2026, February

Reading Time: 6 minutes

Maximising PCB Real Estate with High-Density Board-to-Board Solutions

A medical device designer faces a familiar dilemma: the product enclosure cannot grow larger, yet the feature list keeps expanding. Additional sensors, more processing power, enhanced communication capabilities; each requirement demands PCB space that simply doesn't exist. Traditional board-to-board connectors with 2.54mm pitch consume valuable area that could house critical components.

PCB designers working on high-density electronic assemblies encounter this challenge repeatedly. Consumer electronics, industrial IoT devices, and portable instrumentation all trend toward smaller form factors whilst demanding increased functionality. When board space becomes the primary constraint, every square millimetre matters.

High-density board-to-board connectors address this fundamental design challenge through fine-pitch contact spacing and optimised footprints. Understanding how these connectors enable compact assemblies whilst maintaining signal integrity and current capacity helps designers maximise available PCB real estate without compromising performance.

The Board Space Challenge in Modern Electronics

Electronic products face relentless pressure toward miniaturisation. Smartphones pack computing power that once required desktop towers into devices measuring millimetres thick. Industrial sensors must fit into existing mounting points whilst adding wireless connectivity and edge processing. Medical wearables need extended battery life without increasing size.

Board-to-board connections traditionally consume disproportionate PCB area. A 40-position connector at 2.54mm pitch requires roughly 100mm² of board space just for the connector footprint, before accounting for keepout zones and routing channels. In a design where total board area measures 1000mm², that single connector claims 10% of available space.

The situation worsens in stacked board designs. Multiple parallel boards connected through board-to-board connectors need vertical space for the connector stack height, mechanical clearance, and thermal management. Every millimetre of connector height translates directly to product thickness which is often the most constrained dimension in portable devices.

Explore connector solutions that address these space limitations through advanced contact technology and optimised mechanical design.

Fine-Pitch Technology: More Connections in Less Space

High-density board-to-board connectors achieve compact footprints through reduced contact pitch (the centre-to-centre spacing between adjacent pins). Modern fine-pitch connectors offer contact spacing from 0.5mm to 1.27mm, compared to traditional 2.54mm pitch designs.

The space savings prove substantial. A 0.5mm pitch connector delivers the same 40 positions in approximately 20mm² footprint, an 80% reduction compared to 2.54mm pitch. This freed space accommodates additional circuitry, larger power components, or simply enables smaller overall board dimensions.

Manufacturers like Molex and TE Connectivity produce board-to-board connectors at 0.4mm, 0.5mm, 0.6mm, 0.8mm, and 1.27mm pitch. Each pitch increment represents a trade-off between density, current capacity, and manufacturing considerations.

Contact technology enables these tight spacings whilst maintaining reliable electrical performance. Stamped and formed contacts use precisely controlled manufacturing processes that achieve positional accuracy within 0.05mm. Surface treatments (typically gold plating over nickel) ensure consistent contact resistance across thousands of mating cycles.

High Pin Counts Without Footprint Expansion

Fine-pitch technology enables dramatically increased pin counts within constrained footprints. Where a 2.54mm pitch connector might offer 20 positions in a given board area, a 0.5mm pitch connector can provide 100 positions in the same space.

This density increase supports several design strategies. Additional signal pins accommodate expanded communication buses, turning an 8-bit parallel interface into 32-bit without connector size growth. More ground pins improve signal integrity by reducing ground bounce and providing better return paths for high-speed signals. Dedicated power pins distribute current across multiple contacts, reducing individual pin stress and improving thermal performance.

Modern high-density connectors routinely offer 100 to 400 positions in packages measuring 20mm x 30mm or less. Amphenol produces board-to-board solutions that achieve 500+ positions through staggered contact arrangements and multi-row designs.

The mechanical design supports these high pin counts through precise alignment features. Guide posts, polarisation keys, and self-aligning lead-ins ensure proper mating even when positioning tolerances accumulate across manufacturing and assembly processes. Misalignment of just 0.2mm could prevent proper connection in fine-pitch designs however alignment features prevent this failure mode.

Signal Integrity in Compact Interconnects

Reduced contact spacing introduces potential signal integrity challenges that connector designers address through careful electrical design. Contact-to-contact spacing affects crosstalk (the unwanted coupling of signals between adjacent pins). High-speed digital signals with fast edge rates are particularly susceptible.

Ground pin placement proves critical in fine-pitch designs. Strategic positioning of ground contacts between signal pins provides electromagnetic shielding that reduces crosstalk. Many high-density connectors use ground-signal-signal-ground (GSSG) or ground-signal-ground (GSG) arrangements for critical high-speed interfaces.

Impedance control becomes increasingly important as signal speeds rise. Connectors designed for USB 3.0, PCIe, or high-speed serial interfaces specify controlled impedance contacts that maintain consistent 85Ω or 100Ω differential pairs through the connector transition. Samtec offers high-density board-to-board solutions with controlled impedance specifically for high-speed applications.

Contact length affects signal path length and therefore propagation delay. Shorter contacts in fine-pitch connectors actually provide advantages for high-speed signals by minimising stub length and reducing reflections. The typical 3mm to 5mm contact length in high-density connectors compares favourably to 8mm to 12mm contacts in traditional designs.

Current Capacity Considerations

Fine-pitch contacts carry less current than larger contacts (a physical reality governed by contact area and thermal dissipation). A 0.5mm pitch contact typically rates for 0.5A to 1A continuous current, whilst a 2.54mm pitch contact might handle 3A to 5A.

Designers address power delivery requirements through multiple parallel pins. Rather than routing power through two or three large pins, high-density designs might use ten to twenty fine-pitch contacts connected in parallel. This distribution actually provides advantages: improved thermal spreading, redundancy if individual contacts fail, and lower inductance through parallel current paths.

Temperature rise specifications guide pin count allocation for power distribution. Connector datasheets specify current ratings at a defined temperature rise (commonly 30°C above ambient). Exceeding current ratings doesn't necessarily cause immediate failure, but reduces contact life through accelerated oxidation and mechanical stress from thermal cycling.

Voltage ratings in fine-pitch connectors require attention to contact spacing. The 0.5mm spacing between adjacent pins limits working voltage to approximately 100V to 150V before considering environmental factors like altitude or contamination. Applications requiring higher voltages need increased contact spacing or segregated high-voltage pins with local keepout zones.

Stack Height Optimisation

Vertical dimension (the stack height between mated boards) directly affects product thickness. Traditional board-to-board connectors with 10mm to 15mm stack heights prevent designs from achieving slim profiles demanded by modern products.

Low-profile board-to-board connectors achieve stack heights as low as 1.5mm to 4mm whilst maintaining reliable mating. This reduction enables stacking multiple boards within enclosures previously limited to single-board designs. Hirose Electric produces ultra-low-profile solutions specifically for wearable and mobile applications.

The stack height choice affects board rigidity requirements and assembly processes. Lower stack heights demand tighter PCB flatness tolerances. Boards must remain flat within 0.2mm to 0.3mm over the connector area to ensure all contacts mate properly. This may require thicker PCB substrates or additional mounting points to prevent flexing during assembly.

Floating or self-aligning connector designs accommodate some PCB misalignment without requiring extremely tight flatness specifications. The mating portion floats laterally by 0.3mm to 0.5mm, allowing proper engagement even when boards aren't perfectly parallel. This floating action reduces assembly yield losses from PCB warpage or tolerance accumulation.

Practical Applications in Space-Constrained Designs

Industrial IoT sensors demonstrate the practical benefits of high-density board-to-board connections. A vibration monitoring sensor needs separate boards for sensing, processing, and communication where each is optimised for its function. Fine-pitch connectors enable stacking these boards within a 40mm diameter housing that mounts in existing sensor locations.

Portable medical devices benefit similarly. A handheld diagnostic tool might stack a display board, processor board, battery management board, and sensor interface board. Using 0.8mm pitch connectors instead of 2.54mm pitch reduces overall device thickness by 15mm to 20mm. This is the difference between a pocket-portable device and one requiring a carrying case.

Consumer electronics achieve extreme miniaturisation through high-density interconnects. Wireless earbuds measuring 15mm x 20mm contain multiple stacked boards connected through ultra-fine-pitch solutions. Without these compact connectors, the functionality simply wouldn't fit within the form factor consumers expect.

Selection Criteria for Your Design

Choosing appropriate board-to-board connectors requires balancing multiple parameters:

Contact pitch determines footprint density. Consider 0.5mm to 0.6mm for maximum density where assembly capabilities permit. Use 0.8mm to 1mm pitch for good balance between density and manufacturability. Select 1.27mm pitch when higher current capacity or relaxed assembly tolerances matter more than minimum size.

Stack height affects product thickness. Choose based on enclosure constraints and required board separation. Remember to account for PCB thickness, component heights, and mechanical clearances when calculating total stack height.

Pin count should accommodate current requirements plus 10% to 20% spare capacity for future expansion. Consider signal integrity requirements when allocating ground pins, high-speed designs need more ground contacts than low-speed applications.

Current rating per contact guides power pin allocation. Calculate actual current per pin including derating factors, then add redundancy for reliability.

Frequently Asked Questions

How does fine-pitch contact spacing affect assembly yield?

Fine-pitch connectors require tighter PCB flatness tolerances and more precise placement accuracy. Modern pick-and-place equipment handles 0.5mm pitch reliably, but assembly yields improve with good PCB design practices including controlled flatness and adequate fiducial marks.

Can high-density connectors handle high-speed signals?

Yes, when properly designed. Look for connectors with controlled impedance specifications, ground pin shielding, and short contact lengths. Many manufacturers offer high-density solutions qualified for USB 3.0, PCIe, and multi-gigabit serial interfaces.

What's the trade-off between contact pitch and current capacity?

Finer pitch means lower current per contact, but parallel pins compensate. A 0.5mm pitch connector with ten parallel power pins can deliver similar total current to a 2.54mm pitch connector with three pins, whilst occupying less board space.

Maximising Design Potential

High-density board-to-board connectors transform PCB space from a limiting constraint into a design advantage. The ability to stack multiple boards within compact enclosures whilst maintaining robust interconnection enables product miniaturisation without functionality compromise.

At TRX Electronics, we supply fine-pitch board-to-board connectors from leading manufacturers through our partnerships with Mouser Electronics and TTI Inc. Our technical support helps you navigate the selection process, ensuring your connector choice balances density, performance, and manufacturability.

Ready to optimise your next compact design? Contact our team and let us help you find the right connector solutions for your space-constrained applications.

Reading Time: 6 minutes

Simplifying High-Power Drive Design with Integrated IGBT Solutions

Designing the power stage for a 500kW industrial motor drive involves managing dozens of interconnected challenges simultaneously. Gate drive timing must achieve nanosecond precision across six IGBTs switching hundreds of amperes. Thermal interfaces between semiconductors and heatsinks require careful attention to avoid hotspots. Protection circuits must respond to fault conditions within microseconds. Each discrete component adds complexity, potential failure points, and development time.

Power electronics engineers face mounting pressure to reduce development cycles whilst improving reliability in high-power applications. Industrial motor drives, renewable energy inverters, and traction systems demand power stages that operate continuously at high current levels without thermal runaway or catastrophic failures.

Integrated IGBT power modules address these challenges by combining switching devices, gate drivers, and protection circuits into optimised packages with superior thermal management. Understanding how these modules streamline development whilst enhancing reliability helps engineers deliver robust power electronics faster.

The Complexity Challenge in Discrete IGBT Designs

Traditional high-power drive designs assemble discrete IGBTs, gate driver circuits, current sensors, and protection logic across multiple circuit boards. This approach offers design flexibility but introduces substantial complexity that impacts both development time and operational reliability.

Gate driver design alone presents significant challenges. The gate drive circuit must deliver precise current pulses to charge and discharge the IGBT gate capacitance rapidly whilst maintaining isolation between low-voltage control logic and high-voltage power stages. Layout parasitics (stray inductance and capacitance) affect switching behaviour and can trigger oscillations or shoot-through conditions where both upper and lower devices conduct simultaneously.

Thermal management becomes critical at power levels where hundreds of watts dissipate in compact spaces. Each IGBT, freewheeling diode, and gate driver circuit generates heat. Advanced semiconductor power modules address these thermal challenges through integrated thermal design.

Protection circuit implementation adds further complexity. Desaturation detection monitors IGBT collector-emitter voltage to identify short-circuit conditions. Overtemperature sensing prevents thermal destruction. Undervoltage lockout ensures adequate gate drive voltage before enabling switching. Coordinating these protection functions across multiple devices multiplies design effort.

Integrated IGBT Modules: Complete Power Stage Solutions

IGBT power modules integrate multiple switching devices, gate drivers, and protection circuits into single packages designed for specific applications. A three-phase motor drive module contains six IGBTs with anti-parallel diodes, gate driver circuits for all positions, and comprehensive protection - everything needed for the complete power stage except the DC bus capacitors and output filters.

The integration begins with the power semiconductors themselves. Modern modules from Infineon Technologies and onsemi use direct copper bonding technology that bonds semiconductor dies directly to copper substrates. This construction minimizes thermal resistance whilst providing excellent current distribution across large die areas.

Gate driver integration eliminates external gate drive circuit design. The drivers embedded within the module feature optimized layouts that minimize parasitic inductance in critical gate loop paths. This reduces switching losses and electromagnetic interference whilst improving reliability by eliminating potential layout errors in external gate drive circuits.

Built-in protection circuits monitor critical parameters continuously. Short-circuit protection detects abnormal collector-emitter voltage within 2 to 10 microseconds and disables the gate drive before device destruction occurs. Temperature sensors embedded near the semiconductor dies provide accurate thermal monitoring that enables protective shutdown before junction temperatures reach dangerous levels.

Thermal Management: From Challenge to Advantage

Heat dissipation represents the primary reliability concern in high-power electronics. Junction temperature directly affects IGBT lifetime; every 10°C reduction approximately doubles device lifespan. Integrated modules transform thermal management from a design challenge into a built-in advantage.

The thermal path from semiconductor junction to heatsink mounting surface receives careful optimization during module design. Direct bonded copper substrates provide low thermal resistance (typically 0.01°C to 0.03°C per watt between die and substrate). The base plate material and thickness balance thermal conductivity with mechanical stress management during thermal cycling.

Module manufacturers characterize thermal performance comprehensively, providing accurate thermal resistance values for all thermal paths. This eliminates guesswork in thermal calculations and enables precise heatsink specification. Many modules include thermal interface material pre-applied to the base plate, ensuring optimal thermal coupling without assembly concerns about interface thickness or coverage.

Power cycling capability (the number of temperature cycles from ambient to maximum junction temperature that the module withstands) benefits from integrated design. Manufacturers engineer modules specifically for applications with frequent thermal cycling, using reinforced wire bonding and substrate attachment techniques that resist fatigue failure.

Simplified Design Process and Reduced Development Time

The complexity reduction from using integrated modules directly translates to shorter development cycles. Gate drive timing optimization, protection circuit tuning, and thermal interface design (tasks requiring weeks in discrete designs) become specification exercises when using modules.

Layout complexity drops substantially. Instead of routing high-current paths, gate drive signals, and sense connections across multiple boards, the design interfaces with a single module through standardized connectors. This simplification reduces PCB layer count, manufacturing complexity, and assembly costs.

Testing and validation become more straightforward. Module manufacturers provide comprehensive characterization data including switching waveforms under various load conditions, thermal performance curves, and protection circuit response times. This documented performance reduces the validation testing required before production release.

Design reuse improves across product families. A well-characterized module can serve multiple applications with different power levels by simply paralleling devices or selecting different current ratings within the same package family. The gate drive and protection circuitry scale automatically with the power semiconductors.

Protection Features That Prevent Catastrophic Failures

Built-in protection circuits in integrated modules respond faster and more reliably than external protection implementations. The proximity between sensing circuits and power devices eliminates propagation delays introduced by board-level connections.

Short-circuit protection activates within microseconds when collector-emitter voltage exceeds expected saturation voltage during conduction. The protection circuit transitions the IGBT into an active region that limits current whilst maintaining control, then initiates controlled shutdown that prevents voltage spikes from inductive load energy.

Active clamping during turn-off limits collector-emitter voltage to safe levels even when switching highly inductive loads. This protection prevents voltage overshoot that could exceed device ratings during fault conditions or unexpected load changes.

Interlock functions prevent both upper and lower devices in a half-bridge configuration from conducting simultaneously. Deadtime generation ensures one device turns off completely before the opposite device receives gate drive signals, preventing shoot-through currents that destroy power stages instantly.

Application-Specific Optimization

Module manufacturers offer variants optimized for specific applications. Motor drive modules include features relevant to variable-frequency drives: low inductance construction for clean switching, integrated brake choppers, and thermistor inputs for motor temperature monitoring.

Renewable energy modules designed for solar and wind inverters emphasize efficiency across wide power ranges. These modules use optimized gate drive timing that reduces switching losses during the partial-load operation typical in renewable installations. Microchip Technology provides intelligent power modules with integrated control functions suited for renewable energy applications.

Traction modules for electric vehicles and rail systems feature ultra-low inductance packaging that enables very fast switching with minimal electromagnetic interference. Automotive-grade qualification ensures operation through extreme temperature ranges and vibration environments that standard industrial modules might not withstand.

Selection Criteria for Your Application

Choosing the right IGBT module requires matching several parameters to application requirements:

Current rating should include margin for peak currents during starting and fault conditions. Module ratings specify continuous current at a defined case temperature. Verify that your cooling system maintains case temperature within these limits.

Voltage rating must exceed the maximum DC bus voltage with adequate margin for transient overvoltages. Industrial drives typically use 1200V modules for 690V AC systems and 1700V modules for medium-voltage applications.

Switching frequency capability determines whether the module suits your application. Motor drives typically switch at 4kHz to 16kHz, whilst some renewable energy applications operate at 20kHz or higher for reduced filter requirements.

Thermal characteristics including thermal resistance and power cycling capability must align with your operating profile. Applications with frequent starts and stops require modules rated for extensive thermal cycling.

Frequently Asked Questions

How do integrated modules compare in cost to discrete designs?

Whilst module unit costs exceed discrete component costs, the total system cost typically favours modules when accounting for reduced development time, simpler PCB design, lower assembly costs, and improved reliability that reduces warranty expenses.

Can modules be paralleled for higher current applications?

Yes, modules can be paralleled when current sharing and matched switching characteristics are ensured. Manufacturers often provide guidance on paralleling techniques and offer matched sets for this purpose.

What happens when protection circuits activate?

Most modules provide fault status outputs that signal the control system when protection activates. The module typically enters a safe state with outputs disabled, requiring a reset signal before resuming operation after the fault condition clears.

Building Reliable High-Power Systems

Integrated IGBT modules transform high-power drive development from managing complex discrete designs to selecting optimised solutions that combine proven technology with comprehensive protection. The thermal management advantages and reduced design complexity enable faster development of reliable power electronics.

At TRX Electronics, we supply IGBT power modules from leading manufacturers through our partnerships with Mouser Electronics and TTI Inc. Our technical knowledge helps you navigate module selection for your specific application requirements.

Ready to simplify your next high-power design? Contact our team and let us help you select the right power modules for your industrial applications.