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Understanding the Complex World of Linear Resistors

12.11.2006 // Dennis M. Zogbi // Passives

Dennis Zogbi December 11, 2006
 
 

The basic definition of a linear resistor is a device used to control current in an electric circuit by providing resistance due to a voltage drop across its terminals. This feature makes it applicable both as a resistor, in the classic sense, and as a sensor in the more modern sense. Linear resistors, which will account for more than 1 trillion pieces shipped in 2006 worldwide, will be in substantial demand again in 2007 for wireless handsets, computer motherboards, game consoles, and HDTV. This article explains the diverse nature of the linear resistor market and how engineers choose their resistors based upon type.

Primary Resistor Categories:

There are two commonly used categories for linear resistors based on their configuration: surface mount or through-hole.

Types of Resistors:

Additionally, there are 10 distinct sub-categories within the linear resistor market based upon component type.

  • Thick film chip resistors
  • Multichip resistor arrays
  • Dual-in-line packages (DIP)
  • Integrated passive devices
  • Single-in-line packages
  • Nichrome metal film resistors
  • Wirewound resistors
  • Tin-oxide resistors
  • Bulk metal foil resistors
  • Carbon film resistors.

Linear resistors are common and can be found in bills of material for every electronic box built worldwide because of the scientific maxim that requires resistance in every circuit, regardless of application. The common vernacular to describe this ubiquitous product line is a mixture of resistive element and configuration descriptions.

Resistor Construction (Precious Versus Base Metal Resistors):

To keep with the concept of resistive elements used in linear resistor descriptions, the market can also be broken down into “precious” and “base metal” designs. This type of description is typically reserved for ceramic capacitors but is also applicable in understanding the complex resistor market, which is among the oldest for all electronics, stretching back in its modern sense about 60 years.

Ruthenium & Palladium Based Resistors:

Precious metal elements used in linear resistors are predominantly ruthenium based, and ruthenium oxide or ruthenium pyrochlore mixed with electronic glass, and screened onto an alumina substrate accounts for the way most electronic circuits from computers to wireless handsets solve their ohmic requirements. Palladium mixed with silver is also used in some resistor applications requiring low ohmic values. Precious metal resistors are almost 100% surface mount, and are used in thick film chips, multichip arrays, and dual in-line package type resistors. Single in-line packages, which are through-hole in design, also use precious metals; and this is where we find much of the Pd/Ag use for resistors, especially for subscriber line interface cards used in central office telephone applications.

Nickel-Chromium, Tin Oxide, Tantalum Nitride and Carbon Based Resistors:

Base metal resistors are predominantly based upon nickel chromium. Nickel chromium is consumed in three forms in resistors- as a film, a foil and an extruded wire. Additional base metals used in resistors include tin-oxide, more popularly known as Antimony-10, tantalum nitride, used in integrated passive devices, and carbon film resistors, which are used in CRT type TV sets.

The following list quantifies linear resistors by configuration, type, and construction:

Surface Mount Linear Resistors:

  • Thick Film Chip Resistor: Ru02 or Pd/Ag resistive layer screened on 96% alumina.
  • Multi-Chip Resistor Array: Ru02 or Pd/Ag resistive layer screened on 96% alumina with an alumina bridge.
  • Dual-In-Line-Package (DIP) Resistor Network: Ru02 or Pd/Ag resistive layer screened on 96% alumina - multiple configurations.
  • Integrated Passive Devices: Tantalum nitride or other thin film deposited Oon silicon or other substrate, sold in DIPs or other packaging.

Through Hole Resistors (Axial and Radial):

  • Single-In-Line Package Resistor Network: Ru02 or Pd/Ag resistive layer screened on 96% alumina - multiple configurations.
  • Nichrome Metal Film Resistor: Nickel chromium metal vacuum deposited upon cylindrical alumina core.
  • Nichrome Wirewound Resistor: Nickel chromium wire wrapped around a cylindrical alumina core. Sister component is the wirewound inductor.
  • Tin-Oxide Resistor: Antimony-10 flameproof resistive material deposited upon a cylindrical alumina core.
  • Nichrome Bulk Metal Foil Resistor: Nickel chromium bulk metal foil combined with alumina core.
  • Carbon Film Resistor: Carbon film deposited on an alumina core.

Nature of Resistor Diversity:

The need for so many different types of resistors is ultimately reflective of market demand. When the diversity of ohmic value requirements, power requirements, frequency requirements, and operating environment are considered, the large number of choices in resistors is justified and can further be used to understand the value and volume of demand for resistors by type.

Ohmic Capabilities of Resistors by Type:

In terms of a linear resistor’s capacity to provide an ohmic value in an electronic circuit, we note a correspondence between the resistive element and resistor type, and the historical introduction of the product line. In short, the older types of resistors, such as wirewound, carbon, nickel chromium and tin-oxide have the ability to provide ohmic values to 1 GigaOhm. Products that saw most of their growth after 1990, such as ruthenium based thick film chips, arrays and networks have ohmic handling capabilities to handle the advent of wireless communications to 6 GigaOhms, with thin film designs based upon tantalum nitride or nichrome resistive elements going to 20 GigaOhms. It is also important to note that all resistors, regardless of type, will offer to at least 10 MegaOhms, if not 100 Megaohms, which is a testament to their use as resistors to begin with. It is when we go beyond the 100 Megaohm mark that we see more of an exclusive reliance upon ruthenium thick film designs, or tantalum nitride thin film designs to achieve the required ohmic value. These higher ohmic value requirements are usually telecom infrastructure, satellite or defense communications related; whereas consumer electronic devices, such as handsets and microprocessors operating at above 1 Gigahertz, represent the bulk of unit demand, and is therefore predominantly solved by the all encompassing- ruthenium based thick film chip resistor and resistor array.

Tolerance Handling Capabilities of Resistors by Type:

Many design engineers are now specifying resistors with tighter tolerances. For extremely tight tolerances, such as those found in computing and data networking, many companies look toward nichrome or tantalum based thin film resistors to provide tolerances below 0.05%. The majority of resistors manufactured today have a 5% tolerance rating, which is considered the precision level with the greatest volume and the lowest price. As companies look toward tighter tolerances they generally reach a barrier of 0.5% with the ubiquitous thick film ruthenium chip resistor and must move into the thin film environment to go to tolerances less than 0.1%

Power Handling Capabilities of Resistors by Type:

When we look at power handling requirements, we see why the older legacy products are still lucrative, as their designs, old as they may seem, are still very important in industrial electronics. In terms of power handling we note that almost all resistors, regardless of type, are generally operational from 0.25 to 5 Watts; although the tin-oxide and wirewound versions are generally not sold below 0.5 watts because their customers do not need such low power handling. On the opposite end of the spectrum, we note how wirewound resistors are used well beyond any of the other resistor products when it comes to power. Still, the majority of resistor products have excellent power handling features that encompass most consumer and professional applications.

Resistor Configurations by Type:

In terms of configuration requirements for resistors, which are determined in effect by the design engineer so that they conform to the physical constraints of their PCB canvass, we note the considerable number of sub-categories of resistors, as they are available by configuration, another important determining factor in how and why they are sold. In terms of through-hole products we note with interest how the overwhelming majority of them are axial leaded designs, while only the bulk metal foil and the wirewound resistor maintains any volume on radial leaded designs. In surface mount versions, we note once again how a conformally molded surface mount version of the wirewound and the bulk metal foil resistor are available, while the nickel chromium version is available in a MELF design (surface mount, but cylindrical). In arrays, only the thick film ruthenium chip is available in a multi-chip array format. In traditional resistor networks, configurations for the dual in line package now include bare die models without plastic packaging. There is also a myriad of custom package designs, including stacked resistor designs as well as integrated passive networks that employ packaging previously reserved for semiconductors and other active components.

How Big is the Global Resistor Market?

The global linear resistor market has a global market value of more than $2 billion USD and more than 1 trillion units sold in 2006. 64% of global value of demand for linear resistors is for the thick film chip, the multichip array and the resistor network because of their common usage in consumer digital electronics applications worldwide. The remaining 36% of global consumption value is broken into a fragmented area that contains the remaining types of linear resistor components, with wirewound, thin film tantalum nitride and nichrome metal film accounting for a substantial portion of the remaining revenues for linear resistors on a global basis.
 

What is the Demand by End-Use Market Segment?

Global consumption value for linear resistors based upon end-use market segment is as diverse as the number of products that are made available for consumption. Computer and computer peripherals still dominate demand in terms of value, followed by telecom equipment, consumer audio and video imaging devices; industrial and power and automotive electronics. Specialty markets such as medical and defense account for only 4% of consumption value worldwide.

What are the Technical Trends in Linear Resistors?

The technical trends in linear resistors has been and will continue to be based upon manipulating the scientific maxims that govern the performance of resistors, with emphasis on their requirements in all electronic circuits, and that there is a direct correlation between the physical size of the finished resistor and its performance, insomuch as resistance is equivalent to the available surface area of the finished product. In accordance with that trend, resistor designers have been largely focused on continued miniaturization of fixed resistors down to the ultra-small case size, known as the 01005 chip.

In networks, there is the continued development of multi-chip arrays for the same purpose and the introduction of flip-chip technology for DIP and IPD networks. There is also a movement among traditional thick film resistor manufacturers to purchase new capital equipment required for the production of thin film resistors that use deposited layers of base metal- such as nickel chromium and tantalum nitride. Many customers who want the added precision of thin film, when compared to traditional thick film models are initiating this trend.

Linear Resistor Forecasts:

Global forecasts for growth in linear resistors are excellent for the years 2007 to 2011 due primarily to the increased content of resistors in traditional electronic devices due to the convergence of technologies in specific high growth product markets that require more ohmic content to satisfy the growing number of integrated circuits adding functionality. In wireless handsets for example, resistor content is increasing dramatically, along with capacitor and inductor content, to satisfy demand for new MP3 audio and digital video functions that are becoming standard along with camera modules.

In computers, the trend is also up with respect to resistor content because of the rapid replacement of single core with dual core microprocessors.

In consumer electronics, the movement to HDTV flat panel in the CATV markets is spurring on rapid growth in the resistor segment due to the 12 times increase in resistor content for an HDTV tuner compared to the relatively small resistor content in a traditional CRT monitor.

In automotive electronic subassemblies, the general trend is for higher temperatures under the hood, with design engineers expecting linear resistors to withstand 150 degrees Celsius, a number that is expected to increase to 175 degrees Celsius as engine performance becomes more efficient.

In power markets, the primary focus is on the small DC/DC “brick” converters, which are in fact becoming increasingly smaller (due in part to smaller passive component sizes).

There is also the overall perception in the industry that price erosion is slowing on a year over year basis due to the consolidation of resistor sales among a few major vendors in China. End-users have become reliant on a few major vendors and thus vendors are less likely to lower prices to the degree they have in the past. Thus, the combination of increased resistor content per box and the potential for a solidification of price makes resistors a positive segment for passive component vendors going forward.

To hear more about linear resistors, register for TTI’s Technical Seminar Series: They’re not Just Resistors Anymore!

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Statements of fact and or opinions expressed in MarketEYE by its contributors are the responsibility of the authors alone and do not imply an opinion of the officers or the representatives of TTI, Inc.

Featured Contributor:
Dennis M. Zogbi

Dennis M. Zogbi

Dennis M. Zogbi is the author of more than 260 market research reports on the worldwide electronic components industry. Specializing in capacitors, resistors, inductors and circuit protection component markets, technologies and opportunities; electronic materials including tantalum, ceramics, aluminum, plastics; palladium, ruthenium, nickel, copper, barium, titanium, activated carbon, and conductive polymers. Zogbi produces off-the-shelf market research reports through his wholly owned company, Paumanok Publications, Inc, as well as single client consulting, on-site presentations, due diligence for mergers and acquisitions, and he is the majority owner of Passive Component Industry Magazine LLC.

Paumanok, Inc.

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