Title of Invention

DEVICE AND PROCESS FOR BONDING OPTICAL ELEMENTS.

Abstract This invention relates to device and process tor bonding the optical elements by non-contact soldering to prevent moisture from penetrate into inside the optical elements by performing soldering without being in direct contact with a bonding portion of optical elements and by sealing up completely a gap formed in the bonding portion between the housings during packaging or bonding optical elements. The apparatus for bonding optical elements comprising: at least two optical elements, an inside of which being provided with optical systems while an outside of which being surrounded by housings; alignment apparatus which fixes one end of the each optical element and aligns optical system of the optical elements; laser light sources disposed respectively at both end of the housings, illuminating the laser beams lest the beam should be focused on outer surface of the housings; lead-supplying units disposed respectively at both upper end of the laser light sources, supplying the lead on the laser beams; and a controller for controlling the laser light sources and the lead supplying units.
Full Text BACKGROUND OF THE INVENTION Field of the Invention
The present invention relates to bonding of optical elements such as an optical waveguide, an optical collimator, an optical attenuator, an optical isolator, etc., and in particular, to an apparatus and process for bonding the optical elements by non-contact soldering.
Description of the "Related Art
There are several known methods of soldering electronic devices and optical elements. A first method is to heat a portion to be bonded by means of an electric iron and then supply lead. A second method is to place a high-frequency induction heater around the optical elements and apply constant

heat to the portion to be bonded by high-frequency heating. A third method is to perform soldering by using a laser light source as a heat source, which is available where the electric iron cannot be used due to the high packaging density or there is mass production due to many portions to be bonded, -as shown, for example, in U.S. Patent No. 4,963,714 to Joseph R. Adamski et al entitled Diode Laser Soldering System. Lastly, a fourth method, which is available where there are many different portions to be bonded, is to apply heat to the portions to bonded by changing a light path using a prism. Here, the lead used in the first and second methods is in the form of a wire. The third and fourth methods, however, utilize lead powder plastered around the portions to be bonded.
The soldering processes according to the known process are frequently applied to electronic devices. However, in order to apply such a soldering process to optical devices, the following should be considered:
(1) A possible contact during application of the heat to the bonding portions may affect the
alignment of the optical elements;
(2) Bonding portions of the optical elements should be kept symmetric to prevent
misalignment of the optical elements due to thermal expansion;
(3) Heat should be uniformly applied to symmetrical bonding portions to prevent mi salignment
of the optical elements;
(4) The bonding portions should be filled completely with lead to secure reliability of the
optical elements; and
(5) Reproductbility and mass production of the optical elements should be guaranteed.

Examination of the respective soldering methods mentioned^above-.faasecLon-'t-he-fofegoing cotisiderations shows that neither the first nor second soldering methods meet all of the foregoing five points of consideration. Regarding the third soldering method, while meeting symmetry of optical elements arranged in a plane, it does not meet the foregoing considerations as to symmetry in three-dimensional space. Regarding the forth soldering method, while making connection of desired portions possible, it cannot secure the symmetry.
In short, though very useful to the electronic devices, the conventional soldering methods are not suitable for optical elements due to the misalignment problem. That is to say, during application of heat to the bonding portions, if the lead contacts the surface of the bonding portions, the optical elements may be misaligned. Further, the laser beam applied to the bonding portions of the optical elements cannot be kept symmetric, which causes the misalignment of the optical elements due to the thermal expansion and non-uniform distribution of heat. As a result, the properties of the optical elements are affected., thus lowering reliability of the products. In addition, the reproducibiiity and mass production of the optical elements are also lowered.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an apparatus and process for bonding optical elements by non-contact soldering, in which the interior of the bonding portions of the optical elements is sealed up completely to prevent moisture from penetrating into the optical elements,

Another object of the present invention is to provide an apparatus and process for bonding optical elements by non-contact soldering, capable of minimizing property variations of the optical elements.
To achieve the foregoing objects, an apparatus for bonding optical elements according to the present invention comprises: a couple of optical elements having optical systems therein and which b surrounded by housings; an alignment apparatus which fixes one end of the each optical element and aligns the optical systems of the optical elements; laser light sources arranged respectively at predetermined ends of the housings for illuminating a laser beam lest the beam should be focused on the outer surface of the housings; lead-supplying units arranged respectively at the upper ends of the laser light sources for supplying the lead on the laser beam; and programmable logic control (PLC) which auto-controls the laser light sources and the lead supplying units.
To achieve the foregoing objects, a method for bonding optical elements according to the present invention comprises steps of: fixing a couple of optical elements to an alignment apparatus for aligning the optical systems of the optical elements; illuminating a laser beams from plural laser light sources lest the beams should be in contact with cross-sections of bonding portions of the optical elements which are arranged between housings of the optical elements; after a predetermined time, supplying lead from lead supplying units on the laser beams; dissolving the lead by the laser beams so that the lead flows into gaps formed tn bonding sections between the housings; after a predetermined time, breaking off a driving force of the lead supplying units under auto-control of a programmable logic control (PLC); and, after a predetermined time, breaking off the laser beams

under control of the PLC.
BKiEF DESCRBPTION OF THE ACCOMPANYING DRAWINGS
A more complete appreciation of the present invention, and many of the attendant advantages thereof, win become readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
Fig. 1 is a schematic view representing a construction of an apparatus for bonding optical elements by non-contact soldering process according to a preferred embodiment of the present invention;
Fig. 2 is a plane view representing a position of the laser beam and a lead supplying position in an apparatus for bonding optical elements by non-contact soldering process according to a preferred embodiment of the present invention;
Fig. 3 is a plane view representing the state of the bonding portions' interior being filled with lead, thereby being fixed in manner of a non-contact soldering process according to a preferred embodiment of the present invention;
Fig, 4 is a graph representing the variation of optical properties of optical elements to lead-supplying time during bonding optical elements in manner of a non-contact soldering process according to a preferred embodiment of the present invention;
Fig. 5 is a graph representing temperature changes of a bonding portion during bonding in a non-contact soldering according to a preferred embodiment of the present invention; and

Fig. 6 is a graph representing lead-supplying velocity during bonding in a non-contact soldering process according to a preferred embodiment of the present invention,
DETAILED PESCRBPTION OF THE PREFERRED EMBODIMENT
Referring to Figs. 1 and 2 the apparatus for bonding optical elements according to a preferred embodiment of the present invention includes optical elements 26 and 28 with various built-in optical systems, alignment apparatus 22 and 24 for the optical elements, continuously operable laser light sources 10a and 10b, lead-supplying units 14a and 14b, and lead 16a and 16b. Further, a housing 30 for protecting the optical system from the ambient environment is provided at the outer circumference of optical element 26. Likewise, a housing 32 is provided at the outer circumference of optical element 28, Through holes 34 are formed symmetrically on both sides of housing 32, and the lead 16a and 16b for fixing housings 30 and 32 are flowed into through holes 34, while one end of optical element 26 is fixed to alignment apparatus 22 and one end of the optical element 28 is fixed to alignment apparatus 24.
The continuously operable laser light sources 10a and 10b are arranged at both sides of the optical elements 26 and 28 with a predetermined spacing. Laser light sources 10a and 10b illuminate laser beams 12a and 12b, respectively, lest the foci of the laser beams 12a and 12b should be in contact with outer surface of the housing 32, to apply heat to a bonding portion 40 (see Figs 2 and 3 for more detail on bonding portion 40) and dissolve lead 16a and 16b, thereby making optical elements 26 and 28 fixed. A diameter of the foci of the beams 12a and 12b illuminated from the laser light sources 10a

and 10b is about 0.5mm~3rnm, and an electric power of the beam illuminated from the laser light sources 10a and 10b is about 15W-4OW. Lead-supplying units 14a and 14b, supplying lead 16a and 16b which are in the form of wire, are arranged at the upper end of the each laser light source 10a and 10b. Lead-supplying units 14a and 14b supply lead 16a and 16b on laser beams 12a and 12b. That is to say, lead-supplying units 14a and 14b supply lead 16a and 16b on the beam 12a and 12b so that the lead in contact with the beam in the first place without the lead 16a and 16b being directly contacted with bonding portion 40. Laser light sources 10a and 10b and lead-suppiying units 14a and 14b are automatically controlled by PLC (Programmable Logic Control) 40. Namely, PLC 42 controls the turning on and off(ON/OFF) of laser light sources 10a and 10b and controls the supplying time of lead 16a and 16b so that lead 16a and 16b are supplied symmetrically at left and right side of optical elements 26 and 28.
An explanation of operation the mechanism and the process thereof regarding the bonding apparatus for optical elements by the non-contact soldering process with reference to Figs. 1 through 6 is as follows:
First of all, optical element 26 is fixed and positioned to alignment apparatus 22 and optical element 28 is fixed and positioned to alignment apparatus 24, as represented in Fig, 1. After the foregoing procedure, the alignment apparatus alignsthe optical systems (not shown), which are packed inside optical elements 26 and 28, automatically or manually. After the optical systems are aligned at an optimum position, PLC 42 controls laser light sources 10a and 10b. Then, laser light sources 10a

and 1 Ob illuminate laser beams 12a and 12b, lest the beams should be in contact with the surfaces of both the housing 30 of optical element 26 and the housing 32 of optical element 28. That is to say, laser light sources 10a and 10b illuminate beams 12a and 12b, as represented in Figs. 1 and 2, so that the beams cao be focused within the domain where the foes of the beams are not in contact with the surfaces of bonding portion 40 of the optical elements. In other words, the illumination position of laser beams 12a and 12b are the bonding portion 40 of the optical elements and the laser light sources 10a and 10b may apply heat at its maximum provided that optical elements 26 and 28 are put at vicinity of the focal length of beams 12a and 12b, Here, the diameters of foci of beams 12a and 12b at its focal length are about 0.5mm~3mm. Though they depend on usage, 2,5mm is applied in the embodiment of the present invention. The illumination time of beams 12a and 12b illuminated from laser light sources 10a and 10b consists of three steps to improve bonding reliability of lead 16a and 16b.
After a predetermined time, namely, after laser light sources 10a and 10b heat up, in the vicinity of 100°C, the cross-section of bonding portion 40 sufficiently for a preliminary heating time "Tl", increasing affinity of the lead 16a and 16b, PLC 42 automatically controls lead-supplying units 14a and 14b as represented m Figs. 4 through 6, Then, lead-supplying units 14a and 14b supply lead 16a and 16b on laser beams 12a and 12b. Namely, lead-supplying units 14a and 14b supply lead 16a and 16b at a constant velocity for a primary heating time "T2" as represented in Figs. 4 through 6. Then lead 16a and 16b3 right before it touches bonding portion 403 come into contact with laser beams 12a and 12b in the first place and be dissolved, thereby being melted and flowed into the through holes
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34 of the bonding portion 40. Here, lead-supplying units 14a and 14b supply lead 16a and 16b on beams 12a and 12b at a velocity of about 5mm/sec. After that, under control of PLC 42, lead supplying units 14a and 14b break off supplying lead 16a and 16b at a velocity of about ~25mm/sec at the stage when the primary heating time "T2" elapses. In succession, laser light sources 10a and 10b illuminate beams 12a and 12b, thereby post-heating for the post-heating time "T3" so that lead 16a and 16b supplied already at bonding portion 40 are maintained in a stable formation, under control of PLC 42 as represented in Figs. 4 through 6. Then, PLC 42 turns off laser light sources 10a and 10b after the lapse of the post-heating time "T3". By the foregoing, optical elements 26 and 28 are bonded in manner of a non-contact soldering process as represented in Fig. 3. Here, in general, when the preheating time is too long, with respect to the preheating time, the primary heating time, and the post-heating time of the laser beam illumination time of laser light sources 10a and 10b, a problem may occur that plated portions on the cross-sections of bonding portion 40 of the optical elements may burn out or all fluxes may evaporate away. So, in the embodiment of the present invention, time is controlled at a ratio of preheating time; primary heating time; post-heating time - 1 sec; 1.5 sec-1.7 sec: 1.5 sec, respectively.
While there have been illustrated and described what is to be considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated

for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims.
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We Claim:
1. Device for the bonding of optical elements, comprising alignment
apparatus (22, 24) for alignment of two optical elements ( 26, 28)
which have housings ( 30, 32) to be soldered with each other lead
supply units ( 14a, 14b) and at least one laser light source ( 10a, 10b)
for melting of lead wherein the heating media being the at least one
laser light source ( 10a, 10b) which is assembled on oppositely lying
sides of the aligned optical elements (26, 28) such that the foci of the
laser beams ( 12a, 12b) are outside of the housing ( 30, 32) of the
optical elements ( 26, 28);
two lead - supply units ( 14a, 14b) in each case being assembled above the laser light sources (10a, 10b) and through which leas ( 16a, 16b) in contact with the laser beams ( 12a, 12b) is supplied to the respective focus of the laser beams ( 12a, 12b); and a control means ( 42) which controls the laser light sources ( 10a, 10b) and the lead supply units (14a, 14b).
2. Device as claimed in claim 1, wherein the lead ( 16a, 16b) is
configured as wire.





Device as claimed in claim 1 or 2, wherein the foci of the laser beams (
12a. 12b) have a diameter of 0.5 mm- 3mm.
4. Device as claimed in one of claims 1 to 3, wherein the power of laser
beams ( 12a, 12b) is 15W- 40W.
5. Device as claimed in one of claims 1 to 4, wherein the control means (
42) controls the laser light sources ( 10a, 10b) and the lead supply
units ( 14a, 14b) for a predetermined pre-heating time ( Tl), primary
heating time ( T2) and post heating time ( T3).
6. Device as claimed in claim 5, wherein the pre-heating time ( Tl), the
primary heating time ( T2) and post-heating time ( T3) each amounts
to 1 second , 1.5- 1.7 seconds and 1.5 seconds.
7. Device as claimed in claim 5 or 6 wherein the control means ( 42)
controls the lead supply units ( 14a, 14b) in order to supply the lead ( 16a, 16b) at a velocity of about 5mm/s during the primary heating
time (T2) and in order to break off the lead ( 16a, 16b) at a velocity of


-12.

- 25mm/s from the melting area after the end of the primary heating period ( T2).
8. Device as claimed in one of claims 1 to 7, wherein the device covers an additional alignment apparatus ( 22, 24) at which a predetermined md of each optical element ( 26, 28) is fixed in order to align the optical systems of the optical elements ( 26S 28).
?, Process for the bonding of optical elements with the steps ;
alignment of two optical having in each case a housing, to its bonding.
Supply of lead and heat for the melting of lead for carrying out of a soldered connection between both the housings,
- illumination of bonding locations on oppositely lying positions
with a laser beam in each case whose foci are outside of the
housings ( 30,32) of the optical elements ( 26,28).
- supply of lead ( 16as 16b) from the lead supply units ( 14a, 14b)
to the laser beams ( 12a, 12b) under the control of control means ( 42) after a first predetermined time period ( Tl).


f'3-

- melting of leads ( 16a, 16b) through the laser beams ( 12a, 12b)
during a second predetermined time period( T2), so that the lead (
16a, 16b), flows through the holes in the housing ( 30, 32) and in
an intermediate space, which is formed in the bonding area (40)
between the housings ( 30, 32),
- breaking off the driving force of lead supply units ( 14a, 14b)
under control of control means (42) after lapse of the second
predetermined time period (T2) and
- breaking off laser beams (12a, 12b) under control of control
means ( 42) after lapse of a third predetermined time period (
T3).
10. Process as claimed in claim 9, wherein the first predetermined time period ( Tl) covers a pre-heating time for the heating of a cross section of the bonding area ( 40) of the optical elements ( 26, 28) to a predetermined temperature.
11.Process as claimed in claim 10, wherein the second pre-determined time period (T2) covers a primary heating period during which the
lead supplied through the lead- supply units (14a, 14b) and melted
through the laser beams ( 12a, 12b) flows in the intermediate space


"- IH -¦

which is formed in the bonding area (40) between the housing ( 30, 32).
12.Process as claimed in claims 10 or 11, wherein the third predetermined time period ( T3) covers a post-heating time for heating of the cross section of the bonding area ( 40) of the optical elements ( 26, 28) so that the lead ( 16a, 16b) supplied in the intermediate space in the bonding area (40) maintains a stable shape.
13. Process as claimed In one of claims 9 to 12, wherein the ratio
between the pre-heating time ( Tl), the primary heating time ( T2) and
the post heating time ( T3) is 1 sec : 1.5- 1.7 sec.: 1.5 seconds.
14. Process as claimed in one of claims 9 to 13, wherein the lead ( 16a,
16b) in the step for the supply of lead ( 16a, 16b) to the laser beam
( 12a, 12b) is supplied at a velocity of 5mm/ second during the second time period ( T2).
15.Process as claimed in one of claims 9 to 14, wherein the step of breaking off supply of the lead { 16a, 16b) is carried out at a velocity of ~ 25 mm/s at the end of second time period ( T2).
16.Process as claimed in one of claims 9 to 15, wherein the laser light sources (10a, 10b) in the step of illuminating the laser beams ( 12a, 12b) are supplied with an electric power of 15 to 40 watt.




17.Process as claimed in one of claims 9 to 16, wherein the laser beams ( 12a? 12b) are illuminated during the pre-heating period ( Tl), the primary heating period ( T2) and the post heating period ( T3) with an electrical power of 15 to 40 watt.
Dated this 28th day of August, 1998.


16

OF L.S.DAVAR & co, Applicants' Agent.
This invention relates to device and process tor bonding the optical elements by non-contact soldering to prevent moisture from penetrate into inside the optical elements by performing soldering without being in direct contact with a bonding portion of optical elements and by sealing up completely a gap formed in the bonding portion between the housings during packaging or bonding optical elements. The apparatus for bonding optical elements comprising: at least two optical elements, an inside of which being provided with optical systems while an outside of which being surrounded by housings; alignment apparatus which fixes one end of the each optical element and aligns optical system of the optical elements; laser light sources disposed respectively at both end of the housings, illuminating the laser beams lest the beam should be focused on outer surface of the housings; lead-supplying units disposed respectively at both upper end of the laser light sources, supplying the lead on the laser beams; and a controller for controlling the laser light sources and the lead supplying units.


Documents:

01549-cal-1998-abstract.pdf

01549-cal-1998-claims.pdf

01549-cal-1998-correspondence.pdf

01549-cal-1998-description(complete).pdf

01549-cal-1998-drawings.pdf

01549-cal-1998-form-1.pdf

01549-cal-1998-form-2.pdf

01549-cal-1998-form-3.pdf

01549-cal-1998-form-5.pdf

01549-cal-1998-g.p.a.pdf

01549-cal-1998-letters patent.pdf

01549-cal-1998-priority document others.pdf

01549-cal-1998-priority document.pdf


Patent Number 201383
Indian Patent Application Number 1549/CAL/1998
PG Journal Number 7/2007
Publication Date 16-Feb-2007
Grant Date 16-Feb-2007
Date of Filing 28-Aug-1998
Name of Patentee SAMSUNG ELECTRONICS CO. LTD.
Applicant Address 416, MAETAN-DONG, PALDAL-GU, SUWON-CITY KYUNGKI-DO,
Inventors:
# Inventor's Name Inventor's Address
1 YEONG-JU KIM 259, KONGDAN-DONG, KUMI-SHI, KYONGSANGBUK-DO,
PCT International Classification Number B 23 K 26/20
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 41906/1997 1997-08-28 Republic of Korea