Thick Film Processing with Near-Infrared

TF Series infrared furnaces have been specifically engineered for thick film and hybrid circuit applications. Processes include curing and/or firing of advanced Noble metal, copper, ceramic or glass ink, firing dielectrics, conductors and resistors on ceramic, porcelain and metallic substrates in air, nitrogen or forming gas (mixture of hydrogen/nitrogen) atmospheres. Unique technology provides outstanding performance and low cost of ownership.

Shorter dwell time

As a result of the high equilibrium heat transfer of the near-infrared (NIR) lamps in the furnace, dwell time in a near infrared furnace can be quite short compared to a conventional convection furnace.  The physical structure of thick film materials is developed very quickly, and the overall time/temperature product is relatively small. Dwell time at peak tempeartures can be as short as 3 to 4 minutes instead of 10 minutes. Limiting time at peak temperatures avoids materials migration and diffusion issues.

Because of the penetrating power of high intensity near infrared radiation, the organic volatiles within thick film inks and pastes essentially sublime completely from the structure without eruption.

Faster Processing

Typically parts can complete processing in 15 minutes instead of 45 minutes required by a convection furnace and shorter production time means higher production output per furnace.

Avoid Cooling Shock

With TF-series furnace high efficiency controlled cooling system the cooling system is designed to provide cooling rates consistent with high yield and throughput without promoting cracking.  Product is returned to room temperature, avoiding structural failure due to stress and strain resulting from excessive thermal gradients. 

Use Same Furnace for Drying & Sintering

Use of burnout venturi exhaust after first chamber to eliminate volatiles combined with TF-series zone isolation and precise control allows for both drying and sintering operations in a single furnace.

Lower Operating Energy Costs

The largest savings in energy consumption comes from three primary features of the TF-Series near-infrared furnaces:

1.  Radiant near infrared heat focuses energy on the product in the furnace rather than heating the furnace itself.

2.  TF-series furnaces require much shorter stabilization time (minutes instead of hours) so little energy is spent in bringing the furnace to "Process Ready." 

3.  SCR fired heating elements optimize power use by clipping the incoming sine wave providing full voltage to the heating elements at extremely low power levels.

Thick Film Profiling in a NIR Furnace

For most thick film processes in these infrared furnaces, the rate of temperature rise in the product can be made quite fast, the volatilization and sublimation of organic binders being completed long before sintering temperatures are attained. To achieve this result, the first zone should be driven as hard as practical to maintain the highest intensity near infrared radiation, reaching process temperature at the beginning of subsequent holding zone(s). The holding zones are set to maintain sintering temperatures in the product. Dwell time in these zones should be just sufficient to drive the pyrolysis or polymerization to completion. By limiting the time at temperature in this manner, unacceptable materials migrations or diffusions can be avoided.

 

Profiling a P-series Furnace

DDC Discrete Digital Control System

Thick film P-series furnaces now feature LCI's new DDC disctete digital control system.  This system was developed as a result of customer demand for a sophisticated control system that operates free of a PC workstation.  LCI's DDC control system uses an individual 4-stage temperature controller for each zone and a small, but powerful PLC (programmable logic controller).  Belt speed locks on to the value set by the user, controlled by a PID loop in the PLC.  All customary alert and alarm functions from traditional computer-controlled furnaces have been included in LCI's DDC control system.  Click here for more.

Thick Film Furnace 4-Zone DDC Console

 

TF-Production Series IR Furnace Arrangement

TFP-series	3-Z Chamber	4-Z Chamber

THERMAL PROCESSING
Parameter	TF-300P Models	TF-600P Models	TF-900P Models	TF-1200P Models
Load Station	380 mm (15 inches), add one or more CXX15 for additional 380 mm (15-in) extensions.
HEATING SECTION
Entrance Isolation Baffle with Venturi Exhaust	380 mm (15 inches)
IR Heating Zones, Chamber 1	190 - 380 - 190 mm  (7.5 - 15 - 7.5 in.)	2 x 380 mm  (2x15 in.)	2 x 380 mm  (2x15 in.)	2 x 380 mm  (2x15 in.)
Burnout Venturi Exhaust	not required	Optional	Optional	Optional
IR Heating Zones, Chamber 2	--	2 x 380 mm  (2x15 in.)	2 x 380 mm  (2x15 in.)	2 x 380 mm  (2x15 in.)
IR Heating Zones, Chamber 3	--	--	2 x 380 mm  (2x15 in.)	2 x 380 mm  (2x15 in.)
IR Heating Zones, Chamber 4	--	--	--	2 x 380 mm  (2x15 in.)
COOLING SECTION
Transition Tunnel with Venturi Exhaust	380 mm (15 inches) CDA or N2 convective cooling
Cooling Modules (typical) (varies with part characteristics and required throughput)	1 x 760 mm (30 in.)	1 x 760 mm (30 in.)	2 x 760 mm (30 in.)	3 x 760 mm (30 in.)
Cooling Module Choices	Each of the following Cooling Modules fits in 1 x 760 mm (30 in.) space: CACT - CDA or N2 convective and radiant cooling, exterior fan heat removal (standard). CM - Fan driven ambient air cooling located after Exit Isolation Baffle (not suitabe for use with N2-Nitrogen or FG-Forming Gas).
Exit Isolation Baffle	280 mm, CDA or N2 Convective Cooling (optional). Improves isolation for low-oxygen operation during cooling phase. Omit entirely if cooling is all CM modules, or transition tunnel/CACT isolation is sufficient.
PRODUCT HANDLING
Unload Station	380 mm (15 inches), add one or more CXX15 for additional 380 mm (15-in) extensions.

TF-Series Thick Film NIR Furnace Specifications

SPECIFICATIONS
Parameter	TF-300P Series	TF-600P Series	TF-900P Series	TF-1200P Series
Belt Size: (model, nominal width)	TF-309P, 24 cm (9.5 in.) TF-315P, 38 cm (15 in.)	TF-609P, 24 cm (9.5 in.) TF-615P, 38 cm (15 in.)	TF-909P, 24 cm (9.5 in.) TF-915P, 38 cm (15 in.) TF-924P, 61 cm (24 in.)	TF-1209P, 24 cm (9.5 in.) TF-1215P, 38 cm (15 in.) TF-1224P, 61 cm (24 in.)
Belt Speed	25-510 mm/min (1-20 ipm), other speeds available
Conveyor Belt	BNV- low mass, stabilized Nichrome-V
Control Zones	3	4	6	8
Heating Chamber length	760 mm (30 inches)	1520 mm (60 inches)	2280 mm (90 inches)	3040 mm (120 inches)
Cooling Chamber Length (typical)	760 mm (30 inches)	760 mm (30 inches)	1520 mm (60 inches)	2280 mm (90 inches)
Process Gas (70 psig supply)	CDA - Clean dry air N - Nitrogen FG - Forming gas (premixed hydrogen and nitrogen) HO - Forming gas (on-board hydrogen and nitrogen mixing)
Flowmeters	7	8-10	10-11	11-12
Exhaust	Improved venturi exhaust stacks reduce process gas consumption. Flowmeter controlled.  Number of stacks vary with process requirements.
Temperature Capacity, max	1000°C
Electrical	All models include universal transformers which accommodate 208-480 Vac and 50/60 Hz frequency anywhere in the world, allowing furnace relocation without external equipment. All furnace systems are phase balanced to improve facility efficiency. IR lamp controls automatically keep IR spectrum constant.

Total Length (typ, approximate)	3100-3480 mm  (122-137 in.)	3912-4216 mm  (152-166 in.)	5360-5740 mm  (211-226 in.)	7260 mm  (286 in.)
Total Width (belt nominal width)     6-inch belt     9-iinch belt    15-inch belt     24-inch belt	TF-306P: 610 mm (24") TF-309P: 724 mm (29") TF-315P: 940 mm (37") -	- TF-609P: 724 mm (29") TF-615P: 940 mm (37") TF-624P:1230 mm (45")	- TF-909P: 724 mm (29") TF-915P: 940 mm (37") TF-924P:1230 mm (45")	- TF-1209: 724mm (29") TF-1215: 940mm (37") TF-1224:1230mm (45")
Total Height (typ, approximate)	171 mm (67 inches)	171 mm (67 inches)	171 mm (67 inches)	171 mm (67 inches)

Thick Film IR Furnace Typical Options

Standard features are listed on the Standard Features pages (see link below). Popular options include the following (click on Option Code for description):

POPULAR OPTIONS
Code	Description	Code	Description	Code	Description
DGO	Dual Gas Operation	OA	Oxygen Analyzer	AFR	Coalescing Air Filter & Regulator
UPS	Un-interruptible Power Supply	CXE15	Entr Load Extension, 380 mm	IR-E	Entrance Interface Roller, small diameter
LT	Process Ready Light Tower	CXX15	Exit Unload Extension, 380 mm	IR-X	Exit Interface Roller, small diameter