Design

Company Overview

Advanced Technical Ceramics Company (AdTech Ceramics) is located in Chattanooga, Tennessee.

Founded with a proven employee base and manufacturing capability for multilayer co-fired electronic packages
Processes revolve around 30 plus years of experience in material science, engineering, design, tooling and
manufacturing of multilayer ceramics
Materials include Alumina (HTCC), Aluminum Nitride, BeO and LTCC
Chemical Milling services available (step lids, leads, seal rings) in Kovar, Alloy 42, Spring Steel and Stainless Steel
Market emphasis targets engineering solutions for high reliability applications
Business model focuses on long term stability and growth
Manufacturing capabilities include prototype to high volume production
US owned, US based, ITAR Compliant
MIL-1-45208
ISO 9001:2000 Certified.

AdTech Ceramics continues to drive process, facility and equipment improvements and advancements, and actively
seeks new opportunities in advanced Note: These general guidelines should be used for typical designs. If
exceptions or special requirements are needed they should be reviewed with AdTech Ceramics.

Advanced Technical Ceramics Company
511 Manufacturers Road
Chattanooga, Tennessee 37405
(423) 755-5400
(423) 755-5438 Fax
Internet: www.AdTechCeramics.com
Email: sales@AdTechCeramics.com

Product Capabilities Include

Custom Advanced Packages, Multichip Modules, Substrates and Packages, Microwave Packages

High Frequency Feed Throughs, Power Dissipation Packages, Optical Packages High Lead Count Packages

Custom Pin Grid Arrays, Sensor Packages, Crystal/Oscillator/SAW Packages

Pad Array Carriers (Ball Grid Arrays), Ceramic/Metal Packages, Chemical Milling

Process Overview

Electronic packages produced with the co-fire multilayer ceramic process have four distinct processing stages:

Materials Preparation
Green Processing
Sintering
Post-fire Processing

Materials Preparation

Ceramic materials are prepared by milling precise amounts of raw materials into a homogeneous slurry. This mixture
is principally ceramic powders of controlled particle sizes with fluxes and small amounts of organic binders and solvents.
This slurry is poured onto a carrier and then passed under a blade to produce a uniform strip of specific thickness. When
dried, this strip becomes a ceramic-filled “tape” which is easily handled in rolls or sheets for unfired processing. Metal
powders of exact compositions and particle sizes are prepared as “pastes” for subsequent screen printing on the green
ceramic tape, or in some cases, on the fired ceramic. Likewise, ceramic powders can be prepared as pastes to be used
as screen printed dielectric layers.

Green Processing

Except for very large or complex products, individual products are arranged in arrays for multiple processing. Via holes,
edge castellations and cavities are then punched in the tape. Because of the abrasive nature of ceramics, special tooling
must be used for these operations. Green processing of ceramic is very sensitive to particulates and is done in a Class
10,000 Clean Room.

Via holes are filled with a refractory metal paste, or bore coated, to become the vertical electrical interconnections between
the layers. Conductive circuit patterns are printed onto the ceramic tape with refractory metal pastes using precision screen
printing.

The layers are then stacked and laminated together. At this point the array may be scored to allow post fire operations
in the array, or individual products may be cut or punched out of the array prior to sintering.

Sintering (Firing)

The ceramic-refractory metal composite structure is sintered, or “co-fired,” at temperatures as high as 1600°C in a carefully
controlled atmosphere. During the firing process most ceramics shrink approximately 20% in the X, Y and Z dimension.
Hot pressed AlN is physically constrained in the X and Y dimensions so that all shrinkage occurs in the Z dimension.

Post Fire Processing

Ceramic packages are typically supplied with Gold over Nickel plating on the metallized areas, and can have metal
components attached by brazing. Nickel is plated on all exposed metal surfaces to allow brazing and to provide solderability.
Metal leads, pins, seal rings and heat sinks are attached by brazing with silver or a silver-copper eutectic alloy to form
a strong hermetic joint. Final plating may be either electroless or electrolytic gold. Electrolytic plating requires that all
exposed circuits be temporarily electrically connected through a lead frame, internal tie bar, or a combination of the two.
A combination of electrolytic and electroless plating can be used if designs require. (Note: in this case metal components
must be electrolytic.) Post fire metallizations can be used for applications requiring special flatness or precision tolerances.
Ceramic grinding, lapping and ultrasonic machining are available for applications requiring features not achievable as-fired.

Co-fire Multilayer
Ceramic Process

Structural & Interconnect Design Guidelines

Printer Friendly Version Structural Parameters | Vertical Interconnects | Horizontal Interconnects | Detailed PDF Version

Design considerations for multilayer ceramic packages can be grouped into these categories:

Structural Parameters
Interconnect Layout
Special Features

Structural Parameters

Each ceramic material has specific design and tolerance limitations due to their physical properties and processing
technologies. These include size, number of layers, and flatness.

Features	Description	Alumina	Aluminum Nitride
Length/Width (X/Y)	Standard Tolerances	±1% NLT ±0.13mm ±(.005")	±.005"
	Special Tolerances	±.5%	(Sawed) ± 0.05mm (.002")
Layer Thickness (A)	Standard	0.18mm (.007") to 0.64mm (.025")	0.13mm (.005")
	Special	0.13mm (.005") to 0.76mm (.030")	0.09mm (.0035") to 0.38mm (.015")
	Standard Tolerances	±10%	±10%
	Special Tolerances	±5%	n/a
Package Thickness (Z)	Range	0.25mm (.010") - 8.89mm (.350")	3.4mm (0.135")max
	Standard Tolerances	±10%	±0.08mm (.003")
	Special Tolerances	±5%	±0.03mm (.001")
Flatness	Standard	0.08mm/mm (.003"/inch)	0.03mm/mm (.001")/inch
	Special (Machined)	0.03mm/mm (.001"/inch)	n/a
Surface Finish	As Fired	<1.14µm (45µ")	n/a
	Lapped	<0.51µm (20µ")	<0.64µm(25µ")
	Polished	n/a	<0.13µm(5µ")

Vertical Interconnects

The basic interconnect between layers is the metal-filled via. Also used are bore coated (metallized side wall) vias,
metallized edge castellations and flat edge metallization. Generally, via diameters should be at least the thickness of
the ceramic layer and via pitch 2.5 times the layer thickness. Vias may require a cover pad to be printed with the metal
interconnect pattern to assure optimal electrical connection between layers.

Feature	Description	Alumina	Aluminum Nitride
Filled Via (B)	Diameter Range	0.10mm (.004") - 0.51mm (.020")	0.13mm (.005") - 0.51mm (.020")
(C)	Cover Pad dia (Internal)	Via dia + 0.05mm (.002")	Via DIA+0.05mm (.002")
(C)	Cover Pad dia (External)	Via dia + 0.13mm (.005")	Via DIA+0.38mm (.015")*
(D)	Via-to-Via Centerline	0.30mm (.012") Min.	0.38mm (.015") Min.
(R)	Via-to-Edge (Standard)	w = t + v (web = thickness + via diameter)	0.25mm (.010")
	Via-to-Edge (Sawed Edge)	0.20mm (.008") Internal Via	0.20mm (.008") Internal Via
	Via-to-Edge (Sawed Edge)	0.00 Split Via (see page 10)	n/a
Bore Coated Via (Q)	Diameter Range	0.30mm (.012") - 0.64mm (.025")	n/a
	Cover Pad Diameter	Hole dia + 0.25mm (.010")	n/a
(P)	Castellation Radius (Typical)	0.20mm (.008")	n/a
Edge Metallization (L)	Centerline	0.64mm (.025")Min.	n/a
(J)	Circuit Neckdown (Range)	0.13mm (.005") to Width of Edge Metal	n/a
(K)	Pullback From Edge	0.51mm (.020") (TYP) 0.25mm (.010") Min.	n/a

Horizontal Interconnects

Circuit layout is usually a compromise between maximizing conductor trace width to minimize resistance, and maximizing
the space between conductors, and other metal features such as vias, in order to minimize yield losses. It is desirable to pull
back buried metal features from the ceramic edge, and neck down conductors that terminate with edge metallization. Internal
ground planes should be limited to a maximum of 75% metal coverage.

Feature	Description	Alumina	Aluminum Nitride (AIN)
Internal Metal Circuit (F)	Typical Width	0.15mm (.006") - 0.25mm (.010")	0.15mm (.006”) - 0.25mm (.010")
	Custom Width	0.10mm (.004")	0.10mm (.004")
(G)	Typical Space	0.15mm (.006") - 0.25mm (.010")	0.15mm (.006”) - 0.25mm (.010")
	Custom Space	0.13mm (.005")	0.13mm (.005")
	Maximum Coverage	85%	75%
	Recommended Grid	Equal lines and spaces	Equal lines and spaces
(I)	Typical Space from Edge	0.76mm (.030")	0.254mm (.010")
	Custom Space from Edge (Sawed)	0.13mm (.005")	0.20mm (.008")
Surface Metal Circuit (F)	Typical Width	0.20mm (.008")	0.20mm (.008")*
	Custom Width	0.10mm (.004")	0.10mm (.004")*
(G)	Typical Space	0.20mm (.008")	0.20mm (.008")*
	Custom Space	0.13mm (.005")	0.10mm (.004")*
	Maximum Coverage	100%	100%
(E)	Typical Space from Edge	0.25mm (.010")	0.254mm (.010")*
	Custom Space from Edge	0.00mm (.000")	0.18mm (.007")*
Relation to Vias (M)	Isolation Ring Around Cover Pad	0.38mm (.015")	0.20mm (.008")*
	Custom Isolation Ring	0.25mm (.010")	0.10mm (.004")*
(N)	Circuit to Cover Pad	0.25mm (.010")	0.20mm (.008")*
	Custom Space (External)	0.15mm (.006")	0.10mm (.004")*
	Custom Space (Internal)	0.20mm (.008")	0.20mm (.008")*

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Special Feature Design Guidelines
Special consideration should be given to the design of the following features:

Cavities
Wire Bond Pads
Metal Components
Special Enhancements or Finishes

Cavities
Cavities are punched into the ceramic in its green state. Metallization should generally be pulled back from the edges of
cavities. When cavity floors are metallized, the metallization should extend beyond the cavity wall to assure complete
coverage.

Wire Bond Pad Design
By designing wire bond pads in a radial pattern (from the center of the cavity) it is possible to compensate for variations
in the co-fired shrinkage. For very high density applications wire bond pads can be staggered in a double row around
the die, achieving pads as small as 0.15mm (.006") x 0.15mm (.006") on an effective 0.15mm (.006" )pitch.

Cavity Design

Feature	Description	Alumina	Aluminum Nitride*
Die Attach Pad (A)	Typical Extension	0.51mm (.020")	N/A
	Minimum Extension	0.25mm (.010")	N/A
Circuit Pattern (B)	Typical Pull Back	0.13mm (.005")	N/A
	Minimum Pull Back	0.08mm (.003")	N/A
Metallized Seal Ring (C)	Typical Pull Back	0.25mm (.010")	N/A
	Minimum Pull Back	0.13mm (.005")	N/A

* No cavities in hot press technology

Screened Dielectric
Screen printed dielectrics are frequently used to reduce overall ceramic thickness, cover exposed circuitry, or form
solder or braze dams. The composition of the screened dielectric is the same as that of the base ceramic and is
generally applied in the green state for sintering during the co-fire process.

Metal Component

Feature	Description	Specification
Seal Ring Height (A)	Typical	1.02mm (.040")
	Range	0.25mm (.010") - 5.08mm (.200")
Seal Ring Width (B)	Typical	1.02mm (.040")
	Range	0.25mm (.010") (Minimum)
Metallized Seal Ring Width (C)	Typical	Seal Ring Width + 0.51mm (.020")
Lead Frame Width (D)		0.20mm (.008") (Minimum)
Lead Frame Pitch (E)		>= 0.51mm (.020")
Metallized Lead Frame Pad (F)		D + 0.25mm (.010") (0.13mm (.005") minimum space between pads)
Metal Pin Pitch (G)	Standard	2,54mm (.100")
	Custom	1,27mm (.050")

Metal Components
Metal components such as seal rings, heat sinks and lead frames may be attached to metallized patterns
on the ceramic by high temperature brazing. Leads may be necked down or formed in the braze pad area.
Attachment of metal components to aluminum nitride packages is considered custom and developmental
due to TCE mismatch between brazed metal alloys and the AlN.

HTCC Thermal Enhancements
The thermal performance of co-fired alumina packages may be improved by adding thermal vias, or replacing
the ceramic base with a brazed heat-sink such as Molybdenum (Mo), Copper Tungsten (Cu-W), Copper
Molybdenum (Cu-Mo) or Beryllium Oxide (BeO).

Mechanical Enhancements
The mechanical characteristics of a package may be enhanced through a number of procedures. Lapping, a
precision grinding process, can be used to improve flatness or surface finish. Diamond sawing, grinding and
ultrasonic machining are available to achieve special features or tighter tolerances. Laser disconnect can be
used to allow for all electrolytic plating.

AIN and BeO Solutions
Multi-layer AlN and metallized BeO substrates are also used for elegant thermal solutions for high power
applications. BeO ceramics can be metallized and integrated into HTCC package designs, while AlN
offers the multi layer circuit integration benefits of HTCC along with the thermal performance of BeO.

Design Capabilities
AdTech maintains in-house design capabilities, as well as excellent relationships with outside design service
firms for overflow and special design needs. Additionally, AdTech’s design staff can interface with and accept
customer design data in a number of formats. Capabilities include but are not limited to:

Engineering Software:

AutoCAD
Solid Works
CAM 350

Customer Interface - CAD Data Types:

AutoCAD.DXF or .DWG
Gerber Plot Data (RS274, RS274X)
MDA Plot Data
Barco PDF

AdTech Ceramics can accept customer files via internet e-mail at design@AdTechCeramics.com or FTP upload.

Special Capabilities
AdTech prides itself on being the innovation leader in the ceramic package business. Co-fired ceramic technology
was invented in our Chattanooga facility over 35 years ago, and numerous patents have been issued over the years.
Today, the company remains the leading US-owned non-captive supplier of ceramic electronic packages, and
continues to lead the industry.

Feed Throughs
AdTech’s patented “split-via” concept provides an exceptionally reliable method of edge metallization without
concern for processing damage at the point where metallization wraps around the edges.

Ceramic Pedestals
A Ceramic pedestal may be used in the package design to allow for self-jigging of metal or ceramic Seal-Ring.
Circuitry can be added to a pedestal that connects to package base.

Microwave Design Assistance
AdTech Ceramics produces HTCC and AlN packages for microwave applications in the X through K band
frequency ranges. It has a design process that uses state of the art 3D Finite Element Method (FEM) simulators
and proprietary numerical simulators.

Electromagnetic Simulation

This process can yield market-differentiating performance while maintaining cost effective solutions. The alternative
is to resort to the old cycle of fab, test and redesign. The AdTech solution, on the other hand, offers world class
performance with cost competitive ceramic packaging solutions.

Thermal Modeling

AdTech Ceramics is able to analyze and improve the thermal performance of the ceramic package. It does so by
using its unique combination of proprietary thermal analysis tools, commercially available thermal analysis software
and highly qualified engineering staff. This capability improves performance and reduces cycle time.

Refractory Metal Standoffs

For the ultimate in standoffs, AdTech can co-fire refractory metal "bumps" on BGAs or substrates that will retain
their shape through multiple solder reflow operations. A Ceramic pedestal may be used in the package design to
allow for self-jigging of metal or ceramic Seal-Ring. Circuitry can be added to a pedestal that connects to package base.

Chemical Milling

In addition to ceramic products, AdTech makes and supplies high quality chemically milled products in Kovar, Alloy 42,
Stainless and Spring Steel. Products include step lids, lead frames, seal rings and other applications. Products can
be supplied as etched, or with Ni/Au plating for seam welding applications.

Materials Selection
Multilayer ceramic electronic packages can be produced with a wide choice of materials, each designed to meet
specific application needs. The choices include:

Ceramics
Metallizations
Brazed Components
Platings

Ceramic Materials

AdTech offers a choice of ceramic materials:

Alumina (HTCC)
Aluminum Nitride (AlN)
Low Temp Co-fired Ceramic (LTCC)
Beryllium Oxide (BeO)

Additionally, custom materials can be developed to meet special needs.

Alumina (92% Al₂O₃) - HTCC

Alumina is the most popular ceramic material for multilayer packages. Because it has been used for many years
its performance is well characterized, and it has a proven track record. Alumina offers high strength, good thermal
conductivity, hermeticity, excellent electrical properties and the lowest cost high density interconnect. HTCC is
available in both white and black.

Aluminum Nitride (AlN)

Due to its high thermal conductivity and excellent Thermal Coefficient of Expansion match to Silicon, Aluminum
Nitride is the ceramic material of choice for high heat dissipation and/or large chip applications. AdTech Aluminum
Nitride is produced using hot press technology.

It is ideal for applications requiring very high thermal conductivity (160 W/mK). The patented hot press process
allows precision tolerances (±0.15%).

Aluminum Nitride’s primary application is for MCMs requiring multiple internal
metal patterns (30+ layers possible) with vias only terminating on the top and bottom surfaces. The external metal
patterns are applied to a precision surface finish, flat to within .001"/inch, using thin film processing.

Typical Ceramic Properties

Material		92% Alumina (Al₂O₃)	Aluminum Nitride (AlN)
Color		Black or White	Translucent Gray
Density	g/cc (#/cu. in.)	3.62 (0.131)	3.26 (0.118)
Hardness	kg/mm2	1207 (Knoop)	1200 (Knoop)
Flexural Strength	MPa (psi x 103)	443 (64)	280 (4)
Youngs Modulus	GPa (psi x 106)	275 (40)	340 (49)
Shear Modulus	GPa (psi x 106)	112 (16)	140 (20)
Surface Finish	µm (µ")	<1.14 (<45)	<0.76 (<30)
Thermal Expansion (25-300°C)	10–6/°C (10–6/°F)	6.57 (3.64)	4.00 (2.2)
Thermal Expansion (25-500°C)	10–6/°C (10–6/°F)	7.16 (3.98)	4.50 (2.5)
Thermal Conductivity (25°C)	W/mK (BTU-in/ft2-h-°F)	20.3 (141)	160 (1174)
Dielectric Strength	kv/mm (volts/mil)	11.6 (295)	13.0 (330)
Volume resistivity	ohm-cm2/cm	>1014	>1014
Dielectric Constant (1MHz)		9.2	8.6*
Dielectric Constant (10 GHz)		9.2*	8.2
Dielectric Constant (30 GHz)		9.2	–
Dissipation Factor (1 MHz)		0.0003*	0.0001
Loss Factor (10 GHz)		0.003*	0.0010
Loss Factor (30 GHz)		0.004	–

*Extrapolated Calculation

Typical Component Properties

Material	Molybdenum	Copper Tungsten (15-85)	Alloy 42	Kovar	Copper	BeO	Tungsten
Thermal Conductivity @25° (W/mK)	138	170	10.5	16.7	398	200-250	173
Thermal Coefficient of Expansion @25°C-100°C (x 10– 6/°C)	5.1	7.1	5	5.9	16.8	6.9	4.5
Electrical Resistance @25°C (x 10 –6 ohm-cm)	5.2	6.1	72	49	1.7	n/a	5.5
Specific Gravity (g/cc)	10.2	16.8	8.1	8.4	8.9	2.9	19.3

Metalization
Metallizations are largely dictated by the ceramic base material. Alumina and Aluminum Nitride require refractory
metals such as Tungsten (W) and Molybdenum (Mo) for high temperature sintering in protective atmospheres.

Brazed Components
Kovar and Alloy 42 are the most popular metals for brazed components due to their good thermal coefficient of expansion
match to ceramics and relatively low cost. However, other materials such as Molybdenum and Copper Tungsten, can be
successfully brazed to metallized ceramic for heat sink applications.

Metalization Resistance (Typical)

Ceramic	Alumina	Aluminum Nitride
Metallization	Tungsten	Tungsten or Tungsten-Moly
Buried	.012 ohm/sq (Standard)	.015-.020 ohm/sq
	.008 ohm /sq (High Conductivity)	–
Surface	.005 ohm/sq (Gold Plated)	.005 ohm/sq (Gold Plated)
Vias	.003 ohm (0.25mm (.010") DIA x 0.25mm (.010") length)	–

Plating
AdTech offers electrolytic and electroless Nickel in thicknesses typically from 50µ" to 300µ" and electrolytic and electroless
Gold in thicknesses typically from 30µ" to 100µ". Thicknesses outside these ranges are also possible. A combination of
both plating types can be used if required.

Plating Specifications

Finish	Specification	Specification
Gold	Electroless	Meets MIL-G-45204 or AMS2422
	Electrolytic	MIL-G-45204 or AMS2422
Nickel	Electroless	AMS2404 or AMS2433
	Electrolytic	SAE AMS-QQ-N-290

Customer Interface

Email: sales@AdTechCeramics.com
FTP Capabilities

Mission Statement
Advanced Technical Ceramics Company strives for continuous improvement in quality and service to meet
our customers’ requirements for high-performance ceramic packaging products. AdTech Ceramics’ growth
is driven by sound business ethics, customer satisfaction and the continuous development of new applications
requiring advanced technical ceramic solutions.

Quality Policy
AdTech Ceramics is dedicated to achieving superior levels of customer satisfaction through teamwork and
continuous improvement. We will provide quality to our customers, both internal and external, and will deliver
products and services which will meet or exceed customer expectations in accordance with our Quality
Management System.

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