Components Sourcing

MADPCB is a PCB manufacturing, assembly and design company. When choose our turnkey printed circuit board assembly service, all components, including active and passive parts will be provided by us. That’s to say, we are responsible for full BOM components sourcing. We understand the importance of reducing components cost and shortening PCB and PCBA manufacturing turnarounds by strategic components sourcing management. With long term working relationships with many component manufacturers and distributors both in domestics and overseas, we are able to purchase those hard to find parts at good prices and lead times, and offer them a very wide range of quality components. All component suppliers are audited by passing our quality standards and sourcing lead time requirement, and only trusted sources are permitted to procurement and application in your PCB assembly projects no matter in prototypes, low-volume and high-volume runs.

Passive Rectangular Components | SMD Package Type & Dimensions

 

Passive surface mount devices (SMDs) are mainly comprised of SMD resistors and SMD capacitors. There are several different standard sizes which has been reduced as technology has enabled smaller components to be manufactured and used. It will be seen that the devices size names are derived from their measurements in inches and millimeters. When choose MADPCB’s components sourcing service, the BOM is better to conclude the SMD packages.

Common Passive SMD Package Details

 

 

Of these sizes, the 1812, and 1206 sizes are now only used for specialized components or ones requiring larger levels of power to be dissipated. The 0603 and 0402 SMT sizes are the most widely used, although with miniaturing moving forwards, 0201 and smaller SMD resistors and capacitors are being used increasingly. When using SMD resistors, care must be taken to ensure that the power dissipation levels are not exceeded as the maximum figures are much less than for most leaded resistors.

 

Tantalum Capacitors SMD Packages

 

As a result of the different construction and requirements for tantalum SMT capacitors, there are some different packages that are used for them. These conform to EIA specifications.

 

Common SMD Tantalum Capacitor Package Details

 

 

Other Passive SMD Components

 

There are several types of other component that are not able to able to adopt the standard surface mount component sizes used by the majority of SMD resistors and capacitors.

Surface mount versions of components like many types of inductor, transformer, quartz crystal resonator, temperature-controlled crystal oscillator TCXO, filter, ceramic resonator and the like may require different style packages, often larger than the ones that are sued for surface mount resistors and capacitors.

These packages are unlikely to adopt the standard surface mount component package sizes in view of the unique nature of the components. Whatever the package style chosen it must be able to fit the automated PCB assembly processes and be handled by a pick and place machine.

 

Transistor & Diode Packages

 

SMD transistors and diodes often share the same styles of package. While diodes only have two electrodes a package having three enables the orientation to be correctly selected. Although a variety of SMT transistor and diode packages are available, some of the most popular are given in the list below,

 

• SOT-23 -Small Outline Transistor: The SOT23 SMT package is the most common outline for small signal surface mount transistors. The SOT23 has three terminals for a diode of transistor, but it can have more pins when it may be used for small integrated circuits such as an operational amplifier, etc. It measures 3mm x 1.75mm x 1.3mm.
• SOT223 -Small Outline Transistor: The SOT223 package is used for higher power devices like higher power surface mount transistors or other surface mount devices. It is larger than the SOT-23 and it measures 6.7mm x 3.7mm x 1.8mm. There are generally four terminals, one of which is a large heat-transfer pad. This enables heat to be transferred to the printed circuit boards.

 

Integrated Circuit (IC) SMD Packages

 

There are many forms of package that are used for surface mount ICs. Although there is a large variety, each one has the areas where its use is particularly applicable. IC packages are always expensive parts, and sometimes include programs. At MADPCB, you can choose our components sourcing service for ICs procurement.

• SOIC -Small Outline Integrated Circuit: This surface mount IC package has a dual in line configuration and gull wing leads with a pin spacing of 1.27mm.
• SOP -Small Outline Package: There are several versions of this SMD package:

1. TSOP -Thin Small Outline Package: This surface mount IC package is thinner than SOIC and has a smaller pin spacing of 0.5mm.
2. SSOP -Shrink Small Outline Package: This package has a pin spacing of 0.635mm.
3. TSSOP -Thin Shrink Small Outline Package
4. QSOP -Quarter-size Small Outline Package: It has a pin spacing of 0.635mm.
5. VSOP -Very Small Outline Package: This is smaller than the QSOP and has pin spacing of 0.4, 0.5 or 0.65mm.

• QFP -Quad Flat Pack: The QFP is the generic type of flat package for surface mount ICs. There are several variants as detailed below.

1. LQFP -Low Profile Quad Flat Pack: This package has pins on all four sides. Pin spacing varies according to the IC, but the height is 1.4mm.
2. PQFP -Plastic Quad Flat Pack: A square plastic package with equal number of gull wind style pins on each side. Typically narrow spacing and often 44 or more pins. Normally used for VLSI circuits.
3. CQFP -Ceramic Quad Flat Pack: A ceramic version of the PQFP.
4. TQFP -Thin Quad Flat Pack: A thin version of the PQFP.

 

Electronic Component Overages and Quantities

 

The quantities required for your PCB assembly project is for assembling and shipping PCB assemblies (PCBA) smooth without shipping delay. It also would be for each setup of the feeder and remaining parts will be lost during the removal and re-installation. Thus, if the PCB assembly job is set up more than one time or on future runs, additional components will be required.

 

For electronic component overages and quantities, please check the page of Assembly Reminders. When ask BOM cost quote at MADPCB, we will list all components sourcing quantities, prices and lead time.

 

Continuous Strips & Tapes for Consignment or Partial Turnkey Assembly

 

• Proper SMT machine setup and operation requires parts overages (or extra parts) because there is a small length between the feeder and the picking nozzle of the placement machine can’t be used. When it comes to pick and place process, the machine may throw away some parts, and the parts uploading to the feeders may be missed by manual. Unused and excessive parts supplier by you or purchased by us will be packaged and returned to you together with the PCB assemblies.
• SMT parts which are not supplied on reels should be on one continuous strip of tape. If you need to assemble different PCB boards with the same SMT parts, please do not cut them into more strips, just keep them in the continuous strip of the tape or on the reels.
• Standard of parts sourcing quantity or quantity provided for PCB assembly prototypes as the chart in Component Overages and Quantities. For high-volume PCB assembly runs, extra parts by percentage is ok for MADPCB. All extra parts are necessary for ensuring smooth assembling and shipping your assembled boards on time without shortage.
• If some parts are provided by you, please ship each kit separately. Do not combine multiple orders in one box, unless kits are clearly marked and separated. All kits should have a packing list showing all the items and quantities included in the kit. We appreciate an email sent to us when tracking information, especially when drop shipping multiple components from your suppliers in Consignment or partial assembly project.
• Each SMT component line must be in a single continuous tape – a minimum cut-tape / Reel / mini-reel. If not available on cut tape or reels, they must be on Trays. As a last resort they can be on Tubes.
• Each line item must have extra quantity of components for board assembly process, as per the following guidelines.

 

Working directly with PCB assembly manufacturer, MADPCB will bring you a lot of benefits in components sourcing not only on prices level. Get BOM cost quote today from MADPCB!