The quality of supplied materials complies with the IPC4101B standard, and the manufacturers' quality management system is confirmed by international certificates ISO 9001:2000.

FR4 – fiberglass laminate with fire resistance class 94V-0 is the most common material for the production of printed circuit boards. Our company supplies the following types materials for the production of single- and double-sided printed circuit boards:

• Fiberglass laminate FR4 with a glass transition temperature of 135ºС, 140ºС and 170ºС for the production of single-sided and double-sided printed circuit boards. Thickness 0.5 - 3.0 mm with foil 12, 18, 35, 70, 105 microns.
• Basic FR4 for internal layers of MPP with glass transition temperatures of 135ºС, 140ºС and 170ºС
• FR4 prepregs with glass transition temperatures of 135ºС, 140ºС and 170ºС for pressing MPP
• Materials XPC, FR1, FR2, CEM-1, CEM-3, HA-50
• Materials for boards with controlled heat dissipation:
  • (aluminum, copper, stainless steel) with a dielectric with thermal conductivity from 1 W/m*K to 3 W/m*K produced by Totking and Zhejiang Huazheng New Material Co.
  • Material HA-30 CEM-3 with thermal conductivity 1 W/m*K for the production of single- and double-sided printed circuit boards.

For some purposes, a high-quality non-foil dielectric is required that has all the advantages of FR4 (good dielectric properties, stability of characteristics and dimensions, high resistance to adverse influences). climatic conditions). For these applications we can offer non-foil FR4 fiberglass laminate.

In many cases where fairly simple printed circuit boards are required (in the production of household equipment, various sensors, some components for automobiles, etc.), the excellent properties of fiberglass are redundant, and indicators of manufacturability and cost come to the fore. Here we can offer the following materials:

• XPC, FR1, FR2 - foil getinaks (base made of cellulose paper impregnated with phenolic resin), widely used in the manufacture of printed circuit boards for consumer electronics, audio and video equipment, in the automotive industry (arranged in ascending order of properties, and, accordingly, price ). Excellent stamping.
• CEM-1 is a laminate based on a composition of cellulose paper and fiberglass with epoxy resin. Stamps beautifully.

Our assortment also includes electrodeposited copper foil for pressing MPP produced by Kingboard. Foil is supplied in rolls of various widths, foil thicknesses are 12, 18, 35, 70, 105 microns, foil thicknesses of 18 and 35 microns are almost always available from our warehouse in Russia.

All materials are manufactured in accordance with the RoHS directive, contents harmful substances confirmed by relevant certificates and RoHS test reports. Also, all materials, many items have certificates, etc.

Our company produces printed circuit boards from high-quality imported materials, ranging from standard FR4 to microwave materials and polyimide. In this section, we define the basic terms and concepts used in the field of printed circuit board design and manufacturing. The section tells about completely simple things, familiar to every design engineer. However, there are a number of nuances here that many developers do not always take into account.

*** Additional information available,

Multilayer PCB Design
Let's consider a typical design of a multilayer board (Fig. 1). In the first, most common, option, the internal layers of the board are formed from double-sided copper-laminated fiberglass, which is called the “core”. The outer layers are made of copper foil, pressed with the inner layers using a binder - a resinous material called "prepreg". After pressing at high temperatures, a “pie” of a multilayer printed circuit board is formed, in which holes are then drilled and metallized. The second option is less common, when the outer layers are formed from “cores” held together with prepreg. This is a simplified description; there are many other designs based on these options. However, the basic principle is that prepreg acts as the bonding material between the layers. Obviously, there cannot be a situation where two double-sided "cores" are adjacent without a prepreg spacer, but a foil-prepreg-foil-prepreg... etc. structure is possible, and is often used in boards with complex combinations of blind and hidden holes.

Blind and hidden holes
The term "blind holes" refers to vias that connect the outer layer to the nearest inner layers and do not have access to a second outer layer. It comes from English word blind, and is similar to the term "blind holes". Hidden, or buried (from English buried), holes are made in the inner layers and have no exit to the outside. The simplest options for blind and hidden holes are shown in Fig. 2. Their use is justified in the case of very dense wiring or for boards very saturated with planar components on both sides. The presence of these holes leads to an increase in the cost of the board from one and a half to several times, but in many cases, especially when routing microcircuits in BGA package with small steps, you can’t do without them. Eat various ways formation of such vias, they are discussed in more detail in the section, but for now we will consider in more detail the materials from which the multilayer board is constructed.

Tg—glass transition temperature (structure destruction)
Dk - dielectric constant

Basic dielectrics for printed circuit boards
The main types and parameters of materials used for the manufacture of MPPs are given in Table 1. Typical designs of printed circuit boards are based on the use of standard fiberglass laminate type FR4, with an operating temperature, usually from -50 to +110 °C, glass transition (destruction) temperature Tg about 135 °C. Its dielectric constant Dk can be from 3.8 to 4.5, depending on the supplier and type of material. For increased requirements for heat resistance or when mounting boards in an oven using lead-free technology (t up to 260 °C), high-temperature FR4 High Tg or FR5 is used. For requirements such as continuous operation at high temperatures or sharp changes temperatures polyimide is used. In addition, polyimide is used for the manufacture of high-reliability circuit boards, for military applications, and also in cases where increased electrical strength is required. For boards with microwave circuits (more than 2 GHz), separate layers of microwave material are used, or the entire board is made of microwave material (Fig. 3). Most famous suppliers special materials- Rogers, Arlon, Taconic, Dupont companies. The cost of these materials is higher than FR4 and is roughly shown in the last column of Table 1 relative to the cost of FR4. Examples of boards with different types dielectrics are shown in Fig. 4, 5.

Material thickness
Knowing the available material thicknesses is important for an engineer not only for determining the overall thickness of the board. When designing MPP, developers are faced with the following tasks:
- calculation of the wave resistance of conductors on the board;
- calculation of the value of interlayer high-voltage insulation;
- selection of the structure of blind and hidden holes.
Available options and thicknesses various materials are given in tables 2-6. It should be taken into account that the tolerance on the thickness of the material is usually up to ±10%, therefore the tolerance on the thickness of the finished multilayer board cannot be less than ±10%.

Table 2. Double-sided FR4 “cores” for the internal layers of the printed circuit board

Typically in stock;
h - On request (not always available)
m - Can be manufactured;
Note: to ensure the reliability of the finished boards, it is important to know that for foreign internal layers we prefer to use cores with 35 micron foil rather than 18 micron (even with a conductor and gap width of 0.1 mm). This increases the reliability of printed circuit boards.
The dielectric constant of FR4 cores can range from 3.8 to 4.4 depending on the brand.

Table 3. Prepreg (“bonding” layer) for multilayer printed circuit boards

The dielectric constant of FR4 prepreg can range from 3.8 to 4.4 depending on the brand.
Please check this parameter for a specific material with our engineers by email

Table 4. Rogers microwave materials for printed circuit boards

* Dk - dielectric constant

Table 5. Arlon microwave materials for MPP

Note: Microwave materials are not always in stock, and their delivery time can take up to 1 month. When choosing a board design, you need to check the stock status of the MPP manufacturer.

Dk — Dielectric constant
Tg—glass transition temperature

I would like to note the importance of the following points:
1. In principle, all FR4 core values ​​from 0.1 to 1.0mm are available in 0.1mm increments. However, when designing urgent orders, you should check in advance the availability of materials in the warehouse of the PCB manufacturer.
2. When it comes to the thickness of the material - for materials intended for manufacturing double-sided boards, material thickness is indicated including copper. The “core” thicknesses for the internal layers of the MPP are specified in the documentation without the copper thickness.
Example 1: material FR4, 1.6/35/35 has a dielectric thickness: 1.6-(2x35 µm)=1.53 mm (with a tolerance of ±10%).
Example 2: FR4, 0.2/35/35 core has dielectric thickness: 200 µm (with tolerance ±10%) and total thickness: 200 µm+(2x35 µm)=270 µm.
3. Ensuring reliability. The permissible number of adjacent layers of prepreg in MPP is no less than 2 and no more than 4. The possibility of using a single layer of prepreg between the “cores” depends on the nature of the pattern and the thickness of the adjacent copper layers. The thicker the copper and the richer the pattern of the conductors, the more difficult it is to fill the space between the conductors with resin. And the reliability of the board depends on the quality of the filling.
Example: copper 17 microns - you can use 1 layer 1080, 2116 or 106; copper 35 microns - you can use 1 layer only for 2116.

PCB pad coatings
Let's look at what types of coatings there are for copper pads. Most often, sites are coated with a tin-lead alloy, or PIC. The method of applying and leveling the surface of solder is called HAL or HASL (from English Hot Air Solder Leveling - leveling solder with hot air). This coating provides the best solderability of the pads. However, it is being replaced by more modern coatings, usually compatible with the requirements of the international RoHS directive. This directive requires the prohibition of the presence of harmful substances, including lead, in products. So far, RoHS does not apply to the territory of our country, but it is useful to remember its existence. The problems associated with RoHS will be described in one of the subsequent sections, but for now let's take a look at possible options coverage of MPP sites in Table 7. HASL is applied everywhere, unless there are other requirements. Immersion (chemical) gold plating is used to provide a smoother board surface (this is especially important for BGA pads), but has slightly lower solderability. Soldering in a furnace is performed using approximately the same technology as HASL, but hand soldering requires the use of special fluxes. Organic coating, or OSP, protects the copper surface from oxidation. Its disadvantage is the short shelf life of solderability (less than 6 months). Immersion tin provides flat surface and good solderability, although it also has a limited shelf life for soldering. Lead-free HAL has the same properties as lead-containing HAL, but the composition of the solder is approximately 99.8% tin and 0.2% additives. The contacts of the blade connectors, which are subject to friction during operation of the board, are electroplated with a thicker and more rigid layer of gold. For both types of gilding, a nickel underlayer is used to prevent diffusion of gold.

Table 7. PCB pad coatings

Note: All coatings except HASL are RoHS compliant and suitable for lead-free soldering.

Protective and other types of printed circuit board coatings
To complete the picture, consider functional purpose and PCB coating materials.
- Solder mask - applied to the surface of the board to protect conductors from accidental short circuits and dirt, as well as to protect fiberglass laminate from thermal shock during soldering. The mask does not carry any other functional load and cannot serve as protection against moisture, mold, breakdown, etc. (except when used special types masks).
- Marking - applied to the board with paint over the mask to simplify identification of the board itself and the components located on it.
- Peelable mask - applied to specified areas of the board that need to be temporarily protected, for example, from soldering. It is easy to remove in the future, since it is a rubber-like compound and simply peels off.
- Carbon contact coating - applied to certain areas of the board as contact fields for keyboards. The coating has good conductivity, does not oxidize and is wear-resistant.
- Graphite resistive elements - can be applied to the surface of the board to perform the function of resistors. Unfortunately, the accuracy of the denominations is low - no more accurate than ±20% (with laser adjustment - up to 5%).
- Silver contact jumpers - can be applied as additional conductors, creating another conductive layer when there is not enough space for routing. Mainly used for single-layer and double-sided printed circuit boards.

Table 8. PCB Surface Coatings

Conclusion
The choice of materials is great, but, unfortunately, often when producing small and medium-sized series of printed circuit boards, the stumbling block becomes the availability necessary materials in the warehouse of the plant - manufacturer of MPP. Therefore, before designing an MPP, especially if we are talking about creating a non-standard design and using non-standard materials, it is necessary to agree with the manufacturer on the materials and layer thicknesses used in the MPP, and perhaps order these materials in advance.

To make the base of a printed circuit board, foil and non-foil dielectrics are used - getinax, fiberglass, fluoroplastic, polystyrene, ceramic and metal (with a surface insulating layer) materials.

Foil materials- These are multilayer pressed plastics made of electrically insulating paper or fiberglass impregnated with artificial resin. They are covered on one or both sides with electrolytic foil with a thickness of 18; 35 and 50 microns.

Foil-coated fiberglass laminate of the SF grade is produced in sheets with dimensions of 400×600 mm and a sheet thickness of up to 1 mm and 600×700 mm with a larger sheet thickness; it is recommended for boards that are operated at temperatures up to 120°C.

Higher physical and mechanical properties and heat resistance are provided by fiberglass laminates of SFPN grades.

The dielectric slofodite has a copper foil 5 microns thick, which is obtained by evaporating copper in a vacuum.

For multilayer and flexible boards use heat-resistant fiberglass laminates of the STF and FTS brands; they are operated in the temperature range from minus 60 to plus 150°C.

Non-foil STEF dielectric is metallized with a layer of copper during the manufacturing process of a printed circuit board.

The foil is made from high-purity copper, the impurity content does not exceed 0.05%. Copper has high electrical conductivity and is relatively resistant to corrosion, although it requires a protective coating.

For printed wiring, the permissible current value is selected: for foil 100–250 A/mm2, for galvanic copper 60–100 A/mm2.

For the production of printed cables, reinforced fluoroplastic foil films are used.

Ceramic boards can operate in the temperature range of 20...700ºС. They are made from mineral raw materials (for example, quartz sand) by pressing, injection molding or film casting.

Metal boards are used in products with high current loads.

Aluminum or alloys of iron and nickel are used as a base. An insulating layer on the surface of aluminum is obtained by anodic oxidation with a thickness of tens to hundreds of micrometers and an insulation resistance of 109–1010 Ohms.

The thickness of the conductor is 18; 35 and 50 microns. Based on the density of the conductive pattern, printed circuit boards are divided into five classes:

– the first class is characterized by the lowest density of the conductive pattern and the width of the conductor and spaces more than 0.75 mm;

– the fifth class has the highest pattern density and the width of the conductor and spaces within 0.1 mm.

Since the printed conductor has a low mass, the force of its adhesion to the base is sufficient to withstand alternating mechanical overloads acting on the conductor up to 40 q in the frequency range 4–200Hz.

Standards for printed circuit board materials are presented below in the corresponding section “Standardization of Printed Circuit Board Manufacturing”.

An electronic printed circuit board (Russian abbreviation - PP, English - PCB) is sheet panel, where interconnected microelectronic components are located. Printed circuit boards are used as part of various electronic technology, starting from simple residential calls, household radios, studio radios and ending with complex radar and computer systems. Technologically, the manufacture of electronics printed circuit boards involves the creation of connections with conductive “film” material. Such material is applied (“printed”) on an insulating plate, which is called a substrate.

Electronic printed circuit boards marked the beginning of the formation and development of systems electrical connections, developed in the mid-19th century.

Metal strips (rods) were initially used as bulky electrical components, mounted on a wooden base.

Gradually, metal strips replaced conductors with screws terminal blocks. The wooden base was also modernized, giving preference to metal.

This is what the prototype looked like modern production PP. Similar design solutions were used in the mid-19th century

The practice of using compact, small-sized electronic parts required unique solution on a basic basis. And so, in 1925, a certain Charles Ducasse (USA) found such a solution.

American engineer suggested unique way organizing electrical connections on an insulated plate. He used electrically conductive ink and a transfer stencil schematic diagram onto the plate.

A little later, in 1943, the Englishman Paul Eisler also patented the invention of etching conductive circuits on copper foil. The engineer used an insulator plate laminated with foil material.

However, the active use of Eisler technology was noted only in the period 1950-60, when they invented and mastered the production of microelectronic components - transistors.

Manufacturing technology through holes on multilayer printed circuit boards was patented by Hazeltyne (USA) in 1961.

Thus, thanks to the increase in the density of electronic parts and the close arrangement of connecting lines, the new era PCB design.

Electronic printed circuit board - manufacturing

A generalized vision of the process: individual electronic parts are distributed over the entire area of ​​the insulating substrate. The installed components are then connected by soldering to the circuit circuits.

The so-called contact “fingers” (pins) are located along the extreme areas of the substrate and act as system connectors.

Through contact “fingers”, communication with peripheral printed circuit boards or connection of external control circuits is organized. The electronic printed circuit board is designed for wiring a circuit that supports one function or several functions simultaneously.

Three types of electronic printed circuit boards are manufactured:

1. One-sided.
2. Double-sided.
3. Multilayer.

Single-sided printed circuit boards are characterized by the placement of parts exclusively on one side. If the complete circuit parts do not fit on single-sided board, a two-sided option is used.

Substrate material

The substrate traditionally used in printed circuit boards is typically made from fiberglass combined with epoxy resin. The substrate is covered with copper foil on one or two sides.

Electronics printed circuit boards made from phenolic resin paper, also coated with copper film, are considered cost-effective for production. Therefore, more often than other variations, they are used to equip household electronic equipment.

The connections are made by coating or by etching the copper surface of the substrate. Copper tracks are coated with a tin-lead composition to protect against corrosion. Contact pins on printed circuit boards are coated with a layer of tin, then nickel, and finally gold.

Performing strapping operations

Surface mounting technology involves the use of straight (J-shaped) or angled (L-shaped) branches. Due to such branches, each electronic part is directly connected to a printed circuit.

By using a complex paste (glue + flux + solder), electronic parts are temporarily held at the point of contact. The hold continues until the printed circuit board is inserted into the oven. There the solder melts and connects the circuit parts.

Despite the challenges of component placement, surface mount technology has another important advantage.

This technique eliminates the lengthy drilling process and insertion of bonding gaskets, as is practiced with the outdated through-hole method. However, both technologies continue to be actively used.

Electronic PCB Design

Each individual electronics printed circuit board (batch of boards) is designed for unique functionality. Electronic printed circuit board designers turn to design systems and specialized “software” to layout the circuit on a printed circuit board.

The gap between conductive tracks is usually measured in values ​​of no more than 1 mm. Hole locations for component conductors or contact points are calculated.

All this information is translated into the computer software format that controls drilling machine. An automatic machine for the production of electronic printed circuit boards is programmed in the same way.

Once the circuit diagram is laid out, the negative image of the circuit (mask) is transferred to transparent sheet plastic. Areas of the negative image that are not included in the circuit image are marked in black, and the circuit itself remains transparent.

Industrial manufacturing of electronics printed circuit boards

Electronics printed circuit board manufacturing technologies provide for production conditions in a clean environment. Atmosphere and facilities production premises are automatically controlled for the presence of contamination.

Many electronic printed circuit board manufacturing companies practice unique manufacturing. And in standard form production of double-sided printing electronic board traditionally involves the following steps:

Making the base

1. The fiberglass is taken and passed through the process module.
2. Impregnated with epoxy resin (immersion, spraying).
3. The glass fiber is rolled on a machine to the desired thickness of the substrate.
4. Dry the substrate in an oven and place it on large panels.
5. The panels are arranged in stacks, alternating with copper foil and a backing coated with glue.

Finally, the stacks are placed under a press, where at a temperature of 170°C and a pressure of 700 kg/mm ​​2, they are pressed for 1-2 hours. The epoxy resin hardens and the copper foil is bonded under pressure to the backing material.

Drilling and tinning holes

1. Several backing panels are taken, laid one on top of the other, and firmly fixed.
2. The folded stack is placed in a CNC machine, where holes are drilled according to the schematic pattern.
3. The holes made are cleared of excess material.
4. The internal surfaces of the conductive holes are coated with copper.
5. Non-conductive holes are left uncoated.

Producing a drawing of a printed circuit board

A sample PCB circuit is created using an additive or subtractive principle. In the case of the additive option, the substrate is coated with copper according to the desired pattern. In this case, the part outside the scheme remains unprocessed.

The subtractive process primarily covers the overall surface of the substrate. Then individual areas that are not included in the diagram are etched or cut out.

How does the additive process work?

The foil surface of the substrate is pre-degreased. The panels go through a vacuum chamber. Due to the vacuum, the layer of positive photoresist material is tightly compressed over the entire foil area.

The positive material for photoresist is a polymer that has the ability to solubilize under ultraviolet radiation. Vacuum conditions eliminate any possible remaining air between the foil and the photoresist.

The circuit template is laid on top of the photoresist, after which the panels are exposed to intense ultraviolet light. Since the mask leaves areas of the circuit transparent, the photoresist at these points is exposed to UV radiation and dissolves.

Then the mask is removed and the panels are pollinated with an alkaline solution. This, a kind of developer, helps to dissolve the irradiated photoresist along the boundaries of the areas of the circuit design. Thus, the copper foil remains exposed on the surface of the substrate.

Next, the panels are galvanized with copper. Copper foil acts as a cathode during the galvanization process. Exposed areas are galvanized to a thickness of 0.02-0.05 mm. The areas remaining under the photoresist are not galvanized.

Copper traces are additionally coated with a tin-lead composition or other protective coating. These actions prevent oxidation of copper and create a resist for the next stage of production.

Unneeded photoresist is removed from the substrate using an acid solvent. The copper foil between the circuit design and the coating is exposed. Since the copper of the PCB circuit is protected by a tin-lead compound, the conductor here is not affected by acid.

Techniques for industrial manufacturing of electronic circuit boards

Laminate FR4

You can find a detailed description of the laminate.

Laminates in TePro warehouse

Microwave material ROGERS

NOTE: To use ROGERS material in the production of circuit boards, please indicate this in the order form

Since Rogers material is significantly more expensive than standard FR4, we are forced to introduce an additional markup for boards manufactured using Rogers material. Working fields of used workpieces: 170 × 130; 270 × 180; 370 × 280; 570 × 380.

Metal based laminates

Visual representation of the material

Aluminum laminate ACCL 1060-1 with dielectric thermal conductivity 1 W/(m K)

Description

Aluminum laminate CS-AL88-AD2(AD5) with dielectric thermal conductivity 2(5) W/(m K)

Description

Prepreg

In production we use prepregs 2116, 7628 and 1080 grade A (highest) from ILM.

You can find a detailed description of prepregs.

Solder mask

Properties

Detailed description solder mask you can find .

Frequently asked questions and answers on laminates and prepregs

What is XPC?

What's the difference between FR1 and FR2?

What is FR2?

What is FR3?

What is FR4?

What is FR5?

What is CEM-1?

What is CEM-3?

What is G10?

How can laminates be replaced?

What are "prepregs"?

What does FR or CEM stand for?

Is FR4 really green?

Does the color of the logo mean anything?

Does logo orientation mean anything?

What is UV blocking laminate?

What laminates are suitable for plating through holes?

Is there an alternative for plating through holes?

What is "material thickness"?

What is: PF-CP-Cu? IEC-249? GFN?

What is CTI?

What does #7628 mean? What other numbers are there?

What is 94V-0, 94V-1, 94-HB?