by stirring the oxide film on the surface, so that the contact with the support plate is good, and the formation of bubbles at the interface between the molten solder and the semiconductor chip can be suppressed.

JP 2001-176893 A

However, in the semiconductor chip fixing device of Patent Document 1, formation of bubbles in the molten solder and at the interface between the molten solder and the semiconductor chip can be suppressed. However, since the molten solder is slid down obliquely by the inclined member, Thus, there is a defect that the solder material cannot be attached to a predetermined position. In addition, an inclined member in which wear on the inclined surface or adhesion of solder occurs is a factor that reduces productivity, which is not preferable.
Therefore, the present invention provides a method for fixing an electronic component on a support plate that prevents bubbles from forming in the solder material and at the interface between the solder material and the electronic component such as a semiconductor chip without reducing productivity. For the purpose.

  The fixing method of the electronic component on the support plate of the present invention is a process of heating the linear brazing material (3) in the feeder (4) to a temperature lower than the melting temperature of the brazing material (3) but higher than room temperature. Then, the brazing filler metal (3) is heated to a temperature higher than the melting temperature of the brazing filler metal (3) and moved to the support plate (1) disposed below the feeder (4), and is fed from the feeder (4). The process of bringing the lower end portion of the brazing material (3) into contact with the support plate (1) and the lower end portion of the brazing material (3) were melted by the heat of the support plate (1) to be melted on the support plate (1). A process of dripping a predetermined amount of brazing material (3) by its own weight, a process of attaching an electronic component (2) onto the brazing material (3) adhering to the support plate (1), and a cooling of the support plate (1). And a process of fixing the electronic component (2) on the support plate (1) with the brazing material (3).

  A brazing material (3) that has been heated to a temperature lower than the melting temperature but higher than room temperature is brought into contact with the support plate (1), and the lower end of the brazing material (3) is melted by a predetermined amount by the heat of the support plate (1). Therefore, the brazing material (3) at the lower end melts rapidly and uniformly while radially expanding the area on the support plate (3). The brazing material (3) held at a temperature lower than the melting temperature in the feeder (4) does not melt in the feeder (4) until it contacts the support plate (1). A predetermined amount of molten solder can be reliably supplied to the position. After that, when the surface tension of the molten solder adhering to the support plate (1) becomes larger than gravity, the molten solder stops the area expansion, but the preheated brazing material (3) is brought into contact with the support plate (1). Only the surface temperature of the support plate (1) in contact with the brazing material (3) does not partially decrease. For this reason, the molten solder adhering to the support plate (1) spreads rapidly to the surrounding high temperature region, and it is possible to prevent bubbles from being encapsulated in the molten solder or the occurrence of uneven surfaces on the surface of the molten solder. Therefore, when the electronic component (2) is attached onto the molten solder, it is possible to prevent bubbles from being enclosed in the molten solder or formation of bubbles at the interface between the molten solder and the electronic component (2).

  Prevents the formation of bubbles in the brazing material that fixes the electronic component and the support plate, prevents the electronic component and the support plate from lowering the mechanical adhesive strength, and lowering the thermal conductivity of the brazing material, resulting in poor electrical characteristics Therefore, it is possible to provide a highly reliable electronic component.

  An embodiment of a method for fixing an electronic component on a support plate according to the present invention using a solder material as a brazing material and fixing the semiconductor chip to the support plate will be described below with reference to FIG. In FIG. 1, parts that are substantially the same as those shown in FIG. 2 are given the same reference numerals, and descriptions thereof are omitted.

  As shown in FIG. 1, the soldering apparatus provided with the conveying apparatus (10), the feeder (4), and the die bonder (7) is used for the fixing method of the electronic component on the support plate of this Embodiment. . The transport device (10) includes a rail (6) that transports the lead frame (11), a heater (not shown) that heats the rail (6) to a temperature higher than the melting temperature of the solder material (3), and a rail ( 6) A driving device (not shown) that conveys the lead frame (11) arranged on the rail along the rail (6). Referring to FIG. 2, the rail (6) has a pair of protrusions (6a) facing both edges thereof, and the interval between the protrusions (6a) is substantially equal to the width of the lead frame (11). The lead frame (11) disposed on the rail (6) is sandwiched between the pair of protrusions (6a) and transported, and thus does not fall off from the rail (6). The periphery of the transfer device (10) is surrounded by a cover (5), and a forming gas such as nitrogen is filled in the cover (5) as in the conventional case. The transfer device (10) is disposed in the tunnel of the cover (5) filled with forming gas, and the lead frame (11) transferred on the rail (6) moves in the forming gas in the tunnel.

  The feeder (4) of the present embodiment includes a feeding device (not shown) that feeds the solder material (3) formed in a linear or thread shape by roller feeding or crank feeding from the nozzle (9) at the tip of the feeder (4), A feeder drive device (not shown) is provided for moving the feeder (4) in a vertical direction so as to be movable back and forth with respect to the upper surface of the rail (6) through an opening (16) formed in the cover (5) of the transport device (10). (4) It differs from the conventional feeder (14) in that it has a heating device (15) for heating the linear solder material (3) inside. For the solder material (3), lead-free solder made of a material such as tin (Sn), silver (Ag), copper (Cu) or aluminum (Al) which does not contain lead (Pb) is used. A general solder composed of Sn) and lead (Pb) or other well-known solder may be used. The feeder (4) is installed above the conveying device (10) for supplying the linear solder material (3) onto the lead frame (11). As shown in FIG. 1, the heating device (15) includes, for example, a heating coil (12) disposed around the feeder (4), a power supply device (not shown) that causes a high-frequency alternating current to flow through the heating coil (12), And a control device (15) that controls the high-frequency alternating current value based on the temperature in the heating coil (12) or feeder (4), and the solder material (3) conveyed in the feeder (4) Heat to temperature.

  The heating temperature of the solder material (3) by the heating device (15) is very important. As shown in Patent Document 1, the heating temperature should not be a high temperature at which the solder material (3) melts, and the heating device (15) heats the solder material (3) to such an extent that the linear shape is maintained. To do. When the heating temperature is higher than the melting temperature of the linear solder material (3), it is difficult to control the supply position and supply amount of the molten solder (13) on the support plate (1). In addition, there is a problem that the molten solder (13) adheres to the feeder (4). In contrast, if the heating temperature of the linear solder material (3) is too low, bubbles are generated in the molten solder (13) as in the prior art. Therefore, the heating temperature of the linear solder material (3) by the heating device (15) is preferably set to a temperature range 20 ° C. to 80 ° C. lower than the melting temperature of the solder material (3), and more preferably 30 ° C. A temperature range as low as ˜60 ° C. is desirable. The heating temperature of the linear solder material (3) by the heating device (15) is selected to be higher than room temperature, but is preferably set to 70 ° C or higher, and more preferably 90 ° C or higher. If the heating temperature is less than 70 ° C., the effect of the present invention is significantly reduced. Specifically, when the linear solder material (3) is formed from an alloy of tin (Sn), silver (Ag) and copper (Cu) having a melting temperature of 210 ° C. to 230 ° C., the melting temperature is lower than the melting temperature and 130 ° C. The solder material (3) is heated in the feeder (4) to a temperature of ˜210 ° C.

  As shown in FIG. 1, the die bonder (7) has an upper surface of the rail (6) through a collet (17) and an opening (16) formed in the cover (5) of the transfer device (10) as in the conventional case. And a collet driving device (not shown) that moves the collet (17) in the vertical direction so as to be movable forward and backward, and a vacuum suction device (not shown) that holds the semiconductor chip (2) by vacuum suction on the collet (17).

  When soldering the semiconductor chip (2) using the soldering apparatus of FIG. 1, the rail (6) is first heated to a temperature higher than the melting temperature of the solder material (3) by a heater, and the heated rail (6 ) Place the lead frame (11) on top. Next, the support plate (1) of the lead frame (11) heated to a temperature higher than the melting temperature of the solder material (3) is disposed below the feeder (4). Subsequently, the lead frame (11) is transported by the transport device (10) at a predetermined pitch interval along the rail (6), and the support plate (1) to which the solder material (3) is to be supplied is attached to the feeder (4). Place it below and stop. Thereafter, the linear solder material (3) supplied into the feeder (4) is heated by the heating device (15) to a temperature lower than the melting temperature of the solder material (3) but higher than room temperature.

  A linear solder material (3) is fed out from the feeder (4) by a predetermined amount from the nozzle (9) by the feeding device. The feeder (4) and the solder (3) are moved vertically downward by the feeder driving device, and the lower end of the solder (3) fed out from the feeder (4) by a predetermined amount is brought into contact with the support plate (1). The heat of the heated support plate (1) is transmitted to the linear solder material (3), the lower end of the solder material (3) is melted by a predetermined amount, and a predetermined amount of the molten material on the support plate (1) is melted. The solder material (3) is separated from the linear solder material (3) and dropped by its own weight. As shown in FIG. 1, molten solder (13) is supplied to the upper surface of the support plate (1).

  Solder material (3) preheated to a temperature lower than the melting temperature but higher than normal temperature is brought into contact with the support plate (1), and the lower end of the solder material (3) is melted by a predetermined amount by the heat of the support plate (1). Therefore, the solder material (3) at the lower end is rapidly and uniformly melted while radially expanding the area on the support plate (3). The solder material (3) held at a temperature lower than the melting temperature in the feeder (4) does not melt in the feeder (4) until it contacts the support plate (1). A predetermined amount of molten solder (13) can be reliably supplied to the position. In the present embodiment, the amount of the solder material (3) supplied onto the support plate (1) can be well controlled, and the supply amount of the solder material (3) is small. Therefore, it is possible to prevent an electrical short circuit caused by the solder material (3) adhering to the side surface of the semiconductor chip (2).

  After that, when the surface tension of the molten solder (13) adhering to the support plate (1) becomes larger than gravity, the molten solder (13) stops the area expansion, but the preheated solder material (3) is supported by the support plate (1). Since it is in contact with (1), only the surface temperature of the support plate (1) in contact with the solder material (3) is not significantly reduced. Therefore, the molten solder (13) adhering to the support plate (1) spreads rapidly to the surrounding high temperature region, preventing the formation of bubbles in the molten solder (13) or the occurrence of irregularities on the surface of the molten solder (13). Then, when the semiconductor chip (2) is attached onto the molten solder (13), it is possible to prevent bubbles from forming in the molten solder (13) or at the interface between the molten solder (13) and the semiconductor chip (2). In the present embodiment, as a result of actual measurement, the surface temperature of the support plate (1) is substantially equal in the region where the solder material (3) is in contact with the outer peripheral region.

  Subsequently, as shown in FIG. 1, the lead frame (11) is conveyed again at a predetermined pitch interval, and the support plate (1) supplied with the molten solder (13) is disposed below the die bonder (7). The collet (17) that has vacuum-sucked the semiconductor chip (2) is lowered, and the semiconductor chip (2) is placed on the molten solder (13) attached on the support plate (1) to support the semiconductor chip (2). Adhere to the plate (1). At this time, as in the prior art, the collet (17) with the lower surface of the semiconductor chip (2) held by the collet (17) attached to the upper surface of the support plate (1) via the molten solder (13). Is repeatedly moved in parallel with respect to the support plate (1), the molten solder (13) can be spread over the entire lower surface of the semiconductor chip (2), but the spreading step may be omitted. The support plate (1) is cooled and the semiconductor chip (2) is fixed onto the support plate (1) by the solder material (3).

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the method for fixing an electronic component on a support plate according to the present invention is not only for manufacturing a semiconductor device for fixing a semiconductor chip (2) to a support plate (1), but also for other electronic components (2) such as a chip capacitor. It can be applied to the fixing process. The brazing material (3) described in the present invention includes a solder material indicating a brazing material having a low melting temperature.

Some of the examples by the inventors are shown below.
In Example 1, a solder material (3) made of an alloy of tin (Sn), silver (Ag), and copper (Cu) having a melting temperature of 217 ° C. is lower than the melting temperature but higher than room temperature in the feeder (4). To the support plate (1) heated to a temperature higher than the melting temperature of the solder material (3). The experiment was performed a plurality of times by changing the heating temperature of the solder material (3) in the feeder (4) within a range of 140 ° C to 200 ° C.

  In Example 2, a solder material (3) made of an alloy of tin (Sn), copper (Cu) and nickel (Ni) having a melting temperature of 227 ° C. is used, and the solder material (3) in the feeder (4) is used. The same experiment as in Example 1 was performed in which heating was performed in a temperature range of 150 ° C to 205 ° C. In Example 3, a solder material (3) made of an alloy of tin (Sn) and silver (Ag) having a melting temperature of 221 ° C. is used, and the solder material (3) in the feeder (4) is 145 ° C. to 200 ° C. The same experiment as in Example 1 was performed by heating in the above temperature range. In Example 4, a solder material (3) made of an alloy of tin (Sn), silver (Ag), indium (In), and bismuth (lead) (Bi) having a melting temperature of 202 ° C. is used. The solder material (3) was heated in the temperature range of 125 ° C. to 180 ° C., and the same experiment as in Example 1 was performed. In Example 5, a solder material (3) made of an alloy of tin (Sn) and bismuth (Bi) having a melting temperature of 139 ° C. is used, and the range of 70 ° C. to 115 ° C. is set in the feeder (4). The same experiment was conducted. In Example 6, a solder material (3) made of an alloy of tin (Sn), silver (Ag), copper (Cu) and bismuth (Bi) having a melting temperature of 208 ° C. is used, and 130 ° C. in the feeder (4). The same experiment as in Example 1 was performed within the range of ˜185 ° C. In Example 7, the solder material (3) made of an alloy of tin (Sn) and antimony (Sb) having a melting temperature of 236 ° C. is used, and the temperature in the range of 160 ° C. to 215 ° C. is set in the feeder (4). The same experiment was conducted.

  When the support plate (1) and the semiconductor chip (2) are bonded by the molten solder (13) of the first to seventh embodiments, the conventional fixing without heating the solder material (3) in the feeder (4) Compared with the method, it was possible to suppress the generation of bubbles in the solder material (3) and between the solder material (3) and the semiconductor chip (2). In other examples not described in detail, a general solder containing lead (Pb), a low melting point solder or a high temperature solder was also tested, and similar results were obtained.

  The present invention is suitable for manufacturing a precision device such as a semiconductor device that securely bonds a semiconductor chip with a brazing material layer.

Sectional drawing of the soldering apparatus which implements the fixing method of the electronic component on the support plate by this invention Sectional view of conventional soldering equipment Sectional view showing solder material with bubbles formed due to temperature difference on support plate

Explanation of symbols

  (1) ... Support plate, (2) ... Electronic parts (semiconductor chip), (3) ... Brazing material (solder material), (4) ... Feeder,

Claims (3)

Heating the linear brazing material in a feeder to a temperature lower than the melting temperature of the brazing material but higher than room temperature;
The brazing material is heated to a temperature higher than the melting temperature of the brazing material and moved toward the support plate disposed below the feeder, and the lower end portion of the brazing material fed from the feeder is brought into contact with the support plate. Process,
Melting the lower end of the brazing material by the heat of the support plate, and dropping a predetermined amount of the brazing material melted on the support plate by its own weight;
Attaching an electronic component on the brazing material attached on the support plate;
A method for fixing an electronic component on a support plate, comprising cooling the support plate and fixing the electronic component on the support plate with the brazing material.   The method for fixing an electronic component on a support plate according to claim 1, comprising a step of holding the brazing material in the feeder at a temperature lower by 20 to 80 ° C. than the melting temperature of the brazing material. Forming a linear brazing material from an alloy of tin (Sn), silver (Ag) and copper (Cu) at a melting temperature of 210 ° C. to 230 ° C .;
The method for fixing an electronic component on a support plate according to claim 1, further comprising a step of heating the brazing material in the feeder to a temperature of 130 ° C. to 210 ° C. lower than the melting temperature.

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