3M VHB Tape Application Guide: A Superior Bonding Solution

You’re staring at the pristine roll of VHB tape clutched in your hand, wondering what the next step is to apply it correctly. 

Luckily, each 3M VHB tape has clear application instructions depending on your substrates and environment. 

The engineering process isn’t over at Strouse until your adhesive can be applied effectively. Having worked with 3M VHB for decades, we have the knowledge it takes to teach you the most useful VHB bonding techniques.

Let’s review how to properly prepare surfaces and consider the environment before applying VHB tape.

Should I Use 3M VHB?

First of all, why go through the extra steps of applying VHB tape when there are other options? 

There are multiple reasons you might choose VHB tape over mechanical fasteners. For decades, engineers have had to deal with the downsides of many permanent bonding materials:

• Screws, bolts, and mechanical fasteners significantly increase weight
• Rivets punch through a material, are uneven, and create vulnerable stress points
• Welding is time-consuming and disruptive in an otherwise efficient assembly process
• Liquid and spray adhesives are tedious, time-consuming, and messy

We previously covered why 3M™ VHB™ (Very High Bonding) tape is a superior bonding solution. In short, if you’re considering a bonding solution for your application challenge, 3M VHB tape offers these significant benefits:

• LIGHTWEIGHT — Light 3M VHB acrylic foam tape is available in many thicknesses and widths so that you can select the right material for your project.
• HIGH PERFORMANCE — 10 times stronger than rivets, 3M VHB tape outperforms traditional bonding solutions, spreading the bond along the surface.
• NO MESS — Many solutions (including liquid) require a messy primer, leaving finished products looking unsatisfactory. 3M VHB tapes are smooth and clean.
• SAFE TO USE AND APPLY — Some primers expose employees to harsh chemicals, and their application slows down production.
• VERSATILE AND EASILY DIE CUT — Its construction allows the material to be easily converted. Get 3M VHB die cuttable tape in custom shapes and sizes.

Suppose you still need to figure out the specifics of choosing VHB over another solution. In that case, you can discuss your project with a manufacturer to confirm whether there’s a material that will suffice for your current design. 

Once you know that 3M VHB tape is a strong and reliable solution for your application, you must know how to apply it consistently and efficiently. This article will offer application tips to optimize your process and reduce manual labor.

3M VHB Tape Application Tips

By this point, you’re probably wondering, “How do I use 3M VHB tape?”

Unlike slapping on a line of duct tape, applying VHB involves a great deal of precision. In fact, it varies depending on the substrates you’re applying the tape to.

These seven tips will help you prepare for different situations and demonstrate what to consider when designing your application method. 

TIP #1: SURFACE PREPARATION– CLEANING

Any adhesive bonds better if the substrate surface is clean, saving time and problems down the road. Use a disposable towel or cloth and one of two solvents: 1) isopropyl alcohol solution (70% IPA, 30% water) for dust, dirt, and fingerprints; or 2) acetone for oily surfaces.

• Heavy Oils: Use a degreaser to remove heavy oil/grease from a surface.
• Porous surfaces: Porous and fibered materials, including wood, particleboard, and concrete, must be sealed to provide a unified surface.
• Unique Materials: Special surface preparation is needed for glass, copper, and plastics or rubber that contain components that migrate (e.g. plasticizers).

Steps:

1. If there are tough spots, quickly pre-clean these
2. Remove contaminants with a wet towel/cloth
3. Wipe with a dry towel/cloth

All of the above cleaning prep work must be followed by cleaning with IPA/Water. For additional reading on surface prep, look up the 3M Technical Bulletin “Surface Preparation for 3M™ VHB™ Tape Applications” (70-0704-8701-5).

TIP #2: SURFACE PREPARATION– PRIMING

In certain situations, priming and abrading (#3 below) can improve how the adhesive sticks to specific substrates: plastics, paints, and substrates with low surface energy. Simply put, the primer creates a new surface to improve adhesion.

Steps:

1. Depending on the substrate, apply primer to the clean surface using:
• a disposable towel followed by a dry towel
• a dauber bottle followed by a dry towel
• a foam brush
2. Let dry before taping

TIP #3: SURFACE PREPARATION– ABRADING 

Abrasion is commonly used on surfaces with heavy levels of dirt or oxides to create additional surface area or to smooth a textured surface for improved contact.

Ultra-small circular abrading motion is more desirable than straight-line motion. The bond's strength will improve since the micro-scratches increase the surface area used for bonding.

The 3M Scotch-Brite Hand Pads (7447 Maroon or Heavy-Duty Green) will achieve the right level of abrasion. Palm or dual-action sanders can help with large surface areas. Be careful not to grind the surface with coarse materials, or they will create too much texture for the adhesive to flow into the surface adequately.

Clean the substrate with the IPA/water solution after abrading the surface. The exceptions for these abrading guidelines are 3M VHB tapes 4932 and 4952. They perform best on smooth surfaces.

Steps:

1. Determine the abrasion needed:
• for light abrasion, use a hand pad or an L-abrader tool
• for powered abrasion, use a right-angle grinder or dual-action sander with a coated abrasive
2. Clean the substrate after abrading; all debris should be removed from the bond area

TIP #4: MANUAL SURFACE APPLICATION 

Determine the best application method for your situation by considering your specific application and production volume. Then use the right adhesive tape application equipment.

Steps (by hand):

1. Place the tape at the edge of the surface, applying constant pressure (at least 15 lbs) as you lay it down to ensure good contact
2. Remove the protective liner

Steps (by hand tape applicator):

1. Same steps as above, but a handheld applicator is used instead of bare hands

Steps (by push-through laminator):

1. Push substrate pieces through the laminator
2. Laminator applies tape and pressure
3. Manually cut the tape between pieces

TIP #5: AUTOMATED TAPE APPLICATION 

There are two levels of automated applications:

1. Linear application: A machine tapes pieces that pass on a conveyor
2. Complicated applications: a robot arm applies the tape in multiple locations on every piece; die-cut pieces and tape strips, for example

Want to know more about automated tape applications? You can read about the different types of automation and decide whether it’s suitable for your project.

TIP #6: APPLYING FINAL PRESSURE 

Bond strength depends on the amount of adhesive-to-surface contact developed. Firm application pressure creates better adhesive connection and helps improve bond strength.

Typically, good surface contact can be attained by applying enough pressure to ensure the tape experiences approximately 15 psi (100 kPa). Applying pressure greater than 15 psi across the width of the tape is required to achieve optimal “wet-out” or acceptable contact. A handheld pressure roller, platen pressure, or J-roller can do the job. 

Note that rigid surfaces may require 2 or 3 times more pressure to make the tape experience 15 psi.

TIP #7: VHB TAPE REMOVAL

You may have to remove 3M VHB tape from a substrate because of an application error or repair.

Steps:

1. Apply isopropyl alcohol to the bond’s edge; this lubricates the cutting tool and prevents rebonding of separated tape
2. Using an oscillating tool, cut the tape ⅛” to ¼” deep at each pass
3. Once components are separated, tape residue can be removed using the oscillating tool
4. Use adhesive remover for any remaining residue: spray it on, let it soak, scrub with a hand pad, remove residue, and wipe clean with a towel or cloth

Following these tips will allow you to use most VHBs properly. However, understanding further application process specifics will increase the chances of your tape adhering well and ensure its adhesive bond lasts longer. 

What Else Should I Know About Applying VHB Tape?

In addition to the application requirements and surface preparations, there are other factors to consider, such as the VHB application temperature, bonding time, adhesion to substrates, and storage and shelf life.  

VHB APPLICATION TEMPERATURE

The ideal application temperature range is 70°F to 100°F (21°C to 38°C). Since the pressure-sensitive adhesives use viscous flow to achieve substrate contact area, the minimum suggested application temperature for the 3M VHB tape 5952 family is 50°F (10°C). Check each tape’s specifications for the actual minimum temperature for each tape:

BONDING TIME

During the wet-out period, where the adhesive flows into the textured surface of the substrate, the bond strength will increase. Based on room temperature, 50% of the bond strength will be achieved in 20 minutes. The strength will increase to 90% after 24 hours. It typically takes 72 hours to reach 100% strength.

This period can speed up with warmer temperatures and slow with cooler temperatures. When the wet-out process is in progress, exposure of the substrates to 150°F (66°C) for one hour can increase the bond strength. The bond strength can also be increased with abrasion and primers.

ADHESION TO SUBSTRATES

Adhesion is determined by the adhesive’s flow onto the substrate. Another factor is the amount of tape to the weight/size of the substrate. 

For instance, a general rule for the 5952 tape holding static stresses is using about four square inches of tape for each pound of the substrate (57 cm² of tape per kg). Bond flexibility is beneficial with the 5952 tape unless additional stiffness is required. If not, then this tape can replace any mechanical fasteners.

A good estimate formula is 12 lbs./in.2 (85 kPa) regarding dynamic stresses or loads in general applications.

When it comes to thermal expansion/contraction, assuming good adhesion to the substrates, the tapes can tolerate differential movement up to 3 times their thickness.

STORAGE AND SHELF LIFE

All 3M VHB tapes have a shelf life of 24 months from the date of manufacturing. This schedule is true when the tape is stored at 40°F to 100°F (4°C to 38°C) with 0-95% relative humidity. The optimum storage conditions are 72°F (22°C) and 50% relative humidity.

VHB tapes all feature:

• Fast and easy-to-use permanent bonding method
• High strength and durability
• Virtually invisible fastening capabilities
• Ample strength to replace mechanical fasteners and liquid adhesives
• Creating a permanent seal against water and moisture
• Bonding with differing materials

Your adhesive shelf life will depend on the VHB you choose, so double-check with your datasheet or manufacturer when shelf life is critical to your project to ensure your tape or adhesive product is ready when you need it. 

Application Types, Converter Partnerships, and Finding the Right Tape

3M VHB tape has become the go-to permanent bonding solution for applications in every industry. Yet, different variations suit the project's needs within every industry that uses 3M VHB tape. 

Automotive manufacturers rely on VHB tape to assemble vehicles. Medical device manufacturers choose it to bond critical components in product assembly. As the electronics industry continues to design lighter, thinner, and smaller products, 3M VHB tape delivers a lightweight permanent bond that doesn’t negatively impact product performance. 

Selecting a tape based on your design, industry, and ultimate goal will enable you to plan around its specific application guidelines until you can build your idealized, optimized manufacturing process. 

Naturally, you’ll want to choose the correct VHB tape based on your current application. You can use the guide above or schedule a VHB consultation.

Originally published: April 28, 2021