In PCB assembly, the terms DIP and THT are often used together—and sometimes even used as if they mean exactly the same thing.
Technically, however, they are different.
DIP stands for Dual In-line Package, which describes a specific component package with two parallel rows of leads.
THT stands for Through-Hole Technology, which describes a broader PCB mounting method in which component leads are inserted through holes in the printed circuit board and soldered on the opposite side.
This means:
DIP is one type of through-hole component, while THT is the broader assembly technology.
The confusion comes from manufacturing terminology. In many electronics factories, especially in production planning, terms such as DIP assembly, DIP line, or DIP insertion are commonly used to describe the entire through-hole assembly process.
DIP vs THT: What’s the Difference in PCB Assembly?
This guide explains the difference between DIP and THT, how each term is used in PCB manufacturing, and what equipment is required for a modern through-hole production line.
What Is DIP?
DIP stands for Dual In-line Package.
A traditional DIP component has a rectangular body with two parallel rows of leads extending from opposite sides.
These leads are inserted into corresponding holes in the PCB.
Typical examples can include:
- DIP integrated circuits
- DIP switches
- Certain optocouplers
- Some relays
- Socket-mounted devices
DIP packages were widely used in earlier generations of electronics and are still used in selected applications today.
A DIP package can be manually inserted or automatically inserted depending on:
- Component packaging
- Lead geometry
- Production volume
- Equipment capability
What Is THT?
THT stands for Through-Hole Technology.
It is an assembly method rather than a specific package shape.
With THT assembly, the leads or pins of a component pass through holes in the PCB and are soldered to pads on the opposite side.
THT includes a much wider variety of components than DIP.
Examples include:
- Connectors
- Terminal blocks
- Relays
- Transformers
- Switches
- Large capacitors
- Pin headers
- Fuses
- Selected power components
- Certain sensors
- Electromechanical components
- DIP integrated circuits
Therefore, every conventional DIP component used through PCB holes is a THT component, but not every THT component is a DIP package.
DIP vs THT: The Main Difference
The simplest distinction is:
- DIP describes a component package.
- THT describes an assembly technology.
In engineering documentation, THT is usually the more accurate term when referring to the overall assembly technology.
Why Do PCB Factories Call THT Assembly “DIP Assembly”?
This is mainly an industry terminology habit.
Many electronics manufacturers use phrases such as:
- DIP workshop
- DIP assembly line
- DIP insertion line
- DIP soldering
- DIP production department
In these cases, the term “DIP” often includes many components that are not technically dual in-line packages.
For example, a “DIP line” may assemble:
- Connectors
- Transformers
- Relays
- Terminal blocks
- Capacitors
- Switches
Technically, this would be more accurately described as a THT assembly line.
However, because “DIP line” is already widely understood in many factories, both terms may appear in equipment purchasing and production discussions.
What Is DIP Assembly in Manufacturing?
In practical factory terminology, DIP assembly usually refers to the process of inserting and soldering through-hole components.
A typical process may be:
PCB Loading → Component Preparation → DIP/THT Insertion → Pre-Solder Inspection → Fluxing → Preheating → Wave or Selective Soldering → Cooling → Inspection → Testing
This process may include both true DIP packages and other THT components.
For this reason, when a supplier receives a request for a “DIP production line,” the supplier should not assume that only dual in-line components are involved.
The PCB and BOM should always be reviewed first.
What Is a THT Assembly Process?
A THT assembly process involves several main stages.
Component Preparation
Through-hole components may need preparation before insertion.
This can include:
- Lead cutting
- Lead forming
- Bending
- Sorting
- Kitting
- Orientation checking
Different components require different preparation methods.
Component Insertion
THT components are inserted into PCB holes.
Insertion can be:
- Manual
- Semi-automatic
- Automatic
Manual insertion remains common because many THT parts have irregular sizes and shapes.
Automatic insertion is more suitable when components have standardized geometry and stable packaging.
Pre-Solder Inspection
Before soldering, operators or inspection systems may check:
- Missing components
- Incorrect components
- Wrong polarity
- Incorrect orientation
- Improper insertion depth
- Bent leads
Detecting these problems before soldering can reduce rework.
Fluxing
Flux is applied to support solder wetting.
Important factors include:
- Flux chemistry
- Application volume
- Coverage
- Process consistency
Preheating
The PCB is heated before soldering.
The required process depends on:
- PCB thickness
- Copper distribution
- Component thermal mass
- Flux chemistry
- Solder alloy
Soldering
Common soldering methods include:
- Wave soldering
- Selective soldering
- Manual soldering
The correct method depends on the PCB design and production volume.
Inspection and Testing
After soldering, the PCBA may undergo:
- Visual inspection
- AOI where suitable
- ICT
- Functional testing
- Programming
- Product-specific testing
Is Wave Soldering a DIP or THT Process?
Wave soldering is commonly associated with DIP/THT production because it can solder many through-hole joints efficiently.
A typical wave soldering flow is:
Fluxing → Preheating → Solder Wave → Cooling
The solder wave contacts the exposed leads and pads on the underside of the PCB.
Wave soldering can be suitable when:
- Many THT joints are present
- The PCB design supports the process
- Production volume is medium or high
- Continuous throughput is important
However, wave soldering is not required for every THT assembly.
When Is Selective Soldering Used?
Selective soldering applies solder only to specific through-hole joints or areas.
It may be more suitable when:
- Only a few THT components are present
- The PCB has bottom-side SMT components
- Certain areas must avoid solder contact
- The board is a complex mixed-technology assembly
Selective soldering is therefore increasingly useful in modern SMT + THT manufacturing environments.
DIP Components vs Other THT Components
Understanding component categories helps clarify the terminology.
Typical DIP Components
Examples may include:
- DIP ICs
- DIP switches
- Certain relays
- Some optoelectronic components
These normally have two parallel rows of leads.
Other THT Components
These may include:
- Terminal blocks
- Large connectors
- Transformers
- Radial capacitors
- Axial components
- Pin headers
- Switches
- Fuses
- Power components
These are THT components but are not necessarily DIP packages.
DIP vs THT vs SMT
Another common source of confusion is the relationship between DIP, THT, and SMT.
SMT stands for Surface Mount Technology.
SMT components are mounted directly onto the PCB surface rather than inserting leads through holes.
A key point is that DIP and THT are not equivalent categories to SMT.
A more technically correct comparison is:
SMT vs THT
rather than:
SMT vs DIP
However, “SMT vs DIP” remains common terminology in industry and online searches.
Why Is THT Still Used When SMT Is More Automated?
SMT is widely used because it supports:
- High component density
- High-speed placement
- Compact PCB design
- Automated production
However, THT remains useful for certain component types and mechanical requirements.
Examples include components that may experience:
- Plugging and unplugging
- Mechanical pulling
- Vibration
- High physical stress
Connectors and terminal blocks are common examples.
THT is also frequently used for larger components such as:
- Transformers
- Relays
- Large capacitors
- Certain power devices
This does not mean THT is universally more reliable than SMT.
The appropriate technology depends on the component, product design, operating environment, and manufacturing requirements.
How SMT and THT Are Combined in PCB Assembly
Many modern PCB assemblies use both technologies.
A typical mixed production flow may be:
Solder Paste Printing → SPI → SMT Placement → Reflow → AOI → THT Insertion → Wave/Selective Soldering → Inspection → Testing
In this process:
SMT handles components such as:
- ICs
- Chip resistors
- Chip capacitors
- Small semiconductor packages
THT handles components such as:
- Connectors
- Relays
- Transformers
- Terminals
- Large capacitors
This combination is common in industrial control, power electronics, automotive electronics, energy systems, communication equipment, and many other PCBA applications.
What Equipment Is Needed for THT or DIP Assembly?
A complete THT/DIP line can include:
- PCB loader
- PCB conveyors
- Component preparation equipment
- Manual insertion stations
- Semi-automatic insertion equipment
- Automatic THT insertion machines
- Pre-solder inspection conveyor
- Fluxing system
- Preheating system
- Wave soldering machine
- Selective soldering machine
- Cooling conveyor
- PCB unloader
- Inspection equipment
- Testing equipment
- Rework stations
The exact equipment list depends on the actual PCB.
Manual vs Automatic THT Assembly
Not every through-hole process should be fully automated.
Manual THT Assembly
Manual insertion can be more suitable for:
- Low-volume production
- High-mix products
- Frequent changeovers
- Irregular component shapes
- Prototypes
Advantages include flexibility and lower initial equipment investment.
Automatic THT Assembly
Automatic insertion can be suitable when:
- Production volume is high
- Products are stable
- Components are standardized
- Packaging supports automatic feeding
A hybrid line is often practical:
Automatic insertion for suitable components + manual insertion for irregular components.
What Is a DIP Production Line?
In equipment purchasing, a DIP production line usually means a complete through-hole production process rather than a line that handles only DIP packages.
A common line configuration may be:
Automatic PCB Loader → Insertion Conveyor → Manual/Semi-Automatic THT Insertion → Inspection Conveyor → Wave Soldering → Cooling Conveyor → PCB Unloader → Inspection → Testing
For complex mixed-technology PCBs, wave soldering may be replaced by selective soldering.
How to Choose the Correct THT Production Line
Before selecting equipment, manufacturers should evaluate:
- PCB dimensions
- PCB thickness
- BOM
- THT component types
- True DIP components
- Irregular through-hole components
- Component packaging
- Number of THT joints
- Production target
- Product mix
- Changeover frequency
- Manual vs automatic insertion
- Wave vs selective soldering
- Inspection requirements
- Testing requirements
- Factory layout
- Existing SMT equipment
- Automation level
- Budget
This is more important than deciding whether to call the line a “DIP line” or a “THT line.”
Common Misunderstandings About DIP and THT
Misunderstanding 1: DIP and THT Are Exactly the Same
They are related, but not technically identical.
DIP is a package style. THT is a mounting method.
Misunderstanding 2: Every THT Component Is a DIP Component
Incorrect.
A transformer or terminal block may be through-hole mounted but is not a dual in-line package.
Misunderstanding 3: DIP Is an Alternative to SMT
This wording is common, but the more technically correct comparison is THT vs SMT.
Misunderstanding 4: THT Is an Outdated Technology
THT continues to be used where component size, mechanical design, product requirements, or production considerations make it suitable.
Misunderstanding 5: Every THT Line Needs Automatic Insertion
No.
Manual, semi-automatic, and automatic insertion can all be appropriate depending on the application.
Why Correct Terminology Matters When Buying Equipment
Terminology can directly influence equipment selection.
If a factory simply tells a supplier, “We need a DIP line,” that information is not enough to configure the production system.
The supplier needs to understand:
- Which components are true DIP packages
- Which components are other THT types
- Component dimensions
- Lead geometry
- Packaging
- Number of components per board
- PCB dimensions
- Required output
For example, a line assembling standardized axial or radial components may have very different automation requirements from a line assembling large connectors, relays, and transformers.
The BOM is therefore one of the most important inputs for THT line planning.
DIP/THT and PCBA Production Line Solutions from Fuliu Electronics
Established in 2014, Fuliu Electronics is dedicated to providing customers with high-quality PCBA intelligent manufacturing solutions and services.
With extensive experience in the SMT industry, we specialize in dependable equipment, professional technical support, and complete SMT and PCBA production line solutions.
Our product portfolio includes SMT pick and place machines from Fuji, Panasonic, ASM, Yamaha, JUKI, and Hanwha, together with ERSA reflow ovens from Germany, MagicRay SPI/AOI inspection systems, automatic solder paste printers, supporting PCBA equipment, pre-owned SMT equipment, SMT spare parts, machine leasing, and maintenance services.
For manufacturers planning a DIP/THT production line, Fuliu Electronics can help evaluate:
- PCB dimensions
- BOM
- THT component categories
- DIP component types
- Component packaging
- Production capacity
- Manual vs automatic insertion
- Wave vs selective soldering
- Product mix
- Inspection and testing
- Existing equipment
- Factory layout
- Automation requirements
- Investment budget
For mixed-technology products, SMT and THT can also be planned together as a complete PCBA manufacturing process.
As part of our global growth strategy, Fuliu Electronics is actively expanding into international markets, with key focus areas including India, Vietnam, the Philippines, Indonesia, the Middle East, South Africa, and Europe.
Conclusion
So, DIP vs THT: what’s the difference in PCB assembly?
The most important distinction is simple:
- DIP is a component package.
- THT is an assembly technology.
A DIP component can be part of a THT assembly process, but THT includes many components beyond traditional dual in-line packages.
In real PCB factories, the term DIP assembly line is often used broadly to mean a through-hole production line. That is why both terms frequently appear in equipment purchasing and production discussions.
When planning a production line, terminology is less important than understanding the actual manufacturing requirements.
The correct configuration should be based on:
- PCB design
- BOM
- THT component types
- Component packaging
- Production volume
- Product mix
- Manual or automatic insertion requirements
- Wave or selective soldering
- Inspection
- Testing
- Factory layout
- Automation level
If you are planning a new DIP/THT assembly line, upgrading a through-hole production process, or building a complete SMT + THT PCBA factory, Fuliu Electronics can help evaluate your PCB dimensions, BOM, component types, target capacity, existing equipment, factory layout, automation requirements, and budget to develop a suitable production solution.
Frequently Asked Questions
DIP refers to a Dual In-line Package with two parallel rows of leads, while THT refers to the broader technology of inserting component leads through PCB holes.
Yes.
Traditional DIP components mounted through PCB holes are a type of THT component.
No.
Connectors, transformers, terminal blocks, relays, and many other through-hole components do not necessarily use a DIP package.
“DIP line” has become a common manufacturing term for through-hole assembly, even when the line processes many non-DIP components.
For the overall through-hole manufacturing process, THT assembly is generally the more technically accurate term.
SMT places components directly on the PCB surface, while THT inserts component leads through holes in the PCB.