Soldering device for electronic elements

A device for soldering an electronic element to a substrate has a support head for supporting the substrate, and a pusher having a push head provided above the support head for pushing the electronic element to the substrate. The holder is upwardly moved to push the element to the substrate.

BACKGROUND OF THE INVENTION 
The present invention relates to a device for soldering a small electronic 
element such as an IC chip to a substrate, for preventing the electronic 
element from becoming defective. 
Recently, soldering using a light beam is used for soldering an electronic 
element because the size of the element becomes small. Terminals of an 
electronic element such as IC chip is connected to terminals formed on a 
substrate by a solder with a light beam. 
FIG. 1 shows a conventional soldering method. An electronic element 3 is 
mounted on a substrate sheet 1 so as to position terminals formed on the 
underside of the electronic element 3 to wiring patterns formed on the 
substrate sheet 1. A push rod 4 is lowered to be abutted on the surface of 
the electronic element 3, thereby ensuring the positioning of the element 
3 to the substrate 1. Then, solder 2 is deposited on the periphery of the 
element 3 and a beam 5 is projected on the solder 2. The solder 2 is melt 
and charged into the joint between the element 3 and the substrate 1. 
Thus, the terminals and wiring patterns are electrically connected to each 
other. 
In accordance with the soldering, it is possible to solder the element to 
the substrate at a small hot spot. However, since the hot spot is very 
small, the heating is locally concentrated to raise the temperature at the 
connecting portion, causing thermal stress in the connecting portion due 
to thermal expansion. 
Accordingly, when the solder 2 is solidified, a deformation 6 is formed on 
the substrate 1 as shown in FIG. 2. In the deformation 6, tension stress 
is produced in the joint to break the electrical connection between the 
substrate 1 and the electronic element 3 or the solder 2 is cracked to 
increase the resistance, causing bad electrical connection. 
Even if these defects are not produced, such a deformation 6 causes a 
trouble in an automatic assembling process there-after. It is necessary to 
correct the deformation 6 to be flat. If a force is applied to the 
deformation 6 to flatten the substrate 1, the substrate 1 and the solder 2 
are subjected to the force, causing the electrical connection to break and 
cracking the substrate 1. 
The other soldering methods using heating flux also have these problems. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a soldering device where 
thermal deformation of the substrate is prevented, thereby providing a 
good electrical connection there-between. 
According to the present invention, a device for soldering an electronic 
element to a substrate, comprising a supporting device having a holder and 
a support head mounted on the holder for supporting the substrate, a 
pusher having a push head provided above the support head for pushing the 
electronic element to the substrate, first driving means for vertically 
moving the holder, and second driving means for vertically moving the push 
head. 
In an aspect of the invention, the support head is vertically movably 
provided and supported by a spring. 
The other objects and features of this invention will become understood 
from the following description with reference to the accompanying drawings 
.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 3 showing a soldering device for the electronic element 
to which the present invention is applied, a supporting device 30 is 
provided under a substrate 12 for supporting the substrate at the 
soldering position. The supporting device 30 is disposed corresponding to 
a pusher 20 which is provided on a upper the substrate 12. The substrate 
12 has wiring patterns (not shown) on which terminals 11 of an electronic 
element 10 is positioned. 
The pusher 20 comprises a push head 21 provided with a push rod having an 
arc end, and a pneumatic cylinder 22 for operating the push head 21. The 
push head 21 is moved in the vertical direction shown by arrows a and b by 
the cylinder 22. 
When the substrate 12 is not fed between the push head 21 and the 
supporting device 30, the pusher 20 is raised in the direction a to a rest 
position. 
The supporting device 30 comprises a movable bed 32, and a table 33 
detachably mounted on the bed 32. A hydraulic cylinder 31 is provided for 
operating the table 33. The table 33 is moved in the vertical direction 
shown by arrows c and d by the cylinder 31. A pair of pins 34 are mounted 
on the table 33 opposite to each other, to which a lateral holder 37 is 
secured with bolts 35. A support head 40 is mounted on the holder 37 at 
the central portion thereof and provided corresponding to the push rod of 
the push head 21. The support head 40 is slidably mounted on a rod 41 
secured to the holder 37 with a bolt. A spring 42 is provided between the 
head 40 and the bolt to urge the head in the upward direction. 
Furthermore, if the cylinder 31 operates to raise the table 33 in the 
direction c, the head 40 is moved in the upward direction. 
Referring to FIG. 4 showing another embodiment of the supporting device, a 
lateral holder 37a is mounted on the pins 34 with a pair of upper and 
lower bolts 35 and 36. Thus, the position of the holder 37a is vertically 
adjustable on the pins 34. 
The lateral holder 37a has a supporting portion 50 formed at the central 
portion thereof, a recess 45 therein, and a passage 43 axially formed 
therein to be communicated with an air supply source (not shown) for 
passing pressurized air therethrough. The passage 43 communicates with the 
recess 45 which serves as an air chamber. 
A support head 40a comprises a cylindrical casing 44 having a flange 
portion 44a. The lower portion of the casing 44 is engaged with the recess 
45 of the holder 37a, while the flange portion 44a is secured to the 
supporting portion 50 with rivets. 
In the casing 44, a piston rod 46 is slidably mounted through the casing. 
The piston rod 46 has a flange 46a, and a diaphragm 48 formed on the lower 
portion of the flange 46a. The flange 46a and the diaphragm 48 are 
slidably engaged with the inner wall of the casing 44. A spring 47 is 
provided between the flange 46a and a shoulder portion formed on the 
inside wall of the casing 44 to urge the piston rod 46 in the downward 
direction. The lower end of the piston rod 46 extends in the chamber 45 so 
that the air chamber 45 is defined by the diaphragm 48. The pressurized 
air supplied to the chamber 45 is applied to the diaphragm 48. An O-ring 
38 is provided in a recess formed on the outer periphery of the lower 
portion of the casing 44 so as to make the chamber 45 air-tight. A 
resilient lining 49 is provided between the flange 46a and the diaphragm 
48 for preventing the air from leaking from the chamber 45. 
In the embodiment of FIG. 5, the lateral holder 37a is secured to the table 
33 in the first embodiment of FIG. 3. 
Describing a supporting operation during the soldering, the substrate 12 is 
disposed between the pusher 20 and the supporting device 30. Before 
soldering, the electronic element 10 is mounted on the wiring patterns 
formed on the substrate 12 and the substrate 12 provided with the 
electronic element 10 is fed to the soldering position. At the soldering 
position, the push rod 21 is lowered by operating the cylinder 22 to push 
the electronic element 10 to the substrate 12. On the other hand, the 
cylinder 31 is operated to raise the bed 32 to abut the support head 40 on 
the underside of the substrate 12 opposite to the element 10. Thus, the 
substrate 12 having the electronic element 10 is supported by the push rod 
21 and the support head 40 at opposite sides. 
In this state, the solder is deposited to the joint between the wiring 
patterns and the terminals 11 and the light beams 13 are applied to the 
solder. In the present invention, during the soldering, the push head 21 
and the support head 40 restrain the substrate 12 from the thermal 
deformation. 
In a supporting operation of the supporting device shown in FIG. 4, the 
pressurized air is supplied to the air chamber 45 of the holder 37a 
through the passage 43 so that the diaphragm 48 is pushed to urge the 
piston rod 46 in the upward direction. Thus, the upper end of the piston 
rod 46 is projected from the casing 44 to be abutted on the underside of 
the substrate 12. 
In the present invention, the supporting device can be provided with a 
system for moving the bed in X-Y axis directions in synchronism with the 
pusher. 
In accordance with the present invention, during the soldering, the 
substrate is supported together with the electronic element by the push 
rod and the support head which are provided opposite to each other. Thus, 
the soldering is performed in the flat state of the substrate. After 
soldering, the substrate is fed to the assembling process with maintaining 
a good electrical connection between the wiring patterns and terminals. 
While the presently preferred embodiments of the present invention have 
been shown and described, it is to be understood that these disclosures 
are for the purpose of illustration and that various changes and 
modifications may be made without departing from the scope of the 
invention as set forth in the appended claims.