aluminum pcb with high thermal conductivity production process

Aluminum PCB with High Heat Conductivity Production Process

The Basic Level (Al) Manufacturing Process Flow

@2013 Agile Circuit Co., Ltd All Right Reserved ||www.agipcb.com

Contents 1.Foreword ……………………………………………………………………………………..….1 2.Process Introduction……………………………………………………………………..….2 2.1Aluminum PCB ………………………………………….……………………….…………3 2.2 Dry Film..…………………………………………………………………………..………….4 2.3 Drilling……………………………………………….…………………….………………5 2.4 Solder Mask……………………………………………..…………….6 2.5 Gold Planting /V-Cut…………………………….…………………7 2.6 TCA……………………………………………………..……………….8 2.7 TCA Printing……………………………………………….………….9 2.8 Cautions ………………………………………………................10 2.9 CNC…………………………………………………………………….11 2.10 Final Inspection…………..……………………………………….12 3.Test……………………………….……………………………….........13 3.1 LED Ink test……………………………………..………….........14 3.2 Finished Product test……….……………………………………16 4.Improvement…………………………………………………………..17


1.Foreword

Aluminum PCB is a unique metal core printed circuits, which has good heat conductivity, electrical insulation and mechanical processing properties. Make effective treatment of the heat diffusion in the circuit design can reduce operating temperature, increase the power density and reliability, extend product life, smaller footprint, reduce hardware and assembly costs.


2.Process(1)

Dry-film

Pre-engineering

Etching

Solder Mask (Black)

Solder Mask (white)

Drilling

Gold Plating

V-Cut

TCA Printing

Al Circumscribe Printing

Pre-cure

Drilling


Post-cure

CNC

Package

Final Inspection

Shipping

Press

Process(2)


2.1 Aluminum PCB

Insulation level Copper

the basic level (Al)PI level

1.Copper foil use 1oz electrolytic copper foil, insulation thickness 2.5mil-12mil;

2. Glass fiber isn't added to the Insulating layer, because it is the insulation material;

3 .Good heat conductivity, because add high heat conductivity materia

4.Alu base thermal conductivity 1.5w/m.k. and 12.5w/m.k. into film


2.2 Dry Film

Dry Film Resist Coat

Dry Film Resist Coat

Develop

Etch

Strip Resist


Example:

Left is a picture of an aluminum PCB after dry film. Note in the dry film: 1. Films and countertops dirty spots; 2. Note residual copper when inspection; 3.No pit and scratches on the copper foil surface ; 4. No breakage with aluminum plate PCB back PI / PE film, to avoid oxidation; 5. Avoid the PCB edge and angular position of Aluminum printed circuits scratching.


2.3 Drilling

1. 9 positioning holes drilling;

2. Use 1.6mm drill bit;

3. Note shooting holes side draped peaks;

4. Aluminum electronic circuits calibration accuracy of the drilling;

5. Drilling pressure adjustment 6kg/cm2;


2.4 Solder Mask

Black solder mask

White solder mask

1. Black solder mask, use 250 # stencil printing, ink thickness control between 6-10um, pre-bake 25min.

2 White solder mask, use 90 # stencil printing, ink thickness control 35-40um, pre-bake time 30min.

3 final bake, two process bake , 110 .℃

30min, 150 , 60min.℃ 4 Use different film for black solder

mask and white solder mask , solder opening for black with unilateral 0.1mm bigger than white.


2.5 Gold Planting/V-cut

Note: Au thickness of gold plating required 3u"-5u", and Ni120u"-150u".

Note: Aluminum base PCB V-Cut use special V-Cut blade, thickness 1.5mm, residual thickness 0.25mm-0.3mm. “ “ V-Cut positioning holes in the picture is to prevent drift.


2.6. TCA

Cautions1.TeamChem Company TC12/H48

TCA; 2. Use 90 # stencil printing;

3.Pre-cure with 90 , 40min;℃4.Thermal conductive adhesive

proportionate Primary: Hard 9:1 for self-configuration.

5. Thermal conductive adhesive after mixing must be stored at 0-25 , ℃RH50-60% under the conditions


2.7 TCA Printing

self-adhesive and good maneuverability. Not only enable aluminum core and copper surface (gold surface) close union, but also help heat distributing.

Thermal plastic printing: Use 90 # screen printing, block printing for point setting (the print plastic parts 0.3mm smaller than the line ) to prevent the outflow of the glue when lamination, easy to spread. Double printing for aluminum plate and aluminum frame is conducive to binding.

Sample Show: below is picture of WS1 l1210-03-16A (3W) printed plastic .


2.8. Cautions for TCA Printing

1. TCA 9:1 the viscosity ratio of configuration maintain at 12Pa.s; 2.No gel outflow Al frame or ink surface after printing.;

3. TCA must be applied evenly, without skip printing; 4. Pre-bake (Pre-cure) 90 , 40min;℃ 4. Aluminum plate and frame with a 3.15 pin the positioning hole to position

Aluminum board combinations. 5. Aluminum frame and plates combination use roller lamination or hot-

pressing (90 ,5-10kg / cm2 ,10-20 seconds);℃ 6. Post-cure 90 , 90min.℃


2.9 CNC

CNC of Combination of aluminum board use 2.0 dedicated cutter, feed speed control 0.15m/min, turn speed control 30,000 rpm. Attention to

burrs and aluminum frame tilt.


2.10 Final Inspection/Package/Shipping

1 Package: PE film protected to the upper and lower aluminum substrates;

2 Product label affixed on outer package;

3 Put into cardboard box with tape sealing;

4 Keep under the ambient temperature below 30 , ℃humidity less than 60%;

5 Avoid moisture and sunlight.


3.Test

White solder mask ink functional test

High Thermal conductivity aluminum circuit board PCB functional test.


3.1 LED Ink functional test

4 companies ink(TeamChem, UNIVUREA

, Uteik, Taiyo), After tin bleaching 288 , 10sx3 times TeamChem with the ℃highest whiteness and no ink peeling.


3.2 Finished product test

Test Item Test Spec. Test Method Test Result

900-peel strength

IPC-TM-650 2.4.9

25um film thickness

90 x40min pre-bake℃90 x6kg/cm℃ 2x10spress

90 x90min post-cure℃

1.3kg/cm

High temperature

aging testPC-TM-650 2.4.5.1 150 x6H℃ Pass

Solder resist IPC-TM-650 2.4.28.1C 288 x10sx3times℃ Pass

Chemical resistance

IPC-TM-650 2.3.3MEK:23 x1min℃

2N NaoH:23 x1min℃2N Hcl:23 x1min℃

Pass


4.Improvement

After production, some improvement need to do as below: 1.TCA volume; 2. Design range of diffuser compensation when TCA printing; 3. What used for cleaning glue in the stencil after printing; 4 .The gold plating Ni thickness 130-150U ". Gold thickness 3-5u". If

customer requirement Ni thickness 250U "-300U", gold thickness 8U ", could meet or not?

According to above 4 points, how to meet customer’s requirement: a. No glue allow to inflow box for aluminum frame printed; b. The board needs gold line in the center PAD point, which need to consider

pulling. If it could improved to add in Ni, Au thickness, why?


Solutions： 1. Use high-viscosity thermal conductivity adhesive, and use stencil

printing. 2.Consider the pressure, temperature and time when lamination. 3.(1) gold line mainly related to the thickness of nickel. Gold is just

protect nickel from oxidation, purification, is no direct relation. Nickel thickness between 150-200u, gold thickness 3u will be ok.

(2) It need to use high gold if the thickness of gold require 8u; normal gold is unattainable, and prone to uneven color, erythematic.

(3) The phosphorus content is too high may cause undesirable soldering. Phosphorus content is generally controlled at 7-9% or less.


Contact Agile Circuit Co., Ltd

Chris ChowDirector of Sales and Marketing

Agile Circuit Co., Ltd

0316# East Tower of Shiji Square, the First Nanyou Industrial Park, Nan shan Dist,518054 China

Phone: 85-755-86050627

Email:[email protected]

To know more about PCB manufacture and assembly, visit us at http://www.agipcb.com

aluminum pcb with high thermal conductivity production process

Technology

agile circuit

aluminum frame

aluminum board use

aluminum core

aluminum plate pcb

tca printing al

foreword aluminum pcb

stencil printing