JP2014041907A - Electronic component mounting apparatus, printed circuit board, and electronic component mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting apparatus which improves the yield at the time of mounting electronic components.SOLUTION: The electronic component mounting apparatus comprises: heating means 14a to solder a plurality of component-side terminals 31 which a BGA 30 has and a plurality of substrate-side terminals 21 which a printed circuit board 20 has by heating paste solder p which has insulation properties before melting and conductive properties after melting; a converter 41 which applies voltage to predetermined terminals 21a-21e among the substrate-side terminals 21; a conductivity detection section 43 which detects conductivity with the voltage applied by the converter 41 through the BGA 30, from the printed circuit board 20; and a control section 44 which determines success or failure of soldering by monitoring the conductivity state by the conductivity detection section 43.

Description

  The present invention relates to an electronic component mounting apparatus for mounting electronic components on a printed circuit board.

In recent years, surface-mount electronic components are frequently used in computers, mobile phones, digital home appliances, and the like.
As surface-mounted electronic components, for example, there are BGA (Ball Grid Array) and CSP (Chip Size Package) in which hemispherical terminals (bumps) are provided on the back surface of an IC (Integrated Circuit) package. Incidentally, in the BGA, dozens to thousands of terminals arranged in a grid at predetermined intervals (0.5 mm to 1.5 mm) are provided on the back surface of the IC package.
In this way, by providing terminals on the back side of electronic components, the total number of pads (number of contacts with the printed circuit board) is greatly increased, and the mounting area of the IC package is reduced to achieve miniaturization and higher density. Yes.

By the way, electronic components mounted on a printed circuit board are roughly classified into surface mounting components and insertion mounting components. When mounting the insertion mounting component, the lead wire of the electronic component is inserted into the hole provided in the printed board and soldered.
On the other hand, among the surface-mounted components described above, BGA, CSP, and the like are not exposed to the outside when they are placed on the printed board. That is, since the soldering part cannot be visually observed, soldering cannot be performed using the soldering iron.

  When removing and remounting such surface mount components, a dedicated device called a repair device is used. If a defect (such as poor connection) is found on a surface-mounted component installed on a printed circuit board, or for the purpose of recycling, remove the surface-mounted component from the printed circuit board using a repair device, and replace the same type of surface-mounted component. The importance of re-mounting (repairing) technology is increasing.

  For example, Patent Document 1 describes an electronic component mounting board having two test points provided so as to protrude from a solder pad. In the technique described in Patent Document 1, an electronic component is placed on an electronic component mounting substrate, and a conductive cream solder provided on a solder pad is melted and cured. Thereafter, continuity is measured between the two test points by a tester to confirm whether or not the soldering is normally performed (see FIG. 4 and the like).

JP 2010-177274 A

  In the technique described in Patent Document 1, it is necessary to project each test point from the solder pad so that the two test points can be seen with the electronic component mounted on the electronic component mounting board. Therefore, the mounting area of the electronic component mounting board is reduced by projecting the test point in this way.

  Moreover, in the technique described in Patent Document 1, it is inspected whether or not the soldering is normally performed after the solder is cured. Therefore, when unconnected is found in the inspection, the solder has already hardened, so it is necessary to remove and replace the electronic component again. That is, with the technique described in Patent Document 1, there is a possibility that the yield when electronic components are mounted may deteriorate. Further, when the replacement of the electronic component fails, there is a problem that the electronic component that has failed to be replaced is wasted and requires a lot of man-hours.

  Accordingly, an object of the present invention is to provide an electronic component mounting apparatus that improves the yield when mounting electronic components.

In order to solve the above-mentioned problem, the present invention heats an insulating solder member before melting and a conductive solder member after melting, thereby providing a plurality of component-side terminals included in the surface mount component and a plurality of printed circuit boards. Heating means for soldering board-side terminals, voltage applying means for applying a voltage to a predetermined terminal among the board-side terminals, and via the surface mount component by the voltage applied by the voltage applying means It is characterized by comprising a continuity detection means for detecting continuity from the printed circuit board, and a determination means for determining success or failure of the soldering by monitoring a continuity state by the continuity detection means.
Details will be described in an embodiment for carrying out the invention.

  According to the present invention, it is possible to provide an electronic component mounting apparatus that improves the yield when mounting electronic components.

It is explanatory drawing of the electronic component mounting apparatus which concerns on embodiment of this invention. (A) is explanatory drawing (plan view) which shows the connection relation of the electronic component mounted in a printed circuit board, (b) is a cross-sectional schematic diagram of a printed circuit board. (A) is explanatory drawing which shows typically the component side terminal provided in the back surface of BGA, (b) is the elements on larger scale of the area | region S shown to Fig.2 (a) among printed circuit boards, and is conductive. It is explanatory drawing which shows the connection relationship with the terminal for a detection. It is explanatory drawing which shows the structure of a conduction confirmation means. It is explanatory drawing (side view) which shows the procedure which mounts BGA in a printed circuit board, (a) shows the state by which the conduction | electrical_connection confirmation means was connected to the terminal for conduction detection of a printed circuit board, (b) is paste on a printed circuit board A state where the solder is printed is shown, and (c) shows a state where the BGA is placed on the printed board. (A) shows a state where a BGA is placed on a printed circuit board and a voltage is applied between the board-side terminals, and (b) shows that the paste solder and the component-side terminals are melted and the board-side end pair is electrically connected. Indicates the state. (A) is a graph which shows the temperature change near the center of BGA, and the temperature change near four corners, (b) is a graph which shows the change of the output of a heating means.

A mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings as appropriate.
In the following description, “printed circuit board” is a circuit board on which a plurality of electronic components are arranged and fixed, and means printed wiring for connecting electronic components.
The “component side terminal” means a plurality of terminals (bumps) provided on the back surface (surface facing the printed circuit board) of the surface mount component.
The “board side terminal” means a plurality of terminals (pads) provided on the printed board corresponding to the component side terminals.
Below, the case where a surface mounting component is BGA is demonstrated as an example.

<Configuration of electronic component mounting device>
FIG. 1 is an explanatory diagram of an electronic component mounting apparatus according to the present embodiment. The electronic component mounting apparatus 100 (repair apparatus) blows hot air from above on the printed circuit board 20 supported by the support base 17 to melt the solder and remove the BGA 30. Thereafter, the BGA 30 is remounted (repaired) by melting the paste solder applied to the printed circuit board 20.

As shown in FIG. 1, the electronic component mounting apparatus 100 includes a fixed base 11, a lower base 12, a fixed arm 13, an upper base 14, a heating unit 14a, a position adjusting device 15, a nozzle 16, and a support. A stand 17, a bottom heater 18, and a control device 19 are provided.
The fixed base 11 supports and fixes the lower base 12, the support base 17, and the bottom heater 18 from the lower side. The lower base 12 is fixed to the fixed base 11 and stands upward, and has an electronic circuit (corresponding to “control device 19” described later) therein.

One end of the fixed arm 13 is fixed to the side surface of the lower base portion 12 and extends in the lateral direction, and the other end is fixed to the side surface of the upper base portion 14. The upper base portion 14 is located at a predetermined height from the fixed base 11 and has a heating means 14a that generates high-temperature hot air for melting the solder, and an air blowing means (not shown).
The heating unit 14 a is a heater that generates heat by current supplied in accordance with a command from the control device 19. The position adjusting device 15 can be expanded and contracted in the vertical direction (z direction shown in FIG. 1), and adjusts the vertical position of the nozzle 16 when the BGA 30 is removed or remounted. The position adjustment device 15 may be adjusted automatically according to a command from the control device 19 or may be adjusted manually.

The plurality of nozzles 16 protrude downward from the upper base 14 and spray hot air generated by the heating means 14a and the air blowing means (not shown) from the tip. The nozzle 16 also has a function of vacuum-sucking the BGA 30 according to a command from the control device 19 when the BGA 30 is removed.
The support base 17 is erected on the fixed base 11 and supports the printed circuit board 20 from below. Although schematically shown in FIG. 1, the support base 17 can adjust the position of the printed circuit board 20 in the front / back direction (x direction) and the left / right direction (y direction) of the paper surface. Incidentally, the adjustment may be performed automatically in accordance with a command from the control device 19, or may be performed manually.

  The bottom heater 18 heats the entire printed circuit board 20 from below. That is, the BGA 30 is heated from both the upper and lower sides by the hot air jetted from the nozzle 16 located above and the heat from the bottom heater 18 located below. Although details will be described later, the heating is performed when the BGA 30 is removed or remounted.

  The control device 19 (determination means) includes electronic circuits such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and various interfaces. Demonstrate the function. The control device 19 controls the temperature of the heating means 14a and the bottom heater 18, and controls the voltage applied to the board-side terminal 21 (see FIG. 3B) of the printed board 20 and the conduction check (solder joining completion check). Do. The voltage control and conduction confirmation by the control device 19 will be described later.

<Printed circuit board>
FIG. 2A is an explanatory diagram (plan view) showing a connection relationship of electronic components mounted on a printed circuit board. Incidentally, in FIG. 2A, a plurality of electronic components including the BGA 30 (actually installed on the printed circuit board 20) are omitted, and connection terminals with the respective electronic components (that is, the board-side terminals 21 described above). Etc.).
A group of circles in the region S shown in FIG. 2A is the board-side terminal 21 corresponding to the component-side terminal 31 of the BGA 30 (see FIG. 3A). Dozens to thousands are arranged.
Further, a group of □ marks shown in the lower right side of the drawing in FIG. 2A are board-side terminals corresponding to ICs in which a plurality of lead wires protrude from the periphery. In addition, the □ marks illustrated in the lower left and upper left of FIG. 2A also represent the board-side terminals provided on the printed board 20.

  FIG. 2B is a schematic cross-sectional view of the printed circuit board. As shown in FIG. 2B, the printed circuit board 20 has a multilayer structure in which circuit layers from the A layer to the D layer are sequentially laminated. An insulating layer (not shown) is interposed between adjacent circuit layers. If the circuit cannot be accommodated on both sides of the printed circuit board 20, it is possible to cope with such a multilayer structure.

  Note that the three types of lines shown in FIG. 2A respectively indicate wirings corresponding to the A layer, the B layer, and the C layer shown in FIG. 2B (the wirings corresponding to the D layer are omitted). did). For example, the symbol k shown in FIG. 2A indicates that the terminal X1 arranged in the A layer of the printed board 20 is connected to the terminal Y1 of the A layer via the wiring k. Incidentally, although the lines intersect at the locations indicated by the symbols α and β, since these wirings belong to different circuit layers (A layer and B layer), there is no possibility of conduction at the locations.

  In FIG. 2A, the connection relationship between the terminals is schematically shown. However, in reality, a large number of electronic components are densely connected and complicatedly connected through a large number of wirings. And the board | substrate side terminal 21 in which BGA30 is installed in the predetermined position (area | region S shown in FIG. 2) in the printed circuit board 20 is provided in the grid | lattice form.

FIG. 3A is an explanatory diagram schematically showing a component-side terminal provided on the back surface of the BGA. FIG. 3B is a partially enlarged view of the region S shown in FIG. 2A of the printed circuit board, and is an explanatory diagram showing a connection relationship with the continuity detection terminal.
In the printed circuit board 20 of FIG. 2A described above, only the wiring necessary for circuit operation after mounting the electronic components is shown, and the continuity detection wirings 22a to 22e (thick lines in FIG. 3B) are omitted. . On the other hand, in FIG. 3B, the wiring described in FIG. 2A is omitted, and only the continuity detection wirings 22a to 22e are illustrated. The above-described “conduction detection wiring” is used when determining whether or not the board-side terminal 21 of the printed board 20 and the component-side terminal 31 of the BGA 30 are appropriately joined.

  As shown in FIG. 3 (a), a plurality of component-side terminals 31 arranged in a grid pattern on the back surface of the BGA 30 are electrically connected via an internal circuit of the BGA 30 (solid line circles) and Some of the internal circuits of the BGA 30 are not electrically connected (dotted circles). Hereinafter, a pair of the component side terminals 31 that are electrically connected via the internal circuit of the BGA 30 will be referred to as a “component side terminal pair”. For example, a pair of component side terminals 31a shown in FIG. 3A corresponds to a component side terminal pair.

  Further, as shown in FIG. 3B, a plurality of board-side terminals 21 provided in a lattice shape in the region S of the printed board 20 correspond to the component-side terminals 31 of the BGA 30 on a one-to-one basis. Incidentally, the component side terminal 31 of the BGA 30 shown in FIG. 3A is opposed to the board side terminal 21 shown in FIG. 3B (that is, the BGA 30 is turned over from the state of FIG. 3A). It is placed on the printed circuit board 20. Therefore, the corresponding terminals (for example, reference numeral 31a and reference numeral 21a) in FIG. 3A and FIG. 3B have a symmetrical positional relationship.

  Hereinafter, among the board-side terminals 21, those corresponding to the component-side terminal pairs 31a to 31e described above are referred to as “board-side terminal pairs”. As shown in FIG. 3B, the board-side terminal pairs 21a to 21e are shown by solid circles, and the other board-side terminals 21 are shown by broken circles.

Although details will be described later, in this embodiment, the BGA 30 is placed on the printed circuit board 20 via the paste solder p (see FIG. 6A), and then the paste is heated by hot air from the nozzle 16 (see FIG. 1). Solder p is melted.
The paste solder p is insulative before melting, but becomes conductive after melting. Therefore, the heat treatment is performed while applying a voltage to the board-side terminal pairs 21a to 21e corresponding to the component-side terminal pairs 31a to 31e of the BGA 30, and conduction is detected based on the current values detected by the current sensors 42a to 42e. This confirms the melting of the paste solder p.

Note that the board-side terminal pair 21a shown in FIG. 3B is connected to the continuity detection terminal 23a via the continuity detection wiring 22a (thick line). The same applies to the other board-side terminal pairs 21b to 21e.
The continuity detection wirings 22a to 22e and the continuity detection terminals 23a to 23e shown in FIG. 3B are printed on the printed circuit board 20 in advance. That is, at the time of designing the printed circuit board 20, the board-side terminal pairs 21a to 21e used for continuity detection at the time of repair (confirmation of melting of the paste solder p) are set. And the conduction | electrical_connection detection wiring 22a-22e and the conduction | electrical_connection detection terminals 23a-23e corresponding to these some base terminal pair 21a-21e are printed on the printed circuit board 20 previously.

  Note that the positions of the component side terminal pairs 31a to 31e (that is, the corresponding board side terminal pairs 21a to 21e) that are electrically connected in the internal circuit of the BGA 30 are known from the specifications of the BGA 30 to be mounted. Can do.

Further, as shown in FIG. 3B, a DC power source 41 and a current sensor 42a are connected in series to a pair of continuity detection terminals 23a connected to the board-side terminal pair 21a via the continuity detection wiring 22a. ing. Incidentally, the connection is performed when the repair work of the BGA 30 is started.
The DC power supply 41 (voltage application means) schematically represents DC power from the converter 41 provided in the conduction confirmation means 40 (see FIG. 4) described later (details will be described later).

  As shown in FIG. 3B, a DC power source 41 and the like are connected corresponding to the five substrate-side terminal pairs 21a to 21e. Such board-side terminal pairs 21a to 21e are provided at positions corresponding to the component-side terminal pairs 31a to 31d near the four corners of the BGA 30 and the component-side terminal pair 31e near the center (FIG. 3A). reference).

  When the BGA 30 is heated by hot air from the nozzle 16 (see FIG. 1), the temperature near the center of the BGA 30 is likely to rise in plan view, and the temperature near the four corners is difficult to rise. Therefore, by grasping the melting state of the solder at the above-described position, it is possible to grasp the solder melting state in the entire BGA 30.

  Note that, as indicated by reference numeral 21 s in FIG. 3B, there is also a board-side terminal pair that is not used for the above-described conduction check. That is, the printed circuit board 20 has board-side terminal pairs 21a to 21e required for confirmation of conduction (confirmation of melting of the paste solder p), and wiring for detecting conduction is connected to the board-side terminal pairs 21a to 21e. 22a-22e and continuity detection terminals 23a-23e are printed in advance.

<Configuration of continuity confirmation means>
FIG. 4 is an explanatory diagram showing the configuration of the conduction confirmation means. The continuity confirmation means 40 is provided integrally or separately from the electronic component mounting apparatus 100, and confirms continuity (that is, solder bonding) between the board-side terminal pairs 21a to 21e.
In FIG. 4, only the component side terminal pairs 31 a to 31 e that are electrically connected in the internal circuit of the BGA 30 are illustrated, and the other component side terminals 31 are omitted. Further, the board-side terminals 21 other than the board-side terminal pairs 21a to 21e are omitted.

As shown in FIG. 4, the continuity confirmation unit 40 includes a converter 41, current sensors 42 a to 42 e, a continuity detection unit 43, a control unit 44, a storage unit 45, and a notification unit 46.
Converter 41 converts the three-phase AC voltage supplied from AC power supply 50 into a DC voltage in accordance with a command from control unit 44 and outputs the DC voltage between wires m and n. Note that wirings (5 × 2 = 10) branched from the wirings m and n are connected to the above-described five substrate-side terminal pairs 21a to 21e (see FIG. 3).
Below, although the structure corresponding to the board | substrate side terminal pair 21a is demonstrated, it is the same also about the structure corresponding to the other board | substrate side terminal pairs 21b-21e.

The current sensor 42 a (conduction detection means) detects a current flowing through the wiring h branched from the wiring n and outputs the current to the conduction detection unit 43. A resistor R and a switch 47a are connected in series to the current sensor 42a. The switch 47a is turned on / off in accordance with a command from the control unit 44.
The continuity confirmation means 40 is provided with a pair of terminals 48a connected to the pair of continuity confirmation terminals 23a. In FIG. 3B, the resistor R, the switches 47a to 47e, and the terminals 48a to 48e are not shown.

As shown in FIG. 4, the terminal 48 a is connected to a continuity detection terminal 23 a provided on the printed circuit board 20 via a wiring i. The connection is performed when the BGA 30 is mounted.
As described above, the continuity detection terminal 23 a is connected to the board-side terminal pair 21 a via the continuity detection wiring 22 a (thick line) printed on the printed board 20.

  And BGA30 is mounted so that the board | substrate side terminal pair 21a and the component side terminal pair 31a may oppose via the paste solder p (it mentions later for details). The component side terminal pairs 31a are electrically connected to each other in the internal circuit of the BGA 30 (see the alternate long and short dash line).

  The continuity detection unit 43 (conduction detection means) shown in FIG. 4 is based on the current value input from the current sensors 42a to 42e (ie, paste solder p) between the substrate-side terminal pairs 21a to 21e. ) Is detected. For example, when all the current values input from the current sensors 42a to 42e are equal to or greater than a predetermined value, the continuity detection unit 43 determines that the board-side terminal pairs 21a to 21e are conductive, and sends a predetermined continuity signal to the control unit 44. Output to.

The control unit 44 (determination unit) operates by reading a program stored in the storage unit 45 and performs overall control of the operation of the conduction confirmation unit 40. The control unit 44 turns on the switches 47a to 47e at a predetermined timing (for example, when a signal for starting heating of the BGA 30 is input from the control device 19 described above), and directs the switches to the board-side terminal pairs 21a to 21e. Apply voltage.
Thereafter, when the above-described continuity signal is input from the continuity detection unit 43, the control unit 44 outputs a continuity signal to the above-described control device 19 and stops the heating of the BGA 30 by the heating unit 14a (see FIG. 1). In addition, the control unit 44 outputs a control signal to the notification unit 46 to notify the user that the solder is joined. The user is a worker who manages the repair of the BGA 30 or the like.

  The storage unit 45 includes an HDD (Hard disk drive) and the like, and stores a program for operating the control unit 44, each set value, and the like. The notification unit 46 is an alarm, a lamp, or the like, and notifies the user that the solder joint has been completed.

<BGA repair process>
Hereinafter, a repair process for removing a defective BGA from the printed circuit board 20 and re-mounting the same type of BGA 30 as the BGA will be described in the following order.
1. Removal of BGA (not shown)
2. Connection with continuity confirmation means: FIG. 5 (a)
3. Paste solder printing: Fig. 5 (b)
4). Placement of BGA: Fig. 5 (c)
5. Application of voltage and start of heating: FIG. 6 (a)
6). Confirming conduction and stopping heating: FIG. 6 (b)

(1. Removal of BGA)
When removing the BGA 30 from the printed circuit board 20, the control device 19 (see FIG. 1) joins the BGA 30 and the printed circuit board 20 by injecting hot air from above with the nozzle 16 and radiating heat from below with the bottom heater 18. Melt the solder. Incidentally, the heating means 14a (see FIG. 1) and the bottom heater 18 are heated to a predetermined temperature set in advance.
Then, the BGA 30 is adsorbed by the nozzle 16 that has generated the negative pressure and removed from the printed circuit board 20. In addition, since the excess solder has adhered to the surface of the printed circuit board 20 of the state which removed BGA30, the said solder is removed using a solder sucking wire (not shown).

(2. Connection with continuity checking means)
Fig.5 (a) is explanatory drawing (side view) which shows the state by which the conduction | electrical_connection confirmation means was connected to the terminal for conduction | electrical_connection detection of a printed circuit board. Incidentally, the BGA 30 indicated by a broken line in FIG. 5A shows a correspondence relationship between the board-side terminal 21 and the component-side terminal 31. The hatched component-side terminal pair 31a is electrically connected in the internal circuit of the BGA 30. As described above, the DC power supply 41 schematically represents the DC voltage output from the converter 41 (see FIG. 4). Represents.

After removing the BGA 30, the continuity detection terminal 23a of the printed circuit board 20 is connected to the terminal 48a (see FIG. 4) provided in the continuity confirmation means 40 via the wiring i. The connection may be performed manually or automatically.
5 and 6, only the component-side terminal pair 31a and the board-side terminal pair 21a are shown, but the other component-side terminal pairs 31b to 31e and the board-side terminal pairs 21b to 21e are connected in the same manner. When performing the connection, the connection is made so that the voltage from the converter 41 is applied to a predetermined board-side terminal pair.

(3. Paste solder printing)
FIG.5 (b) is explanatory drawing (side view) which shows the state by which the paste solder was printed on the printed circuit board to which the conduction | electrical_connection confirmation means was connected.
The paste solder p (solder member) is used to join the component side terminals 31 (see FIG. 3A) arranged in a grid and the corresponding board side terminals 21 (see FIG. 3B). Used for. The paste solder p is in a state where an insulating flux and a conductive alloy are mixed.

When printing the paste solder p, a metal mask (not shown) in which holes are formed in a lattice shape in accordance with the board-side terminals 21 of the printed board 20 is prepared in advance on the metal plate. Incidentally, when repairing the BGA 30, a metal mask corresponding to the mounting location (size) of the BGA 30 is used in order to perform local soldering.
Then, on the printed circuit board 20 in a state where the defective BGA is removed, a metal mask is placed on the place where the BGA is installed. In this state, the board-side terminal 21 of the printed board 20 is exposed, and the other parts are hidden.

  Further, the paste solder p is printed (applied) on the board-side terminal 21 of the printed board 20 using a paste printer (not shown). The printing is performed not only on the board-side terminal pairs 21a to 21e described above, but also on all board-side terminals 21 corresponding to the component-side terminals 31 of the BGA 30.

After the paste solder p is printed, when the metal mask (not shown) is removed, the paste solder p is printed on all the board-side terminals 21 (see FIG. 5B).
When circuit elements are densely packed on the printed circuit board 20 and it is difficult to print the paste solder p on the board-side terminal 21, the paste solder p may be applied to the component-side terminal 31 of the BGA 30.

(4. BGA placement)
FIG.5 (c) is explanatory drawing (side view) which shows the state at the time of mounting BGA on the printed circuit board on which the paste solder was printed.
The printed circuit board 20 on which the paste solder p is printed is attached to the support base 17 (see FIG. 1), and positioning is performed while adsorbing the BGA 30 by the nozzle 16. That is, the component side terminals 31 of the BGA 30 are positioned so as to face the corresponding board side terminals 21 via the paste solder p. The positioning uses a position adjusting mechanism (not shown) in the xy direction provided on the support base 17 described above.

(5. Application of voltage and start of heating)
FIG. 6A is an explanatory view (side view) showing a state in which a BGA is placed on a printed board on which paste solder is printed and a voltage is applied between the board-side terminals.
As shown in FIG. 6A, in the state where the BGA 30 is placed on the printed board 20, the paste solder p is interposed between the corresponding board side terminal 21 and the component side terminal 31. In this state, the control unit 44 of the conduction confirmation unit 40 (see FIG. 4) switches on the switches 47a to 47e and applies a voltage to the board side terminal pairs 21a to 21e (voltage application process).
Incidentally, the user may manually determine the timing for switching the switches 47a to 47e.

6A shows only one board-side terminal pair 21a, the control unit 44 (see FIG. 4) applies a predetermined voltage to all board-side terminal pairs 21a to 21e. At this time, the control unit 44 outputs a signal to the control device 19 (see FIG. 4) of the electronic component mounting apparatus 100 to inform the start of voltage application.
Upon receiving the signal, the control device 19 injects hot air from the nozzle 16 (see FIG. 1) and radiates heat from the bottom heater 18 to heat the place where the BGA 30 is placed (heating process).
As described above, the paste solder p before melting is non-conductive (insulating). Therefore, even if the component-side terminal pair 31a shown by hatching in FIG. 6A is electrically connected in the internal circuit of the BGA 30, it is conductive between the board-side terminal pair 21a until the paste solder p is melted. There is no.

  That is, since the board-side terminal pair 21a is non-conductive at the start of heating, the detection value of the current sensor 42a is zero. The controller 19 (see FIG. 4) continues heating by the heating unit 14a until all the board-side terminal pairs 21a to 21e are turned on (that is, until a heating stop signal described later is input from the control unit 44).

(6. Confirm continuity and stop heating)
FIG. 6B is an explanatory view (side view) showing a state in which the paste solder and the component side terminals are melted and the substrate side terminal pair is electrically connected.
When voltage application and heating are continued from the state of FIG. 6A described above and the paste solder p is sufficiently heated and melted, the insulating flux volatilizes and only the conductive substance (alloy or the like) remains. Incidentally, as shown in FIG. 6B, the component-side terminal 31 is also melted together with the paste solder p (see symbol G).
If it does so, between the fuse | melted solder (paste solder p and component side terminal pair 31a) and the internal circuit of BGA30, between board | substrate side terminal pair 21a will conduct | electrically_connect and an electric current will flow.

The continuity detection unit 43 (see FIG. 4) outputs a continuity detection signal to the control unit 44 when continuity is detected between all the board-side terminal pairs 21a to 21e (conduction detection step). The continuity can be detected based on whether or not the current value input from the current sensors 42a to 42e is equal to or greater than a predetermined value.
When the continuity detection signal is input from the continuity detection unit 43, the control unit 44 outputs a heating stop signal to the control device 19 included in the electronic component mounting apparatus 100, and stops the heating of the BGA 30 (heating stop process). In addition, the control unit 44 operates the notification unit 46 to notify the user that conduction has been made by an alarm, a buzzer, or the like (that is, that the board-side terminal 21 and the component-side terminal 31 have been joined).

  In the present embodiment, the board-side terminal pairs 21a to 21e corresponding to the part-side terminal pairs 31a to 31e (see FIG. 3A) provided near the four corners and the center of the part-side terminals 31 of the BGA 30 are used. It is a continuity detection target (see FIG. 3B). Here, the component side terminal pairs 31a to 31d are located at the locations (four corners) where the temperature is difficult to rise among the component side terminals 31, and the component side terminal pair 31e is the location where the temperature is most likely to rise (center). Part).

  Therefore, when a voltage is applied to the board-side terminal pairs 21a to 21e corresponding to the above-described five component-side terminal pairs 31a to 31e and conduction is confirmed in all the board-side terminal pairs, There is a very high possibility that all the terminals 21 are bonded to the board-side terminal 21. Thus, in this embodiment, the success or failure of the solder joint of the BGA 30 is determined by confirming the continuity of the plurality of board-side terminal pairs 21a to 21e.

<Effect>
In the electronic component mounting apparatus 100 according to the present embodiment, whether the solder (paste solder p and component-side terminal 31) is normally joined by detecting conduction in the predetermined board-side terminal pairs 21a to 21e. Determine whether or not. Accordingly, it is possible to prevent a problem such as solder non-bonding between the BGA 30 and the printed circuit board 20.

  Moreover, when heating BGA30, it is necessary to heat in the range below predetermined heat-resistant temperature. In the present embodiment, when the conduction confirmation means 40 confirms conduction in all the board-side terminal pairs 21a to 21e, the control device 19 stops heating by the heating means 14a. This eliminates the extra heating time and ensures the reliability of the BGA 30.

FIG. 7A is a graph showing a temperature change near the center of the BGA and a temperature change near the four corners, and FIG. 7B is a graph showing a change in the output of the heating means. The time _{t 0} shown in FIG. 7 (a), FIG. 7 (b), a time at which to start heating by the heating means 14a, time _{t 3} is the time at which heating was stopped by the heating means 14a.
Also, BGA heat temperature _{T 2} higher by a predetermined temperature than the melting point _{T 1} of the paste solder p is preset (see FIG. 7 (a)).

As shown in FIG. 7A, after heating is started at time t ₀ , both the temperature near the center of the BGA 30 (solid line) and the temperatures near the four corners of the BGA 30 (broken lines) rise. Then, the vicinity of the center where the temperature is likely to rise reaches the solder melting point T ₁ at time t ₁ . However, in the vicinity of the four corners where the temperature hardly rises at the time t ₁ , the solder melting point is less than T ₁ and an unmelted state.
Then, at time _{t 2} reaches the corner near also solder the melting point of the BGA 30, the conduction in all of the board-side terminal pairs 21a~21e is confirmed at time _{t 3,} the control unit 19 stops the heating of the BGA 30 (Fig. 7 (b)). Even time _{t 3,} the temperature _{T A} in the vicinity of the four corners of the BGA 30, and the temperature _{T B} in the vicinity of the center is made lower than BGA heat temperature _{T 2.}

To perform solder joint properly, without exceeding the BGA heat temperature T ₂ in the up conspicuous place of the temperature, and it is necessary to heat at all connection points to above the solder melting point T ₁ sufficiently. In this embodiment, since the heating can be stopped immediately when the solder is melted in the entire BGA 30, it is possible to reliably avoid the problems of the BGA 30 due to the excessive heating while performing the heating necessary for the solder bonding.
Moreover, since the heating time of the BGA 30 is minimized, the efficiency of repair work of the BGA 30 can be improved.

  In addition, when mounting a surface-mounted component such as the BGA 30, the soldering location is not exposed, so it is impossible to visually confirm the success or failure of the soldering. Therefore, conventionally, a printed circuit board similar to the printed circuit board 20 on which the BGA 30 to be replaced is installed is prepared separately, and the condition for determining the heating time and temperature of the BGA 30 can be determined (temperature profile). I was doing). Note that the printed circuit board used to create the temperature profile has been discarded.

  Further, if heating is performed under the same conditions as the printed circuit board used for creating the temperature profile, confirmation that the soldering of the BGA 30 is successful cannot be obtained. Therefore, conventionally, the soldering is performed by setting the heating time longer than the actually required time, and thus there is a possibility that the heat resistance temperature of the BGA 30 and the electronic components around the BGA 30 may be exceeded.

On the other hand, in this embodiment, when the conduction | electrical_connection accompanying melting of the paste solder p is detected, it determines with soldering having been successful and stops heating. As a result, the success or failure of the solder joint can be determined directly by detecting continuity between the board-side terminal pairs 21a to 21e, rather than indirectly predicting using the temperature profile.
Therefore, it is possible to greatly reduce the risk of repair of BGA30 beyond BGA heat temperature T ₂ fails, it is possible to improve the yield in performing repair.

  In the present embodiment, it is not necessary to create a temperature profile in advance, so that it is not necessary to prepare a printed circuit board and a BGA for creating a temperature profile. Therefore, the repair work of the BGA 30 can be performed appropriately and efficiently without wasting the printed circuit board.

  In the present embodiment, the continuity detection wirings 22a to 22e and the continuity detection terminals 23a to 23e connected to the board side terminal pairs 21a to 21e are printed on the printed circuit board 20 in advance. Therefore, a voltage can be applied to the board | substrate side terminal pair 21a-21e corresponding to this by applying a voltage to the terminals 23a-23e for conduction | electrical_connection detection. In addition, since the conduction | electrical_connection detection terminals 23a-23e can be confirmed visually, wiring connection etc. can be performed easily.

≪Modification≫
As mentioned above, although the electronic component mounting apparatus 100 according to the present invention has been described in the above embodiment, the embodiment of the present invention is not limited to this, and various modifications can be made.
For example, in the above embodiment, the case where the BGA 30 is repaired (replaced) has been described. However, the present invention is not limited to this. That is, the present invention can also be applied when the BGA 30 is mounted on the printed circuit board 20 in the manufacturing stage.

  In the above embodiment, the case where the electronic component to be repaired is the BGA 30 has been described as an example. However, the present invention can also be applied to other surface-mounted electronic components (for example, CSP). Of the QFP (Quad Flat Package) and SOP (Small Outline Package) whose connection terminals extend from the periphery of the IC package, those that have a heat spreader (joint) at the bottom of the component are also "surface mounted components" included. Even in this case, the solder joint can be confirmed using the same method as in the above embodiment.

  Moreover, although the said embodiment demonstrated the case where there existed the component side terminal pairs 31a-31e electrically connected in the internal circuit required for circuit operation | movement of BGA30 itself, it is not restricted to this. That is, when an appropriate component-side terminal pair is not found (or is insufficient) in the internal circuit required for the circuit operation of the BGA 30, a component-side terminal pair dedicated to confirming conduction may be prepared in the BGA 30 in advance. .

Moreover, although the said embodiment demonstrated the case where a voltage was applied to the board | substrate side terminal pair 21a-21e corresponding to the four corners of BGA30 and the component side terminal pair 31a-31e of a center part, it does not restrict to this. That is, the conduction confirmation may be performed by applying a voltage to the board-side terminal pair corresponding to at least one component-side terminal pair.
In addition, it is preferable to include what corresponds to the some component side terminal pair located in the outer peripheral part (including four corners) of BGA30 as a board | substrate side terminal pair used as the object of conduction | electrical_connection detection. This is because the temperature of the outer periphery of the BGA 30 is moderately increased due to heating (that is, the temperature is difficult to increase), and when the conduction can be confirmed at that location, it can be said that other solder locations are also melted.

Moreover, although the said embodiment demonstrated the case where hot air was injected from the nozzle 16 and the BGA30 was heated uniformly, it is not restricted to this. For example, you may control separately the heating means which heats the center part of BGA30, and the heating means which heats an outer peripheral part. In this case, when conduction (that is, melting of solder) is confirmed in the central portion, heating of the central portion is stopped while continuing heating of the outer peripheral portion of the BGA 30. Thus, at the point where the temperature is likely to rise among the BGA 30, it can be reliably avoided from exceeding the BGA heat temperature _{T 2.}

Moreover, although the said embodiment demonstrated the case where the bottom heater 18 was provided, the bottom heater 18 may be abbreviate | omitted.
Moreover, although the said embodiment demonstrated the case where the control apparatus 19 stopped heating automatically, when conduction confirmation was carried out by the conduction confirmation means 40, it is not restricted to this. When continuity is confirmed by the continuity confirmation unit 40, the notification unit 46 may notify the user of continuity (that is, melting of solder), and the user may manually stop heating. In this case, the user may continue heating for a predetermined time after being notified of the conduction by the notification unit 46, and then stop heating. As a result, it is possible to perform soldering more reliably.

  Moreover, although the said embodiment demonstrated the case where the paste solder p was used as a solder member which joins the component side terminal 31 of BGA30 and the board | substrate side terminal 21 of the printed circuit board 20, it does not restrict to this. That is, other types of solder members (for example, conductive adhesives) may be used as long as the solder members are insulating before melting and conductive after melting.

  Moreover, in the said embodiment, about the case where wiring 22a-22e for conduction | electrical_connection detection connected to board | substrate side terminal pair 21a-21e is provided independently from the wiring required for the circuit operation at the time of use of the printed circuit board 20. Although explained, it is not limited to this. That is, the continuity detection wirings 22a to 22e may be provided so as to branch from the wirings necessary for the circuit operation described above.

  Moreover, although the said embodiment demonstrated the case where the printed circuit board 20 was a four-layer structure (A layer-D layer: refer FIG.2 (b)), it is not restricted to this. For example, it goes without saying that the printed circuit board 20 can be applied to a single-layer structure, a two-phase structure (a structure in which circuits are printed on both sides), and other multilayer structures.

DESCRIPTION OF SYMBOLS 100 Electronic component mounting apparatus 14a Heating means 18 Bottom heater (heating means)
19 Control device (heating means, determination means)
20 Printed circuit board 21 Board side terminal 21a, 21b, ..., 21e, 21s Board side terminal pair 22a, 22b, ..., 22e Conduction detection wiring 23a, 23b, ..., 23e Conduction detection terminal 30 BGA (Surface mount parts)
31 Component-side terminals 31a, 31b,..., 31e Component-side terminal pair 40 Continuity confirmation means 41 Converter, DC power supply (voltage application means)
42a, 42b, ..., 42e Current sensor (conduction detection means)
43 Continuity detection unit (conduction detection means)
44 Control unit (voltage application means, determination means)
p Paste solder (solder member)

Claims (4)

Heating means for soldering a plurality of component-side terminals included in the surface mount component and a plurality of substrate-side terminals included in the printed circuit board by heating the insulating solder member before melting and the conductive solder member after melting. ,
Voltage applying means for applying a voltage to a predetermined one of the substrate-side terminals;
Continuity detection means for detecting continuity from the printed circuit board through the surface-mounted component due to the voltage applied by the voltage application means;
An electronic component mounting apparatus comprising: determination means for determining success or failure of the soldering by monitoring a conduction state by the conduction detection means. The printed circuit board on which the surface mounting component is mounted by the electronic component mounting apparatus according to claim 1,
A printed circuit board comprising a plurality of continuity detection wirings, one end of which is connected to the predetermined terminal among the board side terminals and the other end of which is connected to a continuity detection terminal for detecting the continuity. The predetermined terminal is predetermined so that the component-side terminal corresponding to the predetermined terminal among the substrate-side terminals is located at a plurality of locations including an outer peripheral portion of the surface-mounted component. The printed circuit board according to claim 2. A heating step of soldering a plurality of component side terminals included in the surface mount component and a plurality of substrate side terminals included in the printed circuit board by heating the insulating solder member before melting and the conductive solder member after melting. ,
At least during the heating step, a voltage applying step of applying a voltage to a predetermined terminal among the substrate side terminals,
A conduction detecting step of detecting conduction from the printed circuit board through the surface-mounted component due to a voltage applied in the voltage applying step;
A determination step of determining success or failure of the soldering by monitoring a conduction state in the conduction detection step.

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