Removing UV adhesive from a printed circuit board doesn't just require the right solvent — it requires an entirely different set of constraints than removal from glass or metal, because a mistake here can damage a component instead of just a surface finish. Why Electronics Demand a Different Standard On a PCB or precision electronic assembly, the removal process has to satisfy three requirements simultaneously that don't apply to most other substrates: no electrostatic discharge (ESD) risk to sensitive components, no conductive or corrosive residue left anywhere near circuit traces, and no thermal exposure that exceeds the tolerance of nearby solder joints or plastic connector housings. Any one of these failing can turn a successful adhesive removal into a functional failure of the board itself. ESD Precautions Before Starting Standard removal tools and PPE aren't automatically ESD-safe. Grounding straps, ESD-safe work mats, and ionizing air blowers should be part of the setup whenever removal work happens near active circuitry, even if the adhesive itself is on a mechanical rather than electrical component of the assembly. Static discharge during a scraping or wiping motion can damage a component that shows no visible sign of failure until it's back in service — making this precaution easy to skip and expensive to have skipped. Selecting Non-Conductive, Non-Corrosive Solvents Isopropyl alcohol remains the standard choice for electronics-adjacent removal work precisely because it's non-conductive, evaporates cleanly without leaving a conductive film, and has a long track record of compatibility with common PCB substrates and conformal coatings. Stronger solvents like acetone or MEK, while faster on tougher bonds, carry a higher risk of attacking adjacent conformal coatings or plastic connector housings — a trade-off that often isn't worth the time saved on an electronics assembly. Thermal Limits Near Solder Joints Heat-based removal near a populated board requires knowing the reflow temperature of the nearest solder joints, not just the adhesive's glass transition temperature. A heat gun set to soften a UV bond can easily exceed the temperature at which nearby solder begins to reflow, risking a shifted or cold-formed joint that may not fail immediately but degrades long-term reliability. Localized, low-wattage heating with continuous temperature monitoring — rather than a general-purpose heat gun setting — is the safer default near populated boards. Cleanroom-Compatible Materials and Technique For assemblies built or serviced in a cleanroom environment, standard shop wipes and scrapers introduce particulate contamination that a cleanroom process can't tolerate. Non-linting, cleanroom-rated wipes and low-particulate tools should replace standard shop equipment for any removal work performed inside or destined to return to a cleanroom environment. Email Us for a recommended cleanroom-compatible tool and solvent list for electronics rework. Working Around Fine Geometry Component-dense boards leave very little clearance for mechanical scraping tools, which is where ultrasonic cleaning becomes especially valuable — the cavitation action reaches into gaps a physical tool simply can't access without risking contact with an adjacent component. A mild solvent bath combined with ultrasonic agitation is often the only practical method for removing adhesive…

Most substrate damage during UV adhesive removal doesn't come from a bad method — it comes from a good method applied impatiently. Recognizing the handful of mistakes that account for nearly all avoidable damage is often more useful than memorizing another removal technique. Mistake 1: Skipping the Compatibility Test The single most common cause of substrate damage is applying a solvent or heat level to the full part without first testing it on a small, inconspicuous area. A solvent that's perfectly safe on one plastic grade can craze a visually similar but chemically different grade within seconds. A five-minute test on a corner or a scrap piece from the same batch catches this before it becomes a full-part failure. Mistake 2: Applying Force Before the Bond Has Actually Softened Whether working with heat or solvent, there's a strong temptation to test for progress by applying mechanical force early. If the bond hasn't reached its glass transition temperature or the solvent hasn't had sufficient dwell time, that force transfers into the substrate instead of the adhesive interface — leading to chips, cracks, or gouges. A reliable check (visual softening, slight color change, or gentle test pressure well below full force) should confirm readiness before real mechanical effort is applied. Mistake 3: Using the Wrong Solvent for the Substrate Acetone and MEK are effective on many acrylic-based UV adhesives, but they are also aggressive enough to craze or cloud plastics like polycarbonate and acrylic almost instantly. Reaching for a "strong" solvent because a milder one seems slow is one of the fastest ways to convert a salvageable plastic part into scrap. Matching solvent strength to substrate sensitivity — not just adhesive resistance — has to come first. Mistake 4: Overheating Instead of Holding Steady Temperature A common misconception is that more heat always means faster softening. In reality, exceeding an adhesive's degradation point (rather than just its glass transition temperature) can cause charring that actually makes mechanical removal harder, while simultaneously risking damage to the substrate underneath. Email Us if you don't have a documented Tg for the adhesive in question — working from an assumed range is a common source of overheating mistakes. Mistake 5: Using Metal Tools on Soft or Finished Surfaces Reaching for a metal scraper because it "feels" more effective than a plastic one is a frequent source of avoidable scratching on softer substrates or cosmetic finishes. Metal tools should be reserved for hardened substrates like steel or dense ceramic; plastic or nylon scrapers protect softer materials while still displacing softened adhesive effectively. Mistake 6: Flooding the Part Instead of Targeting the Bond Line Soaking an entire component in solvent when only the bond area needs treatment increases both chemical exposure risk to unrelated surfaces and the chance of solvent migrating into gaps, gaskets, or nearby components. Targeted application with a needle-point applicator or a small saturated swab limits exposure to exactly where it's needed. Mistake 7: Ignoring Environmental Conditions Extreme cold makes some substrates more brittle and…

A bond removed successfully but a surface left scratched, hazed, or discolored isn't a successful rework — it's a cosmetic failure that just moved from one problem to another. Protecting the finish underneath the adhesive deserves the same planning as removing the adhesive itself. Why Finish Damage Is Often Permanent Unlike a bond line, which can be re-cleaned or re-treated if the first attempt falls short, a scratched glass surface, a hazed plastic panel, or a solvent-etched metal finish typically can't be restored to its original condition without secondary processing like polishing or refinishing — and in many cases, not even then. That asymmetry is why surface protection deserves its own dedicated plan rather than being treated as an afterthought to the removal method. Identifying What "Protected" Means for Each Substrate Glass is generally chemical-resistant but prone to fine scratching from mechanical tools and thermal shock from uneven heating. Metals resist most chemicals and heat well but can lose a cosmetic finish (brushed, polished, or anodized) to aggressive scraping or prolonged solvent exposure. Plastics are the most vulnerable overall — susceptible to chemical crazing, clouding, and heat-induced warping, sometimes from exposure levels that wouldn't register as a concern on glass or metal. Tool Selection as a Protection Strategy The choice of scraper material has an outsized effect on finish preservation. Metal blades should be reserved for hardened substrates like steel or dense ceramic; using them on softer finishes almost guarantees visible marking. POM (polyoxymethylene) or nylon plastic scrapers displace softened adhesive effectively while remaining soft enough to avoid gouging most substrates. On glass specifically, a razor blade held at a shallow angle — generally under 15 degrees — minimizes the microscopic scratching that can later develop into stress fractures under thermal or mechanical load. Masking as a First Line of Defense Before any solvent or heat touches the bond area, mask the surrounding finish with high-temperature tape or a liquid masking agent. This step matters most in electronics assembly, where a chemical vapor drifting beyond the intended bond area can etch a nearby cosmetic surface or damage a fragile component the removal process was never meant to touch. Email Us for masking material recommendations compatible with your specific solvent choice. Controlled, Targeted Chemical Application Soaking an entire part in solvent when only the bond line needs treatment is one of the most common sources of avoidable finish damage. Precision applicators — needle-point droppers or small saturated swabs — limit solvent contact to the bond line itself, protecting the surrounding finish from prolonged exposure that weakens coatings or causes discoloration over time. Gradual Force Application Sudden mechanical shock is a leading cause of chipping in brittle materials like tempered glass or ceramic. A steady "peel" motion, which concentrates force at the adhesive interface, generally protects the surface far better than a "shear" motion that transmits stress broadly across the substrate. Increasing force incrementally, and stopping to re-soften with heat or solvent rather than pushing through resistance, keeps that stress concentrated where…

The moment a technician reaches for the solvent bottle is usually the wrong moment to be deciding whether this job should have gone to a specialist instead. That decision needs to be made before the first tool touches the part — and it depends on more than just how confident the team feels. The Real Question Behind "Can We Do This In-House?" Most facilities can handle basic UV adhesive removal internally — a heat gun, IPA, and a plastic scraper cover a large share of routine rework. The harder question is recognizing the specific conditions where in-house rework carries more risk than it's worth, and outsourcing to a specialist with dedicated equipment and process controls becomes the better economic and quality decision. Factor 1: Part Value and Failure Consequence A low-value component that can be scrapped and replaced if removal goes wrong is a reasonable candidate for in-house trial-and-error. A high-value optical assembly, a finished metal housing with a cosmetic finish, or any part where damage means scrapping an otherwise-complete assembly changes the calculus considerably — the cost of a failed in-house attempt can exceed what a specialist rework service would have charged. Factor 2: Substrate Sensitivity Glass and metal substrates tolerate a wide range of in-house methods without much risk, which is why most general shop-floor guidance defaults to these materials as examples. Sensitive plastics, optical coatings, or assemblies with adjacent electronics narrow the safe method window considerably, and getting it wrong on the first attempt is often irreversible. If the substrate falls into this higher-sensitivity category and the team hasn't handled that specific material-adhesive combination before, that's a strong signal to at least consult a specialist before attempting removal in-house. Factor 3: Equipment Availability Basic thermal and chemical removal require only modest equipment — a temperature-controlled heat gun, appropriate solvents, and standard PPE. Ultrasonic cleaning, plasma treatment, or precision laser ablation require capital equipment that most facilities won't have on hand for occasional rework. If the safest method for a given job happens to require equipment the facility doesn't own, that's a direct case for outsourcing rather than substituting a less-ideal in-house method just because it's available. Factor 4: Volume and Frequency A one-off rework job rarely justifies the equipment investment for the ideal method — accepting a slightly slower or more labor-intensive in-house approach is usually the pragmatic choice. Recurring rework at meaningful volume flips that logic: investing in the right equipment, or establishing a standing relationship with a specialist rework partner, pays back quickly once volume crosses a certain threshold. Email Us if you're trying to estimate where that threshold sits for your specific rework volume and adhesive type. Factor 5: Technician Experience with the Specific Chemistry Experience with UV adhesive removal in general doesn't automatically transfer across chemistries — a technician comfortable removing acrylic-based bonds from glass may not have the calibrated judgment needed for a structural epoxy-based bond on a heat-sensitive plastic housing. If the specific adhesive-substrate combination is unfamiliar to the team, a…

Threaded fasteners bonded with a UV adhesive create a specific removal problem the flat-surface methods don't fully solve: the cured resin isn't just sitting on top of a surface, it's locked into the helical geometry of the thread itself, where a scraper can't reach and a solvent has trouble penetrating evenly. Why Threaded Assemblies Behave Differently On a flat bond line, solvent or heat has a direct, uninterrupted path to the adhesive. In a threaded assembly, the adhesive fills the gap between mating thread flanks in a continuous spiral, meaning any removal method has to work its way along that entire path rather than across a single accessible plane. This geometry also traps solvent vapor and heat differently than an open surface, which changes both dwell time expectations and the mechanical force required at the end. Assessing Fastener and Component Material First Before choosing a method, confirm whether the fastener and mating component are the same material or a dissimilar pair (steel bolt into an aluminum housing, for example). Dissimilar metal pairs respond differently to heat due to differing thermal expansion rates, which can actually be used as an advantage — heating a threaded assembly can cause the two materials to expand at different rates, mechanically loosening the bond at the thread interface independent of any chemical softening. Thermal Approach for Metal-to-Metal Threaded Joints For metal fasteners in metal housings, controlled heat applied directly to the fastener head — using an localized heat gun or, for larger assemblies, an induction heater — conducts down the length of the thread and softens the adhesive along its full engagement length more evenly than heat applied only at the surface. Once the assembly reaches the adhesive's glass transition temperature, a wrench applying steady, low rotational force (rather than a sudden high-torque attempt) is far less likely to strip the threads or shear the fastener than attempting removal cold. Chemical Penetration Along the Thread Path Where heat isn't practical — near heat-sensitive components, or on fasteners threaded into plastic housings — a capillary-action solvent application works better than a surface soak. Applying solvent at the exposed thread root and allowing capillary action to draw it along the helical gap reaches further into the joint than a surface application alone. This is slower than a flat-surface soak of the same nominal area, since the solvent path is longer and more restricted, so plan for extended dwell time — often several hours for a fully engaged fastener. Avoiding Thread Damage During Mechanical Removal The most common damage mode in threaded-assembly rework is stripping the internal or external threads by applying rotational force before the adhesive has actually softened. A useful check: apply gentle test torque well below the fastener's rated breakaway torque before attempting full removal — resistance that doesn't yield at that low torque level means the bond needs more dwell time, not more force. Email Us if a fastener isn't responding after a full thermal or chemical cycle; it may indicate a higher-strength structural…

Removing the visible bulk of a cured UV adhesive is only half the job. A microscopic film left behind at the bond line can act as a release agent on the next application, causing a rebonded joint to fail well below its rated strength — and that failure often doesn't show up until the part is already back in service. Why Invisible Residue Is a Real Risk Cured UV adhesive that has been softened and scraped away rarely leaves a substrate perfectly clean. Trace amounts of swollen polymer, oily solvent residue, or partially degraded resin can remain even on a surface that looks clear to the eye. Because these residues sit exactly where the new adhesive needs to achieve intimate molecular contact with the substrate, even a thin film measured in microns can prevent proper wet-out and reduce the effective bond area of the next application. Visual Inspection: The First but Insufficient Check A standard visual check under normal shop lighting catches obvious leftover material — chunks, streaks, or an uneven surface texture. It does not reliably catch thin films, especially on substrates like clear plastics or polished metal where a residue layer can be nearly transparent. Treat visual inspection as a first pass that rules out gross contamination, not a final confirmation that the surface is ready for rebonding. UV Fluorescence Inspection Many industrial UV adhesives include a fluorescent tracer specifically so that residue can be detected under a low-intensity UV flashlight even after the bulk material has been removed. Running a UV light over the cleaned area in a darkened space reveals any remaining fluorescing residue as a visible glow, even at thicknesses too thin to see under normal light. This is one of the fastest and most reliable checks available and should be a standard step whenever the original adhesive is known to contain a tracer. Solvent Wipe Test For adhesives without a fluorescent tracer, a clean lint-free cloth lightly dampened with isopropyl alcohol and wiped across the cleaned area can reveal residue that a dry visual inspection misses — any tackiness, discoloration transferred to the cloth, or resistance during the wipe indicates incomplete removal. Repeat with a fresh section of cloth until a wipe comes away completely clean. Surface Energy and Wettability Checks Residual adhesive film changes a substrate's surface energy, which affects how the next coating or adhesive wets out across the surface. A simple water-break test — applying a small amount of clean water to the surface and observing whether it sheets evenly or beads up — can flag contamination indirectly. Beading in specific spots often correlates with leftover residue exactly where the wetting is uneven, even when that residue isn't otherwise visible. Email Us if you need a more rigorous surface-energy verification method for a high-reliability rebonding application. When to Escalate to Plasma or Ultrasonic Cleaning If wipe tests or fluorescence inspection reveal persistent residue that standard IPA cleaning can't fully clear, plasma treatment or a final ultrasonic cleaning pass can achieve a…

The removal method almost never determines whether a rework job goes smoothly — the fifteen minutes of prep beforehand does. Skipping masking or misidentifying the adhesive chemistry before applying heat or solvent is where most avoidable rework damage actually happens. Why Prep Deserves Its Own Procedure It's tempting to treat prep as a formality and move straight to scraping or soaking. But because UV-cured bonds are thermosets that don't offer a second chance once a solvent has etched a plastic surface or heat has warped a housing, the preparation phase is where nearly all of the risk in a removal job can be eliminated in advance. Step 1: Document the Assembly Before Touching It Photograph or sketch the part in its current state, noting the adhesive's approximate location, thickness, and any visible discoloration or degradation. This record matters if the part needs to be handed to a different technician mid-process, and it establishes a baseline to compare against once removal begins — useful for confirming the bond is actually softening rather than just looking different. Step 2: Confirm Substrate and Adhesive Identity Check work orders, part specifications, or the original bonding process documentation to confirm both the substrate material and the adhesive chemistry (acrylic vs. epoxy-based). If this information isn't available, a small compatibility test on a scrap sample or a non-visible edge of the actual part is the safer alternative to guessing. Step 3: Mask Adjacent Surfaces and Components Use high-temperature tape or a liquid masking agent on any surface within splash or heat radius that shouldn't be exposed to the removal process. This step matters most on assemblies where the adhesive sits near coated surfaces, gaskets, or components sensitive to solvent vapor — a masked boundary prevents a five-minute removal job from becoming a two-part repair. Step 4: Secure and Position the Part Clamp or fixture the part so that mechanical force, if needed later, can be applied without the part shifting or the technician's hand slipping. This is especially important for brittle substrates like glass or ceramic, where an unsecured part under prying force is more likely to crack than one held firmly in a controlled position. Step 5: Stage Tools and Materials Within Reach Lay out the specific tools the chosen method requires — plastic scrapers for sensitive substrates, a temperature-controlled heat gun with a thermocouple for thermal work, or pre-measured solvent with lint-free applicators for chemical work — before starting the removal itself. Interrupting a solvent dwell period or a heat cycle to go find a missing tool often costs more time than the prep step would have taken. Email Us if you're setting up a rework station and want a recommended tool list for a specific substrate and adhesive combination. Step 6: Run a Small-Scale Compatibility Test Before committing the full bond line to solvent or heat, test the chosen method on the smallest possible representative area — an edge, a corner, or a scrap piece from the same production batch. This single step…

Every removal job comes with an unspoken budget question: is this worth an hour of labor, or five minutes and a heat gun? Picking a method without weighing that trade-off up front is how rework lines end up either over-engineering simple jobs or under-resourcing difficult ones. The Real Cost Variables in Adhesive Removal Cost in a rework context isn't just the price of a solvent bottle — it's labor time, equipment amortization, scrap risk, and throughput impact on the rest of the line. A method that looks cheap on paper (a five-dollar can of acetone) can be the most expensive option in practice if it requires a two-hour soak that ties up a workstation and a technician the whole time. Mechanical Removal: Low Equipment Cost, High Labor Time Scraping, prying, and abrasive removal require minimal capital investment — precision blades, plastic scrapers, and abrasive pads are inexpensive and always available. The trade-off is labor intensity: mechanical removal is almost entirely manual, scales poorly across batches, and carries the highest risk of substrate scratching if rushed. It's the right call for a single urgent part or low-volume rework, but a poor fit for recurring high-volume jobs. Thermal Removal: Fast Per-Part, But Equipment-Dependent A controlled heat gun can soften a bond above its glass transition temperature in a matter of minutes, making thermal removal one of the fastest per-part methods available. The cost trade-off shows up in equipment: a basic heat gun is cheap, but achieving consistent, controllable temperatures across a batch — without warping heat-sensitive plastics or shocking glass — usually calls for a temperature-controlled hot air station or convection oven, which raises the upfront equipment cost considerably. For batch work, that investment pays back quickly in reduced per-part labor time. Chemical Removal: Low Labor, High Dwell Time Solvent-based removal has the lowest active-labor requirement of the three main methods — once applied, the solvent does the work while the technician moves to other tasks. The cost hidden in this method is time-to-completion: dwell times for a densely cross-linked bond can run from thirty minutes to several hours, which means chemical removal is efficient for background/batch processing but a poor choice when a single part needs to be turned around immediately. Solvent cost itself is modest, but ventilation infrastructure and PPE requirements add a fixed overhead cost regardless of volume. Ultrasonic and Advanced Methods: High Upfront Cost, Best for Precision Volume Ultrasonic cleaning tanks and ultrasonic-assisted solvent baths carry a meaningfully higher equipment cost than any of the three core methods above, but they excel at intricate geometries and high-volume precision parts where manual access is difficult. The economics favor this route specifically when part complexity or volume makes manual methods impractical, not as a general-purpose first choice. Email Us if you're trying to size the right equipment investment against your actual rework volume. Building a Decision Framework A simple way to frame the decision: for one-off or low-volume rework, start with the lowest capital-cost option that's safe for the substrate…

Not every bonded assembly can tolerate a solvent soak — a moisture-sensitive electronic component, a solvent-reactive plastic housing, or simply a facility without proper solvent ventilation all rule out the chemical approach, and that's exactly where thermal and mechanical removal methods take over. Why Some Assemblies Rule Out Chemical Removal Entirely Polycarbonate and acrylic substrates can craze or cloud under extended solvent contact well before a typical soak dwell time is complete. Electronic assemblies with exposed connectors or moisture-sensitive components risk solvent ingress into areas that should stay dry. And facilities without dedicated fume extraction or solvent-rated storage simply may not have the infrastructure to run a solvent-soak process safely at all. In any of these situations, thermal or mechanical removal accomplishes the same end goal — a clean, adhesive-free surface ready for rework — through an entirely different mechanism. Thermal Softening With Controlled Heat Cured UV adhesive softens measurably as it approaches its glass transition temperature, and a calibrated heat gun or infrared heating element applied locally to the bond line takes advantage of that softening without solvent exposure. The key process variable is dwell time and temperature control rather than just applying maximum heat: overheating risks scorching a plastic substrate, discoloring a painted finish, or damaging nearby heat-sensitive components, while insufficient heat leaves the adhesive too rigid to separate cleanly. A non-contact infrared thermometer aimed at the bond line during heating lets a technician confirm the surface has actually reached the softening range before attempting separation, rather than guessing based on elapsed time alone. Mechanical Separation Once Softened Once heat has softened the bond, a thin, sharp, non-marring tool — a plastic or brass scraper rather than steel, which can gouge a softer substrate — worked steadily along the bond line separates the joint with far less force than attempting mechanical removal on a fully rigid, unheated bond. Working from multiple directions around the perimeter, rather than concentrating force at one point, reduces the risk of substrate fracture on brittle materials like glass or ceramic. Cryogenic Embrittlement for Elastomeric or Flexible Adhesives Where an adhesive is formulated with enough flexibility to resist the thermal-softening approach, cooling the bond line rapidly with a canned cryogenic spray takes the opposite approach: dropping the adhesive below its brittle transition temperature makes it easier to fracture cleanly with mechanical force, rather than deforming or stretching under an applied load. This method works especially well on gasket-forming or vibration-damping adhesive formulations that stay rubbery at room temperature and resist both solvent penetration and heat softening. Ultrasonic-Assisted Mechanical Removal for Delicate Assemblies For precision electronics or optical assemblies where both heat and solvent exposure carry real risk to nearby components, an ultrasonically vibrating scraper or blade reduces the cutting force needed to separate a bond line, lowering the risk of cracking a delicate substrate compared to manual mechanical force alone. This approach trades speed for control, and is generally reserved for high-value assemblies where substrate damage during removal would be more costly than the…

Guessing at a removal method and adjusting on the fly wastes hours on a dense structural bond and risks substrate damage on a delicate one — the smarter approach is answering four questions about the original bond before touching a heat gun or a solvent. Question One: Do You Actually Know the Original Cure Conditions? A rework request that includes the adhesive's technical data sheet, the cure dose it received, and roughly how long ago it was bonded starts from a position of knowledge. A rework request on a part with no cure history — inherited from a prior production run, a returned field unit, or an assembly bonded by a since-departed process engineer — starts from genuine uncertainty, and that uncertainty should change your approach: start with the gentlest method available (isopropyl alcohol and light heat) and escalate only as needed, rather than assuming an aggressive solvent is safe from the outset. Question Two: Is the Bond Rigid Structural or Flexible Encapsulant? This single fact predicts removal difficulty more reliably than knowing whether the base chemistry is epoxy or acrylic. A rigid, high-cross-link-density structural bond has little free volume for solvent to diffuse into, so chemical swelling proceeds slowly and thermal-mechanical methods — softening above glass transition temperature combined with careful prying — tend to outperform solvent soaking alone. A flexible, lower-cross-link encapsulant or conformal coating has far more room for solvent diffusion, so the same acetone or MEK soak that barely touches a structural bond can fully swell a flexible one within minutes. If you don't know which category a given bond falls into, a small test area with a mild solvent, checked after a short dwell, answers the question faster than guessing from the adhesive's marketing description. Question Three: How Old Is the Bond, and What Has It Been Exposed To? Photopolymerized networks don't necessarily stop changing the moment the UV lamp switches off. Extended field service, particularly at elevated temperature, can drive additional cross-linking in some chemistries or, conversely, can embrittle others through oxidative degradation — either direction makes the bond behave differently than a freshly cured reference sample. A bond eighteen months old with unknown field history should be treated as an unknown quantity, tested on a small area first, rather than assumed to behave like the data sheet's fresh-cure numbers. Question Four: What Can the Substrate Actually Tolerate? Glass and most metals absorb aggressive solvents and sustained heat without damage, so the substrate rarely limits your method choice on those materials — the adhesive's own cross-link density becomes the deciding factor instead. Polycarbonate, acrylic, and many engineering plastics are far less forgiving: aggressive solvents can craze or stress-crack these substrates faster than they soften the adhesive, which usually pushes the practical choice toward isopropyl alcohol and moderate heat even if it's the slower option, simply because the alternative risks the part itself. Email Us if you're working from an unknown cure history on a batch of parts — walking through these four questions with…