The Advantages of COB technology in LED

COB (known as Chip-on-Board) is semi-conductor assembly technology where micro-chip also known as die is electrically interconnected instead of using traditional assembly process or individual IC packaging on the final product board. The general term meaning of this technology is direct chip attachment also refereeing to DCA. In DCA many kinds are available as substrate in form of ceramic glass or ceramic substrate which has substances of excellent dielectric and thermal property. It is also available in form of flex substrate, which exhibits bendable ability. Other names are known as COG (chip-on-glass) or COF (chip-on-flex).

COB process consists of three main categories to perform when manufacturing the Chip-on-Board. The first process is 'die mount or die attach', the second is 'wire bonding' and lastly 'the encapsulation of die wires'. 

 

 

In many COB assembly technology, FCOB(flip-chip-on-board) have chips facing downward on the board and does not require wire bonding which employs chip which the bond pads are pop up and it connects directly to pads on the board. It is necessary to underfill flip-chip on active surface to protect bumps from chemical and thermo-mechanical damage.

 

 In context of COB manufacturing process, 1) 'die attach' consists of applying die attach holding to board or substrate mounting chip or die over die attach materials. 2) For wire bonding, thermosonic (Au or Cu) ball bending and ultrasonic (Al) wedge bending are used to connect wires between die and substrate. Last part the encapsulation is done dispensing chemical liquid (usually epoxy) over die and wires. Die and bond wires are encapsulated to protect chemical and mechanical damage.

 

The advantages of COB include:
Better performance due to deceased interconnection between length and resistance.
And better protection against reverse engineering;
Reduced space and cost;
Shorter time to the market.
Higher reliability with better heat dispatch and small number of solder joint.

 

Applications
LED Backlight for LCD TV
LED Front light for E-Book
Agriculture & Horticulture Lighting
Street & Parking Lot Lighting

Invention
Reflective Pocket in PCB for LED Die Attachment (COB)
Patent pending

Advantages
Improved output efficiency of LED lighting
Avoid photonic absorption and scattering over the pocket wall

 

 

 

 

 

Baggio WANG FAN
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SHENZHEN JAAPSON TECHNOLOGY CO LTD
Building 2, Tongfuyu Industrial Park,Shenzhen, China, 518104
Tel: 86-755-82596922
Fax:86-755-82596922/82596923
skype: baggiowang0214
baggio.wang@funsunpcb.com
baggio@jaapson-pcb.com
www.jaapsonpcb.com

JAAPSON, The Expert in HDI Multi-layer PCBs

What is ENEPIG pcb

ENEPIG is suitable for soldering, gold wire bonding, aluminum wire bonding and contact resistance. It is formed by the sequential deposition of electroless Ni (120 to 240 micro inches) followed by 2 to 10 micro inches of electroless Palladium with an immersion gold flash of 2 to 6 micro inches on the top.

What is ENEPIG?

ENEPIG or Electroless Nickel - Electroless Palladium - Immersion Gold is a surface finish for Printed Circuit Boards that has been around for a decade but is only recently coming back into vogue. The high price of palladium had kept it out of reach for most businesses. With the price of palladium now less than the price of gold, this surface finish becomes the best choice for wire bonding, ROHS assembly and just all boards overall. ENEPIG works well with lead free and conventional eutectic solder alloys (Eutectic means its 63% tin and 37% lead.) ENEPIG is called the "Universal" surface finish as it can be used for all assembly processes.

So why is ENEPIG the "universal" finish?
Excellent ROHS lead free and leaded solderability

• Because palladium completely dissolves into the solder leaving an oxide free nickel surface which allows a reliable tin nickel inter metallic.

High wire bond pull strengths (aluminum wire: up to 10g; gold wire: up to 8g). .

• After numerous tests, it holds high pull weights.
• Good for aluminum wedge and gold ball bonding

Low contact resistance

• Due to the controlled deposition of precious metals the electrical resistance is more uniform so it's easier to predict amperage.

Suitable for conductive adhesives

• You can connect components without the use of solder.

Finish is corrosion resistant and pore-free

• Multiple layers of metal provide a higher corrosion resistant coating.

Unlimited shelf life

• Doesn't tarnish

Nickel acts a barrier layer to further reduce copper dissolution during wave solder, thus ensuring good solderability.

• Nickel prevents the mixing of copper and solder.

ENEPIG delivers great solder joint strength with various alloys during multiple reflow soldering, especially SAC305. The middle palladium layer helps to stabilize and control the inner metallic layer. Because of the mixture, ENEPIG after testing showed amazing wire bonding, both with aluminum and gold.

Mr. Baggio Wang

SHENZHEN JAAPSON TECHNOLOGY CO LTD

Building 2, Tongfuyu Industrial Park,Shenzhen, China, 518104

Tel: 86-755-82596922

Fax:86-755-82596922/82596923
baggio.wang@funsunpcb.com

baggio@jaapson-pcb.com 

www.jaapsonpcb.com

JAAPSON, the special-tech PCB manufacture