59:
180:
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properties, mechanical properties, and cost are taken into account when making a decision. For example, a high current device for a space application might require a large diameter aluminium wire bond in a hermetically sealed ceramic package. If cost is a large constraint, then avoiding gold wire bonds may be a necessity. Some recent work has been done to look at copper wire bonds in automotive applications. This is only a small sampling, as there is a vast body of work reviewing and testing what material systems work best in different applications.
51:
475:
requirements". A wire can be pulled to destruction, but there are also non-destructive variants whereby one tests whether the wire can withstand a certain force. Non-destructive test methods are typically used for 100% testing of safety critical, high quality and high cost products, avoiding damage to the acceptable wired bonds tested.
160:. Large diameter copper wire can and does replace aluminium wire where high current carrying capacity is needed or where there are problems with complex geometry. Annealing and process steps used by manufacturers enhance the ability to use large diameter copper wire to wedge bond to silicon without damage occurring to the die.
39:
31:
400:
While wirebond manufacturing tends to focus on bond quality, it often does not account for wearout mechanisms related to wire bond reliability. In this case, an understanding of the application and use environment can help prevent reliability issues. Common examples of environments that lead to wire
321:
In wedge bonding, the wire must be drawn in a straight line according to the first bond. This slows down the process due to time needed for tool alignment. Ball bonding, however, creates its first bond in a ball shape with the wire sticking out at the top, having no directional preference. Thus, the
470:
While there are some wire bond pull and shear testing techniques such as MIL-STD-883, ASTM F459-13, and JESD22-B116, these tend to be applicable for manufacturing quality rather than reliability. They are often monotonic overstress techniques, where peak force and fracture location are the critical
225:
Junction size, bond strength and conductivity requirements typically determine the most suitable wire size for a specific wire bonding application. Typical manufacturers make gold wire in diameters from 8 micrometers (0.00031 in) and larger. Production tolerance on gold wire diameter is +/-3%.
163:
Copper wire does pose some challenges in that it is harder than both gold and aluminium, so bonding parameters must be kept under tight control. The amount of power used during ultrasonic bonding must be higher and copper has a higher fusing current so it has a higher current carrying capacity. The
359:
Much work has been done to characterize various metal systems, review critical manufacturing parameters, and identify typical reliability issues that occur in wire bonding. When it comes to material selection, the application and use environment will dictate the metal system. Often the electrical
363:
From a manufacturing perspective, the bonding parameters play a critical role in bond formation and bond quality. Parameters such bond force, ultrasonic energy, temperature, and loop geometry, to name a few, can have a significant effect on bond quality. There are various wire bonding techniques
168:
coated copper wire is a common alternative which has shown significant resistance to corrosion, albeit at a higher hardness than pure copper and a greater price, though still less than gold. During the fabrication of wire bonds, copper wire, as well as its plated varieties, must be worked in the
137:
The wire bonding industry is transitioning from gold to copper. This change has been instigated by the rising cost of gold and the comparatively stable, and much lower, cost of copper. While possessing higher thermal and electrical conductivity than gold, copper had previously been seen as less
474:
Wire pull testing applies an upward force under the wire, effectively pulling it away from the substrate or die. The purpose of the test is as MIL-STD-883 2011.9 describes it: "To measure bond strengths, evaluate bond strength distributions, or determine compliance with specified bond strength
152:
and microelectronic applications. Copper is used for fine wire ball bonding in sizes from 10 micrometers (0.00039 in) up to 75 micrometers (0.003 in). Copper wire has the ability of being used at smaller diameters providing the same performance as gold without the high material cost.
380:) that affect susceptibility to manufacturing defects and reliability issues. Certain materials and wire diameters are more practical for fine pitch or complex layouts. The bond pad also plays an important role as the metallization and barrier layer(s) stackup will impact the bond formation.
408:
growth can create brittle points of fracture. Much work that has been done to characterize the intermetallic formation and aging for various metal systems. This not a problem in metal systems where the wire bond and bond pad are the same material such as Al-Al. This does become a concern in
310:
Ball bonding usually is restricted to gold and copper wire and usually requires heat. For wedge bonding, only gold wire requires heat. Wedge bonding can use large diameter wires or wire ribbons for power electronics application. Ball bonding is limited to small diameter wires, suitable for
266:
of the alloy system. Homogeneity is given special attention during the manufacturing process. Microscopic checks of the alloy structure of finished lots of 1% silicon-aluminium wire are performed routinely. Processing also is carried out under conditions which yield the ultimate in surface
942:
383:
Typical failure modes that result from poor bond quality and manufacturing defects include: fracture at the ball bond neck, heel cracking (wedge bonds), pad liftoff, pad peel, overcompression, and improper intermetallic formation. A combination of wire bond pull/shear testing,
97:(PCB) to another, although these are less common. Wire bonding is generally considered the most cost-effective and flexible interconnect technology and is used to assemble the vast majority of semiconductor packages. Wire bonding can be used at frequencies above 100 GHz.
325:
Compliant bonding transmits heat and pressure through a compliant or indentable aluminium tape and therefore is applicable in bonding gold wires and the beam leads that have been electroformed to the silicon integrated circuit (known as the beam leaded integrated circuit).
276:
482:. However, to promote certain failure modes, wires can be cut and then pulled by tweezers, also mounted on a pull sensor on a bond tester. Usually wires up to 75 μm diameter (3 mil) are classified as thin wire. Beyond that size, we speak about thick wire testing.
318:. Heat is used to make the metal softer. The correct combination of temperature and ultrasonic energy is used in order to maximize the reliability and strength of a wire bond. If heat and ultrasonic energy is used, the process is called thermosonic bonding.
334:
There are multiple challenges when it comes to wire bond manufacturing and reliability. These challenges tend of be a function of several parameters such as the material systems, bonding parameters, and use environment. Different wire
164:
formation of oxides is inherent with this material, so storage and shelf life are issues that must be considered. Special packaging is required in order to protect copper wire and achieve a longer shelf life.
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281:
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875:
279:
286:
Demonstration of ultrasonic wedge bonding of an aluminium wire between gold electrodes on a printed circuit board and gold electrodes on a sapphire substrate, reverse bonding order
58:
536:
V. Valenta et al., "Design and experimental evaluation of compensated bondwire interconnects above 100 GHz", International
Journal of Microwave and Wireless Technologies, 2015
698:
153:
Smaller diameters are possible due to copper's higher electrical conductivity. Copper wire bonds are at least as reliable if not more reliable than gold wire bonds.
930:
764:
1026:
314:
In either type of wire bonding, the wire is attached at both ends using a combination of downward pressure, ultrasonic energy, and in some cases heat, to make a
876:
https://www.researchgate.net/publication/225284187_Compliant_Bonding_Alexander_Coucoulas_1970_Proceeding_Electronic_Components_Conference_Awarded_Best_Paper
471:
outputs. In this case the damage is plasticity dominated, and does not reflect some wearout mechanisms that might be seen under environmental conditions.
278:
1214:
1038:
1021:
1135:
535:
631:
1065:
173:
or a similar anoxic gas in order to prevent corrosion. A method for coping with copper's relative hardness is the use of high purity varieties.
142:
and susceptibility to corrosion. By 2015, it is expected that more than a third of all wire bonding machines in use will be set up for copper.
1219:
898:
674:
179:
251:" (brittle gold-aluminium intermetallic compound) sometimes associated with pure gold bonding wire. Aluminium is particularly suitable for
176:
Long-term corrosion effects (Cu2Si) and other stability topics led to increased quality requirements when used in automotive applications
462:
Proper understanding of the use environment and metal systems are often the most important factors for increasing wire bond reliability.
258:
In order to assure that high quality bonds can be obtained at high production speeds, special controls are used in the manufacture of 1%
232:
are generally preferred to pure aluminium wire except in high-current devices because of greater drawing ease to fine sizes and higher
1229:
601:
237:
1082:
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1086:
491:
432:. The presence of halides such as chlorine can accelerate this behavior. This Au-Al corrosion is often characterized with
414:
410:
86:
1193:
1058:
351:-Aluminium (Cu-Al) require different manufacturing parameters and behave differently under the same use environments.
90:
1140:
1130:
369:
244:
974:"ASTM F459-13: Standard Test Methods for Measuring Pull Strength of Microelectronic Wire Bonds (Withdrawn 2023)"
871:
A.Coucoulas, "Compliant
Bonding" Proceedings 1970 IEEE 20th Electronic Components Conference, pp. 380-89, 1970.
1105:
259:
954:
MIL-STD-883: Test Method
Standard for Microcircuits, Method 2011.7 Bond Strength (Destructive Bond Pull Test)
263:
54:
The interconnections in a power package are made using thick (250 to 400 μm), wedge-bonded, aluminium wires.
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1051:
385:
478:
The term wire pull usually refers to the act of pulling a wire with a hook mounted on a pull sensor on a
623:
219:
94:
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dissimilar metal systems. One of the most well known examples is the brittle intermetallics formed in
82:
1171:
511:
389:
365:
252:
211:
1120:
1078:
945:." International Symposium on 3D Power Electronics Integration and Manufacturing (3D-PEIM), 2016.
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43:
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Under temperature cycling, thermomechanical stress is generated in the wire bond as a result of
206:. This process brings together the two materials that are to be bonded using heat, pressure and
790:
548:
233:
222:. Very tight controls during processing enhance looping characteristics and eliminate sagging.
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904:
894:
680:
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593:
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93:. Wire bonding can also be used to connect an IC to other electronics or to connect from one
1224:
1125:
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805:
731:
963:
MIL-STD-883: Test Method
Standard for Microcircuits, Method 2023.5 Nondestructive Bond Pull
262:
wire. One of the most important characteristics of high grade bonding wire of this type is
1033:
63:
851:
1110:
1100:
459:
models have been used to predict the fatigue life of wire bonds under such conditions.
872:
1208:
1074:
817:
763:
Brökelmann, M.; Siepe, D.; Hunstig, M.; McKeown, M.; Oftebro, K. (October 26, 2015),
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S.K. Prasad, Advanced
Wirebond Interconnection Technology. New York: Springer, 2004.
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148:
has become one of the preferred materials for wire bonding interconnects in many
479:
170:
67:
401:
bond failures include elevated temperature, humidity, and temperature cycling.
723:
448:
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can be a concern. This is most common in Au-Al metal systems and is driven by
240:
are most commonly used in sizes larger than 100 micrometers (0.0039 in).
207:
908:
735:
684:
589:
838:"The Great Debate: Copper vs. Gold Ball Bonding | Semiconductor Digest"
724:"A comparison of copper and gold wire bonding on integrated circuit devices"
597:
436:
for temperature and humidity. This is not as common in other metal systems.
425:
340:
199:
165:
134:
and can be up to several hundred micrometres for high-powered applications.
109:
17:
888:
50:
656:
Chauhan, Preeti; Choubey, Anupam; Zhong, ZhaoWei; Pecht, Michael (2014).
572:
336:
267:
cleanliness and smooth finish and permits entirely snag-free de-reeling.
139:
973:
943:
Predicting and avoiding die attach, wire bond, and solder joint failures
791:"What is the future of bonding wire? Will copper entirely replace gold?"
809:
581:
315:
210:
energy referred to as thermosonic bonding. The most common approach in
931:
Ensuring suitability of Cu wire bonded ICs for automotive applications
348:
156:
Copper wire up to 500 micrometers (0.02 in) can be successfully
119:
114:
728:
40th
Conference Proceedings on Electronic Components and Technology
722:
Khoury, S.L.; Burkhard, D.J.; Galloway, D.P.; Scharr, T.A. (1990).
444:
131:
57:
49:
37:
29:
873:
http://commons.wikimedia.org/File:CompliantBondingPublic_1-10.pdf
344:
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wire can be drawn in any direction, making it a faster process.
188:
124:
38:
30:
1047:
699:"Heraeus Bonding Wires for Semiconductor Technology catalogue"
451:, the die, the die adhesive, and the wire bond. This leads to
105:
Bondwires usually consist of one of the following materials:
1005:
455:
due to shear or tensile stresses in the wire bond. Various
421:
and
Horsting voiding, can also lead to wire bond failures.
766:
Copper wire bonding ready for industrial mass production
392:
can be used to screen manufacturing and quality issues.
236:
strengths in finished devices. Pure aluminium and 0.5%
424:
Under elevated temperature and humidity environments,
717:
715:
27:
Technique used to connect a microchip to its package
1186:
1149:
1093:
568:"Red Micro Wire encapsulates wire bonding in glass"
417:. Additionally, diffusion related issues, such as
77:is a method of making interconnections between an
651:
649:
624:"Product Change Notification - CYER-27BVXY633"
1059:
8:
1066:
1052:
1044:
1136:Transient liquid phase diffusion bonding
996:JESD22-B116: Wire Bond Shear Test Method
330:Manufacturing and reliability challenges
274:
202:and other elements is normally used for
178:
42:Aluminium wires wedge-bonded to a BC160
893:(3rd ed.). New York: McGraw-Hill.
528:
404:Under elevated temperatures, excessive
441:coefficient of thermal expansion (CTE)
34:Gold wire ball-bonded on a silicon die
7:
1006:How to test bonds: How to Wire Pull?
66:package. This package has an Nvidia
634:from the original on March 20, 2014
604:from the original on March 20, 2014
566:Mokhoff, Nicolas (March 26, 2012).
390:destructive physical analysis (DPA)
130:Wire diameters start from under 10
290:The main classes of wire bonding:
214:is to ball-bond to the chip, then
25:
1027:J-Devices Copper (Cu) Wirebonding
198:doped with controlled amounts of
1215:Semiconductor device fabrication
890:Wire Bonding in Microelectronics
91:semiconductor device fabrication
1:
1039:Amkor Silver (Ag) Wirebonding
1022:Amkor Copper (Cu) Wirebonding
492:Purple plague (intermetallic)
1220:Packaging (microfabrication)
445:epoxy molding compound (EMC)
1194:Wafer bond characterization
372:) and types of wire bonds (
1246:
887:Harman, George G. (2010).
311:interconnect application.
1230:Electronics manufacturing
1141:Surface activated bonding
1131:Thermocompression bonding
370:thermocompression bonding
245:semiconductor fabrication
243:All-aluminium systems in
1106:Plasma-activated bonding
736:10.1109/ECTC.1990.122277
347:-Aluminium (Au-Al), and
355:Wire bond manufacturing
230:Alloyed aluminium wires
1177:Tape-automated bonding
789:Breach, C. D. (2010).
386:nondestructive testing
368:, ultrasonic bonding,
339:metal systems such as
287:
192:
71:
55:
47:
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443:mismatch between the
396:Wire bond reliability
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271:Attachment techniques
182:
95:printed circuit board
62:Inside a wire-bonded
61:
53:
41:
33:
730:. pp. 768–776.
406:intermetallics (IMC)
343:-Aluminium (Al-Al),
191:wire bonding details
138:reliable due to its
83:semiconductor device
1172:Thermosonic bonding
1077:techniques used in
659:Copper Wire Bonding
630:. August 29, 2013.
549:"K&S - ACS Pro"
512:Thermosonic Bonding
411:gold-aluminium IMCs
366:thermosonic bonding
253:thermosonic bonding
238:magnesium-aluminium
212:thermosonic bonding
1121:Glass frit bonding
1032:2018-12-06 at the
978:ASTM International
810:10.1007/BF03214983
430:galvanic corrosion
419:Kirkendall voiding
288:
193:
79:integrated circuit
72:
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48:
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1157:Compliant bonding
1094:Substrate bonding
900:978-0-07-164265-1
859:www.aecouncil.com
676:978-1-4614-5760-2
497:Kirkendall effect
453:low cycle fatigue
305:Compliant bonding
283:
260:silicon-aluminium
187:LED package with
16:(Redirected from
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1126:Adhesive bonding
1116:Eutectic bonding
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804:(3): 150–168.
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1167:Ball bonding
1162:Wire bonding
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981:. Retrieved
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773:, retrieved
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747:. Retrieved
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669:: Springer.
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636:. Retrieved
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606:. Retrieved
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502:Ball Bonding
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129:
104:
75:Wire bonding
74:
73:
18:Wire Bonding
1150:Connections
1008:April 2016.
775:January 30,
553:www.kns.com
480:bond tester
264:homogeneity
216:stitch-bond
171:forming gas
146:Copper wire
68:GeForce 256
1209:Categories
983:2024-04-22
852:"AEC Q006"
823:2024-02-06
749:2024-02-06
523:References
434:Peck's law
208:ultrasonic
44:transistor
1016:Resources
909:609421363
818:137609854
744:111130335
685:864498662
638:March 20,
608:March 20,
590:0192-1541
449:leadframe
426:corrosion
341:Aluminium
234:pull-test
220:substrate
200:beryllium
166:Palladium
110:Aluminium
101:Materials
87:packaging
1187:See also
1030:Archived
667:New York
632:Archived
602:Archived
598:56085045
573:EE Times
486:See also
413:such as
337:bond pad
140:hardness
85:and its
1225:Welding
706:Heraeus
582:UBM plc
466:Testing
457:fatigue
218:to the
89:during
1085:, and
907:
897:
816:
742:
683:
673:
596:
588:
447:, the
388:, and
349:Copper
120:Silver
115:Copper
1179:(TAB)
855:(PDF)
814:S2CID
794:(PDF)
770:(PDF)
740:S2CID
702:(PDF)
663:(PDF)
335:bond-
1087:NEMS
1083:MEMS
905:OCLC
895:ISBN
777:2016
681:OCLC
671:ISBN
640:2014
610:2014
594:OCLC
586:ISSN
345:Gold
316:weld
189:gold
125:Gold
70:GPU.
1079:ICs
806:doi
732:doi
64:BGA
46:die
1211::
1081:,
976:.
903:.
857:.
812:.
802:43
800:.
796:.
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726:.
714:^
704:.
679:.
665:.
648:^
626:.
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376:,
255:.
132:μm
1067:e
1060:t
1053:v
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