U.S. patent application number 13/981871 was filed with the patent office on 2014-03-13 for electronic component mounting line and electronic component mounting method.
This patent application is currently assigned to PANASONIC CORPORATION. The applicant listed for this patent is PANASONIC CORPORATION. Invention is credited to Tadashi Maeda, Hiroki Maruo, Tsubasa Saeki.
Application Number | 20140073088 13/981871 |
Document ID | / |
Family ID | 48668019 |
Filed Date | 2014-03-13 |
United States Patent
Application |
20140073088 |
Kind Code |
A1 |
Maeda; Tadashi ; et
al. |
March 13, 2014 |
ELECTRONIC COMPONENT MOUNTING LINE AND ELECTRONIC COMPONENT
MOUNTING METHOD
Abstract
Disclosed is an electronic component mounting line on which a
substrate undergoes solder paste printing, electronic component
placements, and then reflow, while being moved from upstream to
downstream. The line includes: a substrate feeding machine; a
printing machine for applying solder paste to a first placement
area of the substrate; a first electronic component placement
machine for placing a first electronic component on the first
placement area; a second electronic component placement machine for
dispensing a thermosetting resin onto a reinforcement position on a
peripheral edge portion of a second placement area of the
substrate, and for placing on the area the second electronic
component having solder bumps; and a reflow machine for bonding the
electronic components to the substrate, by heating and cooling the
resultant. The second electronic component is placed after the
resin is dispensed, such that a peripheral edge portion thereof
comes in contact with the resin.
Inventors: |
Maeda; Tadashi; (Yamanashi,
JP) ; Maruo; Hiroki; (Osaka, JP) ; Saeki;
Tsubasa; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PANASONIC CORPORATION |
Osaka |
|
JP |
|
|
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
48668019 |
Appl. No.: |
13/981871 |
Filed: |
October 19, 2012 |
PCT Filed: |
October 19, 2012 |
PCT NO: |
PCT/JP2012/006721 |
371 Date: |
July 25, 2013 |
Current U.S.
Class: |
438/107 |
Current CPC
Class: |
H01L 2924/351 20130101;
B23K 2101/42 20180801; H01L 24/81 20130101; B23K 3/0669 20130101;
H05K 3/3442 20130101; H05K 2203/0126 20130101; H05K 3/305 20130101;
H05K 13/0469 20130101; B23K 1/203 20130101; Y02P 70/613 20151101;
Y02P 70/50 20151101; Y10T 29/49169 20150115; H05K 13/0465 20130101;
H05K 3/3436 20130101; B23K 1/008 20130101; B23K 1/0008 20130101;
H01L 2924/351 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
438/107 |
International
Class: |
H01L 23/00 20060101
H01L023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2011 |
JP |
2011-282124 |
Claims
1. An electronic component mounting line on which a substrate
undergoes solder paste printing, electronic component placements,
and reflow in recited order, while being moved from upstream to
downstream, the line comprising: a substrate feeding machine for
feeding the substrate having a first placement area for placement
of a first electronic component with a solder paste between the
area and the component, and a second placement area for placement
of a second electronic component having solder bumps; a screen
printing machine for applying the solder paste to the first
placement area of the substrate that has been fed by the substrate
feeding machine; a first electronic component placement machine for
placing the first electronic component on the first placement area
of the substrate to which the solder paste has been applied; a
second electronic component placement machine comprising: a
dispensing head for dispensing a thermosetting resin onto at least
one reinforcement position arranged on a peripheral edge portion of
the second placement area of the substrate; and a placing head for
placing the second electronic component on the second placement
area of the substrate; and a reflow machine for bonding the first
and second electronic components to the substrate, by heating the
substrate on which the first and second electronic components have
been placed, to melt the solder paste and the solder bumps and to
cure the thermosetting resin; and then cooling the substrate, the
second electronic component placement machine, after dispensing the
thermosetting resin onto the reinforcement position, places the
second electronic component such that a peripheral edge portion of
the second electronic component comes in contact with the
thermosetting resin that has been dispensed onto the reinforcement
position.
2. The electronic component mounting line in accordance with claim
1, wherein the second electronic component placement machine has an
upstream-side substrate holder and a downstream-side substrate
holder, the substrate is held by the upstream-side substrate holder
as the thermosetting resin is dispensed onto the reinforcement
position, and is then moved to the downstream-side substrate
holder, and the substrate is held by the downstream-side substrate
holder as the second electronic component is placed on the second
placement area.
3. The electronic component mounting line in accordance with claim
2, wherein the second electronic component placement machine, while
dispensing the thermosetting resin onto the reinforcement position
on the substrate held by the upstream-side substrate holder, also
places the second electronic component on the second placement area
of another substrate held by the downstream-side substrate
holder.
4. The electronic component mounting line in accordance with claim
1, wherein the second electronic component placement machine has a
transferring unit for forming a flux coating, and, before placing
the second electronic component on the second placement area,
brings the flux coating in contact with the solder bumps on the
second electronic component, to transfer the flux to the solder
bumps.
5. An electronic component mounting method in which a first
electronic component and a second electronic component are mounted
on a substrate that is being moved from upstream to downstream on
an electronic component mounting line, the first electronic
component having connection terminals for solder paste connection,
the second component having solder bumps, the method comprising: a
first step of preparing the substrate including: a first placement
area having first electrodes for connection to the connection
terminals; and a second placement area having second electrodes for
connection to the solder bumps; a second step of applying a solder
paste to the first electrodes, by using a screen printing machine
arranged on the electronic component mounting line; a third step of
placing the first electronic component on the substrate such that
the connection terminals land on the solder paste on the
corresponding first electrodes; a fourth step of dispensing a
thermosetting resin onto at least one reinforcement position
arranged on a peripheral edge portion of the second placement area;
a fifth step of placing the second electronic component on the
substrate such that the solder bumps land on the corresponding
second electrodes; and bringing the thermosetting resin that has
been applied to the reinforcement position, in contact with a
peripheral edge portion of the second electronic component; and a
sixth step of bonding the first and second electronic components to
the substrate by heating the substrate on which the first and
second electronic components have been placed, to melt the solder
paste and the solder bumps and to cure the thermosetting resin, by
using a reflow machine arranged on the electronic component
mounting line; and then cooling the substrate, the third step being
performed by a first electronic component placement machine
arranged on the electronic component mounting line; and the fourth
and fifth steps being performed in recited order, by a second
electronic component placement machine comprising a dispensing head
for dispensing the thermosetting resin and a placing head for
placing the second electronic component.
6. The electronic component mounting method in accordance with
claim 5, wherein the second electronic component placement machine
has an upstream-side substrate holder and a downstream-side
substrate holder, in the fourth step, the thermosetting resin is
dispensed onto the reinforcement position on the substrate held by
the upstream-side substrate holder, and in the fifth step, the
second electronic component is placed on the second placement area
of the substrate that has been moved from the upstream-side
substrate holder to the downstream-side substrate holder and is
held by the downstream-side substrate holder.
7. The electronic component mounting method in accordance with
claim 6, wherein the fourth step as well as the fifth step are
performed, such that, while the thermosetting resin is being
dispensed onto the reinforcement position on the substrate held by
the upstream-side substrate holder, the second electronic component
is placed on the second placement area of another substrate held by
the downstream-side substrate holder.
8. The electronic component mounting method in accordance with
claim 5, wherein the second electronic component placement machine
has a transferring unit for forming a flux coating, and in the
fifth step, before placement of the second electronic component on
the second placement area, the solder bumps on the second
electronic component are brought in contact with the flux coating,
to transfer the flux to the solder bumps.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electronic component
mounting line for mounting on a substrate, small electronic
components such as chip components and electronic components such
as chip-scale packages.
BACKGROUND ART
[0002] Electronic components such as integrated circuits,
resistors, and capacitors are mounted on printed circuit boards.
With electronic components made more compact in recent years,
electronic components mounted on one printed circuit board are
increasing in number and kind. Due to demands for downsized
electronic components, chip scale packages (CSPs) are placed on
substrates.
[0003] A CSP has a main surface on which terminals are arranged in
a regular array, and a solder bump is formed on each of these
terminals. For a CSP to be surface mounted on a printed circuit
board, the solder bumps formed on the terminals are made to land on
electrodes called lands on the printed circuit board. This is
followed by heating, reflowing, and cooling in this order, thereby
creating an interconnection between the CSP and the printed circuit
board. This enables the terminals on the CSP to be electrically
connected to the lands on the printed circuit board, and to be
bonded to the printed circuit board due to the solder.
[0004] When thermal stress generated by thermal cycles, or external
force, is applied to a CSP that is surface mounted on a printed
circuit board, the portion of the CSP bonded to the printed circuit
board may lack sufficient strength if it is only due to solder.
Moreover, connection only due to solder lacks sufficient strength
against impact caused by dropping. Therefore, reinforcing resin is
used to reinforce the solder-bonded portion of the CSP.
[0005] One method of reinforcing the solder-bonded portion by using
reinforcing resin, is to allow an underfill material to enter the
interstices between the main surface of the CSP with the solder
bumps thereon and the printed circuit board. Moreover, Patent
Literature 1 proposes a method of providing reinforcing resin on a
printed circuit board in advance before placing thereon an
electronic component such as a CSP, only at positions
(reinforcement positions) which correspond to those on a peripheral
edge portion of the electronic component. This method is much
better compared to using an underfill material, in terms of
facilitating repair work on electronic components.
[0006] In addition to CSPs, the following are usually mounted on
printed circuit boards: electronic chip components mounted by using
solder paste, such as chip resistors and chip capacitors; and
components with lead-wires such as connectors. Moreover, the
facility used for mounting of such electronic components on printed
circuit boards, is an electronic component mounting line which
comprises in the given order: a screen printing machine for
printing solder paste; an adhesive dispensing machine for
dispensing an adhesive for temporary bonding; an electronic
component placement machine (first electronic component placement
machine) for placing small electronic chip components; an
electronic component placement machine (second electronic component
placement machine) for placing large electronic components
including CSPs, and other kinds of electronic components such as
connectors; and a reflow machine for melting solder. The
accomplished configuration of such an electronic component mounting
line has a history of over 20 years, and is capable of performing
in one continuous flow, processes which involve: placement of
electronic components of sizes ranging from miniscule to large, up
to 30 millimeters square; and reflow of the resultant assembly.
PRIOR ART
Patent Literature
[0007] [Patent Literature 1] Japan Laid-Open Patent Publication No.
2008-78431
SUMMARY OF INVENTION
Technical Problem
[0008] Usually, the following steps of (1) to (5) are performed in
the given order, when a conventional electronic component mounting
line is utilized for mounting on one printed circuit board, CSPs
through solder bump bonding and other components through solder
paste bonding: (1) a printed circuit board is conveyed on the line
to a screen printing machine, and this machine screen prints solder
paste onto the printed circuit board at positions where electronic
components are to be mounted; (2) an adhesive dispensing machine
dispenses an adhesive serving as reinforcing resin, on the printed
circuit board, specifically at a position corresponding to that of
a peripheral edge portion of the CSP; (3) an electronic component
placement machine places on the printed circuit board, the
electronic components to be mounted by using solder paste; (4)
another electronic component placement machine places CSPs, etc. on
the printed circuit board; and then (5) the resultant assembly is
reflowed.
[0009] However, a conventional electronic component mounting line
can cause the following problem.
[0010] As illustrated in FIG. 10(a), the reinforcing resin 105 in
the step (2) needs to be dispensed on the printed circuit board 101
at a reinforcement position 104 arranged close to a land 102b, with
its height adjusted for contact with the CSP 210 that would later
be placed on the printed circuit board 101 in the step (4). That
is, the reinforcing resin 105 is adjusted in height so that it
reaches an inner substrate 211 of the CSP 210, when the CSP 210 is
placed on the printed circuit board 101.
[0011] Here, when the step (3) of placing the electronic components
to be mounted by using solder paste comes between the steps (2) and
(4), idle time is created between the steps (2) and (4), and the
reinforcing resin may flow out in a planar direction during this
interval. As a result, the reinforcing resin may come in contact
with the solder paste that has been placed and printed on the land
in the step (1), and this may cause reduced reactivity of the
solder paste. Thus, there is a possibility of poor bonding due to
insufficient melting of the solder during reflow, and due to
insufficient wetting by and spreading of the solder. Moreover, when
the reinforcing resin gradually loses its shape over time and its
height becomes too low, as illustrated in FIG. 10(b), the
reinforcing resin cannot come in contact with the CSP 210 when the
CSP 210 is placed on the substrate. Thus, there are instances where
the initial aim of reinforcement cannot be achieved.
[0012] The present invention aims to provide an electronic
component mounting line and an electronic component mounting
method, both capable of preventing the foregoing problem,
specifically, poor quality of mounting of electronic components on
a substrate due to reinforcing resin gradually flowing over
time.
Solution to Problem
[0013] An electronic component mounting line of the present
invention enables a substrate to undergo solder paste printing,
electronic component placements, and reflow in this order, while
being moved from upstream to downstream, the line comprising:
[0014] a substrate feeding machine for feeding the substrate having
a first placement area for placement of a first electronic
component with a solder paste between the area and the component,
and a second placement area for placement of a second electronic
component having solder bumps;
[0015] a screen printing machine for applying the solder paste to
the first placement area of the substrate that has been fed by the
substrate feeding machine;
[0016] a first electronic component placement machine for placing
the first electronic component on the first placement area of the
substrate to which the solder paste has been applied;
[0017] a second electronic component placement machine comprising:
a dispensing head for dispensing a thermosetting resin onto at
least one reinforcement position arranged on a peripheral edge
portion of the second placement area of the substrate; and a
placing head for placing the second electronic component on the
second placement area of the substrate; and
[0018] a reflow machine for bonding the first and second electronic
components to the substrate, by heating the substrate on which the
first and second electronic components have been placed, to melt
the solder paste and the solder bumps and to cure the thermosetting
resin; and then cooling the substrate,
[0019] the second electronic component placement machine, after
dispensing the thermosetting resin onto the reinforcement position,
places the second electronic component such that a peripheral edge
portion of the second electronic component comes in contact with
the thermosetting resin that has been dispensed onto the
reinforcement position.
[0020] Moreover, an electronic component mounting method of the
present invention enables a first electronic component and a second
electronic component to be mounted on a substrate that is being
moved from upstream to downstream on an electronic component
mounting line, the first electronic component having connection
terminals for solder paste connection, the second component having
solder bumps, the method comprising:
[0021] a first step of preparing the substrate including: a first
placement area having first electrodes for connection to the
connection terminals; and a second placement area having second
electrodes for connection to the solder bumps;
[0022] a second step of applying a solder paste to the first
electrodes, by using a screen printing machine arranged on the
electronic component mounting line;
[0023] a third step of placing the first electronic component on
the substrate such that the connection terminals land on the solder
paste on the corresponding first electrodes;
[0024] a fourth step of dispensing a thermosetting resin onto at
least one reinforcement position arranged on a peripheral edge
portion of the second placement area;
[0025] a fifth step of placing the second electronic component on
the substrate such that the solder bumps land on the corresponding
second electrodes; and bringing the thermosetting resin that has
been applied to the reinforcement position, in contact with a
peripheral edge portion of the second electronic component; and
[0026] a sixth step of bonding the first and second electronic
components to the substrate by heating the substrate on which the
first and second electronic components have been placed, to melt
the solder paste and the solder bumps and to cure the thermosetting
resin, by using a reflow machine arranged on the electronic
component mounting line; and then cooling the substrate,
[0027] the third step being performed by a first electronic
component placement machine arranged on the electronic component
mounting line; and the fourth and fifth steps being performed in
recited order, by a second electronic component placement machine
comprising a dispensing head for dispensing the thermosetting resin
and a placing head for placing the second electronic component.
Advantageous Effects of Invention
[0028] According to the electronic component mounting line and the
electronic component mounting method of the present invention, the
second electronic component placement performs the step of
dispensing the thermosetting resin onto the reinforcement position,
and then, the step of placing the second electronic component.
Therefore, the second electronic component is placed on the
substrate after the thermosetting resin is dispensed onto the
reinforcement position, without idle time in between the two steps.
This results in preventing poor bonding caused by the thermosetting
resin, provided as a reinforcing resin, losing its shape over time
and consequently spreading out or deforming.
[0029] While the novel features of the invention are set forth
particularly in the appended claims, the invention, both as to
organization and content, will be better understood and
appreciated, along with other objects and features thereof, from
the following detailed description taken in conjunction with the
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0030] FIG. 1 is an oblique view of a first electronic component
which is a chip component.
[0031] FIG. 2A is a vertical sectional view of a second electronic
component having solder bumps.
[0032] FIG. 2B is a bottom view of the second electronic component
of FIG. 2A.
[0033] FIG. 3 is a vertical sectional view of an example of a
substrate before the electronic component is placed thereon.
[0034] FIG. 4 is an explanatory diagram showing the overall
configuration of an electronic component mounting line A according
to one embodiment of the present invention.
[0035] FIG. 5 is a top view of a part of the electronic component
mounting line, the part having a configuration which includes a
first electronic component placement machine and a second
electronic component placement machine, linked in this order.
[0036] FIG. 6A is conceptual drawing of a transferring unit as seen
from above, which is for forming a flux coating.
[0037] FIG. 6B is a conceptual drawing of the transferring unit of
FIG. 6A in vertical section, showing how it operates when the flux
coating is formed.
[0038] FIG. 6C is a conceptual drawing of the transferring unit of
FIG. 6A in vertical section, showing when the solder bumps on the
CSP are brought into contact with the flux coating, to transfer the
flux to the solder bumps.
[0039] FIG. 7 is an explanatory drawing to explain the former
process in an electronic component mounting method for the
electronic component mounting line.
[0040] FIG. 8 is an explanatory drawing to explain the latter
process in the electronic component mounting method for the
electronic component mounting line.
[0041] FIG. 9 is a top view of the second electronic component
placement machine with a modified configuration.
[0042] FIG. 10 is a drawing showing the second electronic component
and a reinforcing resin in vertical section, to explain the
relation between the two in terms of height.
DESCRIPTION OF EMBODIMENTS
[0043] First, a description will be given on a first electronic
component, a second electronic component, and a substrate which
constitute a substrate with electronic components mounted thereon
that is produced by utilizing an electronic component mounting line
of the present invention.
[0044] FIG. 1 is an oblique view of an example of a first
electronic component 200. The first electronic component 200 has at
least one connection terminal 201 bonded thereto with a solder
paste. Examples of electronic components that are bonded with
solder paste include: chip components as exemplified by 0402 size
and 1005 size chips; and components with lead-wires such as
transistors, etc. Moreover, even in the case of components with
bumps, they are classified as the first electronic component if
they are mounted by using solder paste and do not require
reinforcement using reinforcing resin, or application (transfer) of
flux to the bumps.
[0045] FIG. 2A is a vertical sectional view of an example of a
second electronic component 210, and FIG. 2B is a bottom view
thereof. The second electronic component 210 is a CSP comprising: a
thin inner substrate 211; and a semiconductor device 212 mounted on
the upper surface thereof and encapsulated with a resin sealant
213. The lower surface of the inner substrate 211 corresponds to a
main surface 211s of the second electronic component 210; the main
surface 211s has thereon terminals arranged in a regular array; and
the terminals have thereon solder bumps 214, respectively. The
second electronic component requires reinforcement using
reinforcing resin; and therefore, before the second electronic
component is placed on a substrate, flux is applied (transferred)
to the solder bumps 214.
[0046] As illustrated in FIG. 3, the substrate 101 comprises: a
first placement area and a second placement area. The first
placement area has thereon first electrodes 102a for connection to
the connection terminals 201 of the first electronic component 200.
The second placement area has thereon second electrodes 102b for
connection to the solder bumps 214, respectively, of the second
electronic component 210. Arranged on a peripheral edge portion of
the second placement area corresponding to a peripheral edge
portion of the second electronic component 210, is at least one
reinforcement position 104 for application of reinforcing resin,
that is, of thermosetting resin, thereto.
[0047] On the substrate 101, usually two or more of the
reinforcement positions 104 are arranged on the peripheral edge
portion of the second placement area having the second electrodes
102b thereon. Here, the peripheral edge portion of the second
placement area on the substrate 101 is a frame-like area which
corresponds to the peripheral edge portion 211x of the main surface
211s of the second electronic component 210 to be placed on the
second placement area. The reinforcement positions 104 are arranged
on the frame-like area, at predetermined positions. The main
surface of a typical CSP is rectangular. On the rectangular-shaped
second electronic component, the reinforcement positions are
preferably arranged such that they correspond to at least the four
corners, or positions close thereto, of the rectangular shape.
[0048] Next, a description will be given on an example of how
relevant machines are arranged on the electronic component mounting
line of the present embodiment, with reference to drawings. FIG. 4
shows the arrangement of the machines, in its entirety, on the
electronic component mounting line 300 according to the present
embodiment.
[0049] The electronic component mounting line comprises machines
that are linked to one another at their respective substrate
carrying conveyors. The line enables a substrate to undergo solder
paste printing, electronic component placements, reflow, etc. in
this order, as the substrate is carried from upstream to
downstream, by the substrate carrying conveyors that are linked to
one another. The electronic component mounting line 300
comprises:
[0050] (i) a substrate feeding machine 301 for feeding the
substrate 101 on which the electronic components are to be
mounted;
[0051] (ii) a screen printing machine 302 for applying the solder
paste to the pre-selected electrodes (first electrodes 102a)
provided on the first placement area of the substrate 101 that has
been fed by the substrate feeding machine 301;
[0052] (iii) a first electronic component placement machine 303
comprising a first placing head, for placing the first electronic
component 200 on the first electrodes 102a to which the solder
paste has been applied;
[0053] (iv) a second electronic component placement machine 304X
comprising: a dispensing head for dispensing the reinforcing resin
105 onto the reinforcement positions 104 on the substrate 101; and
a second placing head for placing the second electronic component
210 on the second placement area;
[0054] (v) a reflow machine 305 arranged to be after the second
electronic component placement machine 304X, for solder bonding the
first electronic component 200 and the second electronic component
210 to the substrate 101, by heating the substrate 101 to melt the
solder thereon; and
[0055] (vi) a substrate collecting machine 306.
[0056] FIG. 5 is a top view of a part of the electronic component
mounting line 300, the part having a configuration which includes
the first electronic component placement machine 303 and the second
electronic component placement machine 304X, linked in this order.
As illustrated in FIG. 5, the first electronic component placement
machine 303 and the second electronic component placement machine
304X form a line for carrying the substrate 101 that comes from the
screen printing machine 302. This line is formed through the
attachment of the substrate carrying conveyors 309a and 309b that
are respectively provided on the corresponding machines 303 and
304X. The substrate carrying conveyors 309a and 309b serve to carry
the substrate to specific working locations (substrate holders)
within the respective machines 303 and 304X, and position it there
where the electronic component placements and the resin dispensing
are to be performed. Note that the arrow in FIG. 5 indicates the
upstream-to-downstream direction in which the electronic component
mounting line 300 runs.
[0057] The first electronic component placement machine 303 places
the first electronic component 200 on the first electrodes 102a
disposed on the substrate 101 that comes from the screen printing
machine 302. The first electronic component placement machine 303
comprises: the substrate carrying conveyor 309a disposed in the
middle; a first component feeding unit 313 disposed on both sides
of the substrate carrying conveyor 309a; and the first placing head
323. The substrate carrying conveyor 309a comprises a substrate
holder 310a which holds the substrate while it is worked on by the
first placing head 323.
[0058] Arranged on the first component feeding unit 313, are tape
feeders for feeding the first electronic component 200. The first
placing head 323 is supported by an X-Y movement mechanism (not
illustrated). This X-Y movement mechanism is controlled by a
pre-selected control unit, and enables movements of the first
placing head 323 to and from the first component feeding unit 313
and the substrate carrying conveyor 309a in the space
thereabove.
[0059] The first placing head 323 comprises a suction nozzle 323d
that moves up and down due to a built-in up-and-down movement
mechanism. The placing head 323 picks up the first electronic
component 200 from the first component feeding unit 313, by the
suction nozzle 323d moving up/down and performing suction; and
then, places the first electronic component 200 on the substrate
101, by the suction nozzle 323d moving up/down and performing
suction release (vacuum break) from above the first placement area
of the substrate 101.
[0060] The first placing head 323 places the connection terminal
201 of the first electronic component 200 on the substrate 101,
such that it lands on the corresponding first electrode 102a to
which the solder paste has been applied in advance.
[0061] The second electronic component placement machine 304X has
the following functions: to dispense the reinforcing resin 105 on
the substrate 101 that comes from the first electronic component
placement machine 303, at the reinforcement positions 104 arranged
on the peripheral edge portion of the second placement area which
includes the second electrodes 102b; and to place the second
electronic component, such that the peripheral edge portion thereof
comes in contact with the reinforcing resin 105 that has been
dispensed onto the reinforcement positions 104. That is, the second
electronic component placement machine 304X is configured to
perform the following steps in the given order: the step of
dispensing the reinforcing resin 105 onto the reinforcement
positions 104; and the step of placing the second electronic
component 210 on the second placement area.
[0062] Specifically, the second electronic component placement
machine 304X comprises: the substrate carrying conveyor 309b
disposed in the middle; and the dispensing head 324 having a
dispensing nozzle 324d for ejecting the reinforcing resin 105; a
second component feeding unit 315; and the second placing head 325.
The substrate carrying conveyor 309b comprises a substrate holder
310b which holds the substrate while it is worked on by the
dispensing head 324 and the second placing head 325.
[0063] The dispensing head 324 is supported by an X-Y-Z movement
mechanism (not illustrated). This X-Y-Z movement mechanism is
controlled by a pre-selected control unit, and enables movements of
the dispensing head 324 in a horizontal direction and up-and-down
directions in the space above the substrate carrying conveyor 309b.
The movements of the dispensing head 324, the ejection of the
reinforcing resin 105 from the dispensing nozzle 324d, etc. are
controlled by commands from the control unit.
[0064] The second component feeding unit 315 is a tray feeder, and
arranged thereon are trays accommodating the second electronic
components 210, respectively.
[0065] The second placing head 325 is supported by an X-Y movement
mechanism (not illustrated). This X-Y movement mechanism is
controlled by a pre-selected control unit, and enables movements of
the second placing head 325 to and from the second component
feeding unit 315 and the substrate carrying conveyor 309c in the
space thereabove. The second placing head 325 comprises a suction
nozzle 325d that moves up and down due to a built-in up-and-down
movement mechanism. The second placing head 325 picks up the second
electronic component 210 from the second component feeding unit
315, by the suction nozzle 325d moving up/down and performing
suction; and then, places the second electronic component 210 on
the substrate 101, by the suction nozzle 325d moving up/down and
performing suction release (vacuum break) from above the second
placement area of the substrate 101.
[0066] The second electronic component placement machine 304X may
include a transferring unit 320 for providing a flux coating. The
transferring unit 320 has a mechanism capable of providing the flux
coating with a thickness suited for transferring the flux to the
bumps 214 on the second electronic component 210. For example, as
illustrated in FIG. 6A, the transferring unit 320 comprises: a base
table 320a disposed at the bottom; a transferring table 321
disposed on the base table 320a; and a squeegee unit 322 disposed
on the transferring table 321. The squeegee unit 322 comprises a
first squeegee member 322a and a second squeegee member 322b, both
with a length nearly equal to the length of the transferring table
321 in a Y-axis direction; and they are arranged in parallel to the
Y-axis direction with a certain amount of space therebetween. The
squeegee members can freely move up and down due to an up-and-down
movement mechanism built in the squeegee unit 322. That is, they
can move freely, to and fro, within the coating formed on the
transferring table 321. As illustrated in FIG. 6B, the transferring
unit 320 produces the flux coating by moving the squeegee units 322
in a relatively horizontal direction within the transferring table
321, so as to spread the flux on the transferring table 321 to
obtain a thin layer thereof.
[0067] After picking up the second electronic component 210, the
second placing head 325 moves to a position above the transferring
unit 320; and as illustrated in FIG. 6C, makes the suction nozzle
325d move down and up so that the solder bumps 214 on the second
electronic component 210 come in contact with the coating of the
flux 206, thereby transferring the flux 206 to the solder bumps
214. Thereafter, the second placing head 325 moves to the second
placement area of the substrate, and places the second electronic
component 210 on the substrate 101, such that the solder bumps 214
land on the corresponding second electrodes 102b. Such movements of
the second placing head 325 are controlled by commands from a
pre-selected control unit.
[0068] Here, on the electronic component mounting line 300 of FIGS.
4 and 5, the first electronic component placement machine 303 is
arranged upstream of the second electronic component placement
machine 304X. However, the order in which the first electronic
component placement machine 303 and the second electronic component
placement machine 304X are arranged, is not limited to the above.
That is, the first electronic component placement machine 303 may
be arranged downstream of the second electronic component placement
machine 304X. Moreover, the electronic component mounting line may
comprise two or more of the first electronic component placement
machines, and likewise, may comprise two or more of the second
electronic component placement machines. Furthermore, these first
electronic component placement machines and these second electronic
component placement machines can be arranged in any order.
[0069] Next, a description will be given on the method for
producing a substrate with electronic components mounted thereon,
by utilizing the electronic component mounting line 300 of the
present invention.
[0070] According to FIGS. 7 and 8, first, the substrate 101 with no
components placed thereon as illustrated in FIG. 7(a) is carried
out of the substrate feeding machine 301 (step one), and is sent to
the screen printing machine 302.
[0071] Next, the screen printing machine 302 performs the solder
printing process (step two) in which the solder paste 103 is
printed on the first electrodes 102a disposed on the substrate 101
(FIG. 7(b)). After completing printing of the solder paste, the
screen printing machine 302 sends the substrate 101 to the first
electronic component placement machine 303.
[0072] Next, as illustrated in FIG. 7(c), the first electronic
component placement machine 303 performs a first electronic
component placement process (step three) in which the first
electronic component 200 is placed on the substrate 101.
Specifically, the substrate carrying conveyor 309a carries the
substrate 101 to a predetermined working location and positions it
there; the suction nozzle 323d of the placing head 323 holds by
suction, the first electronic component 200 fed from the first
component feeding unit 313; and then, the placing head 323 moves in
a horizontal direction to position the first electronic component
200 at the first placement area.
[0073] Next, the suction nozzle 323d moves up/down and releases the
hold, so that the connection terminals 211 of the first electronic
component 200 land on the solder paste that has been printed on the
first electrodes 102a, thereby placing the first electronic
component 200 on the substrate 101. After completing placement of
the first electronic component, the first electronic component
placement machine 303 drives the substrate carrying conveyor 309a
and sends the substrate 101 to the second electronic component
placement machine 304X.
[0074] Next, as illustrated in FIG. 8(a), the second electronic
component placement machine 304X performs a resin dispensing
process (step four) in which the reinforcing resin 105 is dispensed
on the substrate 101, at the reinforcement positions 104 arranged
on the peripheral edge portion of the second placement area
intended for placement of the second electronic component 210.
Specifically, the substrate carrying conveyor 309b carries the
substrate 101 to the predetermined substrate holder 310b and
positions it there; the dispensing head 324 moves in a horizontal
direction and positions the dispensing nozzle 324d above the
reinforcement position 104; and then, the dispensing nozzle 324d
dispenses the reinforcing resin 105 onto the reinforcement position
104. The dispensing pattern of the reinforcing resin 105 is not
particularly limited, and for example, is dispensed onto the
reinforcement positions corresponding to the four corners of the
rectangular-shaped second electronic component, which are on the
peripheral edge portion thereof.
[0075] The reinforcing resin 105 is dispensed to have a height
sufficient for the reinforcing resin 105 to come in contact with
the inner substrate 211 which is a part of the package of the
second electronic component 210 to be placed on the substrate 101
in a later process. That is, the viscosity and thixotropy of the
reinforcing resin 105 are adjusted such that, as illustrated in
FIG. 10(a), the height thereof is sufficient for the reinforcing
resin 105 to reach the inner substrate 211 of the second electronic
component 210, when the second electronic component 210 is placed
on the substrate 101.
[0076] A thermosetting resin is used as the reinforcing resin.
Examples of the thermosetting resin include epoxy resin, phenol
resin, melamine resin, and urethane resin.
[0077] After completing dispensing of the reinforcing resin 105
onto all of the reinforcement positions 104, the second electronic
component placement machine 304X goes on to perform the second
electronic component placement process (step five) in which the
second electronic component 210 is placed on the substrate 101, as
illustrated in FIG. 8(b).
[0078] Specifically, the suction nozzle 325d of the placing head
325 holds by suction, the second electronic component 210 fed from
the second component feeding unit 315; the placing head 325 moves
in a horizontal direction and positions the second electronic
component 210 above the transferring unit 320 which forms the flux
coating; and then, the suction nozzle 325d moves up/down while
maintaining the suction, so that the bumps 214 on the second
electronic component 210 are brought into contact with the coating
of the flux 206, thereby transferring the flux 206 to the bumps
214.
[0079] The flux 206 may be of any material as long as it is
effective for removing oxides that are present on the electrode
surfaces and bump surfaces at the time of solder bonding. The flux
composition is not particularly limited, and for example, contains
a base material such as rosin, an activator such as an organic acid
or halide, a solvent, a thixotropy-promoting agent, etc. The flux
may be a thermosetting flux containing a thermosetting resin
component.
[0080] Subsequently, the placing head 325 moves in a horizontal
direction and positions the second electronic component 210 at the
second placement area; and then, as illustrated in FIG. 8(c), makes
the bumps 214 on the second electronic component 210 that have been
coated with the flux 206, to land on the corresponding second
electrodes 102b.
[0081] Here, the reinforcing resin 105 starts to become fluid
immediately after it is dispensed onto the reinforcement positions
104 by the second electronic component placement machine 304X.
However, since the second electronic component 210 is placed by the
second electronic component placement machine 304X also, the
reinforcing resin 105 can come in contact with the peripheral edge
portion 211x of the second electronic component 210, before greatly
losing its shape. Moreover, after the reinforcing resin 105 is
dispensed onto the reinforcement positions 104, the second
electronic component is placed on the second placement area while
the substrate 101 is held by the substrate holder 310b and not
moved. Therefore, the reinforcing resin 105 does not lose its shape
from vibration, etc. that occur when the substrate 101 is moved.
Furthermore, by coming in contact with the second electronic
component 210, the reinforcing resin 105 is able to have its
fluidity suppressed. Therefore, the reinforcing resin 105 is less
likely to come in contact with the solder paste that is on the
first electrode 102a adjacent thereto; and is less likely to become
the cause of poor bonding.
[0082] After completing placement of the second electronic
component, the second electronic component placement machine 304X
drives the substrate carrying conveyor 309b and sends the substrate
101 to the reflow machine 305.
[0083] Next, the reflow machine 305 performs a reflow process (step
six) in which the substrate 101 is heated inside an oven to melt
the solder thereon. In the reflow process, the substrate 101 on
which the first electronic component 200 and the second electronic
component 210 have been placed, is heated. Inside the reflow
machine, the molten solder bumps and solder paste become wet and
spread to the electrodes. Moreover, the reinforcing resin 105
cures, and as illustrated in FIG. 8(d), forms a resin-reinforced
portion 105a. This results in obtaining a mounting structure in
which the first electronic component 200 and the second electronic
component 210 are bonded to the surface of the substrate 101, with
the solder. During the reflow process, the reinforcing resin 105 is
in contact with the second electronic component, but is not in
contact with the solder paste on the first electrode; and
therefore, the first electronic component 200 and the second
electronic component 210 are mounted on the substrate 101 in a
satisfactory manner. Thereafter, the substrate 101 is carried out
of the reflow machine 306, and is collected by the substrate
collecting machine 307.
[0084] After completing placement of the first electronic
component, a unit 304Y drives the substrate carrying conveyor 309c
and sends the substrate 101 to the reflow machine 306.
[0085] FIGS. 7 and 8 are drawings to explain the case where the
steps one to six are carried out in this order. However, note that
the step three may be carried out after the step five. That is, the
steps two, four, five, and three may be carried out in this order.
In this case, the first electronic component placement machine 303
is arranged downstream of the second electronic component placement
machine 304X, on the electronic component mounting line. Moreover,
the combination of the steps four and five may be carried out two
or more times. In this case, two or more of the second electronic
component placement machines 304X may be arranged on the electronic
component mounting line; and the steps four and five may be carried
out repeatedly two or more times, by one of these second electrode
component placement machines 304X.
[0086] Next, with reference to FIG. 9, a description will be given
on the second electronic component placement machine 304Y which is
a modification of the second electronic component placement machine
304X. In FIG. 9, elements having the same functions as those in
FIG. 5, are given the same corresponding reference numerals as in
FIG. 5.
[0087] The substrate carrying conveyor 309a, disposed in the middle
of the second electronic component placement machine 304Y,
comprises: an upstream-side substrate holder 310c which holds the
substrate 101 while it is worked on by the dispensing head 324; and
a downstream-side substrate holder 310d which holds the substrate
101 while it is worked on by the second placing head 325.
[0088] The dispensing head 324 moves in a horizontal direction and
up-and-down directions in the space above the upstream-side
substrate holder 310c, such movements enabled by an X-Y-Z movement
mechanism that is controlled by a pre-selected control unit. On the
other hand, the second placing head 325 moves to and from the
second component feeding unit 315 and the downstream-side substrate
holder 310d in the space thereabove, such movements enabled by an
X-Y movement mechanism that is controlled by a pre-selected control
unit. That is, the dispensing head 324 and the second placing head
325 share the space above the substrate carrying conveyor 309b of
the same second electronic component placement machine. As such,
the second electronic component placement machine 304Y is
configured to allow the dispensing head 324 to move in the space on
the upstream side, and the second placing head 325 to move in the
space on the downstream side.
[0089] At the upstream-side substrate holder 310c, the dispensing
head 324 dispenses the thermosetting resin 105 onto the
reinforcement positions 104 on the substrate 101. After work at the
upstream-side substrate holder 310c is finished, the substrate 101
is carried on the substrate carrying conveyor 309b and sent to the
downstream-side substrate holder 310d that is disposed within the
same second electronic component placement machine. Then, the
second placing head 325 places the second electronic component 210
on the second placement area of the substrate 101 held by the
downstream-side substrate holder 310d.
[0090] Since the second electronic component placement machine 304Y
is capable of placing the second electronic component 210 on the
second placement area of another substrate 101 held by the
downstream-side substrate holder 310d, while dispensing the
reinforcing resin 105 onto the reinforcement positions 104 on the
substrate 101 held by the upstream-side substrate holder 310c, the
steps four and five that were described with reference to FIG. 8,
can be carried out together. Therefore, compared to the second
electronic component placement machine X that was described with
reference to FIG. 5, there is more improvement in work efficiency
when producing a substrate with electronic components mounted
thereon.
[0091] The configuration of the electronic component mounting line
of the present invention is not limited to the foregoing
embodiment, and can be changed as appropriate. For example, a test
machine may be arranged between the screen printing machine and the
first electronic component placement machine or the second
electronic component placement machine 304X; between the screen
printing machine and the second electronic component placement
machine 304Y; and/or between the reflow machine and the substrate
collecting machine. Alternatively, in addition to the second
electronic component placement machine including the dispensing
head, an adhesive dispensing machine for dispensing an adhesive for
temporary bonding of various electronic components, may be arranged
between the screen printing machine and the second electronic
component placement machine 304X; between the screen printing
machine and the second electronic component placement machine 304Y;
and/or downstream of the first electronic component placement
machine.
[0092] Alternatively, as already mentioned in the foregoing, the
electronic component mounting line may be configured to include two
or more of the first electronic component placement machines, or
may be configured to include two or more of the second electronic
component placement machines. The second electronic component
placement machines 304X and 304Y may be used together in a
combination.
[0093] The second electronic component placement machine may be a
multipurpose-type machine which has a function to dispense, in
addition to the reinforcing resin, an adhesive for temporary
bonding as well as other kinds of adhesives and resins.
[0094] The first electronic component placement machine may be a
multipurpose-type machine having a function to place electronic
components other than the first electronic component. Likewise, the
second electronic component placement machine may be a
multipurpose-type machine having a function to place electronic
components other than the second electronic component. That is,
there are no particular limitations to the kinds of machines used
as the first electronic component placement machine and the second
electronic component placement machine, as long as they function as
intended when arranged on the electronic component mounting
line.
INDUSTRIAL APPLICABILITY
[0095] According to the electronic component mounting line of the
present invention and the electronic component placement machines
in the present invention, it is possible to suppress poor bonding
at portions bonded by solder bumps, such poor bonding caused by
thermosetting resin, provided as reinforcing resin, losing its
shape over time and thus spreading or deforming. Thus, the present
invention is useful in the field of surface mounting, in which
pluralities of CSPs and chip components are mounted on the same
substrate.
[0096] Although the present invention has been described in terms
of the presently preferred embodiments, it is to be understood that
such disclosure is not to be interpreted as limiting. Various
alterations and modifications will no doubt become apparent to
those skilled in the art to which the present invention pertains,
after having read the above disclosure. Accordingly, it is intended
that the appended claims be interpreted as covering all alterations
and modifications as fall within the true spirit and scope of the
invention.
EXPLANATION OF REFERENCE NUMERALS
[0097] 101: substrate (printed circuit board) [0098] 102a: first
electrode [0099] 102b: second electrode [0100] 103: solder paste
[0101] 104: reinforcement position [0102] 105: reinforcing resin
[0103] 200: first electronic component [0104] 201: connection
terminal [0105] 210: second electronic component [0106] 211: inner
substrate [0107] 211s: main surface [0108] 211x: peripheral edge
portion [0109] 212: semiconductor device [0110] 213: sealing resin
[0111] 214: bump [0112] 300: electronic component mounting line
[0113] 301: substrate feeding machine [0114] 302: screen printing
machine [0115] 303: first electronic component placement machine
[0116] 304X, 304Y: second electronic component placement machine
[0117] 305: reflow machine [0118] 306: substrate collecting machine
[0119] 309a, 309b: substrate carrying conveyor [0120] 310a, 310b,
310c, 310d: substrate holder [0121] 313: first component feeding
unit [0122] 315: second component feeding unit [0123] 323: first
placing head [0124] 323d: suction nozzle [0125] 324: dispensing
head [0126] 324d: dispensing nozzle [0127] 325: second placing head
[0128] 325d: suction nozzle [0129] 320: transferring unit [0130]
320a: base table [0131] 321: transferring table [0132] 322:
squeegee unit [0133] 322a: first squeegee member [0134] 322b:
second squeegee member
* * * * *