Embedded Resistors

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EMBEDDED RESISTORS IN HI-SPEED PCBS

High-speed printed circuit boards (PCBs) can be found everywhere.
From the smartphones and the medical devices to military radars and satellites up in space, printed circuit boards allow electronics to perform specific functions and tasks to better our lives.
In the past, circuit boards had simplified integrated circuits (ICs) that only consisted of a few transistors and a resistor.

EMBEDDED RESISTORS IN HI-SPEED PCBS
Embedded Resistors Offering Benefits vs. SMTs

Embedded Resistors Offering Benefits vs. SMTs

Surface mounted resistors (SMTs), have small rectangular ceramic bodies with metalized ends that are contacts.
The PCB will have pads where the ends of the SMTs will form the connection. On the other hand, embedded resistors are planar resistive elements made into a thin film. This type of resistor becomes part of the etched and printed circuitry on the standard printed circuit board layer as it eliminated the need for solder joints.

How to Best Specify Embedded Resistors in Your Gerber Data

All of the material manufacturers have their standard design parameters for long-term stability and how to best manage the tolerance requirements for each design.
Engineering teams here at Epec will work with you to design the best-in-class features that will ensure that your design meets your specifications. Mentor graphics has an effective platform for the design of embedded passive components.

How to Best Specify Embedded Resistors

Your Reliable Embedded Resistors Supplier

Embedded Resistors

The venture is the trusted embedded resistors manufacturer in China. We offer a better solution and do more for your PCB products.

Since we are more than 10 years in manufacturing, we can assure you of the quality and satisfying products. The embedded resistors had a great advantage. It has short wire lengths, depletion in parasitic effects, and it has an improvement of design.

If you have a business or planning to have a business, Venture is your excellent partner and fabricator. Anytime, we are 24/7 available. You can have high quality, durable, and longevity products from us. Your demand is our priority. Venture products can be accessible at a low price.

Your Leading Embedded Resistors Manufacturer in China

Embedded Resistors

Venture is the embedded resistors expert manufacturer in China. For more than 10 years of fabricating PCB products for design, assembly, and turnkey solution. The embedded resistors are one of the demand products nowadays due to the density and difficulty of electronics design. Venture has a great solution for you. The embedded resistors can be found in some applications that include:

  • Smartphones
  • Medical Devices
  • Modules
  • Satellites Up in Space
  • Military Radars

The embedded resistors had two categories such as passive and active. Venture offers an excellent advantage in embedded resistors. You can assure that we can meet your size requirement since we offer cutting sizes and cost drive remodeling in PCB technology. With these embedded resistors, you can improve the reliability, enhanced the integrity, maximize routing area, minimize series inductance, and lessen signal paths.

The component of this embedded resistors had a thickness of 0.13 mm to 0.33 mm. Venture can manufacture base on your specifications. We have the Venture Electronics and experts to assist you to meet your requirement. Aside from that, we proudly offer you the best production, durable, and cost-effective. Venture always available 24/7.

Embedded Resistors

Why Venture is your trusted manufacturer? That’s because we are certified ISO 9001, CE, SGS, and more. We also have upgraded machines and equipment for fabrication. Lastly, we accept the small or large quantity of orders from our customers and client. Venture can provide all your needs and progression for your businesses.

Venture can supply and ship PCB products worldwide. If you are a fabricator or retailer, these embedded resistors provide you a practical solution to some issues. Venture will always guarantee a suitable production step for you. Venture can assist you with your business progression. Venture is your best partner and manufacturer of embedded resistors and other PCB products in China.

Send us your embedded resistors inquiries and orders now!

Embedded Resistors: The Ultimate FAQ Guide

Embedded-Resistors-The-Ultimate-FAQ-Guide

This guide will help you choose a perfect embedded resistors for all your applications.

But, before importing embedded resistors, read this guide.

It has all the useful information you’re looking for.

How Does Embedded Resistor Vs. Surface Mounted Resistor Compare?

Surface mounted (SMT) resistors feature tiny rectangular ceramic bodies having metalized ends serving as contacts.

The PCB will consist of pads where the surface mounted resistor will make the connection.

Figure 1 Surface Mount Resistor Vs. Embedded Resistor

Surface Mount Resistor Vs. Embedded Resistor

Conversely, embedded resistors refer to planar resistive components formed into a fine film. This resistor type forms part of the PCB layer since it eliminates the necessity for solder joints.

Embedded Resistor PCB moves individual passives from the circuit board surface and places them within it.

This, as a result, creates more space on the surface for mounting of more active parts that enhance functionality.

Why Use Embedded Resistors In PCB?

Some of the benefits of embedded resistor PCB you will enjoy include:

Increased Routing Area

Removing the discrete SMT resistors from the PCB ensures less use of space by the connecting vias and traces. The embedded resistor creates more space on the circuit board surface.

This allows PCB manufacturers to include more functions or decrease the PCB size for devices and applications that require miniaturization.

Figure 2 PCB Embedded Resistors

PCB Embedded Resistor

Shorter Wiring Lengths

The length of wiring from the passive PCB components may get sophisticated when using discrete SMT resistors to connect to the integrated circuitries.

However, embedded resistors require no vias and enhance the routing. This allows the manufacturing of more simplified PCBs that are more compact and smaller in size.

Consequently, you can save on operational costs whilst still being capable of fabricating complex PCBs for a number of applications.

Reduction In EMI And Parasitic Effects

Components and circuit will have differing electrical fields. If these circuitries are positioned near one another, they start to accumulate electrical charge.

This electrical charge may have negative impacts (parasitic capacitance) since it can alter the desired circuits output. Moreover, electromagnetic emissions from outside sources can cause electromagnetic interference that will affect the PCB performance.

Embedded resistors can minimize cross talk, EMI, parasitic capacitance and noise produced by other circuitries and parts close to the PCB.

You can place the embedded resistor beneath the integrated circuit pin to guarantee better electrical performance and avoid inductance.

Enhanced Integrity

The overall PCB integrity is improved when you embed resistors into the circuit board. Embedded resistor PCB manufacturing process facilitates more stability over broader frequencies.

Additionally, the embedded resistor technology increases the PCB lifespan, and minimizes reflection of signal from the load courtesy of enhanced line impedance matching.

Which Are The Design Tools Used In Embedded Resistors Fabrication?

Majority of software developers are presently creating the required tools to effectuate the embedded resistor elements in the multilayer PCB.

In addition to an Excel program, here are the recommended CAD software to use to develop more sophisticated resistor element geometries:

  • Allegro
  • PAD power PCB
  • Intergraph
  • Mentor

A number of resistor elements will probably remain on the finished board external surface. To prevent procurement errors, the embedded resistors will need a distinctive reference designator.

For instance, you will define SMT resistor as R110 whilst embedded resistors will be marked as BR110 on material list and schematic diagram.

What Is The Manufacturing Process Of Embedded Resistor PCB?

The fabrication process of embedded resistor PCB may seem similar to conventional PCB fabrication process though there is difference.

Here are the main stages involved in embedded resistor PCB manufacturing process:

Step 1: Application Of Photoresist To Laminate

Step 2: Printing And Developing Composite Image

Step 3: Etching Unwanted Copper Utilizing Any Standard Etchant (First Etching Process)

Step 4: Etching Unwanted Resistive Material Using Copper Sulfate Solution (Second Etching Process)

Step 5: Stripping Photoresist

Step 6: Applying Photoresist, Printing And Developing Conductor Protect Image (Second Print)

Step 7: Etching Away of Copper Above The Designed Resistor Utilizing Selective Alkaline Etchant (Third Etching Process)

Step 8: Stripping Photoresist

Step 9: Testing

Testing serves as a crucial component of embedded resistor PCB fabrication. It is important to evaluate the embedded resistor circuit board to make sure it operates perfectly and effectively.

Early identification of errors will assist you in correcting and possibly substituting the defective embedded resistor.

Figure 3 Steps of Manufacturing Embedded Resistor

Steps of Manufacturing Embedded Resistor

How Do You Perform Reverse Lamination Of Embedded Resistor PCB?

The process of reverse lamination of embedded resistor PCB include the following steps:

Step 1: Involves printing and curing polymer resistor ink on the copper foil.

Step 2: You then laminate the foil with component side-down onto single-sided FR4 core with FR4 prepreg.

Step 3: Entails masking and etching the foil to pattern circuit traces and open up resistors.

Step 4: Continue to manufacture PCB applying standard process.

Figure 5 Illustration of Basic Calculation of Embedded Resistor Squares

Reverse Lamination of Embedded Resistor

Are There Flexible Types of Embedded Resistor PCB?

Yes, there are flexible embedded resistor PCB that constructed using flexible plastic, which enables forming it into various designs and shapes.

For that matter, you must put the embedded resistor material into consideration.

The material ought to be flexible to allow for easy embedding into the printed circuit board.

Because of their nature, there are various applications of flex embedded resistor PCBs. Nevertheless, they are moderately costly to design and manufacture.

What Are The Key Factors To Consider When Designing PCB Embedded Resistor?

Some of the important considerations during embedded resistor designing for your printed circuit board include:

Physical Layout Of Embedded Resistor

The embedded resistor layout refers to the appearance of the resistor prior to implanting it within the circuit board.

For instance, you will have to ensure there is adequate space if you intend to implant a rounded embedded resistor.

Similarly, it is easy to implant flat embedded resistor into PCB because it will not take much space due to its shape.

Moreover, the physical layout might equally be in connection with the embedded resistor size.

Before beginning the embedding process, you need to factor in whether you will be using a large or small resistor.

Type Of Embedded Resistor Material

There exist several cost-effective types of materials you can use for manufacturing of embedded resistors.

Nonetheless, the 3 common types of embedded resistor materials comprise of:

  • Wire wound
  • Metal film
  • Carbon composition

Dielectric Constant

Dielectric constant of material is among the vital factors to consider when designing a PCB embedded resistor.

It measures the materials capacity to store power if within an electrical field.

Typically, materials having high dielectric constant tend to disintegrate easily when exposed to heavy electric fields.

For that matter, select an embedded resistor material with lower dielectric constant.

Coefficient Of Thermal Expansion (CTE)

CTE describes the change in embedded resistor size with temperature changes in PCB.

It helps in measuring the rigidity of the embedded resistor material.

You should opt for an embedded resistor with higher coefficient of thermal expansion.

How Does The Tolerance Level Of Embedded Resistor Impact Its Applicability?

To achieve high performance gadgets, the embedded resistor PCB must attain specific power and tolerance ratings.

This enables the PCB design and fabrication to meet circuit signal quality and electrical timing requirements.

The PCB material stability if exposed to usual printed circuit board manufacturing processes will equally influence the final embedded resistor PCB tolerance.

The tolerance of embedded resistor is one major factor dictating their applicability.

The tolerance level to which you can fabricate an embedded resistor dictates the applications under which you can employ them.

Also, it probably influences its effects on the final product performance.

You can pre-sort by value or even substitute discrete SMT resistors during assembly if their value isn’t within the desired range.

However, embedded resistors do not give such opportunity and need to be within tolerance value of design before you complete PCB fabrication process.

Can You Trim Embedded Resistors To The Required Resistance Value After Fabrication?

Yes, trimming of embedded resistors to the required after you have fabricated them is possible.

This depends on the fabrication technique and the application of the embedded resistor.

To facilitate trimming, the embedded resistor design must have a resistance value which is below that required by the application.

You then accomplish trimming by making holes into the embedded resistor to raise its resistance value.

Embedded resistor trimming is usually achieved employing a laser for micromachining a trough within the resistive element.

The path-shape and length of the trough dictates properties of resistance change attained.

You can use various different path-shapes based on the specified trimming requirements.

While you cut the trough by laser, you measure the resistor value and use it as feedback to manage the trimming process.

What Are The Design Rules For Laser Trimming Of Embedded Resistor?

Designing rules for laser trimming operation requires that circuitries be rectangular or square and should comprise of arcs, lines, or blend thereof.

The “length” of resistor is normally the resistor dimension parallel to the flow of current.

Also, resistor “square” within the corner sections of an angled style resistor needs to be regarded as a half of the sheet resistance value.

Figure 5 Illustration of Basic Calculation of Embedded Resistor Squares

Illustration of Basic Calculation of Embedded Resistor Squares

Which Are The Laser Trimming Methods For Embedded Resistors?

Depending on design complexity, you can use precision embedded resistors in your PCB, which utilizes laser trimming.

You can attain a 1 percent tolerance through various laser trimming methods including:

Resistor Trim TypeRecommended ApplicationAdvantagesDisadvantages
L CutDC·       Enhanced accuracy

·       Lower tolerance

·       DC only application

·       Modestly higher cost compared to plunge cut

PlungeDCMinimal Cost·       Restricted to DC only uses

·       High tolerances

Serpentine CutDC (High Value Resistors)·       Enhanced accuracy

·       Lower tolerances

·       Broader ultimate value flexibility

·       DC only application

·       Higher cost in comparison to L cut or plunge cut (dependent on number of cuts needed)

Scan CutAll·       Higher frequency applications

·       Exceptional tolerance accuracy

·       Highest cost

Figure 6 Laser Trimming Types

Laser Trimming Types

Which Are The Possible Embedded Resistor Configurations That Determine The Laser Trimming Technique Used?

Design for laser trimming of embedded resistor can be difficult and needs design for manufacturing.

Configuration for embedded resistor type can be engineered in a number of shapes.

The method of laser trimming will depend on the resistor configuration, which include:

  • Rectangular Configuration: Represents the most popular type of embedded resistor.

Figure 7 Rectangular Configuration of Embedded Resistor

Rectangular Configuration of Embedded Resistor

  • L-Bent Configuration: This resistor “square” within the corner section of an angled style resistor ought to be considered as ½ of the sheet resistance value.

Figure 8 L-Bent Configuration of Embedded Resistor

L-Bent Configuration of Embedded Resistor

  • Serpentine Configuration: This resistor type is often utilized for high value embedded resistors. The sum of corners sophisticate calculation of resistor value.

The resistor “square” found in corner sections of serpentine style resistor ought to be considered as ½ of the sheet resistance value.

Figure 9 Serpentine Configuration of Embedded Resistor

Serpentine Configuration of Embedded Resistor

  • Top-hat Configuration: The broad trim range is the primary advantage of top-hat design. Through trimming a solo laser plunge cut, you can create a 9 square resistor.

You can manipulate the resistance between these values through restricting the trim amount. For that matter, it is possible to create an embedded resistor having a trimmable range greater than 3 times the initial value.

This type of embedded resistor needs to be trimmed irrespective of the tolerance specification.

Figure 10 Top Hat Configuration of Embedded Resistor

Top Hat Configuration of Embedded Resistor

What Are The Applications Of Embedded Resistors?

The common uses of embedded resistors involve employing them in the following in industries:

  • Defense
  • Aerospace
  • High Speed Digital Devices
  • RF Applications
  • Satellite and Cellular Communications

Which Are The Common Resistive Alloy Used To Form The Substrate Material For PCB Embedded Resistor?

To start, you deposit a resistive alloy film onto copper foil so as to form the embedded resistor base material.

Typically, roll-to-roll sputtering procedure is used in depositing or electrodepositing the resistive alloy onto the conductive copper foil.

The thickness of resistive alloy dictates the general resistance value of the layered copper foil. Alloys often employed for embedded resistor applications comprise of:

  • Nickel Chromium (NiCr).
  • Nickel Phosphorous (NiP)
  • Nickel Chromium Aluminum Silicon (NCAS)
  • Chromium Silicon Monoxide (CrSiO)

Why Is Nickel-Chrominum Alloy The Best Metal Alloy For Embedded Resistor?

Nickel-chromium alloys have high electrical resistivity that make them ideal for a wide range of applications.

To reduce temperature coefficient of resistance and enhance temperature stability, you can alloy nickel and chromium with silicon and aluminum.

What Is The Typical Power Dissipation Of Embedded Resistors?

Power dissipation refers to the rate at which the embedded resistor elements lose resist energy.

The power capacity of embedded resistors will rely on size of embedded resistor components, temperature rating of adjacent substrate materials, and PCB stack-up.

Ultimately, it depends on the embedded resistor PCB manages the heat produced.

Normally, the power dissipation of most embedded resistor designs functioning at an ambient below 70 degrees Celsius is about 1/10 to 1/8 W.

What Are The Factors That Impact The Thermal Dissipation Of Embedded Resistor?

Design for heat and power dissipation is a factor of the resistor area and power rating of the resistor alloy.

You may size the resistor accordingly when there is need for higher power loading.

Figure 11 PCB Embedded Resistor

PCB Embedded Resistor

Here are the common factors that affect heat dissipation of embedded resistors:

  • Circuit configuration
  • Type of material and circuit thickness
  • Thermal conductivity of substrate material
  • Closeness of ground or power planes to the embedded resistor
  • Ambient temperature
  • Extra system heat sinking or cooling
  • Total resistor area (resistor size)

You must consider all the thermal dissipation aspects of the system in the embedded resistor PCB design.

Crucial thermal dissipation requirements might need actual prototypes or thermal profile modeling to ensure you attain proper configuration.

How Does The Size Of Embedded Resistor Affect Its Power Handling Capacity?

The heat dissipation capability of thin film embedded resistor relies on its dimensions.

Resistors with shorter length and narrower width will experience higher burnout power density.

This is due to the shorter path of heat conduction to the environment.

The burnout power density falls with increasing size of embedded resistor, though the overall power increases due to bigger resistor physical size. This implies that the size of embedded resistor and total power dissipation is not linear.

Therefore, it is advisable to operate the embedded resistor at power level below 30 to 40 percent of the value of burnout power.

This maintains low resistor temperature with no major resistance change.

Why Should The Electrical Current Not Surpass The Rated Current-Carrying Capacity Of Embedded Resistor?

The electrical current ought not to surpass the rated current-carrying potential of the embedded resistor.

This is due to the fact that excess current could result in permanent destruction to the created resistor element.

How Can You Enhance The Embedded Resistor Tolerance?

The ultimate resistance tolerance of the resistor is dependent on resistivity difference of embedded film and etch accuracy of copper etch procedures.

To reduce the effect of etching on the tolerance of embedded resistor, you should utilize a specified resistor width.

However, make sure you adjust the length of resistor to attain the right resistor value.

Another method of improving the resistor tolerance is employing lager dimensions.

This is because the line-width alteration in the copper etch operation is usually predetermined and hence unrelated to line-width.

For that matter, it is preferred to work with embedded resistor designs having lengths and widths greater than 0.010” (0.25mm).

What Is The Recommended Mechanical And Thermal Spacing Allowance For Embedded Resistor?

Mechanical and thermal spacing allowances at microvia and plated through holes can be difficult.

A minimum of 0.010” (0.25 mm) is preferred for copper interconnection between the start of embedded resistor pattern and the hole.

This guarantees sufficient isolation from strains due to drilling of holes and assembly soldering.

Figure 12 Spacing Allowance of Embedded Resistor

Spacing Allowance of Embedded Resistor

Which Is The Preferred Method For Depositing The Nickel-Chromium Alloy To Embedded Resistor?

A sputtering mechanism helps in the deposition of thin film Nickel-Chromium alloy on the copper base material applying a roll-to-roll procedure.

The sputtering method avails a means of depositing a thin layer having uniform chemical composition and thickness.

Both chemical composition and thickness features are vital to the variation of sheet resistance of resistive foil.

Through regulating sputtering parameters and installing correct shielding, you can fabricate an embedded resistor with tight resistance tolerance.

How Do You Perform In-Process Quality Testing For Embedded Resistor?

You must validate the value and tolerance of the embedded resistor elements.

Flying probe test is the extensively applied technique for validating the target value of embedded resistor prior to lamination of extra circuitry layers.

Some flying probe testing can as well conduct signal integrity testing in addition to identifying opens and shorts location.

To facilitate test probe entry, you must provide land features for every developed resistor element.

The lands provided should not be configured in a manner that would need probes to contact or cross over other probes.

When modifying the embedded resistor element through laser trimming, ensure that probe contact does not impede the laser access whilst making a trim.

For best assessment and trim precisions, place the test lands close to resistor-to-circuit termination spot to guarantee precise measurement of resistor value.

When creating land configuration for test-probe access, the measurements and shape of probe tip will dictate the least land size.

The probes should feature a 0.002” (50 μm) in every X,Y, and Z directons.

The diameter of the land pattern ought to exceed the probe tip. This allows for uniform pad scrub and probe pressure and accommodate positional tolerances of probe.

Which Are The Common Implantation Challenges And Concerns With Embedded Resistors?

Fabricated embedded resistor element ratings and tolerance that span between 5-10 percent will probably fulfil the operation specifications of the end product.

Nonetheless, you will not be able to modify the value after completing the lamination process.

The desired values of embedded resistor might go off the defined resistance target.

This is because of physical stresses encountered during lamination and assembling of PCB, which makes laser trimming impractical.

However, high precision resistors should be employed as discrete SMD for mounting onto the PCB exterior surface.

These types of resistors often have a tolerance in the range of 1 to 2 percent.

For all your embedded resistors, contact Venture now.

 

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